2024-07414. Air Plan Approval; Wyoming; Revisions to Regional Haze State Implementation Plan

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency (EPA) is proposing to approve a State Implementation Plan (SIP) revision submitted by the State of Wyoming on December 30, 2022, and supplemented on August 31, 2023, and November 16, 2023, addressing regional haze (Wyoming 2022 SIP revision). The Wyoming 2022 SIP revision replaces Wyoming's previously approved source-specific nitrogen oxide (NO_X) determination for PacifiCorp's Jim Bridger power plant (Jim Bridger) Units 1 and 2 of 0.07 lb/MMBtu for each unit associated with the installation of selective catalytic reduction (SCR) controls to address the long-term strategy. Specifically, the Wyoming 2022 SIP revision finds that conversion from coal-firing to natural gas-firing, together with NO_X emission and heat input limits of 0.12 lb/MMBtu (30-day rolling average), 1,314 tons/year, and 21,900,000 MMBtu/year, respectively, allows for identical reasonable progress during the first planning period as the installation SCR controls. Separately, we are also proposing to approve Wyoming's monthly and annual NO_X and sulfur dioxide (SO₂) emissions limits for Jim Bridger Units 1-4. The EPA is proposing this action pursuant to sections 110 and 169A of the Clean Air Act (CAA).

DATES:

Comments: Written comments must be received on or before May 10, 2024.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-R08-OAR-2022-0536, to the Federal Rulemaking Portal: https://www.regulations.gov. Follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from https://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 https://www.epa.gov/​dockets/​commenting-epa-dockets.

Docket: All documents in the docket are listed in the https://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 electronically in https://www.regulations.gov. Please email or call the person listed in the FOR FURTHER INFORMATION CONTACT section if you need to make alternative arrangements for access to the docket.

FOR FURTHER INFORMATION CONTACT:

Jaslyn Dobrahner, Air and Radiation Division, EPA, Region 8, Mailcode 8P-ARD, 1595 Wynkoop Street, Denver, Colorado 80202-1129, telephone number: [phone], email address: [e-mail].

SUPPLEMENTARY INFORMATION:

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

I. What action is the EPA proposing?

II. Background

A. Requirements of the Clean Air Act and the EPA's Regional Haze Rule

B. Best Available Retrofit Technology (BART)

C. Long-Term Strategy and Reasonable Progress Requirements

D. Consultation With Federal Land Managers (FLMs)

E. Monitoring, Recordkeeping, and Reporting

III. Wyoming's Regional Haze SIP Submittals

A. Background and Wyoming's Initial Regional Haze SIP

B. November 2017 Regional Haze Progress Report

C. May 2020 Regional Haze SIP Revision

D. December 2022 Regional Haze SIP Revision

E. Wyoming's Reassessment of Reasonable Progress Under Long-Term Strategy

1. Costs of Compliance

2. Time Necessary for Compliance

3. Energy and Non-Air Quality Environmental Impacts of Compliance

4. Remaining Useful Life

5. Reasonable Progress Demonstration

F. Summary of Wyoming's Additional Proposed Revisions to the Emission Limits for Jim Bridger

IV. The EPA's Evaluation and Proposed Approval of Wyoming's Regional Haze SIP Revisions

A. The EPA's Proposed Approval of Wyoming's Reasonable Progress Determination for Jim Bridger Units 1 and 2

1. Basis for the EPA's Proposed Approval

a. Costs of Compliance

b. Other Statutory Factors

c. Analysis of Projected Emissions Reductions Achievable

2. Summary of the EPA's Evaluation of Wyoming's Reasonable Progress Demonstration

B. The EPA's Proposed Approval of Wyoming's Long-Term Strategy for Jim Bridger Units 1 and 2

C. Monthly and Annual NO_X and SO₂ Emission Limits for Jim Bridger Units 1-4

D. Monitoring, Recordkeeping, and Reporting

E. Consultation With Federal Land Managers

V. Clean Air Act Section 110( l)

VI. Summary of the EPA's Proposed Action

VII. Incorporation by Reference

VIII. Statutory and Executive Order Reviews

I. What action is the EPA proposing?

The Jim Bridger power plant is located in Sweetwater County, Wyoming, and is owned in part, and operated, by PacifiCorp. The power plant is composed of four 530 megawatt (MW) tangentially fired boilers burning pulverized coal for a total net generating capacity of 2,120 MW.

On January 30, 2014, the EPA promulgated a final rule titled, “Approval, Disapproval and Promulgation of Implementation Plans; State of Wyoming; Regional Haze State Implementation Plan; Federal Implementation Plan for Regional Haze,” approving, in part, a regional haze SIP revision submitted by the State of Wyoming on January 12, 2011 (2014 final rule).^[1] In the 2014 final rule, the EPA approved Wyoming's determination to require low-NO_X burners (LNB) and separated overfire air (SOFA) at Jim Bridger Units 1-4, with a NO_X best available retrofit technology (BART) emission limit of 0.26 pounds per million British Thermal Units (lb/MMBtu) (30-day rolling average) for Jim Bridger Units 1-4.^[2] The EPA also approved Wyoming's determination to require SCR at Jim Bridger Units 1-4, with a NO_X emission limit of 0.07 lb/MMBtu (30-day rolling average), as part of its long-term strategy.^[3]

The EPA is proposing to approve a SIP revision submitted by the State to the EPA on December 30, 2022, and supplemented on August 31, 2023, and November 16, 2023, which will replace the previously approved NO_X emission limit of 0.07 lb/MMBtu (30-day rolling average) at Jim Bridger Units 1 and 2 for Wyoming's long-term strategy.^[4] The Wyoming 2022 SIP revision amends the State's previously approved long-term strategy for the first Regional Haze planning period and is requiring Jim Bridger Units 1 and 2 to operate consistent with conversion from coal-firing to natural gas-firing by January 1, 2024, with NO_X emission limits of 0.12 lb/MMBtu (30-day rolling average) and 1,314 tons/year for each unit and a heat input limit of 21,900,000 MMBtu/year per unit. The Wyoming 2022 SIP revision reflects changes to Chapters 7 and 8 of Wyoming's regional haze SIP narrative ^[5] and incorporates certain conditions of Wyoming air quality permits #P0025809 and #P0036941, some conditions of which were memorialized in a Wyoming court-approved consent decree between Wyoming and PacifiCorp.^[6 7] Ultimately, the Wyoming 2022 SIP revision finds conversion from coal-firing to natural gas-firing, together with NO_X emission and heat input limits, to be sufficient for reasonable progress during the first planning period, and finds the emission limits associated with the installation of SCR controls are no longer required. The State also included NO_X and SO₂ monthly and annual emissions limits for Jim Bridger Units 1-4.^[8]

II. Background

A. Requirements of the Clean Air Act and the EPA's Regional Haze Rule

In section 169A of the CAA, Congress created a program for protecting visibility in national parks and wilderness areas. This section of the CAA establishes “as a national goal the prevention of any future, and the remedying of any existing, impairment of visibility in mandatory Class I Federal areas which impairment results from manmade air pollution.” ^[9]

The EPA promulgated a rule to address regional haze on July 1, 1999.^[10] The Regional Haze Rule revised the existing visibility regulations ^[11] to integrate provisions addressing regional haze and established a comprehensive visibility protection program for Class I areas. The requirements for regional haze, found at 40 CFR 51.308 and 40 CFR 51.309, are included in the EPA's visibility protection regulations at 40 CFR 51.300 through 40 CFR 51.309.^[12]

The CAA requires each state to develop a SIP to meet various air quality requirements, including protection of visibility.^[13] Regional haze SIPs must assure reasonable progress toward the national goal of preventing future and remedying existing manmade visibility impairment in Class I areas. A state must submit its SIP and SIP revisions to the EPA for approval.^[14] Once approved, a SIP is enforceable by the EPA and citizens under the CAA; that is, the SIP is federally enforceable.

B. Best Available Retrofit Technology (BART)

Section 169A(b)(2) of the CAA requires SIPs to contain such measures as may be necessary to make reasonable progress toward meeting the national visibility goal. Section 169(b)(2)(A) specifies that one such requirement for the first regional haze planning period is for certain categories of existing major stationary sources built between 1962 and 1977 to procure, install, and operate BART as determined by the states through their SIPs. Under the Regional Haze Rule, states (or the EPA, in the promulgation of a federal implementation plan (FIP)) are directed to conduct BART determinations for “BART-eligible” sources—typically larger, often uncontrolled, and older stationary sources—that may reasonably be anticipated to cause or contribute to any visibility impairment in a Class I area.^[15] States must consider the following five factors in making BART determinations: (1) the costs of compliance; (2) the energy and non-air quality environmental impacts of compliance; (3) any existing pollution control technology in use at the source; (4) the remaining useful life of the source; and (5) the degree of improvement of visibility which may reasonably be anticipated to result from the use of such technology.^[16] Rather than requiring source-specific BART controls, states also have the flexibility to adopt an emissions trading program or other alternative program as long as the alternative will achieve greater reasonable progress toward natural visibility conditions than BART.^[17]

One such BART alternative is included in 40 CFR 51.309 and is an option for nine states termed the “Transport Region States,” which include Arizona, California, Colorado, Idaho, Nevada, New Mexico, Oregon, Utah, and Wyoming. Transport Region States can adopt regional haze strategies based on recommendations from the Grand Canyon Visibility Transport Commission (GCVTC) for protecting the 16 Class I areas on the Colorado Plateau.^[18]

As part of its overall plan for making reasonable progress towards the national visibility goal for the 16 Class I areas, the GCVTC submitted an annex to the EPA, known as the Western SO₂ Backstop Trading Program, containing annual SO₂ emissions reduction milestones and detailed provisions of a backstop trading program to be implemented automatically if measures fail to achieve the SO₂ milestones. The EPA approved the Backstop Trading Program as a BART alternative for SO₂ emissions.^[19] Transport Region States' SIPs must also contain any necessary long-term strategy and BART requirements for stationary-source particulate matter (PM) and NO_X emissions.^[20]

C. Long-Term Strategy and Reasonable Progress Requirements

In addition to the BART requirements, the CAA's visibility protection provisions also require that states' regional haze SIPs contain a “long-term (ten to fifteen years) strategy for making reasonable progress toward meeting the national goal. . . .” ^[21] The long-term strategy must address regional haze visibility impairment for each mandatory Class I area within the state and for each mandatory Class I area located outside the state that may be affected by emissions from the state. It must include the enforceable emission limitations, compliance schedules, and other measures necessary to achieve the reasonable progress goals.^[22] The reasonable progress goals are calculated for each Class I area based on the control measures states have selected by analyzing the four statutory “reasonable progress” factors, which are: “the costs of compliance, the time necessary for compliance, the energy and non-air quality environmental impacts of compliance, and the remaining useful life of any existing source subject to such requirement.” ^[23] Thus, the four reasonable progress factors are considered by a state in setting the reasonable progress goal for the first planning period pursuant to § 51.308(d)(1)(i)(A), by virtue of the state having first considered them, and certain other factors listed in § 51.308(d)(3) of the Regional Haze Rule, when deciding what controls are to be included in the long-term strategy. Then, the numerical levels of the reasonable progress goals are the predicted visibility outcome of implementing the long-term strategy in addition to ongoing pollution control programs stemming from other CAA requirements.

Unlike BART determinations, which are required only for the first regional haze planning period SIPs,^[24] states are required to submit updates to their long-term strategies, including updated reasonable progress analyses and reasonable progress goals, in the form of SIP revisions by July 31, 2021, and at specific intervals thereafter.^[25] In addition, each state must periodically submit a report to the EPA at five-year intervals beginning five years after the submission of the initial regional haze SIP, evaluating the state's progress towards meeting the reasonable progress goals for each Class I area within the state.^[26]

By meeting all the requirements of 40 CFR 51.309, including the section 309-specific BART requirements, a Transport Region State can be deemed to be making reasonable progress toward the national goal for the 16 Class I areas on the Colorado Plateau.^[27] For stationary sources, these requirements include any necessary long-term strategies for PM and NO_X emissions.^[28] Additionally, the State of Wyoming includes several non-Colorado Plateau Class I areas, and was also required to submit a long-term strategy for those Class I areas.^[29] Wyoming's 2022 SIP revision addresses emissions reductions approved under its long-term strategy for the first implementation period. As a result, the time period relevant to this rulemaking is the first implementation period.

D. Consultation With Federal Land Managers (FLMs)

The Regional Haze Rule requires that a state consult with Federal Land Managers before adopting and submitting a required SIP or SIP revision. Further, when considering a SIP revision, a state must include in its proposal a description of how it addressed any comments provided by the FLMs.^[30]

E. Monitoring, Recordkeeping, and Reporting

The CAA requires that SIPs, including regional haze SIPs, contain elements sufficient to ensure emission limits are practically enforceable. CAA section 110(a)(2) states that the monitoring, recordkeeping, and reporting provisions of states' SIPs must: “(A) include enforceable emissions limitations and other control measures, means, or techniques (including economic incentives such as fees, marketable permits, and auctions of emissions rights), as well as schedules and timetables for compliance, as may be necessary or appropriate to meet the applicable requirements of this chapter; . . . (C) include a program to provide for the enforcement of the measures described in subparagraph (A), and regulation of the modification and construction of any stationary source within the areas covered by the plan as necessary to assure that national ambient air quality standards are achieved, including a permit program as required in parts C and D of this subchapter; . . . (F) require, as may be prescribed by the Administrator—(i) the installation, maintenance, and replacement of equipment, and the implementation of other necessary steps, by owners or operators of stationary sources to monitor emissions from such sources, (ii) periodic reports on the nature and amounts of emissions and emissions-related data from such sources, and (iii) correlation of such reports by the State agency with any emissions limitations or standards established pursuant to this chapter, which reports shall be available at reasonable times for public inspection.” ^[31]

Accordingly, 40 CFR part 51, subpart K, Source Surveillance, requires the SIP to provide for monitoring the status of compliance with the regulations in the SIP, including “[p]eriodic testing and inspection of stationary sources,” ^[32] and “legally enforceable procedures” for recordkeeping and reporting.^[33] Furthermore, 40 CFR part 51, appendix V, Criteria for Determining the Completeness of Plan Submissions, states in section 2.2 that complete SIPs contain: “(g) Evidence that the plan contains emission limitations, work practice standards and recordkeeping/reporting requirements, where necessary, to ensure emission levels”; and “(h) Compliance/enforcement strategies, including how compliance will be determined in practice.” ^[34]

III. Wyoming's Regional Haze SIP Submittals

A. Background and Wyoming's Initial Regional Haze SIP

On January 12, 2011, Wyoming submitted its first regional haze SIP pursuant to 40 CFR 51.309. The State determined that NO_X BART for Jim Bridger Units 1-4 was new LNBs with SOFA at an emissions rate of 0.26 lb/MMBtu (30-day rolling average). Compliance with the BART emission limits was required by March 4, 2019, for all four Jim Bridger units.^[35] The State also determined that SCR at an emissions rate of 0.07 lb/MMBtu (30-day rolling average) should be installed at all four units as part of the State's long-term strategy to achieve reasonable progress at several Class I areas, and required compliance with the emission limits by December 31, 2022, December 31, 2021, December 31, 2015 and December 31, 2016, for Units 1-4, respectively.^[36]

On June 4, 2012, we proposed to approve the State's BART and reasonable progress determinations of 0.26 lb/MMBtu (30-day rolling average) and 0.07 lb/MMBtu (30-day rolling average), respectively, for Units 3 and 4, including the associated dates for compliance with these emissions limits.^[37] We subsequently finalized our proposed action for Units 3 and 4.^[38]

For Jim Bridger Units 1 and 2, we also proposed to approve the State's BART and reasonable progress determinations of 0.26 lb/MMBtu (30-day rolling average) and 0.07 lb/MMBtu (30-day rolling average), respectively. In the alternative, we proposed to find NO_X BART for Jim Bridger Units 1 and 2 was an emissions limit of 0.07 lb/MMBtu (30-day rolling average), consistent with the installation of LNB/SOFA + SCR, with a compliance deadline of five years.^[39] In our final rule, upon consideration of new information and a review of the State`s analysis of the BART factors, we found that the source-wide visibility improvement associated with the installation of LNB/SOFA + SCR to be 1.25-1.5 deciviews,^[40] while the unit-specific visibility benefits for Units 1 and 2 were 0.27-0.37 deciviews. We found that the average cost-effectiveness of LNB/SOFA + SCR at $2,635 and $3,403/ton of NO_X for Units 1 and 2, respectively, was in line with what we had found to be acceptable in other BART determinations.^[41] But we also found that the incremental cost-effectiveness ^[42] of $7,447 and $8,968/ton NO_X for Units 1 and 2, respectively, was on the high end of what we had found to be reasonable in other determinations.^[43] Ultimately, we finalized the State's determination to require LNB/SOFA as BART controls with a corresponding emissions limit of 0.26 lb/MMBtu by March 4, 2019, for Jim Bridger Units 1 and 2, and to require an emissions limit of 0.07 lb/MMBtu (30-day rolling average) with the installation SCR as part of the State's long-term strategy to achieve reasonable progress by 2022 and 2021 for Jim Bridger Units 1 and 2, respectively.^[44]

B. November 2017 Regional Haze Progress Report

Under the Regional Haze Rule, states are required to submit progress reports to the EPA documenting actual changes in visibility and emission reductions within the state.^[45] The first progress report must be in the form of a SIP revision and is due five years after submittal of the initial regional haze SIP.^[46] On November 28, 2017, Wyoming submitted its first progress report, which detailed the progress made toward achieving progress for visibility improvement and declared a determination of adequacy of the State's regional haze plan to meet reasonable progress goals.

In June 2020, we approved Wyoming's progress report SIP revision.^[47] We found that between 2002 and 2008, Wyoming's NO_X emissions were reduced by 57,296 tons, a 20 percent reduction during that time period. Additionally, we found that other haze-causing pollutants were also reduced between the same time period.^[48] We also found that all the monitoring sites within Wyoming's Class I areas showed improvement in visibility conditions between the baseline (2000-2004) and current (2005-2009) periods on both the 20 percent worst visibility and 20 percent best visibility days. When considering only anthropogenic impairment within the baseline (2000-2004) and most current (2012-2016) periods, all the monitoring sites also showed improvement on the 20 percent most impaired days.^[49]

C. May 2020 Regional Haze SIP Revision

On May 14, 2020, Wyoming submitted a proposed revision to its regional haze SIP for the long-term strategy at Jim Bridger Units 1 and 2 (Wyoming's May 2020 SIP revision).^[50] The proposed revision included a four-factor reasonable progress analysis to replace the 0.07 lb/MMBtu (30-day rolling average) anticipated NO_X reductions for Jim Bridger Units 1 and 2 as part of Wyoming's long-term strategy to improve visibility during the first planning period. Wyoming's May 2020 SIP revision also included plant-wide (Units 1-4) month-by-month emission limits for NO_X and SO₂ (Table 2) as well as an annual total emissions cap of NO_X and SO₂ for Units 1-4 of 17,500 tons/year.

On January 18, 2022, the EPA proposed to disapprove Wyoming's May 2020 SIP revision.^[51] Our proposed disapproval was based on the following: (1) the reasonable cost-effectiveness of the existing reasonable progress control requirements for Jim Bridger Units 1 and 2 (emission limits of 0.07 lb/MMBtu consistent with the installation of SCR); (2) the appreciable visibility improvement estimated to result from compliance with the existing control requirements; and (3) the State's previous determination that the costs of those control requirements were reasonable and necessary to satisfy statutory requirements. The EPA also made the determination that Wyoming's proposed revision to replace its previously approved long-term strategy would not provide for similar or greater emissions reductions or visibility improvement as is required under the Clean Air Act and thus could not propose approval of Wyoming's May 2020 SIP revision. We have not issued a final rule for our proposed disapproval.

D. December 2022 Regional Haze SIP Revision

On December 30, 2022, Wyoming submitted a regional haze SIP revision (Wyoming 2022 SIP revision).^[52 53] The Wyoming 2022 SIP revision proposes to replace Wyoming's previously approved long-term strategy with conversion of Jim Bridger Units 1 and 2 from coal-firing to natural gas-firing by January 1, 2024, together with NO_X emission and heat input limits, to allow for identical reasonable progress during the first planning period as would occur from the emission reductions from requiring a NO_X emissions limit of 0.07 lb/MMBtu (30-day rolling average) at Jim Bridger Units 1 and 2. The State also included monthly and annual NO_X and SO₂ emissions limits for Jim Bridger Units 1-4. On August 31, 2023, Wyoming submitted a supplement containing associated permit amendments addressing heat input limit and monitoring, recordkeeping, and reporting requirements for Jim Bridger Units 1 and 2.^[54] On November 16, 2023, Wyoming submitted a supplement containing an amended permit to correct a typographical error found in the August 31, 2023, supplement.^[55]

The Wyoming 2022 SIP revision requires, beginning on January 1, 2024, Jim Bridger Units 1 and 2 to meet a NO_X emission limit of 0.12 lb/MMBtu (30-day rolling average) along with an annual NO_X emission limit of 1,314 tons/year per unit, and a 41.6% reduction in maximum annual heat input limit equaling 21,900,000 MMBtu/year per unit.^[56] As a result, the Wyoming 2022 SIP revision replaces the requirement for Jim Bridger Units 1 and 2 to comply with the 0.07 lb/MMBtu emission limits in 2021 and 2022 (Table 1). The Wyoming 2022 SIP revision does not, however, remove or revise the existing NO_X BART determination for Jim Bridger Units 1 and 2 (consistent with current LNB/SOFA NO_X emissions controls) or change the existing reasonable progress emission limits of 0.07 lb/MMBtu for Jim Bridger Units 3 and 4 (consistent with installed SCR emissions controls).

Table 1—Existing and Proposed NO _X Emission Limits for Jim Bridger Units 1-4

Unit	Existing NO X BART emission limit (30-day rolling average; lb/MMBtu) 1	Existing NO X reasonable progress emission limit (30-day rolling average; lb/MMBtu) 2	Proposed NO X reasonable progress emission limits
			NO X (30-day rolling average; lb/MMBtu)	NO X (tons/year)
1	0.26	0.07	3  0.12	3 5  1,314
2	0.26	0.07	3  0.12	3 5  1,314
3	0.26	0.07	4  NA	NA
4	0.26	0.07	4  NA	NA
1  Compliance date is March 4, 2019; no changes to the NO X BART emission limits are proposed.
2  Compliance dates for each is: Unit 1 = December 31, 2022; Unit 2 = December 31, 2021; Unit 3 = December 31, 2015; and Unit 4 = December 31, 2016.
3  Compliance date is January 1, 2024.
4  No change to existing NO X reasonable progress emission limit of 0.07 lb/MMBtu (30-day rolling average).
5  Correlates to a 41.67% reduction of the maximum heat input (52,560,000 MMBtu/year) or 21,900,000 MMBtu/year with a 0.12 lb NO X lb/MMBtu 30-day rolling average limit.

In addition, the Wyoming 2022 SIP revision includes month-by-month NO_X and SO₂ emission limits across all four Jim Bridger units, as well as an enforceable annual plant-wide NO_X plus SO₂ emissions cap of 17,500 tons per year, effective January 1, 2022 (Table 2). The monthly emissions limit and annual emissions cap for Jim Bridger Units 1-4 are federally enforceable through reference to Wyoming air quality permit #P0025809. The final permit was issued on May 5, 2020.^[57]

Table 2—Enforceable Monthly NO _X and SO ₂ Emission Limits for Jim Bridger Units 1-4, Effective January 1, 2022

Month	Total units 1-4 NO X emission limit	Total units 1-4 SO 2 emission limit
	Monthly average basis (lb/hour)	Monthly average basis (lb/hour)
January	2,050	2,100
February	2,050	2,100
March	2,050	2,100
April	2,050	2,100
May	2,200	2,100
June	2,500	2,100
July	2,500	2,100
August	2,500	2,100
September	2,500	2,100
October	2,300	2,100
November	2,030	2,100
December	2,050	2,100
	Annual emissions cap
Total NO X plus SO 2	17,500 tons/year

E. Wyoming's Reassessment of Reasonable Progress Under Long-Term Strategy

To demonstrate that the replacement of 0.07 lb/MMBtu with natural gas conversion, NO_X limits, and reduced heat inputs for Jim Bridger Units 1 and 2 provided equivalent emissions reductions previously approved by the EPA under long-term strategy, the State submitted a reasonable progress analysis for Jim Bridger Units 1 and 2 in the Wyoming 2022 SIP revision.

In its source-specific reasonable progress assessment for Jim Bridger Units 1 and 2, the State considered the four factors as required by 40 CFR 51.308(d)(1)(i)(A).

In 2014, the EPA approved the State's decision to require NO_X controls of 0.07 lb/MMBtu (30-day rolling average) on Jim Bridger Units 1-4 pursuant to its long-term strategy. The State did not conduct a reasonable progress four-factor analysis for any of the Jim Bridger units at that time but instead opted for controls under the long-term strategy provisions found under 40 CFR 51.308(d)(3).^[58] The State conducted its four-factor reasonable progress analysis for Jim Bridger Units 1 and 2 for the first time in connection with its 2020 and 2022 SIP submittals to replace the emissions reductions approved for Jim Bridger Units 1 and 2 under the long-term strategy. This is acceptable since 40 CFR 51.308(d)(3) provides that a state's “long-term strategy must include enforceable emissions limitations, compliance schedules, and other measures as necessary to achieve the reasonable progress goals established by states having mandatory class I Federal areas.”

Pursuant to 40 CFR 51.308(d)(1)(i)(A), in determining the measures necessary to make reasonable progress, a state must take into account the following four factors and demonstrate how they were taken into consideration in making a reasonable progress determination:

• Costs of Compliance;
• Time Necessary for Compliance;
• Energy and Non-Air Quality Environmental Impacts of Compliance; and
• Remaining Useful Life of Any Potentially Affected Sources.

1. Costs of Compliance

For the source-specific reasonable progress analysis, Wyoming provided costs of compliance for three scenarios: (1) installation of SCR on Units 1 and 2 operating on coal, (2) installation of SCR on Units 1 and 2 operating on natural gas, and (3) conversion of Units 1 and 2 from coal to natural gas, together with NO_X and heat input limits. For the installation of SCR operating on coal and conversion from coal to natural gas scenarios, Wyoming used baseline NO_X emission rates for LNB/SOFA of 0.187 lb/MMBtu for Unit 1 and 0.192 lb/MMBtu for Unit 2 (annual average), reflective of the actual emissions rate (2013-2015) ^[59] and used the 2001-2003 average annual heat input of 42,977,652 MMBtu/year and 40,898,999 MMBtu/year to calculate baseline NO_X emissions in tons/year of 4,018 and 3,926 for Units 1 and 2, respectively.^[60] For the installation of SCR operating on natural gas scenario, Wyoming used the stipulations in the consent decree ^[61] as the baseline: NO_X emission rate of 0.12 lb/MMBtu (30-day rolling average) for both Units 1 and 2 and annual heat input of 21,900,000 MMBtu/year. The NO_X emission rate for SCR operating on either coal or natural gas was assumed to be 0.05 lb/MMBtu (annual), while the NO_X emission rate for conversion from coal to natural gas was assumed to be 0.12 lb/MMBtu (30-day rolling average).^[62] Wyoming based total capital costs to install SCR ($140,428,000 for each Unit 1 and 2) on the actual costs incurred to install SCR technology on Jim Bridger Units 3 and 4.^[63] The total capital costs to convert Units 1 and 2 from coal-fired to natural gas-fired was found to be $14,632,077 and $14,151,451, respectively. The State annualized capital costs using the capital recovery factor approach described in the EPA's Control Cost Manual using amortization periods between one and 14 years reflective of each of the three different scenarios.^[64 65] Total annual costs were calculated as the sum of the annualized capital costs and total operation and maintenance costs. Finally, the cost-effectiveness of each scenario was calculated on a dollar-per-ton of pollutant removed basis by dividing the total annual costs by the reduction in annual NO_X emissions associated with each scenario.

Costs of compliance for Wyoming's reasonable progress analysis for Jim Bridger Units 1 and 2 is summarized in Table 3.^[66]

Table 3—Summary of Jim Bridger Units 1 and 2 NO _X Revised Reasonable Progress Cost Analysis

Scenario	Assumed NO X emissions rate (lb/MMBtu)	Emissions reduction (tons per year)	Total annual cost ($/year)	Average cost effectiveness ($/ton)
Unit 1
SCR operating on coal	1  0.05	2,944	$152,369,457	$51,756
SCR operating on natural gas	1  0.05	766	18,036,235	23,531
Conversion from coal to natural gas 3	2  0.12	2,704	4,018,476	1,486
Unit 2
SCR operating on coal	1  0.05	2,904	94,115,947	32,411
SCR operating on natural gas	1  0.05	766	18,036,235	23,531
Conversion from coal to natural gas 3	2  0.12	2,612	3,962,516	1,517
1  Based on an annual average.
2  Based on a 30-day rolling average.
3  Operating with a heat input limit of 21,900,000 MMBtu/year (equal to 41.6% of maximum annual heat input).

Ultimately, Wyoming determined that conversion to natural gas without the installation of SCR is more cost-effective than conversion to natural gas with the addition of SCR particularly with the additional NO_X and heat input reductions reflected in the consent decree.^[67]

2. Time Necessary for Compliance

The SIP approved by the EPA on January 30, 2014, requires an emission limit of 0.07 lb/MMBtu associated with the installation of LNB/SOFA + SCR on Jim Bridger Unit 1 by December 31, 2022, and on Unit 2 by December 31, 2021. The current LNB/SOFA NO_X emissions controls were installed in 2010 and 2005 for Units 1 and 2, respectively.^[68]

Wyoming stated that because there is an enforceable commitment to cease coal operation and meet natural gas conversion limits at Jim Bridger Units 1 and 2 by January 1, 2024,^[69] SCR installation would take longer than the planned natural gas conversion. Furthermore, according to the State, installing SCR on a converted natural gas unit makes no practical or economic sense.

3. Energy and Non-Air Quality Environmental Impacts of Compliance

Wyoming determined that the conversion to natural gas will result in fewer overall energy and environmental impacts when compared to the installation of SCR, including fewer impacts from: mercury (Hg), greenhouse gases (GHG), carbon monoxide (CO), carbon dioxide (CO₂), PM, sulfuric acid (H₂ SO₄), coal and natural gas consumption, coal combustion residual (CCR) production and disposal, and raw water consumption associated with the burning of coal. Additionally, Wyoming also determined that SCR control technology would require the storage and use of ammonia and would create more CCR. Wyoming also notes that fewer GHGs will be produced with the gas conversion compared to SCR, and that the gas conversion would reduce the Jim Bridger plants auxiliary load demand by approximately 10.4 megawatts of energy compared to SCR. Finally, the State noted that the requirements relating to the natural gas conversion effectively limit the average annual capacity factor (heat input) for Units 1 and 2 to approximately 42%, resulting in significant reductions in the consumption of natural resources.

4. Remaining Useful Life

For the Wyoming 2022 SIP revision, Wyoming evaluated each emission control technology scenario for Jim Bridger Units 1 and 2 using the year 2024 as the end of remaining useful life on coal and the year 2037 as the end of remaining useful life on natural gas.^[70]

5. Reasonable Progress Demonstration

Upon completion of a reasonable progress four-factor analysis, states must demonstrate how the four factors were taken into consideration in making a reasonable progress determination for each class I area within the state.^[71] Taking into consideration the four statutory reasonable progress factors described previously, Wyoming determined that the conversion of Units 1 and 2 from coal-firing to natural gas-firing, together with NO_X emission and heat input limits, provided greater reasonable progress at a lower cost and with fewer negative environmental impacts when compared to SCR as reflected in the 2014 final rule. Accordingly, Wyoming's 2022 SIP revision replaces the emission limits of 0.07 lb/MMBtu (30-day rolling average) associated with SCR installation at Jim Bridger Units 1 and 2 with natural gas conversion together with NO_X emission and heat input limits at those same units as part of the State's long-term strategy to achieve reasonable progress for the first planning period.^[72]

F. Summary of Wyoming's Additional Proposed Revisions to the Emission Limits for Jim Bridger

In addition to Wyoming's revised emission reductions derived from the conversion to natural gas and associated NO_X limits, and reduced heat input for Jim Bridger's Units 1 and 2 under the reasonable progress analysis, the State is requiring monthly and annual NO_X and SO₂ emission limits for Jim Bridger Units 1-4 (summarized in Table 2) and an annual plant-wide NO_X and SO₂ emissions cap of 17,500 tons per year, federally enforceable through reference to permit #P0025809, which is effective through December 31, 2023.

IV. The EPA's Evaluation and Proposed Approval of Wyoming's Regional Haze SIP Revisions

For the reasons described in this section, the EPA proposes to approve Wyoming's 2022 SIP revision. The proposed Wyoming 2022 SIP revision adds a source-specific NO_X reasonable progress analysis and determination for Jim Bridger Units 1 and 2 and finds conversion from coal-firing to natural gas-firing, together with NO_X emission and heat input limits, to be sufficient for reasonable progress and long-term strategy during the first planning period and that the emission limits associated with the installation of SCR are no longer required. Separately, we are also proposing to approve Wyoming's monthly and annual NO_X and SO₂ emission limits for Jim Bridger Units 1-4. Our proposed action is based on an evaluation of Wyoming's regional haze SIP submittal under the regional haze requirements at 40 CFR 51.300-51.309 and CAA section 169A and 169B. The Wyoming 2022 SIP revision was also evaluated for compliance with the general SIP requirements contained in CAA section 110 and other provisions of the CAA and our regulations applicable to this action. The EPA proposes to approve the Wyoming 2022 SIP revision as meeting the relevant statutory and regulatory requirements. Where appropriate, we provide additional rationale to supplement the State's analysis and to support our conclusions. The EPA is not reopening, and thus not accepting comment on, the EPA's 2014 approval of Wyoming's BART determinations for Jim Bridger Units 1-4, the EPA's 2014 approval of the emission limits Wyoming required as long-term strategy controls for Jim Bridger Units 3 and 4, or the EPA's 2022 proposed disapproval of Wyoming's 2020 SIP revision. Any comments on these issues are beyond the scope of this action and will not be addressed in this rulemaking.

A. The EPA's Proposed Approval of Wyoming's Reasonable Progress Determination for Jim Bridger Units 1 and 2

We are proposing to approve Wyoming's December 2022 regional haze SIP revision pertaining to the State's reasonable progress NO_X determinations for Jim Bridger Units 1 and 2.

In our analysis of Wyoming's 2022 SIP revision, we evaluated Wyoming's reasonable progress determination for Jim Bridger Units 1 and 2 under 40 CFR 51.308(d)(1)(i)(A). As a threshold matter and given the considerably shortened remaining useful life of the existing coal-fired boilers due to the proposed natural gas conversion, we propose to find that it is appropriate for Wyoming to reassess its existing long-term strategy to achieve reasonable progress for Jim Bridger Units 1 and 2 by conducting a four-factor analysis.

1. Basis for the EPA's Proposed Approval

Our proposed approval is based on the following: (1) the fact that this is a first planning period reasonable progress determination for BART sources; (2) the costs of compliance; and (3) an analysis of projected emissions reductions achievable.

As explained in the EPA's 2007 Reasonable Progress Guidance for the first planning period, states have latitude to determine appropriate additional control requirements for ensuring reasonable progress.^[73] Unlike BART, which contains very specific applicability criteria to procure, install, and operate the best available retrofit technology and a regulatory framework for how states perform a “one-time” evaluation of emissions controls for the first planning period, the procedure for determining what controls are necessary to make reasonable progress is not as specific and a reasonable progress analysis is performed each planning period.^[74] Thus, although states must consider the four statutory factors, at a minimum, in determining reasonable progress, states also have more flexibility in how to take these factors into consideration.^[75] The text of the CAA and case law likewise support affording states deference in their reasonable progress determinations, provided those determinations are reasonable given the applicable statutory and regulatory requirements and purpose of the regional haze program.^[76]

Furthermore, the EPA's 2007 Guidance provides that reasonable progress analyses for the first implementation period are conducted against the backdrop of a state's BART determinations. In particular, the EPA's 2007 Guidance states that, given the overlap between the statutory BART and reasonable progress factors, it may be reasonable to conclude that any controls required pursuant to a BART determination for a source also satisfy the reasonable progress-related requirements for that source.^[77] Here, the two sources (Units 1 and 2) being analyzed are BART sources for which BART determinations were made and emission limits were required. In its 2022 SIP revision, Wyoming considered what, if any, controls should be required in addition to the BART controls determined appropriate (LNB/SOFA) for the first planning period. Specifically, the State performed a reasonable progress four-factor analysis for Jim Bridger Units 1 and 2 to analyze whether it was appropriate to remove the existing 0.07 lb/MMBtu emission limits associated with SCR in addition to the five-factor BART analysis it performed previously. We propose to find that the outcome of that analysis—that the conversion of Jim Bridger Units 1 and 2 from coal-firing to natural gas-firing, together with NO_X emission and heat input limits, makes reasonable progress for the first implementation period—is not unreasonable and is supported by the EPA's 2007 Guidance and Regional Haze Rule.^[78]

a. Costs of Compliance

In its reasonable progress analysis for Jim Bridger Units 1 and 2, the statutory factor that appears to have been the most significant in Wyoming's reasonable progress determination is the costs of compliance. As an initial matter, we agree with Wyoming's reliance on the revised cost estimates reflected in Wyoming's 2022 SIP revision rather than the cost estimates from EPA's 2014 final rule. Specifically, based on our review, the following elements of Wyoming's revised cost calculation are appropriate: (1) the use of actual annual average (2013-2015) baseline NO_X emissions rates for LNB/SOFA for the installation of SCR operating on coal and conversion from coal-firing to natural gas-firing scenarios; (2) the use of baseline NO_X emissions rates reflected in the consent decree associated with the installation of SCR operating on natural gas scenario; (3) the use of NO_X emissions rates of 0.05 lb/MMBtu (annual average) and 0.12 lb/MMBtu (30-day rolling average) for the installation of SCR firing on coal or natural gas and the conversion from coal-firing to natural gas-firing, respectively; (4) the use of amortization periods of 1.00 (12 months) and 1.67 (20 months) for the installation of SCR firing coal on Units 1 and 2, respectively; and (5) the use of actual costs for the installation and operation of SCR derived from those costs incurred for Units 3 and 4. However, we disagree with Wyoming's amortization period for SCR firing on natural gas and for conversion from coal-firing to natural gas-firing scenarios and are therefore providing supplemental analysis to support our conclusions. Additionally, we are supplementing our cost calculations with a common baseline reflecting the maximum allowable heat input.

With respect to control cost estimates, including amortization periods, our NO_X control cost estimates in the reasonable progress analysis are based on the current version of the EPA's Control Cost Manual, which was revised in 2014 and, as updated, includes a 30-year equipment life for SCR.^[79] The change in the equipment life estimate from 20 to 30 years for SCR affects annual cost estimates and average cost-effectiveness. The updated Control Cost Manual also requires the use of the source's “firm-specific nominal rate” of borrowing instead of the manual's prior instruction to use a 7% interest rate.^[80] In response to comments on Wyoming's 2020 SIP revision, PacifiCorp stated that its actual rate of borrowing is higher than 7%.^[81] Here, we note that PacifiCorp's actual rate of borrowing is 7.303% as provided in Wyoming's 2022 SIP revision.^[82] We agree that this approach is appropriate and consistent with the updated Control Cost Manual. However, we are proposing to find that the State did not use the appropriate amortization period for the installation of SCR on natural gas-firing and conversion from coal-firing to natural gas-firing scenarios. In both of these scenarios, Wyoming used an amortization period of 14 years (2024-2037) based on the expected remaining useful life of Jim Bridger Units 1 and 2 found in PacifiCorp's 2021 Integrated Resource Plan (IRP).^[83] Because there is not an enforceable closure date in the Wyoming regional haze SIP that would effectively shorten the remaining useful life of Jim Bridger Units 1 and 2, we find that the Cost Control Manual requires that the default remaining useful life (30 years) be used as the amortization period of the control technologies being evaluated in the cost analyses.^[84]

With respect to the baseline NO_X emissions rates, Wyoming's cost analyses assessed the installation of SCR operating on coal and conversion to natural gas scenarios against a 2001-2003 baseline heat input of 42,977,652 MMBtu/year and 40,898,999 MMBtu/year for Units 1 and 2, respectively, and 2013-2015 baseline NO_X emission rates for LNB/SOFA. Because reasonable progress analyses for BART sources in the first implementation period are conducted to determine what, if anything, in addition to BART is necessary to make reasonable progress and are a separate control determination than BART,^[85] and because BART controls (LNB/SOFA) are already installed and operating on these units, we believe it was reasonable for Wyoming to consider the cost of potential reasonable progress controls (SCR operating on coal and conversion to natural gas) relative to a baseline of BART (2013-2015 baseline NO_X emission rates for LNB/SOFA) and the 2001-2003 baseline heat input figures. Moreover, because the installation of controls (SCR) operating on natural gas scenario reflects a baseline associated with natural gas firing instead of coal-firing, we also believe it was reasonable for Wyoming to use the baseline heat input (21,900,000 MMBtu/year) and NO_X emission limits (0.12 lb/MMBtu; 1,314 tons/year) required in the consent decree for both Units 1 and 2. Thus, as previously stated, we agree with the State and find the baselines appropriate for each of the three scenarios.

While the Regional Haze Rule does not require states to consider fuel switching ( e.g. from coal to natural gas) as control options, states are free to do so.^[86] In Wyoming and other states, we have approved state-adopted requirements for switching fuels, which have usually been negotiated between the source operator and the state.^[87] Thus, because, as previously described, this is not a BART determination, and because two of the control scenarios (conversion from coal to natural gas and installation of SCR operating on natural gas) involve fuel switching from coal to natural gas, we believe it is also reasonable to consider the cost using a common baseline reflecting potential-to-emit ( e.g., allowable) baseline NO_X emissions rather than the historical baseline emissions reflective of coal- firing. We therefore conducted an additional cost analysis using the maximum allowable heat input limit of 52,560,000 MMBtu/year from Wyoming's 2009 BART Application Analysis as the baseline for potential further controls along with the 30-year amortization period for the SCR on natural gas and conversion from coal-firing to natural gas-firing scenarios (Table 4).^[88 89]

Table 4—The EPA's Summary of Jim Bridger Units 1 and 2 NO _X Revised Reasonable Progress Cost Analysis

Scenario	NO X emissions rate (lb/MMBtu)	Emissions reduction (tons per year)	Total annual cost ($/year)	Average cost effectiveness ($/ton)
Unit 1
SCR operating on coal	1  0.05	3,600	$152,369,457	$42,321
SCR operating on natural gas	1  0.05	767	13,355,567	17,424
Conversion from coal to natural gas 3	2  0.12	3,600	3,530,769	981
Unit 2
SCR operating on coal	1  0.05	3,732	94,115,947	25,220
SCR operating on natural gas	1  0.05	767	13,355,567	17,424
Conversion from coal to natural gas 3	2  0.12	3,732	3,490,829	935
1  Based on an annual average.
2  Based on a 30-day rolling average.
3  Operating with a heat input limit of 21,900,000 MMBtu/year (equal to 41.6% of maximum annual heat input).

Thus, when comparing Wyoming's cost estimates (Table 3) with our revised cost estimates (Table 4) using a common baseline maximum heat input and 30-year amortization periods for SCR on natural gas and conversion from coal-fired to natural gas-fired scenarios, the average cost-effectiveness for SCR on coal for Units 1 and 2, respectively, are $51,756 and $32,411 per ton of NO_X reduced using Wyoming's cost estimates and $42,321 and $25,220 per ton of NO_X reduced using the EPA's revised cost estimates. The average cost-effectiveness for SCR on natural gas for Units 1 and 2, respectively, are $23,531 and $23,531 per ton of NO_X reduced using Wyoming's cost estimates and $17,424 and $17,424 per ton of NO_X reduced using the EPA's revised cost estimates. The average cost-effectiveness for converting from coal-fired to natural gas-fired for Units 1 and 2, respectively, are $1,486 and $1,517 per ton of NO_X reduced using Wyoming's cost estimates and $981 and $935 per ton of NO_X reduced using the EPA's revised cost estimates. As explained previously, while the EPA believes it is appropriate for Wyoming to consider the cost of potential reasonable progress controls (SCR operating on coal and conversion to natural gas) relative to a baseline of BART (2013-2015 baseline NO_X emission rates for LNB/SOFA) using 2001-2003 baseline heat input, comparing the potential reasonable progress controls, including the conversion to a different fuel source, to a common baseline reflecting the maximum allowable heat input of the source (as well as appropriate amortization periods) is appropriate. To that end, the average cost-effectiveness for all three scenarios is reduced using the EPA's revised cost estimates compared to Wyoming's cost estimates.

Nevertheless, despite the reductions in average cost-effectiveness reflected in the EPA's revised cost estimates, we agree with Wyoming's consideration of cost-effectiveness and rejection of SCR operating on coal and operating on natural gas as reasonable progress controls because the cost-effectiveness figures for these controls are well above controls similarly determined in other first planning period actions to be too costly. For example, at the Antelope Valley Station power plant in North Dakota (Units 1 and 2), we determined that reasonable progress for NO_X required an emission-limit corresponding to LNB (0.17 lb/MMBtu).^[90] The average cost-effectiveness values for LNB at each unit were $586 and $661 per ton and that level of control was predicted to achieve NO_X reductions of approximately 3,500 tons per unit. The average cost-effectiveness for LNB + SCR at each unit were $6,746/ton and $7,606/ton and that level of control was predicted to achieve NO_X reductions of approximately 6,500 tons per unit. We ultimately excluded LNB + SCR because the cost-effectiveness values were much higher than LNB. We therefore concluded that requiring higher performing controls during the first planning period was not reasonable.^[91] Similarly, we are proposing here to approve Wyoming's determination that a higher performing control, in this case SCR ^[92] operating on coal or natural gas, is not reasonable given the cost-effectiveness and consideration of the other statutory factors discussed in this document. Here, the cost of SCR controls installed at Jim Bridger Units 1 and 2 whether on coal-fired or natural gas-fired boilers is significantly greater than the cost of conversion from coal to natural gas.

In addition to the Antelope Valley Station, we are also proposing to find that Wyoming's determinations were reasonable and supported by the EPA's reasonable progress determination for Tucson Electric Power's Springerville Generating Station in Arizona (Springerville). For Springerville, cost effectiveness was analyzed after the installation of LNB with over-fire air (LNB/OFA) similar to the analysis of Jim Bridger Units 1 and 2 with LNB/SOFA controls already installed (see Tables 3 and 4). The Springerville Generating Station contains four units, and like Jim Bridger, Springerville Units 3 and 4 already had SCR controls installed at the time of the reasonable progress analysis for Units 1 and 2. We determined the average cost-effectiveness for SCR at Springerville Units 1 and 2 to be $6,829 per ton and $6,085 per ton, respectively.^[93] Ultimately, we concluded that the visibility benefit of SCR, while larger at 0.41 deciviews at the most impacted Class I area, did not warrant the relatively high cost of controls for purposes of reasonable progress in the first planning period.^[94]

Wyoming did not assess visibility impacts; thus, we are not assessing visibility impacts in our review. Nevertheless, the average cost effectiveness associated with the installation of SCR on either the coal-fired or natural-gas fired boilers would be much higher than those we found unreasonable on Springerville Units 1 and 2.

b. Other Statutory Factors

Of the four reasonable progress factors, cost was the most significant factor in our analysis of controls for Units 1 and 2. However, we also considered the other three statutory factors: time necessary for compliance, energy and non-air quality environmental impacts, and remaining useful life.

With respect to time necessary for compliance, the December 31, 2022, and December 31, 2021, compliance deadlines to install SCR on Jim Bridger Units 1 and 2 have existed since 2014. Therefore, we do not agree with the State that the time necessary for compliance is “no longer accurate or relevant.”

Relevant to energy and non-air quality environmental impacts, the EPA's 2007 Guidance references the EPA's BART Guidelines, which provide, among other things, that (1) the fact that a control technology uses energy in and of itself does not disqualify that technology, and (2) the fact that a control technology creates waste that must be disposed of does not necessarily suggest selection of that technology is unwarranted, especially if the control has been applied to similar facilities elsewhere and the waste is similar to those other applications.^[95] The 2007 Guidance also provides that to the extent energy and non-air quality environmental impacts of compliance are quantifiable, they should be included in the engineering analysis supporting the cost of compliance estimates.^[96] Wyoming analyzed and included relevant information in this regard in its revised cost analysis for the Wyoming 2022 SIP revision.^[97] We also agree with the State that the requirements relating to natural gas conversion effectively limits the average annual capacity factor (heat input) to approximately 42%, which is significant and may result in reducing the consumption of natural resources.

With respect to remaining useful life, we agree with the State that the remaining useful life of the existing coal-fired boilers under the SCR on coal-firing scenario is shortened to the end of 2023 by the enforceable provisions in the consent decree. However, as stated previously, the State did not provide an enforceable closure mechanism that would ensure that the remaining useful life of Jim Bridger Units 1 and 2 under the natural gas conversion and SCR on natural gas-firing scenarios would not extend beyond 2037.

Overall, despite disagreeing with certain aspects of Wyoming's reasonable progress analyses, consideration of the three other statutory factors—remaining useful life, time necessary for compliance, and energy and non-air quality environmental impacts—does not alter analysis that the costs of compliance is the determining factor for the selection of controls at Jim Bridger Units 1 and 2.

c. Analysis of Projected Emissions Reductions Achievable

We also analyzed the three scenarios based on their associated NO_X emissions and emissions reductions achievable (Tables 5 and 6).

Table 5—Jim Bridger Units 1 and 2 Emissions Limits When Converted to Natural Gas

Permitted conversion	NO X
Coal-fired to natural gas-fired boilers 1	0.12 lb/MMBtu (30-day rolling average) 1,314 tons/year.
1  Operating with a heat input limit of 21,900,000 MMBtu/year (equal to 41.6% of maximum annual heat input).

Table 6—Jim Bridger Units 1 and 2 Coal to Natural Gas Emissions Comparison

Fuel	Permitted controls	NO X
		Emission limit (lb/MMBtu, 30-day rolling average)	Annual emissions (tons/year)	Annual reduction (tons/year)
Coal	Existing controls + SCR	1  0.07	1,314	3,600
Natural gas	Heat input limit, NO X limits	0.12	1,314	3,600
1  Equivalent to 0.05 lb/MMBtu annual average.

As previously discussed, the EPA approved Wyoming's NO_X emission limit of 0.07 lb/MMBtu (30-day rolling average) for Jim Bridger Units 1 and 2 that reflected existing LNB/SOFA with the installation of SCR on both units under the State's long-term strategy. The installation of SCR on Jim Bridger Units 1 and 2 would reduce NO_X emissions by 3,600 tons/year resulting in total NO_X emissions of 1,314 tons/year when operated at maximum heat input. Likewise, the conversion from coal to natural gas, together with NO_X emission and heat input limits, would result in an equivalent NO_X emissions reduction of 3,600 tons/year resulting in equivalent total NO_X emissions of 1,314 tons/year. Thus, once Units 1 and 2 are converted from coal to natural gas under the conditions of the consent decree, the NO_X annual emissions are equivalent to the annual emissions achieved with coal-fired SCR controls.

Notably, and as mentioned previously,^[98] we recognize the need to adjust the averaging periods ( e.g., annual actual average, 30-day rolling average), as appropriate. In the Wyoming 2022 SIP revision, the State chose to use an annual NO_X emissions rate of 0.05 lb/MMBtu to represent the installation of SCR on coal-fired or natural gas-fired boilers, which we are proposing to find appropriate. Generally, the NO_Xannual average emission rate is based on the expected annual emission performance under a 30-day rolling average emission rate. The latter value will necessarily be higher than the former because of the shorter averaging period and a margin for compliance.

For example, the relationship between annual average and 30-day rolling average can be observed at Jim Bridger Units 3 and 4 which are subject to a 30-day rolling average emission limit of 0.07 lb/MMBtu and are achieving actual annual emission rates of approximately 0.05 lb/MMBtu.^[99] Thus, we find that an estimated actual annual emission limit of 0.05 lb/MMBtu appropriately corresponds to the 30-day rolling average emission limit of 0.07 lb/MMBtu.

2. Summary of the EPA's Evaluation of Wyoming's Reasonable Progress Demonstration

We are proposing to find that Wyoming's determination was not unreasonable based on the circumstances described herein. However, we note that it may be necessary to reassess higher performing controls for reasonable progress sources, including Jim Bridger Units 1 and 2, in future planning periods.^[100]

Regardless, considering the fact that this is a first planning period reasonable progress determination for BART sources which the State has already required controls for the first planning period, the costs of compliance, and the analysis of projected emissions reductions achievable, it is not unreasonable for Wyoming to conclude that conversion from coal-firing to natural gas-firing, together with NO_X emission and heat input limits, on Jim Bridger Units 1 and 2 is sufficient to make reasonable progress in the first planning period. Thus, we are proposing to fully approve Wyoming's reasonable progress determination for Jim Bridger Units 1 and 2 for the first implementation period.

B. The EPA's Proposed Approval of Wyoming's Long-Term Strategy for Jim Bridger Units 1 and 2

Under 40 CFR 308(d)(3), a state's “long-term strategy must include enforceable emissions limitations, compliance schedules, and other measures as necessary to achieve the reasonable progress goals established by States having mandatory Class I Federal areas.” Wyoming submitted the Wyoming 2022 SIP revision to replace the approved reductions under the long-term strategy with comparable emission reductions as analyzed under reasonable progress. As described in more detail previously, we are proposing to find that the conversion of Jim Bridger Units 1 and 2 to natural gas along with associated NO_X limits and decreasing heat input, results in NO_X annual emissions that are equivalent to the annual emissions achieved with coal-fired SCR controls (a reduction of NO_X emissions by 3,600 tons/year resulting in total NO_X emissions of 1,314 tons/year when operated at maximum heat input). Since reasonable progress is a subset of the requirements for the long-term strategy, adoption of the emission reductions under reasonable progress for Jim Bridger Units 1 and 2 will also ensure that the long-term strategy requirements are met. Because Wyoming has demonstrated that the proposed emissions reductions for Jim Bridger Units 1 and 2 under reasonable progress are equivalent to the long-term strategy emissions reductions Wyoming is proposing to replace for those same units, we are also proposing to approve Wyoming's reasonable progress NO_X emissions limit derived for natural gas conversion and reduced heat inputs for Jim Bridger Units 1 and 2 as meeting the requirements of long-term strategy.

C. Monthly and Annual NO_X and SO₂ Emission Limits for Jim Bridger Units 1-4

Our proposed approval of Wyoming's reasonable progress determination for Jim Bridger Units 1 and 2 is based solely on the source-specific NO_X reasonable progress analysis, as this analysis and determination pertains to NO_X only. As previously stated, Wyoming did not provide a rationale or analysis for the inclusion of the monthly and annual NO_X and SO₂ emission limits. Furthermore, these limits include both NO_X and SO₂ emissions reductions which is outside of the scope of this proposed rulemaking. Nevertheless, we acknowledge that (1) per the EPA's 2007 Reasonable Progress Goals Guidance, Wyoming has discretion to evaluate factors (beyond the four statutory factors) that it considers relevant in formulating its long-term strategy,^[101] and (2) the inclusion of the monthly and annual NO_X and SO₂ emissions limits will reduce haze-causing pollutants. Indeed, the State has opted to adopt and make enforceable these monthly and annual NO_X and SO₂ emission limits, as proposed by PacifiCorp, through a state permit. Thus, we propose to find that these limits are relevant to Wyoming's progress towards natural visibility conditions at its Class I areas. However, because we are proposing that Wyoming's regional haze obligations under 40 CFR 51.308(d)(1)(i)(A) are met by the determinations made pursuant to the NO_X reasonable progress analysis, we propose to accept these limits solely as a SIP-strengthening measure, thus making them federally enforceable through incorporation and reference to Wyoming air quality permit #P0025809.^[102]

D. Monitoring, Recordkeeping, and Reporting

We are proposing to approve certain monitoring, recordkeeping, and reporting requirements found in Wyoming air quality permit #P0036941 associated with the conversion from coal-firing to natural gas-firing which, if finalized, will replace the monitoring, recordkeeping, and reporting requirements associated with EPA's 2014 final rule found in 40 CFR 52.2636(e) through 40 CFR 52.2636(k).^[103] We are also proposing to approve an additional monitoring, recordkeeping, and reporting condition into the SIP associated with permit #P0025809 related to the monthly and annual NO_X and SO₂ emission limits for Jim Bridger Units 1-4.^[104] The condition will be in addition to, and does not replace, existing requirements.^[105]

The BART emission limits for Units 3 and 4 identified for the Jim Bridger power plant in Table 1 of 40 CFR 52.2636 and associated NO_X -related monitoring, recordkeeping, and reporting requirements found in 40 CFR 52.2636(e) through 40 CFR 52.2636(k) will remain in effect for the BART limits and reasonable progress limits will therefore not be impacted upon approval of our proposed revisions.

E. Consultation With Federal Land Managers

There are seven Class I areas in the State of Wyoming. The United States Forest Service manages the Bridger Wilderness, Fitzpatrick Wilderness, North Absaroka Wilderness, Teton Wilderness, and Washakie Wilderness.^[106] The National Park Service manages Grand Teton National Park and Yellowstone National Park. The Regional Haze Rule grants the FLMs, regardless of whether an FLM manages a Class I area within the state, a special role in the review of regional haze implementation plans, summarized in section II.D. of this preamble.

Under 40 CFR 51.308(i)(2), Wyoming was obligated to provide the FLMs with an opportunity for consultation in development of the State's SIP revision no less than 60 days prior to the associated public hearing or public comment opportunity. On June 7, 2022, the State of Wyoming informed the FLMs of the State's draft proposed regional haze SIP revision for the Jim Bridger power plant. In doing so, the State provided the FLMs with a copy of the draft regional haze SIP revision and related consent decree ^[107] and provided the FLMs with 60 days to provide comments as well as the opportunity to discuss the draft SIP during a phone call, if requested.^[108] The State received comments from the FLMs, made those comments available during the public comment period, and responded to the comments in the final SIP submittal.^[109] Therefore, we propose to find that Wyoming met its obligations for consultation in development of the State's draft regional haze SIP revision.

V. Clean Air Act Section 110( l )

Under CAA section 110( l ), the EPA cannot approve a plan revision “if the revision would interfere with any applicable requirement concerning attainment and reasonable further progress (as defined in section 7501 of this title), or any other applicable requirement of this chapter.” ^[110] The previous sections of the document explain how the Wyoming 2022 SIP revision will comply with applicable regional haze requirements and general implementation plan requirements, such as enforceability, and that annual NO_X emissions are not greater than what is currently allowed in the SIP. There are no National Ambient Air Quality Standard (NAAQS) nonattainment areas in Wyoming for nitrogen dioxide (NO₂ ) or PM.^[111] Likewise, there are also no NAAQS nonattainment areas in the State of Wyoming for SO_2.

With respect to ozone NAAQS nonattainment areas,^[112] the Upper Green River Basin ozone nonattainment area covers areas in Lincoln, Sublette, and Sweetwater counties and was designated nonattainment for the 2008 8-hour ozone NAAQS on July 20, 2012.^[113] On May 4, 2016, the EPA finalized a determination of attainment for the Upper Green River Basin nonattainment area.^[114] Based on the most recent 3 years of valid data at that time (2012-2014), the Upper Green River Basin attained the 2008 8-hour ozone NAAQS by the attainment date of July 20, 2015, and continued to attain that standard during the most recent monitoring period (from 2020 to 2022).^[115] Thus, the Upper Green River Basin is attaining the 2008 8-hour ozone NAAQS at current emissions levels which would not increase under Wyoming's 2022 SIP revision because the proposed action results in emissions reductions equivalent to the previous SIP. In addition, the Upper Green River Basin is not a nonattainment area for the 2015 ozone NAAQS as it had an attaining design value of 63 ppb ^[116] at the time of the designations in 2017. The current 2020-2022 preliminary design value is also attaining with a value of 67 ppb.^[117]

Therefore, we propose to find that the Wyoming 2022 SIP revision is not anticipated to interfere with applicable requirements of the CAA and therefore CAA section 110( l) does not prohibit approval of this SIP.

VI. Summary of the EPA's Proposed Action

In this action, the EPA is proposing to approve Wyoming's 2022 SIP revision for the NO_X reasonable progress analysis and determination for Jim Bridger Units 1 and 2, including the associated emission and operational limitations, compliance dates, and monitoring, recordkeeping and reporting requirements as well as the separate monthly and annual NO_X and SO₂ emissions limits. Specifically, the EPA is proposing to approve the following as federally enforceable elements of the Wyoming 2022 SIP revision for Jim Bridger Units 1-4:

• The NO_X emission limits found in Wyoming air quality permit #P0036941 (Condition 9 for NO_X lb/MMBtu and tons/year emission limits) for Units 1 and 2.

• The NO_X and SO₂ emission limits found in Wyoming air quality permit #P0025809 (Condition 7 for lb/hr and Condition 9 for tons/year) for Units 1-4.

• The operational limit on annual heat input (based on a 12-month rolling average of hourly heat input values) found in Wyoming air quality permit #P0036941 (Condition 19).

• The compliance dates found in Wyoming air quality permit #P0036941 (Conditions 11 and 16) requiring that Units 1 and 2 comply with NO_X emission rates in lb/MMBtu (30-day rolling average) and tons/year as well as an annual heat input in MMBtu/year; and permit #P0025809 (Conditions 7 and 9) requiring that Units 1-4 comply with the NO_X and SO₂ emission limits in lb/hr and tons/year, respectively.

• The monitoring, recordkeeping and reporting requirements found in Wyoming air quality permit #P0036941 (Conditions 4, 5, 6, 10.i.1, 10.i.4, 17, 18, 19, 20, and 21) and permit #P0025809 (Condition 8.i and 9).

If the above elements are finalized into the SIP, the 0.07 lb/MMBtu NO_X long-term emission limits for Jim Bridger Units 1 and 2 will be removed from the SIP and replaced with the 0.12 lb/MMBtu NO_X reasonable progress emission limit and associated NO_X emissions and heat input limits, while the 0.07 lb/MMBtu NO_X long-term strategy emission limits will remain for Units 3 and 4.

We are also proposing to approve the following non-enforceable elements of the Wyoming 2022 SIP revision for:

• Jim Bridger Units 1 and 2, Chapters 7.3.6 PacifiCorp Jim Bridger Electric Generating Station of Wyoming's regional haze narrative, Addressing Regional Haze Visibility Protection For The Mandatory Federal Class I Areas Required Under 40 CFR 51.309, which contain a source-specific NO_X reasonable progress analysis.

• Jim Bridger Units 1-4, Chapter 8.3.3 Long-Term Control Strategies for BART Facilities (Jim Bridger Power Plant (Units 1 and 2) only) of Wyoming's regional haze narrative, Addressing Regional Haze Visibility Protection For The Mandatory Federal Class I Areas Required Under 40 CFR 51.309, which contains (1) plant-wide monthly NO_X and SO₂ emission limits and an annual emissions cap for NO_X plus SO₂ ; ^[118] and (2) a compliance date to convert Units 1 and 2 to natural gas along with an associate NO_X 30-day rolling average (lb/MMBtu), NO_X annual emission cap (tons/year), and annual heat input (MMBtu/year).

Conditions of Wyoming Air Quality Permit #P0036941 Proposed for Approval

Condition 9 for NO _X lb/MMBtu and tons/year emission limits; Condition 11 for fuel compliance date; Conditions 16, 19 for heat input limit and associated compliance date; and Conditions 4, 5, 6, 10.i.1, 10.i.4, 17, 18, 19, 20, and 21 for associated monitoring, recordkeeping, and reporting requirements.

Conditions of Wyoming Air Quality Permit #P0025809 Proposed for Approval

Condition 7 (lb/hr emission limits) and 9 (tons/year emission limits) for NO _X and SO ₂ monthly-block and annual emission limits and compliance dates, and Condition 8.i for associated monitoring, recordkeeping, and reporting requirements.

Amended Sections of Wyoming Regional Haze SIP Narrative Proposed for Approval  ¹

Chapter 7.3.6, Chapter 8.3.3 (Jim Bridger Power Plant (Units 1 and 2) only)

¹  Wyoming 2022 SIP revision.

Together these proposed amendments modify:

• 40 CFR 52.2620(d)—air quality permit amendments adding (1) the requirement to convert to natural gas and associated NO_X emissions limits and annual heat input for Jim Bridger Units 1 and 2, (2) the monthly and annual NO_X and SO₂ emission limits for Jim Bridger Units 1-4, and (3) associated monitoring, recordkeeping and reporting requirements;

• 40 CFR 52.2620(e)—regional haze narrative amendments adding (1) a source-specific NO_X reasonable progress analysis and determination for Jim Bridger Units 1 and 2 along with associated NO_X emission limits and annual heat input, and (2) the monthly and annual NO_X and SO₂ emission limits for Jim Bridger Units 1-4; and

• 40 CFR 52.2636(c)-(d)—NO_X and SO₂ emissions limits, heat input, and associated compliance dates for Jim Bridger Units 1-4.

The proposed revisions to both 40 CFR 52.2620 and 40 CFR 52.2636 are included in this document. We are not proposing to change any other regulatory text in 40 CFR 52.2620 or 40 CFR 52.2636.

VII. Incorporation by Reference

In this document, the EPA is proposing to include regulatory text in an EPA final rule that includes incorporation by reference. In accordance with the requirements of 1 CFR 51.5, the EPA is proposing to incorporate by reference the SIP amendments described in section VI. of this preamble. The EPA has made, and will continue to make, these materials generally available through https://www.regulations.gov (refer to docket EPA-R08-OAR-2022-0536) 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).

VIII. Statutory and Executive Order Reviews

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 requirements of the CAA and applicable Federal regulations. 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);

• 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

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).

Executive Order 12898 (Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations, 59 FR 7629, Feb. 16, 1994) directs Federal agencies to identify and address “disproportionately high and adverse human health or environmental effects” of their actions on minority populations and low-income populations to the greatest extent practicable and permitted by law. The EPA defines environmental justice (EJ) as “the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies.” The EPA further defines the term fair treatment to mean that “no group of people should bear a disproportionate burden of environmental harms and risks, including those resulting from the negative environmental consequences of industrial, governmental, and commercial operations or programs and policies.”

The State did not evaluate environmental justice considerations as part of its SIP submittal; the CAA and applicable implementing regulations neither prohibit nor require such an evaluation. The EPA did not perform an EJ analysis and did not consider EJ in this action. Due to the nature of the action being taken here, this action is expected to have a neutral to positive impact on the air quality of the affected area. Consideration of EJ is not required as part of this action, and there is no information in the record inconsistent with the stated goal of E.O. 12898 of achieving environmental justice for people of color, low-income populations, and Indigenous peoples.

List of Subjects in 40 CFR Part 52

• Environmental protection
• Air pollution control
• Carbon monoxide
• Greenhouse gases
• Incorporation by reference
• Intergovernmental relations
• Lead
• Nitrogen dioxide
• Ozone
• Particulate matter
• Reporting and recordkeeping requirements
• Sulfur oxides
• Volatile organic compounds

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

Dated: April 2, 2024.

KC Becker,

Regional Administrator, Region 8.

For the reasons stated in the preamble, the Environmental Protection Agency proposes to amend 40 CFR part 52 as follows:

PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

1. The authority citation for part 52 continues to read as follows:

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

Subpart ZZ—Wyoming

2. In § 52.2620:

a. The table in paragraph (d) is amended by adding the entries “Jim Bridger Units 1 and 2” and “Jim Bridger Units 1-4” in alphabetical order at the end of the table.

b. The table in paragraph (e) is amended by revising the entry “(25) XXV”.

The additions and revision read as follows:

§ 52.2620

Identification of plan.

* * * * *

(d) * * *

Regulation	Rule title	State effective date	EPA effective date	Final rule citation/date	Comments
*         *         *         *         *         *         *
Jim Bridger Units 1 and 2	Air Quality SIP Permit containing conversion to natural gas requirements, P0036941	August 29, 2023	[date 30 days after date of publication of the final rule in the Federal Register ]	[ Federal Register citation of the final rule], [date of publication of the final rule in the Federal Register ]	Only the following permit provisions: NO X emission limits (Condition 9 for NO X lb/MMBtu and tons/year emission limits); emission limit compliance date (Condition 11 for fuel compliance date); heat input limit and associated compliance date (Condition 16, 19); and associated monitoring, recordkeeping, and reporting requirements (Conditions 4, 5, 6, 10.i.1, 10.i.4, 17, 18, 19, 20, and 21).
Jim Bridger Units 1-4	Air Quality SIP Permit containing additional requirements, P0025809	5/5/2020	[date 30 days after date of publication of the final rule in the Federal Register ]	[ Federal Register citation of the final rule], [date of publication of the final rule in the Federal Register ]	Only the following permit provisions: NO X and SO 2 monthly-block and annual emission limits (P0025809 Condition 7 for lb/hr emission limits, and Condition 9 for tons/year emission limits); emission limit compliance dates (P0025809, Conditions 7 and 9); and associated monitoring, recordkeeping, and reporting requirements (P0025809, Condition 8.i).

(e) * * *

Rule No.	Rule title	State effective date	EPA Effective date	Final rule citation/date	Comments
*         *         *         *         *         *         *
(25) XXV	Wyoming State Implementation Plan for Regional Haze for 309(g)	5/23/22	[date 30 days after date of publication of the final rule in the Federal Register ]	[ Federal Register citation of the final rule], [date of publication of the final rule in the Federal Register ]	Excluding portions of the following: Chapters 6.4, 6.5.7, 6.5.8, and 7.5. EPA disapproved (1) the NO X BART determinations for (a) Laramie River Units 1-3, (b) Dave Johnston Unit 3, and (c) Wyodak Unit 1; (2) the State's monitoring, recordkeeping, and reporting requirements for BART units; and (3) the State's reasonable progress goals.
*         *         *         *         *         *         *

3. In § 52.2636:

a. Revise table 1 in paragraph (c)(1).

b. Add tables 3 and 4 in numerical order in paragraph (c)(1).

c. Revise paragraph (d)(1).

The revisions and additions read as follows:

§ 52.2636

Implementation plan for regional haze.

(c) * * *

(1) * * *

Table 1 to § 52.2636

[Emission limits for BART units for which the EPA approved the State's BART and Reasonable Progress determinations]

Source name/BART unit	PM emission limits— lb/MMBtu	NO X emission limits- lb/MMBtu (30-day rolling average)
FMC Westvaco Trona Plant/Unit NS-1A	0.05	0.35
FMC Westvaco Trona Plant/Unit NS-1B	0.05	0.35
TATA Chemicals Partners (General Chemical) Green River Trona Plant/Boiler C	0.09	0.28
TATA Chemicals Partners (General Chemical) Green River Trona Plant/Boiler D	0.09	0.28
Basin Electric Power Cooperative Laramie River Station/Unit 1	0.03	N/A
Basin Electric Power Cooperative Laramie River Station/Unit 2	0.03	N/A
Basin Electric Power Cooperative Laramie River Station/Unit 3	0.03	N/A
PacifiCorp Dave Johnston Power Plant/Unit 3	0.015	N/A
PacifiCorp Dave Johnston Power Plant/Unit 4	0.015	0.15
PacifiCorp Jim Bridger Power Plant/Unit 1 1  2	0.03	0.26/0.12
PacifiCorp Jim Bridger Power Plant/Unit 2 1  2	0.03	0.26/0.12
PacifiCorp Jim Bridger Power Plant/Unit 3 1  2	0.03	0.26/0.07
PacifiCorp Jim Bridger Power Plant/Unit 4 1  2	0.03	0.26/0.07
PacifiCorp Naughton Power Plant/Unit 1	0.04	0.26
PacifiCorp Naughton Power Plant/Unit 2	0.04	0.26
PacifiCorp Wyodak Power Plant/Unit 1	0.015	N/A
1  The owners and operators of PacifiCorp Jim Bridger Units 1, 2, 3, and 4 shall comply with the NO X emission limit for BART of 0.26 lb/MMBtu and the PM emission limit for BART of 0.03 lb/MMBtu and other requirements of this section by March 4, 2019. The owners and operators of PacifiCorp Jim Bridger Units 1, 2, 3, and 4 shall comply with the NO X emission limit for reasonable progress of 0.12 lb/MMBtu by January 1, 2024, for Jim Bridger Units 1 and 2 and 0.07 lb/MMBtu by December 31, 2015, for Unit 3, and December 31, 2016, for Unit 4.
2  Additional NO X and SO 2 emissions control measures and associated compliance dates for Jim Bridger Units 1-4, are found in § 52.2636(c) Tables 3 and 4.

* * * * *

Table 3 to § 52.2636

[NO _X and SO ₂ Emission Limits for Jim Bridger Units 1-4, Effective January 1, 2022]

Month	Total units 1-4 NO X emission limit (monthly average basis)  1 2 (lb/hour)	Total units 1-4 SO 2 emission limit (monthly average basis)  1 2 (lb/hour)
January	2,050	2,100
February	2,050	2,100
March	2,050	2,100
April	2,050	2,100
May	2,200	2,100
June	2,500	2,100
July	2,500	2,100
August	2,500	2,100
September	2,500	2,100
October	2,300	2,100
November	2,030	2,100
December	2,050	2,100
1  Effective January 1, 2022, through December 31, 2023.
2  In addition to monthly NO X and SO 2 emission limits, an annual, plant-wide NO X plus SO 2 emissions cap of 17,500 tons per year is effective January 1, 2022, through December 31, 2023.

Table 4 to § 52.2636

[NO _X Emission Limits and Heat Input for Jim Bridger Units 1-2, Effective January 1, 2024]

Unit	NO X emission limit (tons/year)	Heat input (MMBtu/year)
Unit 1	1,314	21,900,000
Unit 2	1,314	21,900,000

* * * * *

(d) Compliance date. (1) The owners and operators of PacifiCorp Jim Bridger Units 1, 2, 3, and 4 shall comply with the NO_X emission limit of 0.26 lb/MMBtu and PM emission limit of 0.03 lb/MMBtu and other requirements of this section by March 4, 2019. The owners and operators of PacifiCorp Jim Bridger Units 1 and 2 shall comply with the NO_X emission limit of 0.12 lb/MMBtu by January 1, 2024. The owners and operators of PacifiCorp Jim Bridger Units 3 and 4 shall comply with the NO_X emission limit of 0.07 lb/MMBtu by: December 31, 2015, for Unit 3, and December 31, 2016, for Unit 4. The owners and operators of PacifiCorp Jim Bridger Units 1, 2, 3, and 4 shall comply with the NO_X and SO₂ emission limits contained in § 52.2636(c) Table 3 by January 1, 2022. The owners and operators of PacifiCorp Jim Bridger Units 1 and 2 shall comply with NO_X emission and heat input limits contained in § 52.2636(c) Table 4 by January 1, 2024.

* * * * *

Footnotes

1.  79 FR 5032 (January 30, 2014).

2.  Wyoming determined that all four units are subject to BART. 77 FR 33022, 33030, 33035 (June 4, 2012).

3.  The BART determination compliance date for all units was March 4, 2019. Long-term strategy determination compliance dates for each include: Unit 1 = December 31, 2022; Unit 2 = December 31, 2021; Unit 3 = December 31, 2015; and Unit 4 = December 31, 2016.

4.  On May 23, 2022, Wyoming submitted a draft SIP revision and requested that the EPA parallel process this revision to their Regional Haze 309(g) first planning period SIP. Parallel processing generally refers to concurrent state and federal proposed rulemaking actions. In this action, however, the state submitted a final SIP revision after the state concluded its state rulemaking action thus we are proposing action on the state's final SIP revision and are not parallel processing the rulemaking.

5.  State of Wyoming, “Addressing Regional Haze Visibility Protection For The Mandatory Federal Class I Areas Required Under 40 CFR 51.309,” Revised May 23, 2022 (“Wyoming 2022 SIP revision”).

6.  Consent Decree, State of Wyoming v. PacifiCorp, Docket No. 2022-CV-200-333, First Judicial District Court, Laramie, Wyoming. (February 14, 2022).

7.  An EPA Administrative Compliance Order On Consent found PacifiCorp in violation of the Wyoming SIP and the Clean Air Act and ordered PacifiCorp to comply, no later than June 9, 2023, with the terms of the Wyoming 2022 SIP revision, based on the requirements found in the February 14, 2022 consent decree. EPA Administrative Compliance Order On Consent, PacifiCorp—Jim Bridger Power Plant, CAA-08-2022-0006 (EPA June 9, 2022).

8.  These limits represent a separate SIP component from Wyoming's long-term strategy analysis and determination. See sections IV.C. and VI.

9.  42 U.S.C. 7491(a). Areas designated as mandatory Class I Federal areas consist of national parks exceeding 6,000 acres, wilderness areas and national memorial parks exceeding 5,000 acres, and all international parks that were in existence on August 7, 1977. 42 U.S.C. 7472(a). In accordance with section 169A of the CAA, the EPA, in consultation with the Department of Interior, promulgated a list of 156 areas where visibility is identified as an important value. 44 FR 69122 (November 30, 1979). The extent of a mandatory Class I area includes subsequent changes in boundaries, such as park expansions. 42 U.S.C. 7472(a). Although states and tribes may designate as Class I additional areas whose visibility they consider to be an important value, the requirements of the visibility program set forth in section 169A of the CAA apply only to “mandatory Class I Federal areas.” Each mandatory Class I Federal area is the responsibility of a “Federal Land Manager.” 42 U.S.C. 7602(i). When we use the term “Class I area” in this action, we mean a “mandatory Class I Federal area.”

10.  64 FR 35714, 35714 (July 1, 1999) (codified at 40 CFR part 51, subpart P).

11.  The EPA had previously promulgated regulations to address visibility impairment in Class I areas that is “reasonably attributable” to a single source or small group of sources, i.e., reasonably attributable visibility impairment (RAVI). 45 FR 80084, 80084 (December 2, 1980).

12.  The EPA revised the Regional Haze Rule on January 10, 2017. 82 FR 3078 (January 10, 2017). Under the revised Regional Haze Rule, the requirements 40 CFR 51.308(d) and (e) apply to first implementation period SIP submissions and 51.308(f) applies to submissions for the second and subsequent implementation periods. 82 FR 3087; see also 81 FR 26942, 26952 (May 4, 2016).

13.  42 U.S.C. 7410(a), 7491, and 7492(a); CAA sections 110(a), 169A, and 169B.

14.  42 U.S.C. 7491(b)(2); 7410.

15.  40 CFR 51.308(e). The EPA designed the Guidelines for BART Determinations Under the Regional Haze Rule (Guidelines) 40 CFR appendix Y to part 51 “to help States and others (1) identify those sources that must comply with the BART requirement, and (2) determine the level of control technology that represents BART for each source.” Guidelines, section I.A. section II. of the Guidelines describes the four steps to identify BART sources, and section III. explains how to identify BART sources ( i.e., sources that are “subject to BART”).

16.  40 CFR 51.308(e)(1)(ii).

17.  40 CFR 51.308(e)(2). WildEarth Guardians v. EPA, 770 F.3d 919, 934 (10th Cir. 2014).

18.  The Colorado Plateau is a high, semi-arid area in southeast Utah, northern Arizona, northwest New Mexico, and western Colorado. The 16 mandatory Class I areas are Grand Canyon National Park, Mount Baldy Wilderness, Petrified Forest National Park, Sycamore Canyon Wilderness, Black Canyon of the Gunnison National Park Wilderness, Flat Tops Wilderness, Maroon Bells Wilderness, Mesa Verde National Park, Weminuche Wilderness, West Elk Wilderness, San Pedro Park Wilderness, Arches National Park, Bryce Canyon National Park, Canyonlands National Park, Capital Reef National Park, and Zion National Park.

19.  64 FR 35714 (July 1, 1999); 68 FR 33764 (June 5, 2003).

20.  40 CFR 51.309(d)(4)(vii).

21.  42 U.S.C. 7491(b)(2)(B).

22.  40 CFR 51.308(d)(3).

23.  42 U.S.C. 7491(g)(1); 40 CFR 51.308(d)(1)(i).

24.  Under the Regional Haze Rule, SIPs are due for each regional haze planning or implementation period. The terms “planning period” and “implementation period” are used interchangeably in this document.

25.  40 CFR 51.308(f). The deadline for the 2018 SIP revision was moved to 2021. 82 FR 3078 (January 10, 2017); see also 40 CFR 51.308(f). Following the 2021 SIP revision deadline, the next SIP revision is due in 2028. 40 CFR 51.308(f).

26.  Id. § 51.308(g); 51.309(d)(10).

27.  40 CFR 51.309(a).

28.  40 CFR 51.309(d)(4)(vii).

29.  79 FR 5199 (March 3, 2014).

30.  40 CFR 51.308(i); CAA 169A(d).

31.  42 U.S.C. 7410(a)(2)(A), (C), and (F).

32.  40 CFR 51.212.

33.  Id. § 51.214.

34.  40 CFR part 51, appendix V.

35.  79 FR 5221. Installation of new LNB with SOFA (LNB/SOFA) corresponds to a NO_X emissions limit of 0.26 lb/MMBtu (30-day rolling average).

36.  Id. Installation of SCR corresponds to a NO_X emissions limit of 0.07 lb/MMBtu (30-day rolling average).

37.  Id. See also 40 CFR 51.308(e)(1)(iv).

38.  79 FR 5046, 5221.

39.  77 FR 33053-54.

40.  Deciview is the unit of measurement on the deciview index scale for quantifying in a standard manner human perceptions of visibility. 40 CFR 51.301.

41.  79 FR 5040, 5048. Note that the text at 79 FR 5048 misstates the average cost-effectiveness for LNB/SOFA + SCR at Units 1 and 2. The correct figures are stated in Tables 5 and 6 at 79 FR 5040.

42.  The incremental cost-effectiveness of each NO_X control technology on a dollar-per-ton of pollutant removed basis is calculated by dividing the difference of the total annual costs of one control technology compared to the total annual costs of the next most stringent control technology divided by the difference in the reduction in annual NO_X emissions of one control technology compared to the reduction in annual NO_X emissions of the next most stringent control technology. See 40 CFR part 51, appendix Y, IV.D.e.

43.  79 FR 5040, 5048.

44.  79 FR 5048, 5049.

45.  40 CFR 51.309.

46.  Id.

47.  85 FR 21341 (April 17, 2020) (Proposed rule); 85 FR 38325 (June 26, 2020) (Final rule).

48.  85 FR 21346.

49.  Id at 21348.

50.  Letter dated May 12, 2020, from Todd Parfitt, Director, Wyoming Department of Environmental Quality, to Gregory Sopkin, Regional Administrator, EPA Region 8, Subject: State Implementation Plant Approval Request—Regional Haze 309(g) SIP revision for PacifiCorp Jim Bridger Power Plant.

51.  87 FR 2571 (January 18, 2022).

52.  Letter dated December 30, 2022, from Todd Parfitt, Director, Wyoming Department of Environmental Quality, to KC Becker, Regional Administrator, EPA Region 8, Subject: Approval Request—Parallel Process Regional Haze Round One State Implementation Plan (SIP) revision for PacifiCorp Jim Bridger Power Plant.

53.  On May 23, 2022, the state submitted a proposed SIP revision with a request to parallel process the draft SIP (letter dated May 20, 2022, from Todd Parfitt, Director, Wyoming Department of Environmental Quality, to KC Becker, Regional Administrator, EPA Region 8, Subject: Request to Parallel Process the Draft 309(g) Regional Haze Round 1 State Implementation Plan for PacifiCorp Jim Bridger Power Plant).

54.  Letter dated August 31, 2023, from Todd Parfitt, Director, Wyoming Department of Environmental Quality, to KC Becker, Regional Administrator, EPA Region 8, Subject: Supplemental Information for Wyoming's Parallel Process Regional Haze Round One State Implementation Plan (SIP) revision for PacifiCorp Jim Bridger Power Plant.

55.  Letter dated November 16, 2023, from Todd Parfitt, Director, Wyoming Department of Environmental Quality, to KC Becker, Regional Administrator, EPA Region 8, Subject: Supplemental Information for Wyoming's Parallel Process Regional Haze Round One State Implementation Plan (SIP) revision for PacifiCorp Jim Bridger Power Plant.

56.  The reduction in maximum annual heat input is based off the maximum annual heat input limit of 52,560,000 MMBtu/year per unit.

57.  Letter dated May 5, 2020, from Nancy E. Vehr, Administrator, Air Quality Division, Wyoming Department of Environmental Quality, to James Owens, Director, Environmental Services, PacifiCorp, Subject: Permit #P0025809 (Permit #0025809).

58.  See 77 FR 33040 (listing stationary sources evaluated under the four reasonable progress factors and not including Jim Bridger).

59.  Wyoming 2022 SIP revision, Appendix C at 2-3. Note: The Wyoming 2020 SIP revision identifies identical baseline NO_X emission rates that reflect the actual emissions rate from 2013-2015.

60.  Wyoming 2022 SIP revision, cost supplement.

61.  Consent Decree, State of Wyoming v. PacifiCorp, Docket No. 2022-CV-200-333, First Judicial District Court, Laramie, Wyoming. (February 14, 2022).

62.  Throughout, we refer to the averaging periods— annual average for 0.05 lb/MMBtu and 30-day rolling average for 0.12 lb/MMBtu—which Wyoming provided in the Wyoming 2022 SIP revision. However, we recognize the need to adjust the averaging periods, as appropriate. Indeed, this concept is discussed in similar rulemakings for Wyoming (79 FR 5167 (January 30, 2014), 84 FR 10434 (March 21, 2019)), and we discuss the impact of such adjustments in section IV. of this document.

63.  Wyoming 2022 SIP revision, Appendix C at 5. Note: The Wyoming 2022 SIP revision cites the February 4, 2019, S&L Report as the basis for the total capital costs.

64.  EPA, “Cost Control Manual,” Section 4, Chapter 2, June 2019, page 80, available at https://www.epa.gov/​economic-and-cost-analysis-air-pollution-regulations/​cost-reports-and-guidance-air-pollution. (last visited February 2024).

65.  The amortization period in years for SCR operating on coal was 1.00 (December 2022-December 2023) and 1.67 (May 2022-December 2023) for Units 1 and 2, respectively. The amortization period for SCR operating on natural gas and conversion from coal to natural gas was 14 (2024-2037) for both Units 1 and 2.

66.  Wyoming 2022 SIP revision at 3, 4, and cost supplement.

67.  Wyoming 2022 SIP revision at 4.

68.  Id. at 6.

69.   Consent Decree, Wyoming v. PacifiCorp, Docket No. 2022-CV-200-333. First Judicial District Court, Laramie, Wyoming. (February 14, 2022).

70.  Wyoming 2022 SIP revision at 4.

71.  40 CFR 51.308(d)(1)(i)(A).

72.  Wyoming 2022 SIP revision at 8.

73.  The EPA's 2007 Guidance at page 4-2.

74.  Compare 40 CFR 51.308(e) and part 51, appendix Y with 40 CFR 51.308(d).

75.  The EPA's 2007 Guidance at page 5-1.

76.  42 U.S.C. 7407(a) (“Each State shall have the primary responsibility for assuring air quality within [its] entire geographic area.”); id. section 7401(a)(3) (“[A]ir pollution prevention . . . is the primary responsibility of States and local governments.”); Oklahoma v. EPA, 723 F.3d 1201, 1204 (10th Cir. 2014) (“The Clean Air Act uses a cooperative federalism approach to regulate air quality.”) (Internal quotation marks omitted), Luminant Generation Co. v. EPA, 675 F.3d 917, 921 (5th Cir. 2012) (Congress gave states “the primary responsibility for implementing [air quality] standards.”) (Internal quotation marks omitted); Union Elec. Co. v. EPA, 427 U.S. 246, 250 (1976) (states have “wide discretion” in formulating SIPs).

77.  See the EPA's 2007 Guidance at pages 4-2—4-3.

78.  40 CFR 51.308(d)(1).

79.  EPA, “Cost Control Manual,” Section 4, Chapter 2, June 2019, page 80, available at https://www.epa.gov/​economic-and-cost-analysis-air-pollution-regulations/​cost-reports-and-guidance-air-pollution (last visited February 2024).

80.  Id. at Section 1, Chapter 2, November 2017, pages 14-17, available at https://www.epa.gov/​economic-and-cost-analysis-air-pollution-regulations/​cost-reports-and-guidance-air-pollution (last visited February 2024).

81.  Letter dated October 25, 2019, from James Owen, Director, Environmental, PacifiCorp, to Nancy Vehr, Administrator, Wyoming Department of Environmental Quality, Air Quality Division, at page 7. (Originally submitted as part of Wyoming 2020 SIP revision).

82.  Wyoming 2022 SIP revision, cost supplement.

83.  Wyoming 2022 SIP revision at 3.

84.  EPA, “Cost Control Manual,” Section 4, Chapter 2, June 2019, page 80, available at https://www.epa.gov/​economic-and-cost-analysis-air-pollution-regulations/​cost-reports-and-guidance-air-pollution (last visited February 2024). However, we also note that PacifiCorp's 2021 Integrated Resource Plan Update lists retirement for Jim Bridger Units 1 and 2 as 2037. PacifiCorp, “PacifiCorp Integrated Resource Plan Update,” March 2022, page 13.

85.  The EPA's 2007 Guidance at page 4-2.

86.  40 CFR part 51, appendix Y.

87.  83 FR 31332 (July 5, 2018), 84 FR 10433 (March 21, 2019).

88.  See `Firing Rate' in Wyoming BART Application Analysis (AP-6040), page 3. (May 28, 2009).

89.  EPA Supplemental NO_X Revised Reasonable Progress Analysis. March 13, 2024.

90.  76 FR 58570, 58632 (September 21, 2011); 77 FR 20894, 20896-97, 20899 (April 6, 2012). LNB here refers to LNB with close-coupled overfire air and SOFA.

91.  76 FR at 58631-32; 77 FR at 20899.

92.  Antelope Valley was not a BART source and did not have LNB installed at the time of the reasonable progress analysis; therefore, LNB was assessed as a potential reasonable progress control in addition to LNB + SNCR and LNB + SCR. In contrast, Jim Bridger Units 1 and 2 are operating LNB/SOFA pursuant to those units' BART determinations.

93.  79 FR 9318, 9359 (February 18, 2014).

94.  79 FR 9360; see also 79 FR 52420, 52420 (September 3, 2014).

95.  The EPA's 2007 Guidance at pages 5-2 and 5-3; 40 CFR part 51, appendix Y, IV.D.4.h-i.

96.  The EPA's 2007 Guidance at pages 5-2 and 5-3.

97.  Wyoming 2022 SIP revision, cost supplement.

98.  See footnote #63.

99.  83 FR 55656, 55662 (November 7, 2018).

100.  Wyoming's regional haze second planning period proposed SIP revision was due July 31, 2021. 40 CFR 51.308(f).

101.  The EPA's 2007 Guidance at page 5-1.

102.  We are not evaluating the monthly and annual NO_X and SO₂ emission limits beyond our proposed acceptance of these limits as a SIP-strengthening measure.

103.  Permit #P0036941, Conditions 4, 5, 6, 10.i.1, 10.i.4, 17, 18, 19, 20, and 21.

104.  Permit #P0025809, Condition 8.i.

105.  The monitoring, recordkeeping, and reporting requirements associated with Permit #P0025809 correspond to the monitoring, recordkeeping, and reporting requirements promulgated at 40 CFR 52.2636(e) through 40 CFR 52.2636(k) and differ only as necessary to accommodate the differences in emissions rates used for the monthly annual NO_X and SO₂ emissions limits. Specifically, the monitoring, recordkeeping, and reporting requirements at 40 CFR 52.2636(e) through 40 CFR 52.2636(k) assume lb/MMBtu rates for NO_X on a 30- day rolling basis, while the monitoring, recordkeeping, and reporting requirements for the monthly and annual NO_X and SO₂ emissions limits in Permit #P0025809 assume lb/hr rates for NO_X and SO₂ on a monthly-block basis.

106.  Our 2014 final rule modeled visibility improvement for six Class I areas in Wyoming (Bridger Wilderness, Fitzpatrick Wilderness, Teton Wilderness, Washakie Wilderness, Grand Teton National Park, and Yellowstone National Park) as well as three additional Class I areas in Colorado (Mt. Zirkel Wilderness, Rawah Wilderness, and Rocky Mountain National Park).

107.  Consent Decree, State of Wyoming v. PacifiCorp, Docket No. 2022-CV-200-333. First Judicial District Court, Laramie, Wyoming. (February 14, 2022).

108.  Email from Amber Potts, Wyoming Department of Environmental Quality, to Federal Land Managers. June 7, 2022.

109.  Per the CAA 169A(d), states shall include a summary of the conclusions and recommendations of the FLMs in the notice to the public.

110.  Note that “reasonable further progress” as used in CAA section 110( l) is a reference to that term as defined in section 301(a) ( i.e.,42 U.S.C. 7501(a)), and as such means reductions required to attain the NAAQS set for criteria pollutants under section 109. This term as used in section 110( l) (and defined in section 301(a)) is not synonymous with “reasonable progress” as that term is used in the regional haze program. Instead, section 110( l) provides that the EPA cannot approve plan revisions that interfere with regional haze requirements (including reasonable progress requirements) insofar as they are “other applicable requirement[s]” of the CAA.

111.  See Wyoming 2020 SIP revision at 13.

112.  NO_X is an ozone precursor.

113.  77 FR 30088 (May 21, 2012).

114.  81 FR 26697 (May 4, 2016).

115.  EPA, “Air Quality System Preliminary Design Value Report,” October 5, 2022.

116.  EPA, “Ozone Design Values Report, 2016,” October 2, 2017.

117.  EPA, “Upper Green River Basin 2020-2022 Preliminary Ozone Design Value Report,” Row 18, October 5, 2022.

118.  The revised text in Chapter 8 refers only to Jim Bridger Units 1 and 2. However, the monthly and annual NO_X and SO₂ emissions limits contained within the permit referenced, #P0025809, apply to Units 1-4 (Wyoming 2022 SIP revision at 8).