2021-21562. Air Plan Approval; MS; BART SIP and Regional Haze Progress Report

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Final rule.

SUMMARY:

The Environmental Protection Agency (EPA) is approving two Mississippi State Implementation Plan (SIP) revisions from the Mississippi Department of Environmental Quality (MDEQ) dated October 4, 2018, and August 13, 2020. The October 4, 2018, SIP revision contains the State's first periodic report describing progress towards reasonable progress goals (RPGs) established for regional haze and contains the associated determination that the State's regional haze SIP is adequate to meet these RPGs for the first implementation period (Progress Report). The August 13, 2020, SIP revision addresses best available retrofit technology (BART) determinations for 14 electric generating units (EGUs) (BART SIP). These EGUs were initially addressed in EPA's prior limited approval and limited disapproval actions on Mississippi's regional haze SIP because of deficiencies arising from the State's reliance on the Clean Air Interstate Rule (CAIR) to satisfy certain regional haze requirements. EPA is approving the BART SIP and finds that it corrects the deficiencies that led to the limited approval and limited disapproval of the State's regional haze SIP. EPA is therefore withdrawing the limited disapproval of Mississippi's regional haze SIP and replacing the prior limited approval with a full approval of the regional haze SIP as meeting all regional haze requirements of the Clean Air Act (CAA or Act) for the first implementation period. EPA is also approving the Progress Report and associated adequacy determination.

DATES:

This rule is effective November 5, 2021.

ADDRESSES:

EPA has established a docket for this action under Docket Identification No. EPA-R04-OAR-2019-0447. All documents in the docket are listed on the www.regulations.gov website. Although listed in the index, some information may not be publicly available, i.e., Confidential Business Information or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the internet and will be publicly available only in hard copy form. Publicly available docket materials can either be retrieved electronically through www.regulations.gov or in hard copy at the Air Regulatory Management Section, Air Planning and Implementation Branch, Air and Radiation Division, U.S. Environmental Protection Agency, Region 4, 61 Forsyth Street SW, Atlanta, Georgia 30303-8960. EPA requests that if at all possible, you contact the person listed in the FOR FURTHER INFORMATION CONTACT section to schedule your inspection. The Regional Office's official hours of business are Monday through Friday 8:30 a.m. to 4:30 p.m., excluding Federal holidays.

FOR FURTHER INFORMATION CONTACT:

Michele Notarianni, Air Regulatory Management Section, Air Planning and Implementation Branch, Air and Radiation Division, U.S. Environmental Protection Agency, Region 4, 61 Forsyth Street SW, Atlanta, Georgia 30303-8960. Ms. Notarianni can be reached via telephone at [phone] or electronic mail at [e-mail] .

SUPPLEMENTARY INFORMATION:

I. Background

A. Regional Haze

Regional haze is visibility impairment that is produced by a multitude of sources and activities which are located across a broad geographic area and emit fine particulate matter (PM_2.5) ( e.g., sulfates, nitrates, organic carbon, elemental carbon, and soil dust) and their precursors ( e.g., sulfur dioxide (SO₂), nitrogen oxides (NO_X), and in some cases, ammonia (NH₃) and volatile organic compounds (VOC)). Fine particle precursors react in the atmosphere to form PM_2.5 which impairs visibility by scattering and absorbing light. Visibility impairment ( i.e., light scattering) reduces the clarity, color, and visible distance that one can see. PM_2.5 can also cause serious health effects (including premature death, heart attacks, irregular heartbeat, aggravated asthma, decreased lung function, and increased respiratory symptoms) and mortality in humans and contributes to environmental effects such as acid deposition and eutrophication.

In section 169A of the 1977 Amendments to the CAA, Congress created a program for protecting visibility in the nation's 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, anthropogenic impairment of visibility in 156 national parks and wilderness areas designated as mandatory Class I federal areas. Congress added section 169B to the CAA in 1990 to further address regional haze issues, and EPA subsequently promulgated the Regional Haze Rule (RHR).^[1] The RHR established a requirement to submit a regional haze SIP which applies to all 50 states, the District of Columbia, and the Virgin Islands.^[2] Each jurisdiction was required to submit a SIP addressing regional haze requirements for the first implementation period no later than December 17, 2007.^[3]

B. BART

Section 169A of the CAA directs states to evaluate the use of retrofit controls at certain larger, often uncontrolled, older stationary sources in order to address visibility impacts from these sources. Specifically, section 169A(b)(2) of the CAA requires states to revise their SIPs to contain such measures as may be necessary to make reasonable progress towards natural visibility conditions, including a requirement that certain categories of existing major stationary sources built between 1962 and 1977 procure, install, and operate “Best Available Retrofit Technology” as determined by the state. On July 6, 2005, EPA published the Guidelines for BART Determinations Under the Regional Haze Rule at Appendix Y to 40 CFR part 51 (BART Guidelines) to assist states in the BART evaluation process. Under the RHR and the BART Guidelines, the BART evaluation process consists of three steps: (1) An identification of all BART-eligible sources, (2) an assessment of whether the BART-eligible sources are subject to BART, and (3) a determination of the BART controls.^[4] States must conduct BART determinations for all BART-eligible sources that may reasonably be anticipated to cause or contribute to any visibility impairment in a Class I area, or in the alternative, adopt an emissions trading program or other alternative program as long as the alternative provides greater reasonable progress towards improving visibility than BART. In making a BART determination for a fossil fuel-fired electric generating plant with a total generating capacity in excess of 750 megawatts, a state must use the approach set forth in the BART Guidelines. A state is generally encouraged, but not required, to follow the BART Guidelines in other aspects.

On September 22, 2008, Mississippi submitted a SIP revision to address regional haze in Class I areas impacted by emissions from the State and subsequently amended that submittal on May 9, 2011. EPA finalized a limited approval and a limited disapproval of Mississippi's regional haze SIP in June 2012 because of deficiencies in the regional haze SIP arising from the State's reliance on CAIR as an alternative to BART for the State's BART-eligible EGUs.^[5] See 77 FR 38191 (June 27, 2012) (limited approval); 77 FR 33642 (June 7, 2012) (limited disapproval). In the limited disapproval action, EPA did not subject Mississippi to a Federal Implementation Plan (FIP). Mississippi had requested that EPA not issue a FIP and instead provide the State with additional time to correct the deficiencies in its regional haze SIP through a SIP revision.^[6]

Through a letter dated April 23, 2020,^[7] Mississippi submitted a draft SIP revision addressing BART for 14 EGUs formerly subject to CAIR (draft BART SIP) to EPA for parallel processing and provided public notice for comment on the same date. The State's public comment period closed on May 23, 2020. Mississippi submitted its final BART SIP to EPA on August 13, 2020.

C. Regional Haze Progress Report

The RHR requires each state to submit progress reports that evaluate progress towards the RPGs ^[8] for each mandatory Class I area within the state and for each Class I area outside the state which may be affected by emissions from within the state. See 40 CFR 51.308(g). In addition, the provisions of 40 CFR 51.308(h) require each state to submit, at the same time as each progress report, a determination of the adequacy of the state's existing regional haze plan. The first progress report is due five years after submittal of the initial regional haze plan and must be submitted as a SIP revision. Mississippi submitted its progress report for the first implementation period and a determination of the adequacy of the State's existing regional haze plan to EPA on October 4, 2018.^[9]

D. EPA's Notice of Proposed Rulemaking (NPRM)

In a NPRM published on August 4, 2020 (85 FR 47134), EPA proposed to approve Mississippi's draft BART SIP via parallel processing. Contingent on the Agency finalizing its proposal to approve the BART SIP, EPA also proposed to approve the Progress Report under 40 CFR 51.308(g) and the State's determination of adequacy under 40 CFR 51.308(h). The details of these submissions and the rationale for EPA's proposed approval of the two submissions are further explained in the NPRM. Subsequently, Mississippi submitted its final BART SIP on August 13, 2020, and EPA has concluded that there are no significant changes between the draft and final BART SIPs that warrant a different approach at the final rule stage.^[10]

The comment period for the NPRM originally closed on September 3, 2020. EPA reopened the comment period until October 5, 2020, based on a request from Sierra Club for visibility modeling files related to the NPRM and for a 30-day extension.^[11]

II. Response to Comments

EPA received one set of adverse comments from Sierra Club and the National Parks Conservation Association (hereinafter collectively referred to as the “Commenter”) regarding the proposed approval of Mississippi's BART SIP. These comments are included in the docket for this rulemaking. EPA has summarized the comments and provided responses below.^[12]

Comment 1: The Commenter asserts that EPA cannot approve Mississippi's BART SIP because neither the Agency nor the State reviewed the visibility modeling used to exempt every EGU in Mississippi from BART. The Commenter then focuses on Mississippi Power Company—Plant Daniel (Plant Daniel), claiming that EPA admits it has not verified the visibility modeling analyses for this facility and that EPA could not have verified the analyses because the Agency does not possess any of the underlying modeling files. The Commenter also argues that EPA violated CAA section 307(d) by failing to include the modeling files in the rulemaking docket.

Response 1: EPA disagrees with the Commenter. In formulating the NPRM, EPA had received from MDEQ all of the modeling files needed to thoroughly review the visibility modeling analyses for all six operational BART-eligible facilities,^[13] including Plant Daniel, to assess whether these sources are subject to BART. For each facility, EPA reviewed these modeling files as well as the BART exemption modeling report included in the BART SIP, MDEQ's exemption analysis, the modeling protocol for each facility,^[14] and the Visibility Improvement State and Tribal Association of the Southeast (VISTAS) Modeling Protocol.^[15] Based upon EPA's thorough review of these documents and modeling files, the Agency proposed to approve the SIP submission.

The Commenter is correct that EPA does not possess the meteorological data input files (meteorological files) used in the modeling. However, this did not affect EPA's ability to meaningfully review the SIP for several reasons. First, MDEQ provided EPA with all of the other input and output files used in the visibility modeling. The Agency, by analyzing the model input and output files that MDEQ did provide, was able to confirm that the modeling used the correct meteorological data and VISTAS meteorological domain.^[16] Thus, EPA did not need to review the meteorological files.

Second, the meteorological files used here were standard files originally developed for VISTAS. They were used by the states in Region 4 to support their regional haze SIPs during the first implementation period and continue to be used by many facilities in the southeastern United States for major source preconstruction permit modeling. To date, EPA has already approved numerous SIPs relying on the same files. Thus, these were not new data files specifically developed by these BART-eligible sources that would merit additional scrutiny.

Third, to the extent the Commenter thinks that EPA should scrutinize the meteorological files every time it reviews visibility modeling conducted for a haze SIP, EPA disagrees. The Act vests the Agency with discretion in reaching its technical determinations as well as in how to best marshal its limited resources to meet statutory mandates. Based on EPA's long experience with visibility and preconstruction permit modeling, the Agency generally does not believe that re-assessing standard meteorological files every time they are used by a state or source is the best use of scarce Agency resources. Furthermore, the Commenter has not alleged, much less demonstrated, any deficiency with the meteorological files.

EPA also disagrees with Commenter's claim that EPA violated CAA section 307(d) by not placing the modeling files in the docket. To begin with, CAA section 307(d) does not apply to this SIP action at all. See CAA section 307(d)(1) (expressly listing actions to which CAA section 307(d) applies and not including SIPs). Thus, the Commenter's claim lacks merit.

In any event, the Commenter does not and cannot claim any prejudice as a result of the alleged deficiency. EPA did not post the modeling files to the electronic docket for the proposed rulemaking because the majority of these files are a file type that is not on the list of acceptable file types for upload into the Federal Docket Management System (FDMS).^[17] However, the NPRM provided EPA contacts that the public could reach out to for further information, and the Commenter requested the input files for Plant Daniel from the listed EPA contacts during the initial 30-day public comment period. EPA promptly provided the Commenter with all the files in its possession and worked with MDEQ to obtain the meteorological files. Due to the limited amount of time remaining in the comment period after the Commenter received the meteorological files, the Commenter requested an extension of the comment period for an additional 30 days. EPA granted the request, affording the Commenter ample time to review the files and perform its own modeling.^[18]

Comment 2: The Commenter states that EPA cannot approve MDEQ's determination that Plant Daniel is not subject to BART because that determination is based on unenforceable emissions reductions and an unjustified 2015-2018 emissions baseline in lieu of the 2001-2003 baseline the Commenter prefers. The Commenter advances several supporting arguments. First, the Commenter contends that the BART SIP must contain enforceable BART emission limitations for the facility pursuant to CAA sections 110(a)(2) and 110(k)(3), section 51.308(d)(3) of the RHR, and sections IV and V of the BART Guidelines.

Second, citing to section IV.D.4.d of the BART Guidelines, the Commenter asserts that the emissions baseline should represent a realistic depiction of anticipated annual emissions and, if a utility projects that future operating parameters will differ from past practice and the projection has a deciding effect in the BART determination, those operating parameters or assumptions must be enforceable limitations in the SIP. The Commenter then argues that the baseline used in the Plant Daniel BART modeling analysis is improper because it accounts for flue gas desulfurization (FGD) systems on Units 1 and 2 that are not associated with federally enforceable emission limitations commensurate with BART. The Commenter states that MDEQ's email regarding the enforceability of the FGD emissions limitations identified in Plant Daniel's title V permit application is focused solely on SO₂ and is conclusory, vague, unenforceable, and insufficient to create an enforceable emissions limit for determining whether Plant Daniel is subject to BART.

Third, the Commenter further asserts that the baseline used in Plant Daniel's modeling is improper because it is inconsistent with the RHR's provision regarding baseline visibility conditions and the facility's potential emissions. According to the Commenter, the RHR requires states to determine baseline visibility conditions using a 2000-2004 emissions baseline and it is nonsensical to use a baseline from nearly two decades later.

Finally, the Commenter also claims that the 2015-2018 baseline is arbitrary and capricious as it does not realistically depict potential impacts from Plant Daniel because the facility's capacity factor has steadily dropped since 2015. The Commenter argues that the emissions reductions due to this reduced capacity are not enforceable, and therefore, should not serve as the emissions baseline for the purposes of determining whether the facility is subject to BART.

Response 2: EPA disagrees with the Commenter. The CAA, RHR, and BART Guidelines do not require the result the Commenter seeks. Under the CAA's cooperative federalism framework, states have the primary responsibility for implementing federal standards by promulgating SIPs, and EPA must approve SIP revisions that meet CAA requirements. The CAA and RHR require states to classify a BART-eligible source as a BART-subject source if it may reasonably be anticipated to cause or contribute to any impairment of visibility in any mandatory Class I federal area, but they do not set forth any specific, additional criteria for determining whether a source is subject to BART.^[19] For states that do not choose to treat all BART-eligible sources as BART-subject sources, section III of the BART Guidelines provides recommendations on how to determine which BART-eligible sources are subject to BART. The recommendations address, among other things, how to establish a contribution threshold, what kind of modeling to use, how to develop a modeling protocol, and the selection of an emissions baseline for states such as Mississippi that opt to use an individual source attribution approach. They do not, however, recommend or require that the emissions baseline correspond to enforceable limitations.

Here, Mississippi used the 24-hour average actual emission rate from the highest emitting day over a three-year period from 2015 to 2018, after the source installed new control equipment for SO₂ . As explained further below, EPA believes this was a reasonable choice. More generally, EPA has reviewed Mississippi's BART exemption determination for Plant Daniel and concluded that Mississippi reasonably exercised the discretion provided by the CAA and RHR. Therefore, EPA must approve Mississippi's BART SIP revision as it relates to Plant Daniel.^[20]

EPA now addresses and rejects the Commenter's supporting arguments. First, contrary to the Commenter's assertions, the CAA, RHR, and the BART Guidelines do not require a subject-to-BART determination to be based on enforceable emissions limits or reductions. The CAA sections cited by the Commenter are general SIP provisions that do not specifically address subject-to-BART determinations. Section 110(a)(2)(A) generally requires a SIP to contain enforceable limitations and other control measures to meet the applicable requirements of the Act. As the Commenter notes, this obligation only applies with respect to measures that are “necessary or appropriate to meet the applicable requirements” of the Act, but the provision does not otherwise define the scope of the applicable requirements to which it applies.

The portion of sections 110(a)(2)(C) that the Commenter refers to requires states to demonstrate, in developing infrastructure SIPs, that the state has statutes, regulations, or other provisions that provide for the enforcement of emission limitations included in the SIP pursuant to other applicable requirements of the Act.^[21] Similarly, section 110(a)(2)(E) requires that states have adequate personnel, funding, and authority to adequately implement the provisions of the SIP that are included pursuant to other applicable requirements of the Act.^[22] The Commenter has not alleged that the State provides inadequate enforcement or implementation of its existing SIP provisions.

Section 110(k)(3) requires EPA to approve SIP revisions that meet all applicable requirements of the Act, but it also does not define the parameters of the applicable requirements of the Act. In fact, none of these sections address whether SIPs must contain enforceable limits to support subject-to-BART determinations. To the contrary, CAA section 169A(b)(2) directly addresses this issue and requires SIP limits only for BART-eligible sources that “may reasonably be anticipated to cause or contribute to any impairment of visibility” in a Class I area. These sources are “subject to BART.” See 40 CFR 51.308(e)(1)(ii); see also BART Guidelines at section III (providing guidelines for determining which sources are subject to BART). For these sources, the State must conduct a BART determination and impose SIP limits representing BART. See CAA section 169A(b)(2); 40 CFR 51.308(e), (e)(1)(ii). Conversely, a source that is not reasonably anticipated to cause or contribute to visibility impairment is not subject to BART, and there is thus no need for either a BART determination or corresponding enforceable emission limits. As the NPRM and this final rulemaking notice explain, Plant Daniel is not subject to BART, and therefore, does not need enforceable limits that represent BART.

The provisions of the RHR and BART Guidelines cited by the Commenter are also inapplicable because they only address sources that are subject to BART. The Commenter cites generally to 40 CFR 51.308(d)(3), which requires each regional haze SIP to contain a long-term strategy (LTS). The LTS is the compilation of all control measures a state will use during the implementation period of the SIP submittal to meet any applicable RPGs. Although the LTS must include BART emissions limits, Plant Daniel is not subject to BART. Thus, Plant Daniel does not have any BART emissions limits that must be included in the LTS. See 40 CFR 51.308(e), (e)(1)(ii) (requiring limits representing BART only for sources that are subject to BART).

Similarly, the Commenter's reliance on sections IV and V of the BART Guidelines is misplaced. Section IV of the BART Guidelines addresses BART determinations ( i.e., the analysis of BART options for subject-to-BART sources). Section V addresses how enforceable limits reflecting BART are to be established. Both sections, however, deal specifically with sources that are subject to BART. Plant Daniel, as already noted, is not subject to BART, and thus, these sections of the BART Guidelines are inapposite. By contrast, section III, which the Commenter conspicuously neglects to cite, specifically addresses how to determine whether a source is subject to BART and recommends the use of actual, not enforceable, emissions levels.

The Commenter's allegations regarding section IV.D.4.d of the BART Guidelines is misplaced for the same reason. As just explained, that portion of the Guidelines only applies to sources that are subject to BART, and Plant Daniel is not subject to BART. In addition, even if section IV.D.4.d of the BART Guidelines was applicable to subject-to-BART determinations, it would not preclude the baseline approach used for Plant Daniel because that baseline relies on past actual emissions from 2015-2018, not on future operating parameters. See 82 FR 60520, 60533-34 (December 21, 2017) (explaining that use of recent actual emissions data is consistent with BART Guidelines section IV.D.4.d); Nat'l Parks Conservation Ass'n v. EPA, 788 F.3d 1134, 1143 (9th Cir. 2015) (upholding EPA's use of 2008-2010 emissions notwithstanding the lack of corresponding enforceable limitations because they reflected “a realistic depiction of anticipated annual emissions for the source”).

The Commenter's assertion that the Plant Daniel subject-to-BART evaluation must use a 2000-2004 emissions baseline is also based on inapplicable provisions of the RHR. The 2000-2004 period established in 40 CFR 51.308(d)(2)(i) is the baseline for purposes of measuring reasonable progress at Class I areas. Neither the RHR nor the BART Guidelines requires the use of this particular timeframe as the baseline for a subject-to-BART determination.

Finally, EPA disagrees that Mississippi's use of the 2015-2018 baseline for Plant Daniel was arbitrary and capricious. The three-year period relied on by the State, from October 1, 2015, through September 30, 2018, was a reasonable exercise of discretion for three reasons. First, while the Commenter takes issue with the potential for an increased annual capacity factor in the future, the visibility modeling is not based on the annual capacity factor, but rather based on the maximum daily emissions over a three-year time period. The model is run for every day over a three-year period using the same maximum day emissions. Based on these daily model results, the model estimates the 98th percentile highest visibility impacts for each year. Then, the highest of the three yearly 98th percentile impacts, or the 22nd highest visibility impact over the three years, whichever is more conservative, is compared to the state's BART contribution threshold, which is 0.5 dv for Mississippi. Since the highest daily emissions are used for each day in the modeling, the Commenter fails to allege how an increase in capacity factor here would affect the maximum daily emissions or the visibility modeling results. In any event, the Commenter's suggestion that emissions might increase in the future is beside the point; as already noted, the BART Guidelines specifically recommend the use of past actual emissions data.

Second, the emissions data used was from the most recent three years when the modeling was conducted. That is, the source did not cherry pick data from three years of low emissions, but simply used the most recent data from after the FGD was installed and operating.

Third, prior to the start of the modeled period, the facility had installed control equipment for the purposes of complying with legal requirements outside of the regional haze program. Specifically, Plant Daniel installed low NO_X burners on Units 1 and 2 in 2008 and 2010, respectively, to ensure compliance with CAIR,^[23] and later installed FGD on these units in 2015 to comply with EPA's Mercury and Air Toxics Standards (MATS). Plant Daniel's federally-enforceable title V permit ^[24] requires compliance with MATS ^[25] and applicable New Source Performance Standard (NSPS) ^[26] emissions limits for SO₂ , and Acid Rain Program ^[27] and applicable NSPS ^[28] emissions limits for NO_X .^[29] The operation of the above equipment has resulted in significant emissions reductions that reduced visibility impacts at the Breton Wilderness Area (Breton). The State chose to use an emissions baseline with data beginning shortly after the most recent emission control equipment, FGD, was installed. EPA is, moreover, not aware of evidence that any of these controls will be removed in the future.

Given the above facts, EPA believes the State's decision to use the more recent baseline was reasonable. Cf. Nat'l Parks Conservation Ass'n v. EPA, 788 F.3d 1134, 1143 (9th Cir. 2015) (approving EPA's decision to rely on a more recent, albeit unenforceable, emissions baseline in determining BART where there was “no reason to believe that [the source] would change course and remove the additional combustion controls it had already installed”).

Comment 3: The Commenter contends that the modeling underlying the Plant Daniel BART exemption analysis demonstrates that the source should be subject to BART using a corrected emissions baseline. The Commenter asserts that Plant Daniel excluded several days in May and November 2017 with high SO₂ emissions from the emissions baseline on the grounds that they were attributable to startup, shutdown, and malfunction (SSM) events. The Commenter claims that these days should have been included in the modeling baseline because they are not associated with SSM events and are not identified in the facility's MATS compliance reports.

The Commenter conducted its own BART exemption modeling for Units 1 and 2 at Plant Daniel using emissions input data from 2015-2018 that includes the excluded days. Using the revised emissions input data, the existing modeling protocol, and the 2001-2003 meteorological modeling inputs, the Commenter's revised CALPUFF modeling predicts that the visibility impact at Breton from Units 1 and 2 at Plant Daniel using the 8th highest (98th percentile) day is 0.55 dv, exceeding Mississippi's 0.5 dv subject-to-BART contribution threshold. According to the Commenter, the modeling results also show that visibility impairment due to Plant Daniel during most of the high impact days is dominated by nitrates which underscores the need to evaluate NO_X BART for the facility. The Commenter also ran the model using emissions from 2001-2003 and concluded that the modeled visibility impact using the 8th highest day from Units 1 and 2 exceeds 2.5 dv at Breton.

Response 3: EPA does not agree that the emissions baseline used in the BART modeling needs to be corrected as suggested by the Commenter. Although the Commenter is correct that certain excluded high-emission days were not associated with SSM, the State nonetheless reasonably excluded these days because they did not “reflect steady-state operating conditions during periods of high capacity utilization.” ^[30] Rather, the source was temporarily testing new coal blends on these days, and thus, experienced atypical and higher than normal emissions during this time.^[31]

Regarding the excluded days in May and November 2017 referenced by the Commenter, the BART SIP does not identify these dates as SSM. The BART modeling protocol for Plant Daniel, located in Appendix L.3.2 of the BART SIP, states that the modeled emissions excluded “startup, shutdown, or other nonrepresentative operations, etc.” as identified in Appendix E of the protocol. Table E-1 of the protocol, titled “Summary of Days with Nonrepresentative Emissions,” lists the days between October 1, 2015, to September 30, 2018, with periods of nonrepresentative operations and describes the nature of the operations. Dates associated with startups, malfunctions, and shakedowns are marked accordingly whereas the operations on the excluded days in May and November 2017 are described as “test burn/additional FGD pumps not in operation” or “test burn/OFA damper not tuned” (test burn days).^[32]

EPA obtained clarification from Mississippi Power via MDEQ that the company excluded the test burn days in May and November 2017 from the model because they represent atypical operations, not SSM.^[33] On the days in Table E-1 marked with a test burn entry, Plant Daniel tested blending Powder River Basin subbituminous coal with Illinois Basin bituminous coal to determine the effects of the test coal blends on boiler operations and auxiliary equipment. In order to obtain baseline data on the impacts of these test coal blends on unit operations, Plant Daniel did not optimize the boiler, the emission controls, and the auxiliary equipment for extended operation with these test blends. If Plant Daniel were to use the test coal blends as part of normal operations, the source avers that the boiler and auxiliary equipment would be tuned appropriately, resulting in lower SO₂ and NO_X emission rates than those experienced during the tests.

The Commenter correctly noted that the source also did not identify these days on its MATS compliance reports as test burn days. The MATS compliance reporting asks facilities to answer, “Did the facility burn new types of fuel during the reporting period?” and the source answered “No.” This was because there was no change in fuel type. MATS defines “fuel type” as “each category of fuels that share a common name or classification” ( e.g., bituminous coal, subbituminous coal); ^[34] Plant Daniel burns a blend of bituminous (West Elk) and subbituminous (Powder River Basin) coal during normal operations; ^[35] and the facility burned a blend of the same fuel types—bituminous and subbituminous coal—on the test burn days. In other words, although the source changed the coal blend it burned, it did not change the “fuel type” as defined by MATS.

Excluding the test burn days from the BART exemption modeling is consistent with the BART Guidelines and the VISTAS BART Modeling Protocol because they do not represent normal operations. The BART Guidelines state that “emissions estimates used in the models are intended to reflect steady-state operating conditions during periods of high capacity utilization.” ^[36] Although the Guidelines go on to specifically discourage the use of emissions reflecting SSM, SSM is only one example of an event that does not represent steady-state operating conditions where “such emission rates could produce higher than normal effects than would be typical of most facilities.” Further, the VISTAS BART Modeling Protocol states that “source emissions should be defined using the maximum 24-hour actual emission rate during normal operation for the most recent 3 or 5 years” for CALPUFF modeling.^[37] The Plant Daniel modeling protocol in Appendix L.3.2 of the BART SIP explains that the modeling excluded the days identified in Table E-1 pursuant to the BART Guidelines because those days included periods of nonrepresentative operations.^[38] Based on the information submitted by Plant Daniel and MDEQ, EPA believes that MDEQ reasonably concluded that the test burn days do not represent steady-state operations, and thus, appropriately excluded them from the modeling analysis consistent with EPA's BART Guidelines and the VISTAS BART Modeling Protocol.

Regarding the Commenter's assertion that modeled visibility impairment due to Plant Daniel at Breton is dominated by nitrates which underscores the need to evaluate NO_X BART, the dominance of one visibility impairing pollutant over another at a Class I area is irrelevant to a subject-to-BART determination. If the total modeled visibility impairment from a source due to NO_X, SO₂, and PM combined meets or exceeds Mississippi's BART contribution threshold, the source is subject-to-BART. In this instance, MDEQ determined that Plant Daniel is not subject-to-BART based on modeling the visibility impacts of all three pollutants (including NO_X), and therefore, no BART determination is required for NO_X, SO₂ , or PM.^[39]

Regarding the Commenter's use of a 2001-2003 baseline emissions period, EPA disagrees that the State was required to use that specific period for modeling visibility impacts. The State reasonably determined that the facility's use of the 2015-2018 updated baseline period reflecting operation of new SO₂ and NO_X controls is appropriate, as discussed in Response 2.

Comment 4: The Commenter claims that although Plant Daniel is regularly able to achieve SO₂ emission rates as low as 0.03 lbs/MMBtu, spikes up to 0.6 to 0.8 lbs/MMBtu indicate that the facility operates its FGD systems periodically or inefficiently. According to the Commenter, the spikes appear to be the result of occasional scrubber bypass and an unlawful failure to impose a federally enforceable requirement to continually achieve an emissions limit commensurate with BART.

Response 4: As discussed in the NPRM and this notice, Plant Daniel is not subject to BART, and therefore, no BART emissions limits are required. Furthermore, as discussed in Responses 2 and 3, Mississippi reasonably exercised its discretion in selecting the 2015-2018 baseline for the subject-to-BART modeling for Plant Daniel and excluding the spikes associated with the test burn days. EPA has nonetheless evaluated the Commenter's assertions that Plant Daniel is experiencing spikes in its SO₂ emission rates due to alleged scrubber inefficiency or intermittent scrubber operation.

The majority of the spikes shown in Figure 2 of the Commenter's October 5, 2020, submission occurred after the baseline period ended on September 30, 2018.^[40] EPA requested supplemental information from MDEQ regarding these post-baseline period spikes, and in response, Mississippi Power explained that the spikes beginning in the third quarter of 2018 do not reflect actual SO₂ emissions because they are the result of data substitution in accordance with 40 CFR 75.33 and Appendix A to 40 CFR part 75 (Specifications and Test Procedures) due to FGD bypasses during malfunction/emergency events.^[41] The bypasses were infrequent (less than one percent of unit operating time) and short in duration (less than two hours). Due to the short duration of each bypass, the bypass continuous emission monitoring system (CEMS) did not have time to calibrate and provide valid emissions data. A combination of short duration events beginning in September 2018 and associated CEMS data invalidation resulted in CEMS availability dropping below 90 percent, triggering data substitution requirements under Part 75. Part 75 requires data to be substituted at the maximum potential concentration when CEMS availability is less than 90 percent, resulting in the spikes shown on Figure 2 beginning in the third quarter of 2018.^[42] Mississippi Power affirmed in its response that it operates the FGD systems efficiently and at all times, except during SSM events,^[43] and notes that MATS requires continuous operation of the FGD system.^[44]

Comment 5: The Commenter argues that Mississippi's BART SIP arbitrarily fails to address BART for NO_X emissions from EGUs and that the State cannot rely on CSAPR as a BART alternative. The Commenter claims that Mississippi has not corrected its SIP to formally adopt CSAPR in lieu of source-specific BART for NO_X emissions so that it could rely on CSAPR as a BART alternative and claims that CSAPR is not a valid BART alternative for the following reasons. First, Mississippi cannot exempt Plant Daniel from NO_X BART without going through the BART exemption process, the State has not demonstrated that Plant Daniel meets the BART exemption requirements, and the State has not obtained the concurrence of the Federal Land Managers (FLMs) to exempt the source from BART. Second, the CSAPR “Better than BART” (CSAPR BTB) rule is flawed because it evaluated CSAPR allocations that are more stringent than now required, used presumptive BART limits that are less stringent than required under the statute, and failed to account for uncertainties in emissions reductions under CSAPR. Third, the CSAPR BTB rule is no longer valid given the substantial changes in CSAPR allocations and compliance deadlines, including the United States Court of Appeals for the District of Columbia Circuit's (D.C. Circuit's) 2015 invalidation of certain states' emission budgets and EPA's withdrawal of Texas from the CSAPR trading program. Fourth, NO_X emissions from Mississippi's EGUs are only covered by CSAPR during the ozone season, and therefore, CSAPR does not protect Breton and other Class I areas during the remaining seven months of the year. The Commenter attached comments submitted by Earthjustice, National Parks Conservation Association, and Sierra Club on the CSAPR BTB rule.

Response 5: Mississippi did not rely on CSAPR BTB in its SIP submission, nor does EPA rely on CSAPR BTB in the Agency's approval. Therefore, all comments addressing the State's or EPA's application of CSAPR BTB in this SIP action are incorrect. Moreover, EPA did not purport to revisit CSAPR BTB in this action. All comments generally addressing the validity of CSAPR BTB are therefore beyond the scope. EPA notes that the Commenter's general claims regarding CSAPR BTB have been and are being addressed in separate proceedings.^[45] Finally, to the extent the Commenter is asserting that the sole mechanism by which Plant Daniel can be exempted from BART is under CAA section 169A(c), that is incorrect. See Am. Corn Growers Ass'n v. EPA, 291 F.3d 1, 8 (D.C. Cir. 2002) (rejecting this argument). The subject-to-BART assessment provides a separate method for exempting BART-eligible sources such as Plant Daniel.

III. Final Action

Based on the rationale articulated in the NPRM and in this final rule, EPA is approving the August 13, 2020, BART SIP and finds that it corrects the deficiencies that led to the limited approval and limited disapproval of the State's regional haze SIP. EPA is therefore withdrawing the limited disapproval of the regional haze SIP and replacing the prior limited approval with a full approval of the regional haze SIP as meeting all regional haze requirements of the CAA for the first implementation period. EPA is also approving Mississippi's October 4, 2018, Progress Report as meeting the applicable regional haze requirements set forth in 40 CFR 51.308(g) and the State's determination of adequacy under 40 CFR 51.308(h).

IV. 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. See 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to approve state choices, provided that they meet the criteria of the CAA. These actions merely approve state law as meeting Federal requirements and do not impose additional requirements beyond those imposed by state law. For that reason, these actions:

• Are not significant regulatory actions 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);

• Do not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq. );

• Are 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. );

• Do 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);

• Do not have Federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);

• Are not economically significant regulatory actions based on health or safety risks subject to Executive Order 13045 (62 FR 19885, April 23, 1997);
• Are not significant regulatory actions subject to Executive Order 13211 (66 FR 28355, May 22, 2001);
• Are 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
• Do not provide EPA with the discretionary authority to address, as appropriate, disproportionate human health or environmental effects, using practicable and legally permissible methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).

The SIP is not approved to apply on any Indian reservation land or in any other area where EPA or an Indian tribe has demonstrated that a tribe has jurisdiction. In those areas of Indian country, the rule does not have tribal implications as specified by Executive Order 13175 (65 FR 67249, November 9, 2000), nor will it impose substantial direct costs on tribal governments or preempt tribal law.

The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the Small Business Regulatory Enforcement Fairness Act of 1996, generally provides that before a rule may take effect, the agency promulgating the rule must submit a rule report, which includes a copy of the rule, to each House of the Congress and to the Comptroller General of the United States. EPA will submit a report containing these actions and other required information to the U.S. Senate, the U.S. House of Representatives, and the Comptroller General of the United States prior to publication of the rule in the Federal Register . A major rule cannot take effect until 60 days after it is published in the Federal Register . These actions are not a “major rule” as defined by 5 U.S.C. 804(2).

Under section 307(b)(1) of the CAA, petitions for judicial review of these actions must be filed in the United States Court of Appeals for the appropriate circuit by December 6, 2021. Filing a petition for reconsideration by the Administrator of this final rule does not affect the finality of these actions for the purposes of judicial review nor does it extend the time within which a petition for judicial review may be filed and shall not postpone the effectiveness of such rule or action. These actions may not be challenged later in proceedings to enforce its requirements. See section 307(b)(2).

List of Subjects in 40 CFR Part 52

• Environmental protection
• Air pollution control
• Incorporation by reference
• Intergovernmental relations
• Nitrogen dioxide
• Particulate matter
• Reporting and recordkeeping requirements
• Sulfur oxides

Dated: September 29, 2021.

John Blevins,

Acting Regional Administrator, Region 4.

40 CFR part 52 is amended 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 Z—Mississippi

2. In § 52.1270 amend the table in paragraph (e) by adding entries for “Regional Haze Progress Report” and “BART SIP” at the end of the table to read as follows:

§ 52.1270

Identification of plan.

* * * * *

(e) * * *

EPA Approved Mississippi Non-Regulatory Provisions

Name of non-regulatory SIP provision	Applicable geographic or nonattainment area	State submittal date/effective date	EPA approval date	Explanation
*         *         *         *         *         *         *
Regional Haze Progress Report	Mississippi	10/4/2018	10/6/2021, [Insert citation of publication]
BART SIP	Mississippi	8/13/2020	10/6/2021, [Insert citation of publication]

§ 52.1279

[Amended]

3. Section 52.1279 is amended by removing and reserving paragraph (a).

Footnotes

1.   See 64 FR 35713 (July 1, 1990).

2.   See 40 CFR 51.300(b).

3.   See 40 CFR 51.308(b).

4.   See 40 CFR 51.308(e); BART Guidelines, section I.F.

5.  The State's analysis of reasonable progress controls was not dependent on CAIR, and thus, was not affected by CAIR's invalidation. See 77 FR 11879, 11888 (February 28, 2012) (finding that no controls were necessary for reasonable progress given the areas of influence and consultation with neighboring states).

6.   See 77 FR 33654.

7.  EPA received MDEQ's April 23, 2020, draft BART SIP on April 24, 2020.

8.  An RPG is a visibility goal for a Class I area, in deciviews (dv), as of the end of an implementation period, that provides for reasonable progress towards achieving natural visibility conditions. There are two RPGs for each Class I area for an implementation period: one for the most impaired days and one for the clearest days.

9.  EPA received Mississippi's Progress Report on October 15, 2018.

10.  The changes between the draft and final BART SIP submissions include: Different transmittal letters, proof of adoption in the final BART SIP dated August 13, 2020, and the addition of Appendix M: Comments and Responses to provide a summary of responses to public comments and EPA's comments. In response to EPA comments, MDEQ made changes which expanded on Appendix R in the Table of Contents, clarified the emissions units in Table 2, updated the values in Table L.2.3, and added the source of the data used in Tables L.2.2, L.5.2, L.6.2, and L.7.2. The final BART SIP satisfies the completeness criteria in 40 CFR part 51, Appendix V.

11.   See 85 FR 58319 (September 18, 2020).

12.  EPA did not receive any adverse comments on the Agency's proposed approval of the Progress Report.

13.  The BART-eligible emissions units at Cooperative Energy (formerly South Mississippi Electric Power Association)—Plant Morrow (Plant Morrow) were permanently retired on November 17, 2018; therefore, MDEQ did not perform visibility modeling analyses for the facility. See Appendix L.4 of the BART SIP.

14.  The modeling protocols for each of the six operational facilities are included in Appendix L of the BART SIP.

15.  The VISTAS states, including Mississippi, developed a “Protocol for the Application of CALPUFF for BART Analyses” (VISTAS BART Modeling Protocol). Mississippi, in coordination with VISTAS, used this modeling protocol to apply CALPUFF to determine whether individual sources in Mississippi were subject to BART. The VISTAS BART Modeling Protocol, December 22, 2005, Revision 3.2 (August 31, 2006), is included in Appendix L.8 of the BART SIP. EPA approved Mississippi's use of this modeling protocol in 2012. See 77 FR 11879, 11888-89 (February 28, 2012) (proposal) and 77 FR 38191 (June 27, 2012) (final).

16.  One of the CALPUFF model output files identifies, among other things, the names of the meteorological data files, format of the files (binary), data years, coordinate system, meteorological grid cell spacing (four kilometers as specified by the VISTAS modeling protocol), and the number of vertical layers used in the meteorological input files.

17.  There are two files related to the BART SIP modeling that are technically compatible with FDMS (which is the interface for federal employees to upload files to display at www.regulations.gov ) but were not posted to the electronic docket. EPA did not upload these two files to FDMS because they are integral to the entire set of modeling files and therefore are maintained with the remaining modeling files. The Agency's management of the BART SIP modeling files is consistent with Region 4's standard practice.

18.   See 85 FR 58319 (September 18, 2020). The Commenter did not allege any errors in the modeling input files other than the NO_X and SO₂ emission rates and used all of the input files (with revisions to the NO_X and SO₂ emissions rates as noted in Exhibit A to its comments) in its modeling. The NO_X and SO₂ emissions rates, moreover, were included in Appendix L.3 of the BART SIP which was part of the docket at the time of the proposal. See also Comments and Responses 2 and 3 for additional information and analysis regarding the NO_X and SO₂ emissions rates.

19.   See CAA section 169A; 40 CFR 51.308(e).

20.  EPA generally treats all of the Commenter's comments regarding the subject-to-BART determinations as going to the application of the CAA, RHR, and BART Guidelines in this SIP action. To the extent the Commenter is trying to collaterally attack the RHR or BART Guidelines themselves, those challenges are all beyond the scope of this rulemaking. See Sierra Club v. EPA, 939 F.3d 649, 678-79 (5th Cir. 2019), reh'g denied (Dec. 9, 2019).

21.  Memorandum from Stephen D. Page, Director of Office of Air Quality Planning and Standards, to Regional Air Directors, Regions 1-10, “Guidance on Infrastructure State Implementation Plan (SIP) Elements under Clean Air Act Sections 110(a)(1) and 110(a)(2),” pp. 23-24 (Sept. 13, 2013).

22.   Id. at pp. 39-44. The Commenter's citation to the language from section 110(a)(2)(E) requiring the State to bear “responsibility for ensuring adequate implementation” of the SIP is particularly inapt as that language refers to specific circumstances where the state relies on a local or regional government, agency, or instrumentality for the implementation of a particular SIP provision. The Commenter has not alleged that the State has abdicated this responsibility in any way.

23.  See the Prevention of Significant Determination permit applications dated May 4, 2009, and January 22, 2008, for Plant Daniel Units 1 and 2, respectively, at page 1 of the “APPLICATION OVERVIEW” section (page 3 of the pdf file) for each application. These applications are included in the docket for this rulemaking.

24.  MDEQ issued a title V permit to Plant Daniel containing MATS limits on December 31, 2020, after publication of the NPRM. See State of Mississippi Air Pollution Control Title V Permit No. 1280-00090 (Plant Daniel Title V Permit) which is included in the docket for this rulemaking. The Commenter's arguments regarding the enforceability of the title V permit application are therefore moot.

25.  The permit requires compliance with a SO₂ alternative emissions limit under MATS for hydrochloric acid of 0.20 pounds of SO₂ per million British thermal units (lbs/MMBtu) (input based) or 1.5 lbs/megawatt-hour (output based) (rolling 30-boiler operating day average) for Units 1 and 2. See Plant Daniel Title V Permit Section 3.B.11 (citing 40 CFR 63.9991(a)(1), 63.10000(a) and (b), and Table 2, subpart UUUUU).

26.  The permit requires compliance with a SO₂ limit of 1.2 lbs/MMBtu heat input when firing coal alone or with wood residue or a ≤ng/J value obtained from the equation in Condition 3.B.8 when firing a combination of fuels (rolling 3-hour average) for Units 1 and 2. See id. at Section 3.B.8 (citing 40 CFR 60.43(a)(2) and (b), subpart D). The permit also requires compliance with the applicable requirements of 40 CFR part 60, subparts A and D regarding SO₂ (Section 3.B.5) and SO₂ allowances for Units 1 and 2 under the Acid Rain Program (Sections 3.B.35, 8, and Appendix C (citing 40 CFR parts 72-78)).

27.  Under the permit's Acid Rain Program conditions, NO_X emissions from Units 1 and 2 shall not exceed the annual average alternative contemporaneous emission limitation of 0.45 lbs/MMBtu, Unit 1 has an annual heat input limit of 20,000,000 MMBtu, and Unit 2 has an annual heat input limit of 15,000,000 MMBtu. See id. at Sections 3.B.35, 8, and Appendix C (citing 40 CFR parts 72-78).

28.  The permit requires compliance with a NO_X (expressed as nitrogen dioxide) limit of 0.70 lbs/MMBtu heat input when firing coal alone or with wood residue or ≤ng/J value obtained from the equation in Condition 3.B.9 when firing a combination of fuels (rolling 3-hour average) for Units 1 and 2. See id. at Section 3.B.9 (citing 40 CFR 60.44(a)(3) and (b), subpart D). The permit also requires compliance with the applicable requirements of 40 CFR part 60, subparts A and D regarding NO_X . See id. at Section 3.B.5.

29.  The permit also requires compliance with the Cross-State Air Pollution Rule (CSAPR) NO_X Ozone Group 2 Trading Program. See id. at Sections 3.B.36 and 9.

30.   See BART Guidelines, section III.

31.  See the file named “Plant Daniel Regional Haze BART Info Request-Response” (Plant Daniel Information Response) attached to MDEQ's December 9, 2020, email to EPA. The email and attachment are included in the docket for this rulemaking.

32.   See Appendix L.3.2.3 at p. E-2. Table E-1 on p. E-2 does not include August 22, 2018, where data was substituted for two hours (8:00-9:00 p.m. and 10:00-11:00 p.m.) for Unit 1. According to EPA's Field Audit Checklist Tool ( https://www.epa.gov/​airmarkets/​field-audit-checklist-tool-fact ) these hours were associated with startup.

33.  See Plant Daniel Information Response.

34.   See 40 CFR 63.10042 (“Fuel type means each category of fuels that share a common name or classification. Examples include, but are not limited to, bituminous coal, subbituminous coal, lignite, anthracite, biomass, and residual oil. Individual fuel types received from different suppliers are not considered new fuel types.”).

35.  The MATS compliance reports provided by the Commenter list bituminous and subbituminous coal and No. 2 fuel oil as the fuels burned in Units 1 and 2.

36.   See BART Guidelines, Section III.A.3 (emphasis added) (discussing the kind of modeling used to determine which sources and pollutants need not be subject to BART).

37.   See VISTAS BART Modeling Protocol at p. S-3 (emphasis added) and p. 43.

38.   See Appendix L.3.2.3 at p. E-2. The protocol also states that a total of 25 out of 834 days (2.9 percent) were excluded for SO₂ and 6 out of 834 days (0.7 percent) were excluded for NO_X . Id.

39.  EPA notes that the 2009-2018 IMPROVE monitoring data indicates that sulfates are the predominant pollutant at Breton on the most impaired days. For example, for the period 2014-18, the most recent 5-year period with available data, sulfates accounted for approximately 64 percent of the visibility impairment at Breton on the most impaired days whereas nitrates accounted for only approximately 10 percent of the impairment. This data is available at http://vista.cira.colostate.edu/​Improve/​ .

40.  The spikes in Figure 2 that occurred during the baseline period and are associated with nonrepresentative emissions are explained in Table E-1 of the Plant Daniel BART Modeling Protocol with the exception of the spikes on August 22, 2018, where the facility substituted data for two hours at 8:00-9:00 p.m. and 10:00-11:00 p.m. for Unit 1 due to startup. As discussed in Response 3, Table E-1 identifies days with nonrepresentative emissions associated with SSM and test burns. The table also identifies days with nonrepresentative emissions associated with the shakedown of the FGD systems. Control system shakedowns occur over a limited period of time following installation and, among other things, are used to identify any potential installation problems and to ensure that the new system is operating properly. Therefore, the shakedowns identified in Table E-1 are not evidence of inefficient or routine FGD operation.

41.   See Plant Daniel Information Response.

42.   See 40 CFR part 75, Appendix A, Section 2.1— Instrument Span and Range.

43.  Elsewhere, Mississippi Power also acknowledges that it did not optimize its scrubber operation on test burn days in order to determine the effects of test coal blends on facility operations. See Response 3.

44.  The MATS rule requires continuous operation of the FGD system if the source chooses to comply with the SO₂ surrogate standard. See 40 CFR 63.9991(c)(2). See generally 40 CFR Subpart UUUUU.

45.   See, e.g., Nat'l Parks Conservation Ass'n v. EPA, Nos. 17-1253, 20-1341 (D.C. Cir.); 82 FR 45481 (September 29, 2017) (2017 rule affirming that CSAPR remains better-than-BART after the changes made to CSAPR's geographic scope due to the 2015 D.C. Circuit decision cited by the Commenter); EPA's June 29, 2020, denial of the Commenter's petition for reconsideration of the 2017 Rule, available at https://www.epa.gov/​sites/​production/​files/​2020-06/​documents/​csapr_​btb_​petition_​denial_​sierra_​club_​06-29-20.pdf and https://www.epa.gov/​sites/​production/​files/​2020-06/​documents/​csapr_​btb_​petition_​denial_​npca_​06-29-20_​0.pdf .