2024-18495. Air Plan Approval; North Carolina; Second Period Regional Haze Plan

Table 1—Baseline, Current, and Natural Visibility Conditions in North Carolina's Class I Areas in Deciviews ( dv )

Class I area	Baseline 20% clearest days	Baseline 20% most impaired days	Current 20% clearest days	Current 20% most impaired days	Natural 20% clearest days	Natural 20% most impaired days
Great Smoky Mountains	13.58	29.11	8.35	17.21	4.62	10.05
Joyce Kilmer	13.58	29.11	8.35	17.21	4.62	10.05
Linville Gorge	11.11	28.05	7.61	16.42	4.07	9.70
Shining Rock	7.70	28.13	4.40	15.49	2.49	* 10.25
Swanquarter	12.34	23.79	10.61	16.30	5.71	* 10.01
* The 2022 Plan indicates in Table Ex-1-3 and Table 8-1 that natural conditions are 10.01 and 9.79 deciviews for Shining Rock and Swanquarter, respectively. Tables Ex-1-1, Table 2-2, and Tables 2-6 reflect the correct values shown here which are derived from EPA's June 3, 2020, Technical Addendum available at: https://www.epa.gov/​sites/​default/​files/​2020-06/​documents/​memo_​data_​for_​regional_​haze_​technical_​addendum.pdf.

Table 2—Actual Progress for Visibility Conditions in North Carolina's Class I Areas in Deciviews ( dv )

Class I area	Current minus baseline for 20% clearest days	Current minus baseline for 20% most impaired days	Natural minus current for 20% clearest days	Natural minus current for 20% most impaired days
Great Smoky Mountains	−5.23	−11.90	−3.73	−7.16
Joyce Kilmer	−5.23	−11.90	−3.73	−7.16
Linville Gorge	−3.50	−11.63	−3.54	−6.72
Shining Rock	−3.30	−12.64	−1.91	−5.24
Swanquarter	−1.73	−7.49	−4.90	−6.29

Additionally, Figures 3-1, 3-2, 3-3, and 3-4 of the 2022 Plan provide the URP figures for the 20 percent most impaired days for Great Smoky Mountains (which also represents the URP for Joyce Kilmer), Linville Gorge, Shining Rock, and Swanquarter, respectively. The URPs were developed using EPA guidance ^[49] and used data collected from the IMPROVE monitoring network which is used to measure visibility impairment caused by air pollution at the 156 Class I areas covered by the visibility program. All North Carolina Class I areas are projected to be below the 2028 URP values for the second planning period based on VISTAS' modeling.

3. EPA Evaluation: EPA finds that North Carolina's Haze Plan meets the requirements of 40 CFR 51.308(f)(1) because the State provided for its five Class I areas: baseline, current, and natural visibility conditions for the 20 ( print page 67353) percent clearest days and most impaired days; progress to date for the 20 percent clearest days and most impaired days; differences between the current visibility conditions and natural visibility conditions; and the URP for each Class I area in North Carolina. Therefore, EPA is proposing to approve the portions of the North Carolina SIP submission related to 40 CFR 51.308(f)(1).

C. LTS for Regional Haze

1. RHR Requirement: Each state having a Class I area within its borders or emissions that may affect visibility in a Class I area must develop a LTS for making reasonable progress toward the national visibility goal. CAA 169A(b)(2)(B). As explained in Section II of this document, reasonable progress is achieved when all states contributing to visibility impairment in a Class I area are implementing the measures determined—through application of the four statutory factors to sources of visibility impairing pollutants—to be necessary to make reasonable progress. 40 CFR 51.308(f)(2)(i). Each state's LTS must include the enforceable emission limitations, compliance schedules, and other measures that are necessary to make reasonable progress. 40 CFR 51.308(f)(2). All new ( i.e., additional) measures that are the outcome of FFAs are necessary to make reasonable progress and must be in the LTS. If the conclusion of a FFA and other measures necessary to make reasonable progress for a particular source is that no new measures are reasonable, that source's existing measures are necessary to make reasonable progress, unless the state can demonstrate that the source will continue to implement those measures and will not increase its emission rate. Existing measures that are necessary to make reasonable progress must also be in the LTS. In developing its LTS, a state must also consider the five additional factors in 40 CFR 51.308(f)(2)(iv). As part of its reasonable progress determinations, the state must describe the criteria used to determine which sources or group of sources were evaluated ( i.e., subjected to FFA) for the second planning period and how the four factors were taken into consideration in selecting the emission reduction measures for inclusion in the LTS. 40 CFR 51.308(f)(2)(iii).

States may rely on technical information developed by the RPOs of which they are members to select sources for FFA and to satisfy the documentation requirements under 40 CFR 51.308(f). Where an RPO has performed source selection and/or FFAs (or considered the five additional factors in 40 CFR 51.308(f)(2)(iv)) for its member states, those states may rely on the RPO's analyses for the purpose of satisfying the requirements of 40 CFR 51.308(f)(2)(i) so long as the states have a reasonable basis to do so and all state participants in the RPO process have approved the technical analyses. 40 CFR 51.308(f)(3)(iii). States may also satisfy the requirement of 40 CFR 51.308(f)(2)(ii) to engage in interstate consultation with other states that have emissions that are reasonably anticipated to contribute to visibility impairment in a given Class I area under the auspices of intra- and inter-RPO engagement.

The consultation requirements of 40 CFR 51.308(f)(2)(ii) provide that states must consult with other states that are reasonably anticipated to contribute to visibility impairment in a Class I area to develop coordinated emission management strategies containing the emission reductions measures that are necessary to make reasonable progress. Section 51.308(f)(2)(ii)(A) and (B) require states to consider the emission reduction measures identified by other states as necessary for reasonable progress and to include agreed upon measures in their SIPs, respectively. Section 51.308(f)(2)(ii)(C) speaks to what happens if states cannot agree on what measures are necessary to make reasonable progress. The documentation requirement of 40 CFR 51.308(f)(2)(iii) provides that states may meet their obligations to document the technical bases on which they are relying to determine the emission reductions measures that are necessary to make reasonable progress through an RPO, as long as the process has been “approved by all State participants.”

Section 51.308(f)(2)(iii) also requires that the emissions information considered to determine the measures that are necessary to make reasonable progress include information on emissions for the most recent year for which the state has submitted triennial emissions data to the EPA (or a more recent year), with a 12-month exemption period for newly submitted data.

2. State Assessment: To develop North Carolina's LTS, DAQ set criteria to identify sources to evaluate for potential controls using the four factors outlined in Section II.B, selected sources based on those criteria, considered the four factors for the selected sources, provided emissions limits and supporting conditions for adoption into the regulatory portion of the SIP, and evaluated the five additional factors at 40 CFR 51.308(f)(2)(iv).

a. Source Selection Criteria: With respect to 40 CFR 51.308(f)(2)(i), North Carolina, through VISTAS, used a two-step source selection process: (1) Area of Influence (AoI) analysis, and (2) PSAT ^[50] modeling for sources exceeding an AoI threshold.^[51] North Carolina considered the four factors for sources that exceeded both the AoI and PSAT thresholds. Both sulfates and nitrates were considered in the source selection process. To identify sources having the most impact on visibility at Class I areas for PSAT modeling, DAQ used an AoI threshold of greater than or equal to three percent for sulfate and nitrate combined at any North Carolina Class I area for all sources within and outside of the State. Sources which exceeded North Carolina's AoI threshold are listed in Tables 7-20 through 7-24 of the Haze Plan. Of these sources, five sources in North Carolina exceeded the AoI threshold for any Class I area in the State: Blue Ridge Paper Products—Canton Mill (BRPP); Domtar Paper LLC (Domtar); ^[52] Duke Energy Carolinas LLC (DEC)—Marshall Steam Station (DEC-Marshall); PCS Phosphate Inc.—Aurora (PCS); and SGL Carbon LLC.^[53]

North Carolina, in coordination with the other VISTAS states, set a PSAT threshold of greater than or equal to one percent for sulfate or nitrate. Sources identified based on the State's PSAT threshold are listed in Tables 7-36, 7-37, and 7-38 of the 2022 Plan. Of the 19 sources that exceeded the sulfate PSAT threshold, 16 sources are located in 10 other states and three are located in North Carolina. North Carolina selected the three in-state sources ( print page 67354) (BRPP, Domtar, and PCS) for an emissions control analysis.^[54] The projected 2028 SO₂ emissions (in tons per year (tpy)) from BRPP, Domtar, and PCS are 483, 1,120, and 3,045, respectively.^[55] No sources modeled for PSAT exceeded the PSAT threshold for nitrates. Because no sources exceeded the State's PSAT threshold for nitrates and because ammonium sulfate continues to be the dominant visibility impairing pollutant at the North Carolina Class I areas (as discussed in the following paragraphs), DAQ focused solely on evaluating potential SO₂ controls from BRPP, Domtar, and PCS to address regional haze in potentially affected Class I areas. Section I.A of the TSD provides additional detail regarding the State's source selection process.

The 2022 Plan shows the VISTAS model projections demonstrating that ammonium sulfate is expected to remain the dominant visibility impairing pollutant through 2028, by a factor of four or greater, over ammonium nitrate at Class I areas in North Carolina.^[56] In Section 7.4 of the 2022 Plan, DAQ explains the VISTAS analyses relied upon to support the State's focus on SO₂ control evaluations. Additionally, Section 10.4.1 of the Haze Plan provides the State's responses to FLM comments on the exclusion of NO_X control evaluations from the FFAs.

Although ammonium nitrate contributions to light extinction have increased in recent years (2016-2018), sulfate is still the highest contributor to visibility impairment in North Carolina's Class I areas. DAQ provided light extinction data on the 20 percent most impaired and 20 percent clearest days for the North Carolina Class I areas for the 2009-2013 modeling base period and the 2014-2018 current conditions period which show that ammonium sulfate continues to be the dominant visibility impairing pollutant on the 20 percent most impaired visibility days during the 2009-2013 period and 2014-2018 period.^[57]

In Section 10.4.1, DAQ reviewed more recent visibility monitoring data for the period 2015-2019 from the IMPROVE monitoring network for Great Smoky Mountains, Linville Gorge, and Shining Rock.^[58] Table 3, below, summarizes the percent contribution on the 20 percent most impaired days at Great Smoky Mountains (also Joyce Kilmer), Linville Gorge, and Shining Rock for certain PM species ( i.e., ammonium sulfate, ammonium nitrate, and organic carbon) in 2009-2013 versus 2015-2019.^[59]

Table 3—Five-Year Average (2009-2013 vs. 2015-2019) Percent (%) Particle Contributions to Light Extinction for 20% Most Impaired Days at Great Smoky Mountains,* Linville Gorge, and Shining Rock ⁶⁰

PM species	Great smoky mountains		Linville gorge		Shining rock
	2009-2013 (%)	2015-2019 (%)	2009-2013 (%)	2015-2019 (%)	2009-2013 (%)	2015-2019 (%)
Ammonium Sulfate	76.3	54.4	77.2	56.9	74.5	58.1
Ammonium Nitrate	5.2	16.6	2.5	8.0	5.5	10.3
Organic Carbon	11.1	17.4	12.5	22.4	12.5	19.4
* Monitoring data for Great Smoky Mountains serves as the IMPROVE data for Joyce Kilmer.

Figures 7-27 (Swanquarter), 7-28 (Shining Rock), 7-29 (Linville Gorge), 7-30 (Joyce Kilmer), and 7-31 (Great Smoky Mountains) in the 2022 Plan show that the majority of 2028 predicted nitrate light extinction on the 20 percent most impaired days at North Carolina's Class I areas is not caused by NO_X emissions from EGU and non-EGU point sources.^[61] At Shining Rock, Linville Gorge, Joyce Kilmer, and the Great Smoky Mountains, projected 2028 total sulfate extinction is greater than 17 Mm⁻¹ and total projected 2028 total nitrate extinction is less than 3.5 Mm⁻¹ . At Swanquarter, the projected 2028 sulfate extinction is 16.6 Mm⁻¹ and the projected 2028 nitrate extinction is 4.5 Mm⁻¹. DAQ states that North Carolina sources contribute a small percentage to total nitrate impairment in all cases (ranging from less than one percent of all nitrate visibility impairment at the Great Smoky Mountains to 13 percent at Swanquarter).

DAQ states that it is unclear why ammonium nitrate has started to increase at some but not all VISTAS Class I areas while point and mobile source NO_X emissions have been declining. VISTAS modeling for 2028 suggests that sources outside of North Carolina may be the likely contributor. DAQ indicates that further research is needed to identify the emission sources and geographic locations of those sources contributing to the ammonium nitrate fraction of PM_2.5 contributing to regional haze. DAQ notes that at some locations, one ton of SO₂ reduction can have anywhere from twice to more than 100 times the impact on visibility impairment as one ton of NO_X reduction.^[62]

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In Section 7.7.3.2 of the 2022 Plan, DAQ reviewed North Carolina facilities that were not selected for PSAT modeling and which had an AoI contribution between one and three percent for one or more Class I areas in North Carolina and which were not selected for FFA evaluation. This review included the eight Duke Energy power plants with coal units in North Carolina which, with the exception of DEC-Marshall, did not meet North Carolina's AoI threshold (see Table 7-43 of the 2022 Plan). DAQ reviewed existing SO₂ and NO_X controls for the Duke Energy facilities with coal units and non-EGUs with an AOI contribution between one and three percent sulfate plus nitrate and based on this review, DAQ did not identify any uncontrolled or lightly controlled facilities that were large contributors to anthropogenic light extinction at any of North Carolina's Class I areas that were missed by North Carolina's source selection process.

b. Consideration of the Four Factors: North Carolina considered each of the four CAA factors for BRPP and Domtar and described how the four factors were taken into consideration in selecting the SO₂ measures for inclusion in the State's LTS. For PCS, DAQ considered the four CAA factors for its existing measures for the affected units and determined that there are no technically feasible control measures beyond the existing measures to further reduce SO₂ emissions, and thus, no new measures were evaluated using the four factors. The following subsections summarize the State's evaluation of these facilities. Additional detail is provided in Section I.B. of the TSD.

i. BRPP: During 2017 to 2019, BRPP implemented SO₂ controls on existing processes and replaced two coal-fired boilers with new natural gas-fired boilers to comply with a Special Order by Consent (SOC) between the North Carolina Environmental Management Commission and BRPP.^[63] As a result of the SOC, BRPP reduced actual annual SO₂ emissions by 93 percent (5,470 tons per year) from 2017-level emissions.

The FFA focused on the No. 4 Power Boiler, Riley Bark Boiler, and the Riley Coal Boiler because these three boilers comprise 90.2 percent of the BRPP's total 2019 actual emissions and 91.8 percent of the BRRP's total 2028 projected SO₂ emissions.^[64] These units are equipped with wet flue gas desulfurization (WFGD).^{[65]  [66]} To complete the cost of compliance analysis, BRPP evaluated replacing coal with ultra-low sulfur diesel (ULSD) (all three boilers) and adding dry sorbent injection (DSI) (for the Riley Coal Boiler and No. 4 Power Boiler). Table 7-54 of the 2022 Plan shows that of the new control measures considered, the lowest cost effectiveness was $13,477 per ton of SO₂ removed using a 3.25 percent interest rate and a 30-year equipment life in the cost calculations. The State notes that based on the FFA, BRPP identified no cost-effective control measures to further reduce SO₂ emissions for the three boilers evaluated.

Regarding the other statutory factors, the State identifies the remaining useful life of the source is estimated at more than 25 years, and the equipment life of the control options evaluated is 30 years for both the DSI and ULSD options. The State identifies that the time necessary to comply for both the DSI and ULSD options is at least three years to accommodate time for corporate funding approval, permitting, re-engineering, and planned outage scheduling. Regarding energy and non-air quality environmental impacts of compliance, DAQ explains that adding DSI would increase energy usage as well as PM emissions from materials handling and landfill operations and it would also decrease the useful life of the mill landfill and increase truck traffic on local streets. Regarding ULSD, no significant energy and non-air quality environmental impacts were identified.

Given the 93 percent decrease in SO₂ emissions due to the SOC and the State's determination that there are no cost-effective control SO₂ measures available based on a review of the four factors, DAQ concluded that only existing SO₂ measures are necessary for reasonable progress for the second planning period at BRPP's Riley Coal Boiler, Riley Bark Boiler, and the No. 4 Power Boiler. No source-specific changes were proposed to the North Carolina SIP for BRPP because these existing SO₂ measures are already incorporated into the SIP.^[67]

ii. Domtar: The FFA for Domtar focused on Hog Fuel Boiler 2 (“HFB2”) because this unit is projected to emit approximately 90 percent of the facility's total projected SO₂ emissions in 2028 (1,010 tpy out of 1,120 tpy).^[68] A hog fuel boiler at a paper mill typically burns wood waste known as “hog fuel” to generate electricity for the mill. In addition, Domtar currently routes the majority of its noncondensible waste gases through HFB2. The sulfur compounds from the waste gases accounts for the vast majority of the SO₂ emissions. HFB2 uses low sulfur fuels and inherent bark scrubbing to control SO₂ emissions. To complete the cost of compliance analysis, Domtar evaluated HFB2 for WFGD and DSI.^[69] Table 7-58 of the 2022 Plan provides summary cost data showing that the cost effectiveness of the addition of a WFGD would be $3,660/ton and the addition of DSI would cost $22,092/ton of SO₂ removed using a 3.25 percent interest rate, a 30-year equipment life, and assuming a 95 percent SO₂ control efficiency for the scrubber and a 50 percent control efficiency for DSI.^[70]

Regarding the other statutory factors, the remaining useful life of HFB2 is 20 years or more, and the equipment life assumed in the cost calculations is 30 years for both the WFGD and DSI control options. The time necessary to ( print page 67356) comply for both the WFGD and DSI options is at least three years due to corporate funding approval, permitting, re-engineering, and planned outage scheduling. Regarding energy and non-air quality environmental impacts of compliance, additional electricity would be needed to operate a DSI system, and a DSI system would create additional solid waste. Regarding the WFGD, additional electricity and water would be needed to run the system and additional fan power would be required overcome the additional pressure drop through the WFGD. Other environmental and energy impacts associated with operating a WFGD include generation and disposal of wastewater.

DAQ concluded that there are no cost-effective control SO₂ measures available based on a review of the four factors and that only existing SO₂ measures at HFB2 are necessary for reasonable progress during the second planning period. North Carolina identified permit conditions reflecting these existing measures in Section 7.8.3.1 of the 2022 Plan for incorporation into the North Carolina SIP. In its Commitment Letter, DAQ committed to revise certain permit conditions and submit, no later than one year from the effective date of a final conditional approval action (should EPA finalize the proposed partial conditional approval), a SIP revision requesting incorporation of the revised permit conditions and additional existing specific permit conditions into the SIP. DAQ's commitments are discussed in Section IV.C.3.b.ii of this document.

iii. PCS: The FFA for PCS focused on evaluating Sulfuric Acid Plants (SAPs) 5, 6, and 7 for additional SO₂ controls because these three SAPs accounted for over 97 percent of total facility SO₂ emissions in 2016 and are estimated to account for 94 percent of the total facility SO₂ emissions in 2028. During 2017-2019, PCS implemented upgrades to enhance the SO₂ conversions in the catalytic systems on SAPs 5, 6, and 7 pursuant to a consent decree with EPA entered on February 26, 2015.^[71] Table 7-61 of the 2022 Plan summarizes the SO₂ emissions reductions from the upgrades involving a dual absorption process with cesium catalyst.^[72] PCS' title V permit includes the SO₂ emissions limits required under the consent decree and prohibits relaxation of these emissions limits after the consent decree has been terminated.

For PCS, the State evaluated whether there are any technically feasible control technologies available for SAPs 5, 6, and 7 at the facility beyond the current SO₂ emissions control technology in place (dual absorption process with cesium catalyst) to further reduce SO₂ emissions at these units and concluded that there are none. Given this conclusion and the SO₂ reductions at PCS due to the upgrades, DAQ concluded that only the existing measures for SAPs 5, 6, and 7 are necessary for reasonable progress during the second planning period. North Carolina identified permit conditions reflecting these existing measures in Section 7.8.3.2 of the 2022 Plan for incorporation into the North Carolina SIP.^[73] In its Commitment Letter, DAQ committed to submit, no later than one year from the effective date of a final conditional approval action (should EPA finalize the proposed partial conditional approval), a SIP revision requesting incorporation of additional existing specific permit conditions into the SIP. DAQ's commitments are discussed in Section IV.C.3.b.iii of this document.

c. Documentation of Technical Basis: With respect to emissions information documentation pursuant to 40 CFR 51.308(f)(2)(iii), Section 4 of the 2022 Plan explains the State's use of emissions inventories to develop the plan with additional documentation provided in Appendix B. North Carolina, through VISTAS, developed a 2011 statewide base year emissions inventory which was used to project emissions out to 2028, the end of the second planning period. DAQ also evaluated emissions data from 2017, the year of the most recent triennial emissions data available at the time of the development of the 2022 Plan.^[74] DAQ also provided annual, statewide anthropogenic SO_2, NO_X, and PM_2.5 emissions data from 2011 through 2019 for North Carolina in Tables 13-9, 13-10, and 13-11, respectively, of the 2022 Plan.

With respect to modeling information documentation pursuant to 40 CFR 51.308(f)(2)(iii), Sections 5 and 6 of the 2022 Plan describe the modeling methods used to develop the plan with additional documentation provided in Appendix E and results of the RPG modeling in Section 8 of the plan. Appendix D contains AoI analyses documentation.

With respect to cost and engineering information documentation pursuant to 40 CFR 51.308(f)(2)(iii), Section 7.8 of the 2022 Plan details the State's analysis of proposed FFAs for BRPP and Domtar located in Appendix G which evaluated the four factors, including the cost of compliance factor, and provided detailed cost calculations for potential new control measures assessed as part of the engineering analyses.

With respect to monitoring information documentation pursuant to 40 CFR 51.308(f)(2)(iii), the State assessed baseline (2000-2004), current (2014-2018), and natural visibility conditions for North Carolina's Class I areas in Section 2 of the 2022 Plan with supporting information located in Appendix C.

Section I.D of the TSD provides a more detailed summary of the State's assessment of the documentation of the technical basis for the 2022 Plan under 40 CFR 51.308(f)(2)(iii) and 40 CFR 51.308(f)(6)(v).

d. Assessment of the Five Additional Factors in 40 CFR 51.308(f)(2)(iv): With respect to 40 CFR 51.308(f)(2)(iv), North Carolina considered each of the five additional factors in developing the State's LTS and evaluated their relevancy for the second planning period. With respect to 40 CFR 51.308(f)(2)(iv)(A), North Carolina referenced the State's emissions inventory development for the base year of 2011 as projected out to 2028 for the requirement to assess emission reductions due to ongoing air pollution control programs, including measures to address Reasonably Attributable Visibility Impairment (RAVI). With respect to 40 CFR 51.308(f)(2)(iv)(B), North Carolina summarized the State's existing regulations that mitigate the impacts of construction activities by requiring control of erosion, siltation, and pollution from construction activities and requiring subject facilities to control PM from fugitive dust emission sources generated within plant boundaries.^[75] With respect to 40 CFR ( print page 67357) 51.308(f)(2)(iv)(C), North Carolina summarized existing and planned source retirements in Section 7.2.2 and Section 8.3.5 of the 2022 Plan. With respect to 40 CFR 51.308(f)(2)(iv)(D), North Carolina considered the State's Guidelines for Managing Smoke from Forestry Burning Operations to mitigate PM_2.5 emissions and regional haze impacts associated with prescribed burning.^[76] With respect to 40 CFR 51.308(f)(2)(iv)(E), North Carolina pointed to the development and evaluation of the 2028 RPGs for the North Carolina Class I areas which reflect the net effect on visibility due to projected changes in point, area, and mobile source emissions over the second period. Section I.C of the TSD provides a more detailed summary of the State's assessment of the five additional factors in 40 CFR 51.308(f)(2)(iv).

e. Interstate Consultation: North Carolina consulted with states ^[77] and RPOs that identified North Carolina sources as impacting those states' (or states within the RPOs') Class I areas, and DAQ consulted with the 10 states with one or more sources exceeding North Carolina's PSAT threshold at one or more of North Carolina's Class I areas.

i. State/RPOs Requesting Consultation with North Carolina:

a. MANE-VU Ask: The following summarizes the conclusions of consultation related to the MANE-VU Ask for North Carolina.^[78] Section I.E of the TSD provides a more detailed summary of the State's interstate consultation pursuant to 40 CFR 51.308(f)(2)(ii).

The MANE-VU Ask for states outside of MANE-VU addresses both statewide impacts to visibility and specific emissions units' visibility impacts. States that contributed greater than or equal to two percent of the visibility impairment to a Class I area and had an average mass impact of over one percent (0.01 microgram per cubic meter) on a statewide basis were identified for consultation and included in the Inter-RPO Ask. Additionally, any emissions units having the potential for a 3.0 Mm⁻¹ or greater light extinction impact on any MANE-VU Class I area based on CALPUFF modeling of 2011 SO₂ and NO_X emissions were identified for consultation in the MANE-VU Ask.

In a letter dated October 16, 2017, MANE-VU requested consultation with North Carolina on the basis that North Carolina was identified as impacting MANE-VU Class I area(s) on both a statewide basis and emission unit basis. On a statewide basis, MANE-VU claimed that North Carolina's percent mass-weighted sulfate and nitrate contributions from North Carolina to MANE-VU Class I areas in 2015 exceeds the RPO's two percent threshold for five Class I areas in MANE-VU.^[79] On an emissions unit basis, the No.1 Power Boiler at North Carolina's Kapstone Kraft Corporation (“Kapstone”) was identified as having the potential to exceed the 3.0 Mm⁻¹ or greater visibility impact threshold set by MANE-VU for any Class I area in the MANE-VU region.^[80]

Regarding statewide visibility impacts to MANE-VU Class I areas, North Carolina disagreed with MANE-VU that North Carolina's statewide emissions are impacting visibility at any MANE-VU Class I areas. North Carolina's viewpoints are reflected in the January 27, 2018, letter from VISTAS to MANE-VU. To resolve the disagreement, North Carolina sent a response letter on February 16, 2018, to MANE-VU and noted several disagreements with MANE-VU's analysis.

Regarding Kapstone's visibility impacts to MANE-VU Class I areas, in a letter dated February 16, 2018, DAQ clarified the status of the No. 1 Power Boiler at KapStone that was initially identified in a September 5, 2017, document from MANE-VU as having the potential for a maximum 6.0 Mm⁻¹ light extinction impact on a MANE-VU Class I area based on CALPUFF modeling of the facility's 2011 SO₂ and NO_X emissions.^[81] DAQ reviewed the modeling documentation and found that the maximum potential light extinction impact modeled for the power boiler was 0.28 Mm⁻¹ for MANE-VU Class I areas and 0.47 Mm⁻¹ for Class I areas near the MANE-VU region shown in Table 1 of the 2018 letter. Based on discussions with MANE-VU representatives, there was agreement that the initial light extinction values shown in Table l of the 2018 letter are correct for the No. 1 Power Boiler and that the boiler should not be included in the MANE-VU Ask.

North Carolina documented the State's responses and viewpoints with respect to the MANE-VU Ask in Section 10 and Appendix F-4 of the 2022 Plan. North Carolina proposes that it fulfilled the consultation requirements under 40 CFR 51.308(f)(2)(ii) by the State's active participation in the MANE-VU consultation process and by the State's documented responses to MANE-VU. Thus, DAQ determined that no further action is required under the RHR to address MANE-VU's requests.

b. Proposed Plan Comments from MANE-VU, New Hampshire, and New Jersey: MANE-VU, New Hampshire, and New Jersey provided written comments on the North Carolina haze plan proposed for public comment at the State level.^[82] In total, there are five MANE-VU Inter-RPO Asks for states outside of the MANE-VU Region. Regarding Asks 1, 4, and 5, MANE-VU, New Hampshire, and New Jersey acknowledged in their comments on the North Carolina prehearing plan that the existing measures in North Carolina address these three asks. Regarding Ask 2, MANE-VU determined that this ask does not apply to North Carolina. Regarding Ask 3, DAQ reviewed the MANE-VU, New Hampshire, and New Jersey recommendations for the State to adopt an ultra-low sulfur fuel (ULSF) oil standard consistent with Ask 3 and explained in the 2022 Plan why it would not be reasonable to do so. DAQ evaluated residual and distillate oil use in North Carolina and concluded that adopting an ULSF standard would provide “very little” reduction in SO₂ emissions or any noticeable improvement in visibility in Class I areas in North Carolina and in downwind states.

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ii. North Carolina's Requests for Consultation with Other States: Consultation with other states with sources contributing to regional haze at North Carolina's Class I areas is discussed in Section 10 and Appendix F of the 2022 Plan. As listed in Tables 7-37 and 7-38 of the 2022 Plan, North Carolina requested a FFA of 16 sources in 10 other states because these sources exceeded the State's sulfate PSAT threshold at one or more of North Carolina's Class I areas.^[83] DAQ documented the responses from the 10 states in Section 10.1.1 of the 2022 Plan. Section I.E.3 of the TSD provides more details regarding the consultation related to these sources.

3. EPA Evaluation: EPA has reviewed DAQ's source selection criteria, consideration of the four factors, determinations of controls necessary for reasonable progress, submitted permit conditions, documentation of technical basis, interstate consultation, and consideration of the five additional factors. Based on this review, EPA finds that North Carolina's LTS satisfies 40 CFR 51.308(f)(2) but for concerns with the legal and practicable enforceability of certain Domtar and PCS permit conditions identified for incorporation into the SIP. As discussed above, North Carolina has committed to provide EPA with a SIP submission no later than one year from the effective date of a final conditional approval action that would adequately address the legal and practicable enforceability concerns identified in this document. Therefore, EPA is proposing to conditionally approve the sections of the Haze Plan addressing 40 CFR 51.308(f)(2). If North Carolina submits the required SIP revision by the specified deadline and EPA approves the submission, then the identified enforceability concerns will be cured and the conditional approval of the sections of the Haze Plan addressing 40 CFR 51.308(f)(2) will be converted to a full approval. Sections IV.C.3.b.ii and IV.C.3.b.iii of this document discuss the enforceability concerns with the Domtar and PCS permit conditions, respectively, and North Carolina's commitments to resolve these concerns. Although EPA finds that North Carolina's LTS satisfies 40 CFR 51.308(f)(2) but for the enforceability concerns with certain Domtar and PCS permit conditions identified for incorporation into the SIP, EPA is soliciting comment on the adequacy of DAQ's analyses, including the FFAs, determination of controls necessary for reasonable progress, and the adequacy of the submitted permit conditions, including associated monitoring, recordkeeping, and reporting, and whether the State has met the requirements of 40 CFR 51.308(f)(2)(i) through (iv).

a. Source Selection Criteria: EPA finds that North Carolina's source selection was reasonable. The Haze Plan supports this finding, because it contains information such as Appendix C which includes monitoring and meteorological data used to support selection of sources; Appendix D which provides documentation supporting the AoI analyses (first step of the State's source selection process); and Appendix E which details the visibility and source apportionment data used and results from the PSAT modeling (second step of the State's source selection process). However, EPA finds this source selection requirement is not separable from the overarching requirement of 40 CFR 51.308(f)(2) to establish a LTS. As explained previously in this document, EPA is proposing to conditionally approve North Carolina's LTS due to concerns with the legal and practical enforceability of certain permit conditions identified in the Haze Plan for incorporation into the SIP. Accordingly, EPA finds that the Haze Plan will only meet all requirements of 40 CFR 51.308(f)(2) if North Carolina meets its commitment to submit the corrective SIP revision described in its Commitment Letter no later than one year from the effective date of a final conditional approval action, should EPA finalize the proposed partial conditional approval, and EPA approves that SIP revision. North Carolina included a description of the criteria that the State used to determine which sources the State evaluated for emissions controls.

EPA also finds that North Carolina's source selection resulted in a reasonable set of sources contributing to visibility impairment at Class I areas affected by North Carolina's sources. AoI and PSAT are acceptable and well-established methods for selecting sources for a control analysis and they enable the identification of the sources that have the largest impacts on visibility at Class I areas in North Carolina and neighboring states,^[84] and the State identified three North Carolina sources for a control evaluation and identified 16 out-of-state sources for which they requested a control evaluation through interstate consultation. Additionally, statewide SO₂ emissions are expected to decrease in the second planning period from 2019 levels of 34,712 tpy SO₂ to projected 2028 levels of 32,644 tpy SO₂ (a six percent reduction) which occurred after a 63 percent decrease in statewide SO₂ emissions from 2011 to 2018 by 74,830 tpy SO₂, and statewide NO_X emissions are expected to decrease in the second planning period from 2019 levels of 223,264 tpy NO_X to projected 2028 levels of 138,986 tpy NO_X (approximately a 38 percent reduction) which occurred after a 37 percent decrease in statewide NO_X emissions from 2011 to 2018 by 137,820 tpy NO_X .^[85] Additional emissions reductions from permanent shutdowns which have not been reflected in the 2028 emissions projections and 2028 RPGs are 204 tons of SO₂ and 208 tons of SO₂ based on 2016 actual and projected 2028 SO₂ emissions, respectively, and 248 tons of NO_X and 287 tons of NO_X based on 2016 and projected 2028 NO_X emissions, respectively. Visibility conditions in North Carolina's Class I areas in 2028 are estimated to improve since the 2000-2004 baseline period by 14.1 deciviews (Great Smoky Mountains and Joyce Kilmer), 13.8 deciviews (Linville Gorge), 14.8 deciviews (Shining Rock), and 8.5 deciviews (Swanquarter).^[86] Specific to the second planning period, visibility conditions in North Carolina's Class I areas in 2028 are estimated to improve since the 2014-2018 period by 2.2 deciviews (Great Smoky Mountains, Joyce Kilmer, Linville Gorge, Shining Rock), and 1.0 deciview (Swanquarter). These projected second planning period visibility improvements represent approximately ^[87] 30 percent (Great ( print page 67359) Smoky Mountains and Joyce Kilmer); 32 percent (Linville Gorge), 40 percent (Shining Rock), and 16 percent (Swanquarter) of the additional progress needed to reach natural conditions at each Class I area. Additionally, using the most recently available 20 percent most impaired days IMPROVE data (2018-2022) ^[88] for the 20 percent most impaired days,^[89] in the first four years of the second planning period, North Carolina's Class I areas have already achieved 25 percent (Great Smoky Mountains and Joyce Kilmer),^[90] 25 percent (Linville Gorge), 27 percent (Shining Rock), and 21 percent (Swanquarter) of the remaining progress needed to reach natural conditions. Also, North Carolina is not contributing to visibility impairment at any Class I areas above the URP, and the State appropriately focused on controlling point source SO₂ emissions based on data showing ammonium sulfate is the dominant visibility impairing pollutant at the North Carolina Class I areas.

Although North Carolina did not select any Duke Energy sources for analysis, EPA conducted further review of five Duke Energy facilities to evaluate the reasonableness of North Carolina's source selection—DEC—Belews Creek Steam Station (DEC-Belews Creek), DEC—Cliffside Steam Station (DEC-Cliffside), DEC-Marshall, Duke Energy Progress, LLC (DEP)—Mayo Electric Generating Plant (DEP-Mayo), and DEP—Roxboro Steam Electric Plant (DEP-Roxboro). EPA identified these five facilities for further review because, in the VISTAS AoI analysis, DEC-Belews Creek, DEC-Cliffside, and DEC-Marshall ranked in the top 10 facility sulfate impacts at Shining Rock; DEC-Belews Creek and DEC-Cliffside ranked in the top 10 facility sulfate impacts at Linville Gorge; DEP-Roxboro ranked in the top 10 facility sulfate impacts at Swanquarter; DEP-Roxboro ranked in the top 10 facility sulfate impacts at James River Face in Virginia; and DEP-Mayo ranked in the top 20 facility sulfate impacts at James River Face. EPA assessed whether these five Duke Energy facilities are effectively controlled for SO₂  ^[91] and whether any cost-effective new emissions reduction measures for SO₂ would have likely resulted from a FFA had these sources met the State's source selection criteria.

The 2019 Guidance provides several scenarios in which EPA believes it may be reasonable for a state not to select a particular source for further analysis. Two of these scenarios are applicable to the five Duke facilities—a coal-fired EGU that has add-on flue gas desulfurization (FGD) and meets the applicable alternative SO₂ emission limit of 0.2 pound (lb) per million British Thermal Units (MMBtu) (lb/MMBtu) in the Mercury and Air Toxics Standards (MATS) rule for power plants; ^[92] and an EGU that, during the first period, installed a FGD system that operates year-round with an effectiveness of at least 90 percent. The 2019 Guidance states that in both cases, it is unlikely that an analysis of control measures for a source already equipped with a scrubber and meeting a 0.20 lb/MMBtu limit or greater than 90 percent efficiency would conclude that even more stringent control of SO₂ is necessary to make reasonable progress. See 2019 Guidance at 23.

Each of the five Duke sources are equipped with WFGD and are subject to the alternative SO₂ emissions limit from the MATS rule. EPA evaluated the WFGD SO₂ control efficiencies at each of the coal-fired units at these five sources as follows: DEC-Belews Creek (Units 1, 2); DEC-Cliffside (Units 5 and 6); DEC-Marshall (Units 1-4); DEP-Mayo (Units 1A and 1B); DEP-Roxboro (Units 1, 2, 3A, 3B, 4A, 4B). Data from 2017-2021 indicate that existing WFGD systems at these units at the five Duke facilities routinely achieve 92 to 98 percent SO₂ removal efficiencies with some month-to-month variation in performance.^[93] Because these coal units are subject to the MATS alternative SO₂ emission limit of 0.2 lb/MMBtu and are equipped with WFGD that routinely achieve a high SO₂ control effectiveness, it reasonable to assume that a FFA would likely result in the conclusion that no further controls are necessary.

b. Consideration of the Four CAA Factors: EPA finds that North Carolina reasonably evaluated and determined, under the four CAA factors, the emission reduction measures for the selected sources that are necessary to make reasonable progress but for the concerns with the legal and practicable enforceability of certain Domtar and PCS permit conditions identified for incorporation into the SIP for the reasons discussed below.^[94]

i. BRPP: Regarding BRPP, EPA finds that DAQ's conclusions that existing SO₂ measures at BRPP's Riley Coal Boiler, Riley Bark Boiler, and the No. 4 Power Boiler are necessary for reasonable progress for the second planning period to be reasonable. The State evaluated available and technically feasible SO₂ controls that were based on, where applicable, estimated values of capital costs, annualized costs, and cost per ton of emission reductions, and were consistent with recommendations in EPA's “Air Pollution Control Cost Manual” (Cost Manual).^[95] WFGD with approximately a 90 percent control efficiency is an existing SO₂ control for these units, and the recently installed control measures are estimated to reduce the 2028 projected emissions for the facility from approximately 5,875 tons to 485 tons of SO_2.^[96] Additionally, EPA finds that DAQ reasonably concluded that the addition of DSI controls at $13,477/ton and $14,752/ton for the Riley Coal Boiler and No. 4 power Boiler, respectively, and the ULSD at over $126,000/ton for all three units, are not necessary to make reasonable progress. The associated ( print page 67360) existing SO₂ emissions limits for these boilers, summarized in Table 7-48 of the 2022 Plan, are already adopted into the North Carolina SIP effective November 24, 2020.^[97]

ii. Domtar: Regarding Domtar, EPA finds that DAQ's exclusion of HFB1 from FFA review is reasonable because it is equipped to only burn natural gas and biomass with No. 2 fuel oil as a backup unit and is projected to emit 12 tpy of SO₂ in 2028, which is only one percent of Domtar's total SO₂ emissions. EPA also finds that DAQ's control analysis and conclusions that the existing SO₂ measures at Domtar's HFB2 are necessary for reasonable progress for the second planning period are reasonable, except for EPA's concerns with the legal and practicable enforceability of certain permit conditions identified for incorporation into the SIP from Domtar's title V permit. The State evaluated available and technically feasible SO₂ control measures for HFB2 that were based on, where applicable, estimated values of capital costs, annualized costs, and cost per ton of emission reductions prepared according to EPA's Cost Manual. The cost effectiveness of DSI is $22,092/ton and the cost effectiveness of the WFGD is $3,660/ton using a conservative 3.25 percent interest rate.^[98]

North Carolina's LTS contains deficiencies that preclude full approval and, based on the State's commitment to address these concerns, EPA is proposing to conditionally approve the LTS portion of the Haze Plan. As discussed in Section III of this document, each state's regional haze SIP must include a LTS that contains enforceable emissions limitations, compliance schedules, and other measures that are necessary to make reasonable progress. See CAA section 169A(b)(2), 40 CFR 51.308(f)(2). Furthermore, CAA section 110(a)(2)(A) requires SIPs to “include enforceable conditions and other control measures, means or techniques . . . as may be necessary or appropriate” to meet the requirements of the Act. As EPA has repeatedly stated, to be enforceable, a CAA requirement must be legally and practically enforceable, and there is a considerable body of applicable EPA rules, EPA guidance, and EPA-approved state practices on the topic of practicably enforceable emission limits.^[99] Typically, a primary mechanism for ensuring that a SIP provision is legally and practicably enforceable is for a state to impose sufficient monitoring, recordkeeping, and reporting (MRR) requirements on affected sources.

EPA's rules regarding the preparation, adoption, and submittal of SIPs at 40 CFR part 51 also contain requirements concerning the enforceability of SIP emission limits. For example, SIPs must include enforceable test methods for each emission limit included in the plan. See40 CFR 51.212. SIPs must also provide legally enforceable methods requiring owners or operators of stationary sources to maintain records of and periodically report to the State information regarding the nature and number of emissions from a stationary source and other information as it may be necessary for a state to determine if the source is in compliance with the control strategy. See40 CFR 51.211. Furthermore, the SIP completeness criteria in 40 CFR part 51, appendix V state that complete SIPs contain “evidence that the plan contains emission limitations, work practice standards and recordkeeping/reporting requirements, where necessary, to ensure emission levels” and “compliance/enforcement strategies, including how compliance will be determined in practice.” See40 CFR 51.103; 40 CFR part 51, appendix V, sections 2.2(g), (h).

North Carolina's SIP revision relies on certain existing emission limits in the title V permit for Domtar to achieve reasonable progress towards the national visibility goal. These emission limits must be legally and practically enforceable, as required under sections 110(a)(2)(A) and 169A(b)(2) of the Act, and the SIP must satisfy EPA's rules regarding the enforceability of SIP emission limits. Section 7.8.3.1 of the Haze Plan identifies SO₂ emission limits from Conditions 2.1 A.4 and 2.1 A.7 of Domtar title V Air Quality Permit No. 04291T51 for incorporation into the SIP as well as several other provisions in these Conditions, including A.4.c.^[100] The conditions listed in italics under Section 7.8.3.1 are identified for incorporation into the SIP with the exception of any text marked in strikeout.

Condition 2.1 A.4.a contains an SO₂ emission limit of 2.3 lbs/MMBtu heat input when firing wood or natural gas. This limit also applies when burning waste gases with wood and/or natural gas. However, the SIP revision does not include a methodology to evaluate compliance with the 2.3 lbs/MMBtu emission limit. EPA considers the lack of a compliance methodology as a deficiency because it undermines the enforceability of the emission limit. In its Commitment Letter, North Carolina has committed to address this concern by revising Condition 2.1 A.4 of Permit No. 04291T51 to include a condition containing a procedure to monitor and evaluate compliance with the SO₂ emission limit of 2.3 lbs/MMBtu in Condition 2.1 A.4.a and submitting a SIP revision, no later than one year from the effective date of a final conditional approval action (should EPA finalize the proposed partial conditional approval), requesting incorporation of the condition into the SIP.

Condition 2.1 A.4.c states that monitoring, recordkeeping, and reporting are not required for the combustion of wood residue and natural gas. However, as discussed above, these SIP-approved emission limits must have adequate monitoring, recordkeeping, and periodic reporting requirements in order to be legally and practicably enforceable, and the SIP must satisfy EPA's rules regarding the enforceability of SIP emission limits which require monitoring, recordkeeping, and periodic reporting. To address this concern, North Carolina submitted a letter dated July 30, 2024, withdrawing from the Haze Plan the State's request for EPA to incorporate Condition 2.1 A.4.c into the SIP,^[101] and in its Commitment Letter, North Carolina committed to submit a ( print page 67361) SIP revision, no later than one year from the effective date of a final conditional approval action (should EPA finalize the proposed partial conditional approval), requesting incorporation of Conditions 4 I.B., P, and X into the SIP.^[102]

Condition 2.1 A.7.a contains an SO₂ emission limit of 0.80 lb/MMBtu heat input when firing oil and wood/lignin. Condition 2.1 A.7 identifies fuel sampling and analysis as the method to evaluate compliance with the 0.80 lb/MMBtu emission limit; however, the Condition does not identify a method to convert fuel sampling and analysis data into SO₂ emissions values comparable with the emission limit. This emission limit is not practicably enforceable for SIP purposes without inclusion of a corresponding conversion methodology. In its Commitment Letter, North Carolina has committed to address this concern by revising Condition 2.1 A.6 and/or Condition 2.1 A.7 of Permit No. 04291T51 to include a condition containing a procedure to monitor and evaluate compliance with the SO₂ emission limit of 0.80 lb/MMBtu in Condition 2.1 A.7.a and submitting a SIP revision, no later than one year from the effective date of a final conditional approval action (should EPA finalize the proposed partial conditional approval), requesting incorporation of the monitoring condition into the SIP.

Given the concerns identified above, and North Carolina's Commitment Letter containing the aforementioned commitments to address these identified concerns related to Domtar, EPA is proposing to conditionally approve the sections of the Haze Plan addressing the requirements of 40 CFR 51.308(f)(2), (f)(3), and (i)(2) through(4).

iii. PCS: Regarding PCS, EPA finds that DAQ's control analysis and conclusions that the existing SO₂ measures at PCS' SAPs 5, 6, and 7 are necessary for reasonable progress for the second planning period are reasonable, except for EPA's concerns with the legal and practicable enforceability of certain permit conditions identified for incorporation into the SIP from PCS' title V permit. The State adequately demonstrated that there are no technically feasible SO₂ control measures for sulfuric acid plants beyond dual absorption process with cesium catalyst, the current SO₂ control measure at SAPs 5, 6, and 7.

North Carolina's SIP revision relies on certain existing emission limits in the title V permit for PCS to achieve reasonable progress towards the national visibility goal. However, EPA finds that these emission limits are not legally and practicably enforceable. As discussed above, these emission limits must be legally and practically enforceable, as required under sections 110(a)(2)(A) and 169A(b)(2) of the Act, and the SIP must satisfy EPA's rules regarding the enforceability of SIP emission limits. Section 7.8.3.2 of the Haze Plan identifies SO₂ emission limits from Condition 2.4 A.1 of PCS title V Air Quality Permit No. 04176T72 for incorporation into the SIP as well as several other provisions in Condition 2.4 A.1, including Conditions A.1.m and A.1.o.^{[103]  [104]} The conditions listed in italics under Section 7.8.3.2 are identified for incorporation into the SIP with the exception of any text marked in strikeout. A summary of EPA's finding and North Carolina's commitment to address the lack of enforceability of these emission limits is found below.

The monitoring provision in Condition 2.4 A.1.m requires the permittee to monitor SO₂ emissions in accordance with the CEMS Plan (Attachment 2 to the permit). However, the 2022 Plan excludes Attachment 2 and the reference to Attachment 2 from the request to incorporate Condition 2.4 A.1.m into the SIP. Similarly, the first sentence of the monitoring provision in Condition 2.4 A.1.o requires the permittee to use analyzer data to determine 3-hour rolling averages and 365-day rolling averages per Attachment 2, and the second sentence requires the permittee to round calculations associated with these averages using the procedures specified in Attachment 2. However, the 2022 Plan excludes the second sentence and the reference to Attachment 2 in the first sentence from the request to incorporate Condition 2.4 A.1.o into the SIP. EPA considers this exclusion of monitoring requirements from Conditions 2.4 A.1.m and 2.4 A.1.o to be a deficiency because the lack of monitoring requirements undermines the enforceability of the SO₂ emission limits identified for incorporation into the SIP. In its Commitment Letter, North Carolina has committed to address these concerns by submitting, no later than one year from the effective date of a final conditional approval action (should EPA finalize the proposed partial conditional approval), a SIP revision requesting incorporation of Conditions 2.4 A.1.m (with the exception of Condition 2.4 A.1.m.v) and 2.4 A.1.o in its entirety and Attachment 2 of Permit No. 04176T72 into the SIP.

The SIP revision does not identify any reporting requirements from title V permit No. 04176T72 for incorporation into the SIP. As discussed above, these emission limits must have adequate monitoring, recordkeeping, and periodic reporting requirements in order to be legally and practicably enforceable. In its Commitment Letter, North Carolina has committed to address this concern by submitting, no later than one year from the effective date of a final conditional approval action (should EPA finalize the proposed partial conditional approval), a SIP revision requesting incorporation of Conditions 4 I.B., P, and X into the SIP.^[105]

Given the concerns identified above and North Carolina's Commitment Letter containing the aforementioned commitments to address these identified concerns related to PCS, EPA is proposing to conditionally approve the sections of the Haze Plan addressing the requirements of 40 CFR 51.308(f)(2), (f)(3), and (i)(2) through(4).

c. Documentation of Technical Basis: With respect to 40 CFR 51.308(f)(2)(iii), EPA finds that North Carolina adequately documented cost, engineering, emissions, modeling, and monitoring information to determine the measures that are necessary to make reasonable progress. With regard to ( print page 67362) emissions information, as required by the RHR, the State included the required years of the most recent triennial emissions inventory (2017) and the most recent annual emissions data (2019) at the time of the development of the 2022 Plan (40 CFR 51.308(f)(2)(iii)). DAQ also provided statewide actual emissions inventory data for 2011, 2014, 2016, 2017, 2018, and 2019 in its 2022 Plan. Additionally, the State provided 2028 emissions data used in the source selection process. With regard to cost and engineering information, the State provided the underlying cost calculations associated with the cost summaries in Section 7.8 of the plan for BRPP and Domtar, and the proposed FFAs in Appendix G provide engineering analyses evaluating potential new control measures.^[106] With regard to monitoring data, the State provided IMPROVE data for the modeling base period plus baseline, current (2014-2018), updated current (2015-2019), and natural conditions for all VISTAS Class I areas with more detailed data provided for the North Carolina Class I areas. With regard to modeling information, the State documented the modeling input and outputs and assumptions in the Haze Plan and the results of the modeling related to RPGs and PSAT source impacts at Class I areas.

d. Assessment of the Five Additional Factors in 40 CFR 51.308(f)(2)(iv): EPA finds that North Carolina considered each of the five additional factors in 40 CFR 51.308(f)(2)(iv), discussed the measures the State has in place to address each factor (or discussed why such measures are not needed), and, where relevant, explained how each factor informed DAQ's and VISTAS' technical analyses for the second planning period.

With respect to 40 CFR 51.308(f)(2)(iv)(A), EPA finds that DAQ adequately addressed the requirement to assess emission reductions due to ongoing air pollution control programs, including measures to address RAVI, through the State's emissions inventory work for the base year of 2011 as projected out to 2028.

With respect to 40 CFR 51.308(f)(2)(iv)(B), EPA finds that North Carolina adequately evaluated measures to mitigate the impacts of construction activities by describing various State regulations that address control of erosion, siltation, and pollution from construction activities and that require subject facilities to control PM from fugitive dust emission sources generated within plant boundaries.

With respect to 40 CFR 51.308(f)(2)(iv)(C), EPA finds that North Carolina adequately considered source retirement and replacement schedules by summarizing existing and planned source retirements throughout the 2022 Plan, including in Section 7.2.2 (retirements accounted for in the 2028 inventory/RPGs) and Section 8.3.5 (retirements not accounted for in the 2028 inventory/RPGs). Additionally, retirement schedules for various Duke Energy power plant facilities are included in Table 7-43 of the 2022 Plan.

With respect to 40 CFR 51.308(f)(2)(iv)(D), EPA finds that North Carolina adequately addressed the requirement to consider the State's basic smoke management practices for prescribed fire used for agricultural and wildland vegetation management purposes and smoke management programs for the following reasons. The State describes its Guidelines for Managing Smoke from Forestry Burning Operations to mitigate PM_2.5 emissions and regional haze impacts associated with prescribed burning and highlights interagency coordination related to educating North Carolina citizens on open burning and related topics.^[107]

With respect to 40 CFR 51.308(f)(2)(iv)(E), EPA finds that North Carolina assessed the anticipated net effect on visibility due to projected changes in point, area, and mobile source emissions over the second period in development of the 2028 RPGs for the North Carolina Class I areas. DAQ used the 2011 base year emissions inventory to project emissions from various source sectors to 2028, the end of the second planning period. DAQ, through VISTAS, completed CAMx modeling to estimate visibility impairment in 2028 based on projected 2028 emissions from the 2011 base year inventory and using IMPROVE monitoring data for 2009-2013.^[108] For North Carolina, estimated visibility improvements by 2028 in each Class I area are based on: estimated emissions reductions associated with existing federal and state measures implemented or expected to be implemented during the second planning period; emissions reductions associated with facility closures that occurred after the 2016 point source emissions base year ( i.e., January 1, 2017 through November 18, 2018); and estimates of emissions changes associated with economic growth and other factors.

e. Interstate Consultation: With respect to interstate consultation pursuant to 40 CFR 51.308(f)(2)(ii), EPA finds that North Carolina adequately consulted with those states with Class I areas where North Carolina emissions may reasonably be anticipated to cause or contribute to visibility impairment and to consult with those states whose sources may reasonably be anticipated to cause or contribute to visibility impairment at North Carolina's Class I areas. No states requested that North Carolina perform a FFA of any of the State's sources. With respect to the MANE-VU Ask, North Carolina adequately took action to resolve disagreements with MANE-VU related to North Carolina's statewide impacts and satisfactorily documented the State's disagreements by sending the February 16, 2018, letter to MANE-VU documenting the State's points of disagreement in addition to supporting the January 27, 2018, letter from VISTAS to MANE-VU.^[109] With respect to consultation with other states with visibility impacts to North Carolina's Class I areas, DAQ adequately documented the responses from consulted states in Appendix F and as summarized in Section 10.1.1 and identified whether the State agrees with the conclusions.

f. Conclusions: For the reasons discussed above, EPA finds that North Carolina's LTS satisfies 40 CFR 51.308(f)(2) but for the concerns with the legal and practicable enforceability of certain Domtar and PCS permit conditions identified for incorporation into the SIP. Given this finding and North Carolina's commitment to submit a SIP revision resolving these concerns, EPA is proposing to conditionally approve the sections of the Haze Plan addressing the requirements of 40 CFR 51.308(f)(2), (f)(3), and (i)(2) through(4). ( print page 67363)

D. RPGs

1. RHR Requirement: Section 51.308(f)(3) contains the requirements pertaining to RPGs for each Class I area. Section 51.308(f)(3)(i) requires a state in which a Class I area is located to establish RPGs—one each for the clearest days and the most impaired days—reflecting the visibility conditions that will be achieved at the end of the planning period as a result of the emission limitations, compliance schedules, and other measures required under paragraph (f)(2) to be in states' LTSs, as well as the implementation of other CAA requirements. The LTSs, as reflected by the RPGs, must provide for an improvement in visibility on the most impaired days relative to the baseline period and ensure no degradation on the clearest days relative to the baseline period. Section 51.308(f)(3)(ii) applies in circumstances in which a Class I area's RPG for the most impaired days represents a slower rate of visibility improvement than the uniform rate of progress calculated under 40 CFR 51.308(f)(1)(vi). Under 40 CFR 51.308(f)(3)(ii)(A), if the state in which a mandatory Class I area is located establishes an RPG for the most impaired days that provides for a slower rate of visibility improvement than the URP, the state must demonstrate that there are no additional emission reduction measures for anthropogenic sources or groups of sources in the state that would be reasonable to include in its LTS. Section 51.308(f)(3)(ii)(B) requires that if a state contains sources that are reasonably anticipated to contribute to visibility impairment in a Class I area in another state, and the RPG for the most impaired days in that Class I area is above the URP, the upwind state must provide the same demonstration.

2. State Assessment: North Carolina identified 2028 RPGs for each of its Class I areas in deciviews for the 20 percent clearest days and the 20 percent most impaired in Tables 8-1 and 8-2, respectively, of the 2022 Plan, which are all well below the 2028 URP value for each Class I area by approximately 13 to 23 deciviews (see Table 1) based on VISTAS' modeling. Table 4 summarizes the 2028 RPGs and 2028 URP for North Carolina's Class I areas.

Table 4—North Carolina's Class I Area 2028 RPGs and URP in Deciviews ( dv )

Class I area	2028 RPG for 20% clearest days	2028 RPG for 20% most impaired days	2028 Uniform rate of progress (URP)
Great Smoky Mountains	8.96	15.03	21.49
Joyce Kilmer	8.96	15.03	21.49
Linville Gorge	8.21	14.25	20.71
Shining Rock	4.54	13.31	20.98
Swanquarter	10.77	15.27	18.28