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Response to Comments for the Federal Register Notice for Air Quality State 

Implementation Plans; Promulgation of State Implementation Plan Revisions; 

Infrastructure Requirements for the 2008 Lead, 2008 Ozone, 2010 NO2, 2010 SO2, and 2012 

PM2.5 National Ambient Air Quality Standards; Utah

Docket No. EPA-R08-OAR-2013-0561

July 19, 2016
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Public Comments

Note: This response-to-comment (RTC) document contains EPA’s responses to comments 

received by the close of the public comment period for this action, May 26, 2016. EPA has 

paraphrased the comments.

Sierra Club Comments on EPA Approval of Utah iSIP Pertaining to SO2

Document No. EPA-R08-OAR-2013-0561-0023

Comment 1: National Ambient Air Quality Standards and Implementation of the NAAQs

The Sierra Club (hereinafter referred to as “Commenter”) states that the main objective of 

the infrastructure SIP process “is to ensure that all areas of the country meet the NAAQS” and 

that nonattainment areas are addressed through “nonattainment SIPs.” The Commenter asserts 

the NAAQS “are the foundation upon which air emission standards for the entire country are set”

including specific emission limitations for most large stationary sources, such as coal-fired 

power plants. The Commenter discusses the CAA’s framework whereby states have primary

responsibility to assure air quality within the state pursuant to CAA section 107(a). States carry 

out section 107(a) through SIPs such as infrastructure SIPs required by section 110(a)(2). The 

Commenter points to air monitoring and modeling requirements of infrastructure SIPs and cites 

to the EPA’s Data Requirements Rule for determining the SO2 NAAQS compliance status (80 

FR 51052 (Aug. 21, 2015)).

The Commenter also states that the plain language of the CAA requires infrastructure 

SIPs “to be adequate to prevent exceedances of the NAAQS.” In support, the Commenter quotes 

language in section 110(a)(1) which requires states to adopt a plan for implementation,

maintenance, and enforcement of the NAAQS. The Commenter also quotes language in section

110(a)(2)(A) requiring SIPs to include enforceable emissions limitations as may be necessary to 

meet the requirements of the CAA, which the Commenter claims includes attainment and 

maintenance of the NAAQS. The Commenter contends that EPA interpretations in rulemakings 

require the inclusion of enforceable emission limits in infrastructure SIPs when new or revised 

NAAQS are promulgated. The Commenter also contends that infrastructure SIPs must address 

interstate transport of pollution and quotes language from section 110(a)(2)(D)(i)(I). 

Response 1: The EPA disagrees that section 110 is clear “on its face” and must be interpreted in 

the manner suggested by the Commenter. As we have previously explained in response to similar 

comments the Commenter has made on EPA’s actions approving other states’ infrastructure 

SIPs, section 110 is only one provision that is part of the complicated structure governing

implementation of the NAAQS program under the CAA, as amended in 1990, and it must be 

interpreted in the context of not only that structure, but also of the historical evolution of that 

structure.1

 

1 See 80 FR 46494 (Aug. 5, 2015) (approval of Pennsylvania ozone and SO2 infrastructure SIP); 80 FR 11557 (Mar. 4, 2015) 

(approval of Virginia SO2 infrastructure SIP); 79 FR 62022 (Oct. 16, 2014) (approval of West Virginia SO2 infrastructure SIP); 

79 FR 19001 (April 7, 2014) (approval of West Virginia ozone infrastructure SIP); and 79 FR 17043 (Mar. 27, 2014) (approval 

of Virginia ozone infrastructure SIP).
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The EPA interprets infrastructure SIPs as more general planning SIPs, consistent with the 

CAA as understood in light of its history and structure. When Congress enacted the CAA in 

1970, it did not include provisions requiring states and the EPA to label areas as attainment or

nonattainment. Rather, states were required to include all areas of the state in ‘‘air quality control 

regions’’ (AQCRs) and section 110 set forth the core substantive planning provisions for these 

AQCRs. At that time, Congress anticipated that states would be able to address air pollution 

quickly pursuant to the very general planning provisions in section 110 and could bring all areas

into compliance with a new NAAQS within five years. Moreover, at that time, section 

110(a)(2)(A)(i) specified that the section 110 plan provide for ‘‘attainment’’ of the NAAQS and 

section 110(a)(2)(B) specified that the plan must include ‘‘emission limitations, schedules, and 

timetables for compliance with such limitations, and such other measures as may be necessary to 

insure attainment and maintenance [of the NAAQS].’’

In 1977, Congress recognized that the existing structure was not sufficient and many 

areas were still violating the NAAQS. At that time, Congress for the first time added provisions 

requiring states and the EPA to identify whether areas of a state were violating the NAAQS (i.e., 

in nonattainment) or were meeting the NAAQS (i.e., in attainment) and established specific

planning requirements in section 172 for areas not meeting the NAAQS. In 1990, many areas 

still had air quality not meeting the NAAQS and Congress again amended the CAA and added 

yet another layer of more prescriptive planning requirements for each of the NAAQS. At that 

time, Congress modified section 110 to remove references to the section 110 SIP providing for 

attainment, including removing pre-existing section110(a)(2)(A) in its entirety and renumbering 

subparagraph (B) as section 110(a)(2)(A). Additionally, Congress replaced the clause ‘‘as may 

be necessary to insure attainment and maintenance [of the NAAQS]’’ with ‘‘as may be necessary 

or appropriate to meet the applicable requirements of this chapter.’’ Thus, the CAA has 

significantly evolved in the more than 40 years since it was originally enacted. While at one time 

section 110 of the CAA did provide the only detailed SIP planning provisions for states and 

specified that such plans must provide for attainment of the NAAQS, under the structure of the 

current CAA, section 110 is only the initial stepping-stone in the planning process for a specific 

NAAQS. More detailed, later-enacted provisions govern the substantive planning process, 

including planning for attainment of the NAAQS. 

Thus, the EPA believes that section 110 of the CAA is only one provision that is part of 

the complicated structure governing implementation of the NAAQS program under the CAA, as 

amended in 1990, and it must be interpreted in the context of that structure and the historical 

evolution of that structure. In light of the revisions to section 110 since 1970 and the later 

promulgated and more specific planning requirements of the CAA, the EPA reasonably 

interprets the requirement in section 110(a)(2)(A) of the CAA that the plan provide for 

‘‘implementation, maintenance and enforcement’’ to mean that the SIP must contain enforceable 

emission limits that will aid in attaining and/or maintaining the NAAQS and that the state 

demonstrates it has the necessary tools to implement and enforce a NAAQS, such as adequate 

state personnel and an enforcement program. The EPA has interpreted the requirement for 

emission limitations in section 110 to mean that the state may rely on measures already in place 

to address the pollutant at issue or any new control measures that the state may choose to submit.

Furthermore, as the EPA stated in the Infrastructure SIP Guidance2 which specifically provides 

 

2 See Guidance on Infrastructure State Implementation Plan (SIP) Elements under Clean Air Act Sections 110(a)(1) and 

110(a)(2), Stephen D. Page, Director, EPA’s Office of Air Quality Planning and Standards, to Regional Air Division Directors 
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guidance to states in addressing the 2008 ozone and 2010 SO2 NAAQS, ‘‘[t]he conceptual 

purpose of an infrastructure SIP submission is to assure that the air agency’s SIP contains the 

necessary structural requirements for the new or revised NAAQS, whether by establishing that 

the SIP already contains the necessary provisions, by making a substantive SIP revision to 

update the SIP, or both.’’ Infrastructure SIP Guidance at p. 2.3

The Commenter makes general allegations that Utah does not have sufficient protective 

measures to prevent SO2 NAAQS exceedances. The EPA addressed the adequacy of Utah’s 

infrastructure SIP for 110(a)(2)(A) purposes to meet applicable requirements of the CAA in the 

proposed rulemaking (80 FR 24527, April 26, 2016) and explained why the SIP includes 

enforceable emission limitations and other control measures necessary for maintenance of the 

2010 SO2 NAAQS throughout the State. Finally, the EPA addresses the Commenter’s statement 

that a state must demonstrate the “Good Neighbor” requirements of section 110(a)(2)(D)(i)(I) to 

protect the NAAQS of neighboring states in Response 15.

Comment 2: The 2010 Sulfur Dioxide NAAQS

The Commenter provides a history of the establishment of the SO2 NAAQS and 

discusses the adverse health impacts of SO2 exposure. The Commenter asserts that modeling is 

the appropriate tool for implementation of the 2010 SO2 NAAQS. The Commenter cites to 

several cases upholding EPA’s use of modeling in NAAQS implementation actions, including 

the Montana Sulphur case, Sierra Club v. Costle, 657 F.2d 298 (D.C. Cir. 1981), Republic Steel 

Corp. v. Costle, 621 F.2d 797 (6th Cir. 1980), and Catawba County v. EPA, 571 F.3d 20 (D.C. 

Cir. 2009).4 The Commenter cites to prior EPA statements in the 2010 SO2 NAAQS preamble 

and EPA’s 2012 Draft White Paper for Discussion on Implementing the 2010 SO2 NAAQS, as 

support that modeling could better address the source-specific impacts of SO2 emissions and the 

historic challenges of monitoring SO2 emissions.5

Response 2: The EPA agrees with the Commenter that air dispersion modeling can be an 

important tool in the CAA section 107 designations process for SO2 and in developing SIPs for 

nonattainment areas as required by sections 172 and 191–192, including providing support for

required attainment demonstrations. The EPA agrees that prior EPA statements, EPA guidance, 

and case law support the use of air dispersion modeling in the SO2 designations and attainment 

demonstration processes, the interstate impact of transported emissions, and whether existing 

approved SIPs remain adequate to show attainment and maintenance of the SO2 NAAQS. 

Moreover, while the EPA supports the use of modeling as a tool in such contexts, the EPA notes 

that under the Data Requirements Rule, states still have the option of choosing between 

 

Regions 1–10, (Sept. 13, 2013) (hereinafter “Infrastructure SIP Guidance”), available at 

https://www3.epa.gov/airquality/urbanair/sipstatus/docs/Guidance_on_Infrastructure_SIP_Elements_Multipollutant_FINAL_Sep

t_2013.pdf.

3 Thus, the EPA disagrees with the Commenter’s general assertion that the main objective of infrastructure SIPs is to ensure all 

areas of the country meet the NAAQS, as the infrastructure SIP process is the opportunity to review the structural requirements 

of a state’s air program. While the NAAQS can be a foundation upon which emission limitations are set, as explained in 

responses to subsequent comments, these emission limitations are generally set in the attainment planning process envisioned by 

part D of title I of the CAA, including, but not limited to, CAA sections 172, 181–182, and 191–192.

4 Montana Sulphur & Chem. Co. v. EPA, 666 F.3d 1174 (9th Cir. 2012).

5 The Commenter also cites to the 2012 Montana Sulphur & Chem. Co. case which upheld EPA’s finding that the previously 

approved SIP for an area in Montana was substantially inadequate to attain the NAAQS due to modeled violations of the 

NAAQS; the U.S. EPA, Final Response to Petition From New Jersey Regarding SO2 Emissions From the Portland Generating 

Station; and the Data Requirements Rule for the 1-Hour SO2 Primary NAAQS (80 FR 51052 (Aug. 21, 2015));

76 FR 69052 (Nov. 7, 2011) (using modeling to set emission limits sufficient to prevent air pollution).
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modeling and monitoring to characterize air quality. Thus, the EPA reiterates that while 

infrastructure SIPs must provide the state’s authority to conduct air quality monitoring and 

modeling, they need not provide specific air dispersion modeling for large stationary sources of 

pollutants as the Commenter suggests. Specific air dispersion modeling for large stationary 

sources are helpful support as part of the designations and attainment demonstration process, but 

are outside the scope of this action. 

Comment 3: Utah’s SO2 NAAQS Infrastructure SIP is Inadequate with Respect to the Air 

Monitoring and Modeling Requirements of Sections 110(a)(2)(K) and 110(a)(2)(B). 

The Commenter references the Data Requirements Rule for the 2010 1-Hour Sulfur 

Dioxide (SO2) Primary NAAQS (80 FR 51052 (Aug. 21, 2015)), which requires states to 

characterize SO2 air quality either by air quality monitoring or modeling data. According to the 

Commenter, the Data Requirements Rule requires Utah to notify the EPA whether it will use air 

quality modeling or monitoring to characterize SO2 air quality associated with sources that have 

SO2 emissions exceeding a 2,000 tons per year annual threshold. The Commenter states that the 

EPA should evaluate and determine that the Utah Division of Air Quality’s (UDAQ) modeling 

and monitoring procedures are inadequate to ensure implementation of CAA programs to attain 

and maintain the 1-hour SO2 NAAQS. The Commenter obtained air modeling conducted by the 

UDAQ which was used to determine SO2 concentrations around the Hunter, Huntington, and 

Intermountain Power Plants. The Commenter asserts that UDAQ may be relying on modeling 

analyses to demonstrate that the area around these power plants are attaining the 1-hour SO2

NAAQS rather than for the purpose of informing SO2 ambient air monitor placement.

The Commenter contends that independent analyses of the Hunter and Huntington Power 

Plant’s impacts on 1-hour average SO2 concentrations in the area through third-party modeling 

“showed the maximum actual plant wide SO2 emissions from each of the power plants were 

projected to cause violations on the 1-hour SO2 NAAQS” while UDAQ’s SO2 air modeling 

results indicated no violations of the 1-hour SO2 NAAQS at the receptors modeled for the Hunter 

and Huntington plants based on the modeling of actual emissions from 2012-2014. 

The Commenter contends that “UDAQ has applied an approach to modeling that greatly 

understates SO2 air quality in the vicinity around the Hunter and Huntington plants and most 

likely resulted in un-reported violations of the 1-hour SO2 NAAQS.” The Commenter states that 

“UDAQ arbitrarily excluded areas where it was supposedly not feasible to locate an air monitor,

and questions the validity of UDAQ’s modeling infrastructure and its ability to capture 

maximum SO2 concentrations.” The Commenter contends that UDAQ’s modeling and 

monitoring methodologies are not adequate to ensure that the 1-hour SO2 NAAQS is met 

throughout Utah.

Response 3: The EPA disagrees with the Commenter that Utah’s SO2 NAAQS infrastructure SIP 

is inadequate with respect to the ambient air quality monitoring and modeling requirements of 

sections 110(a)(2)(B) and 110(a)(2)(K) respectively. Infrastructure SIPs are general planning 

SIPs to ensure that a state has adequate resources and authority to implement a NAAQS. 

Infrastructure SIP submissions are not intended to act or fulfill the obligations of the Data 

Requirements Rule. While infrastructure SIPs must address modeling authorities in general for 

section 110(a)(2)(K), that section requires infrastructure SIPs to provide the state's authority for 

air quality modeling and for submission of modeling data to the EPA, not specific air dispersion 

modeling for large stationary sources of pollutants.” In the proposal for this rulemaking action, 
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the EPA provided a detailed explanation of Utah’s authority to conduct air quality modeling and

to submit modeling data to the EPA. Furthermore, as stated in the proposal, the EPA is not acting 

on section 110(a)(2)(B) for the 2010 SO2 NAAQS. The EPA provides further details on the 

Commenter’s statement that Utah’s infrastructure SIP is inadequate for purposes of the 

infrastructure SIP elements (B) and (K) in subsequent responses, including Responses 4 and 5. 

On April 12, 2012, the EPA explained its expectations regarding implementation of the 

2010 SO2 NAAQS via letters to each of the states. The EPA communicated in the April 2012 

letters that all states were expected to submit SIPs meeting the ‘‘infrastructure’’ SIP 

requirements under section 110(a)(2) of the CAA by June 2013. At the time, the EPA was

undertaking a stakeholder outreach process to continue to develop possible approaches for 

determining attainment status under the SO2 NAAQS and implementing this NAAQS. The EPA 

was abundantly clear in the April 2012 letters that the EPA did not expect states to submit 

substantive attainment demonstrations or modeling demonstrations showing attainment for areas 

not designated nonattainment in infrastructure SIPs due in June 2013. Although the EPA had 

previously suggested in its 2010 SO2 NAAQS preamble and in prior draft implementation 

guidance in 2011 that states should, in the unique SO2 context, use the section 110(a) SIP process 

as the vehicle for demonstrating attainment of the NAAQS, this approach was never adopted as a 

binding requirement and was subsequently discarded in the April 2012 letters to states. The April 

2012 letters recommended that states focus on infrastructure SIPs due in June 2013, such as

Utah’s SO2 infrastructure SIP, on traditional ‘‘infrastructure elements’’ in section 110(a)(1) and 

(2) rather than on modeling demonstrations for future attainment for areas not designated as 

nonattainment.6

Although the Commenter’s evaluations of modeling demonstrations could be considered

in the context of NAAQS designations, they are not relevant at the earlier stage of reviewing an 

infrastructure SIP submission. No areas in Utah have been designated for the 2010 SO2 NAAQS 

at this point in time. The CAA does not provide explicit requirements for demonstrating 

attainment of a NAAQS for areas that have not yet been designated for that NAAQS.

As stated previously, the proper inquiry in this action is whether Utah has met the basic 

structural SIP requirements appropriate at the point in time the EPA is acting upon the 

 

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In the EPA’s final SO2 NAAQS preamble (75 FR 35520 (June 22, 2010)) and subsequent draft guidance in March and 

September 2011, the EPA had expressed its expectation that many areas would be initially designated as unclassifiable due to 

limitations in the scope of the ambient monitoring network and the short time available before which states could conduct 

modeling to support their designations recommendations due in June 2011. In order to address concerns about potential violations 

in these unclassifiable areas, the EPA initially recommended that states submit substantive attainment demonstration SIPs based 

on air quality modeling by June 2013 (under section 110(a)) that show how their unclassifiable areas would attain and maintain 

the NAAQS in the future. Implementation of the 2010 Primary 1-Hour SO2 NAAQS, Draft White Paper for Discussion, May 

2012 (2012 Draft White Paper) (for discussion purposes with Stakeholders at meetings in May and June 2012), available at 

http://www.epa.gov/airquality/sulfurdioxide/implement.html. However, the EPA clearly stated in this 2012 Draft White Paper its 

clarified implementation position that it was no longer recommending such attainment demonstrations for unclassifiable areas for 

June 2013 infrastructure SIPs. Id. The EPA had stated in the preamble to the NAAQS and in the prior 2011 draft guidance that 

the EPA intended to develop and seek public comment on guidance for modeling and development of SIPs for sections 110 and 

191 of the CAA. Section 191 of the CAA requires states to submit SIPs in accordance with section 172 for areas designated 

nonattainment with the SO2 NAAQS. After seeking such comment, the EPA has now issued guidance for the nonattainment area 

SIPs due pursuant to sections 191 and 172. See Guidance for 1-Hour SO2 Nonattainment Area SIP Submissions, Stephen D. 

Page, Director, EPA’s Office of Air Quality Planning and Standards, to Regional Air Division Directors Regions 1–10(April 23, 

2014). In September 2013, the EPA had previously issued specific guidance relevant to infrastructure SIP submissions due for the 

NAAQS, including the 2010 SO2 NAAQS. See Guidance on Infrastructure State Implementation Plan (SIP) Elements under 

Clean Air Act Sections 110(a)(1) and 110(a)(2), Stephen D. Page, Director, EPA’s Office of Air Quality Planning and Standards, 

to Regional Air Division Directors Regions 1–10, (Sept. 13, 2013) (hereinafter “Infrastructure SIP Guidance”), available at 

https://www3.epa.gov/airquality/urbanair/sipstatus/docs/Guidance_on_Infrastructure_SIP_Elements_Multipollutant_FINAL_Sep

t_2013.pdf.
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infrastructure submittal. Determination of attainment status under the SO2 NAAQS is due on a 

different schedule from the section 110 infrastructure elements. A state, like Utah, may reference 

preexisting SIP rules and emission reduction measures that control emissions of SO2. These

provisions were discussed in the proposed rulemaking and have the ability to reduce SO2 overall. 

Although the Utah SIP relies on measures and programs used to implement previous SO2

NAAQS, these provisions are not limited to reducing SO2 levels to meet one specific NAAQS 

and will continue to provide benefits for the 2010 SO2 NAAQS.

Comment 4: UDAQ Improperly Excluded Parts of Ambient Air from Its Modeling 

Analysis of the Hunter and Huntington Power Plants’ Impacts on 1‐Hour Average SO2

Concentrations.

The Commenter states that “EPA cannot approve [110(a)(2)(K)] of Utah’s SO2 NAAQS 

infrastructure SIP when it is clear that UDAQ’s modeling will not ensure compliance with the 

SO2 NAAQS.” The Commenter explains that “UDAQ’s SO2 modeling methodology is not 

protective of the 1-Hour SO2 NAAQS because UDAQ improperly excludes ambient air receptors 

where violations of the 1-Hour SO2 NAAQS are likely occurring.” The Commenter states that 

UDAQ excluded receptors from its modeling analyses based on a claim that it would not be 

feasible to place a monitor due to steep and inaccessible terrain.

7 According to the Commenter, 

UDAQ cited the EPA’s “SO2 NAAQS Designations Modeling Technical Assistance Document,” 

February 2016 Draft, for support in excluding receptors from its modeling of the Hunter and 

Huntington plants.

The Commenter then points to the EPA’s proposed approval of 110(a)(2)(K) of Utah’s 

infrastructure SIP, and contends that R308-405-13, which incorporates the EPA’s Guideline on 

Air Quality Models in 40 CFR 51, appendix W, does not allow for exclusion of receptors in 

areas where it is not feasible to place an ambient air monitor and references Sections 4.2.1.2.a., 

b. and 7.2.2. of Appendix W. The Commenter claims that one benefit and purpose of air 

dispersion modeling is to predict pollutant concentrations in all locations potentially impacted by 

a source(s) because it may not be feasible to locate a monitor in all areas impacted by a 

source(s).

The Commenter cites to the EPA’s SO2 NAAQS Modeling Technical Assistance 

Document (“SO2 Modeling TAD”) which states that one of the differences between the modeling 

TAD and Appendix W is the placement of receptors only in areas where it is feasible to place a 

monitor. The Commenter references the EPA’s February 2016 Draft “SO2 NAAQS Source‐

Oriented Monitoring Technical Assistance Document” (“SO2 Monitoring TAD”), which includes 

two examples of water bodies and facility property to illustrate “areas feasible to place a 

monitor.” The Commenter contends that “it is inconceivable that EPA intended areas of steep 

terrain to be excluded in a SO2 modeling analysis” and cites to the EPA’s SO2 Monitoring TAD 

to illustrate that valleys can have significant impacts on pollution transport and dispersion.

The Commenter contends that UDAQ’s approach is inconsistent with the EPA’s historic 

interpretation of “ambient air.” Citing to a 1980 EPA letter, the Commenter asserts “that the only 

exemption from ambient air is an area within a facility boundary and only if it is fenced or 

otherwise physically precludes access to the general public.” The Commenter states that the 

receptors Utah is excluding in the Hunter and Huntington modeling are on public land and are in 

 

7 The Commenter cites State of Utah, 1-Hour SO2 Data Requirements Rule Modeling Demonstration (May 5, 2016) and UDAQ’s 

Modeling Protocol Addendum.
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the ambient air, and therefore the 1‐hour average SO2 NAAQS must apply at those ambient air 

receptors.

The Commenter then goes on to compare the third-party modeling results to the UDAQ’s 

modeling and states that the third-party modeling scenarios showed “that the maximum actual 

plantwide SO2 emissions emitted over an hour at each of the plants could cause exceedances of 

the 1‐hour SO2 (based on the 99th percentile value or 4th‐highest for a given year) at various 

locations near the two power plants.” The Commenter contends that UDAQ’s excluded receptors 

in its modeling demonstration “very likely excluded areas that would have been modeled to 

violate the 1‐Hour SO2 NAAQS” and that emails obtained from UDAQ “strongly imply that the 

exclusion of receptors allowed UDAQ to demonstrate attainment at the Hunter and Huntington 

sites.” The Commenter asserts that the EPA has “approved” UDAQ’s modeling protocol 

including its excluded receptors from its attainment modeling for the Hunter and Huntington 

units. 

Response 4: As provided in previous responses, the EPA disagrees with the Commenter that the 

EPA must disapprove the modeling component of Utah’s SO2 infrastructure SIP because UDAQ 

modeling does not ensure compliance with the SO2 NAAQS. In acting to approve or disapprove 

an infrastructure SIP, the EPA is not required to make findings regarding current air quality 

status of areas within the state, such area’s projected future air quality status, or whether 

modeling methodologies for future attainment demonstrations are sufficient to meet a NAAQS in 

the area. The EPA finds the Commenter’s discussion of UDAQ’s modeling methodology 

(regardless of whether the modeling is intended to inform SO2 monitor placement or to 

demonstrate 1-hour SO2 NAAQS attainment) to be irrelevant to the analysis of Utah’s 

infrastructure SIP. Rather, for the infrastructure SIP requirements of section 110(a)(2)(K), EPA 

considers whether the SIP provides Utah officials with the legal authority to (1) conduct air 

quality modeling to predict the effect on ambient air quality of any emissions of any air pollutant 

for which a NAAQS has been promulgated, and (2) provide such modeling data to the EPA 

Administrator upon request. As explained previously, that determination is separate from the 

NAAQS designations process for which the State prepared its modeling protocols.

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Furthermore, to the extent the Commenter believes certain UDAQ emails “indicate that 

EPA has ‘approved’ UDAQ’s modeling protocol,” and that any such approval should have been 

a final agency action subject beforehand to public comment, the Commenter is mistaken. 

Although the EPA may informally advise states about whether it believes that their modeling 

protocols conform with applicable EPA guidance, that advice does not constitute final agency 

action, and is not subject to notice and comment rulemaking.

Comment 5: UDAQ Improperly Determined Areas Not to Be Feasible for Ambient Air 

Monitoring Around the Hunter and Huntington Plants, and Thus EPA Must Disapprove 

the SO2 Monitoring Element of Utah’s Infrastructure SIP as Inadequate to Protect the 1‐

Hour SO2 NAAQS.

The Commenter states that the EPA must disapprove the SO2 monitoring element of 

Utah’s infrastructure SIP because it is inadequate to protect the 1-hour SO2 NAAQS. The 

Commenter explains that UDAQ improperly determined that areas around the Hunter and 

Huntington Plants are not feasible for ambient air monitor placement and excluded monitor 

locations in areas where violations of the 1‐Hour SO2 NAAQS are likely occurring. The 

 
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Commenter contends that UDAQ’s approach in determining locations that are not feasible for 

location of air monitors “is entirely inconsistent with EPA’s historic interpretation of ambient 

air” and is not protective of public health... 

The Commenter contends that the areas excluded from UDAQ’s Hunter and Huntington 

modeling is unjustified because if the EPA were to allow for certain terrain exclusions from SO2

modeling attainment designation analyses, then sources located within complex terrain and/or 

more remote areas could avoid having to reduce SO2 emissions to comply with the 1‐hour 

average SO2 NAAQS. The Commenter cites to the EPA’s Guideline on Air Quality Models 

which notes that “[o]ften the highest concentrations are predicted to occur under very stable 

conditions, when the plume is near, or impinges on, the terrain.” Section 4.2.1.2.b. of EPA’s 

Guideline on Air Quality Models in 40 C.F.R. Part 51, Appendix W.

The Commenter states that the primary objective of the location of ambient air 

monitoring for SO2 NAAQS designation is to determine peak 1‐hour average SO2 concentrations 

in the area around a source. According to the Commenter, the EPA’s SO2 Monitoring TAD

suggests conducting air modeling to aid in monitoring site identification. The Commenter states 

that based on the EPA’s SO2 Monitoring TAD, the modeling the Commenter conducted for the 

Hunter and Huntington Power Plants are the types of analyses the EPA would use to inform the 

proper siting of ambient air monitors at areas of likely maximum SO2 concentrations near such 

facilities. The Commenter contends that UDAQ excluded many of the locations that, according 

to third-party modeling, could have been in violation of the 1‐hour SO2 NAAQS due to actual 

emissions from the Hunter and Huntington Power Plants. The Commenter further contends that

the UDAQ excluded these areas from its Hunter and Huntington modeling for being 

“inaccessible,” but that the areas actually are accessible via various roads, off‐highway vehicle 

trails, and hiking trails. The Commenter also notes the availability of sulfur dioxide air monitors 

designed for transportation and operation in remote locations. Thus, the Commenter contends 

that the areas UDAQ excluded from monitoring must be considered as feasible locations for 

ambient monitors.

Response 5: The EPA disagrees with the Commenter that it must disapprove the SO2 monitoring 

element of Utah’s infrastructure SIP as inadequate to protect the 2010 SO2 NAAQS due to 

ambient air monitoring around the Hunter and Huntington plants. First, the EPA did not propose 

action on element 110(a)(2)(B) for the 2010 SO2 NAAQS. We only proposed to act on this 

element for the 2008 ozone NAAQS. The Commenter does not identify any way in which their 

concerns are relevant to ambient air monitoring for the 2008 ozone NAAQS. The EPA will act 

on Utah’s submission for element 110(a)(2)(B) for the 2010 SO2 NAAQS in a separate action. 

Comment 6: Utah’s SO2 Infrastructure SIP Lacks Necessary Enforceable Emission 

Limitations in Violation of CAA Section 110(a)(2)(A).

The Commenter contends that Utah’s infrastructure SIP does not meet basic structural 

requirements of section 110(a)(2)(A) for the 2010 1-hour SO2 NAAQS because rules containing 

emission limits and control measures for emitting activities were not analyzed for the 2010 SO2

standard and that establishing such limits and measures through SIP‐approved permits is 

insufficient. The Commenter points to air dispersion modeling of the Hunter and Huntington 

plants it had conducted, and contends that emission limitations relied on in the State’s 

infrastructure SIP do not prevent exceedances and therefore Utah’s infrastructure SIP must be 

disapproved under sections 110(a)(1) and (a)(2). The Commenter contends that the State’s 
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infrastructure SIP must include enforceable emission limitations under section 110(a)(2)(A) as 

section 110(a)(2)(E) is a separate component requiring adequate personnel, funding, and 

authority to carry out state implementation plans.

Response 6: The EPA disagrees with the Commenter that the EPA must disapprove Utah’s SO2

infrastructure SIP for the reasons provided by the Commenter, including the Commenter’s 

modeling results and insufficient SO2 emission limits. The EPA is not, in this action, making a 

determination regarding Utah’s current air quality status or whether its control strategy is 

sufficient to attain and maintain the NAAQS. Therefore, the EPA is not making any judgment on 

whether the Commenter’s submitted modeling demonstrates the NAAQS exceedances that the 

Commenter claims.

The EPA disagrees with the Commenter that infrastructure SIP submissions are required 

to contain emission limits assuring in-state attainment of the NAAQS. However, the EPA does 

recognize that in the past, states have, in their discretion, used infrastructure SIP submittals as a

”vehicle” for incorporating regulatory revisions or source-specific emission limits into the state’s 

plan. See 78 FR 73442 (Dec. 6, 2013) (approving regulations Maryland submitted for

incorporation into the SIP along with the 2008 ozone infrastructure SIP to address ethics 

requirements for State Boards in sections 128 and 110(a)(2)(E)(ii)). While these SIP revisions 

are intended to help the state meet the requirements of section 110(a)(2), these “ride-along” SIP

revisions are not intended to signify that all infrastructure SIP submittals must, in order to be 

approved by the EPA, have similar regulatory revisions or source specific emission limits. 

Rather, the regulatory provisions and source specific emission limits the state relies on when 

showing compliance with section 110(a)(2) have, in many cases, likely already been 

incorporated into the state’s SIP prior to each new infrastructure SIP submission; in some cases 

this was done for entirely separate CAA requirements, such as for previous NAAQS.

As stated in previous responses, the EPA’s longstanding position regarding infrastructure 

SIPs is that they are general planning SIPs to ensure that the state has adequate resources and 

authority to implement a NAAQS in general throughout the state. Infrastructure SIPs do not

determine whether each individual area of the state is meeting the applicable NAAQS, as this 

question is addressed through the NAAQS designations process. As previously mentioned, the 

EPA has interpreted this to mean, with regard to the requirement for emission limitations, that 

states may rely on measures already in place to address the pollutant at issue or any new control 

measures that the state may choose to submit.

Comment 7: EPA Must Disapprove Utah’s SO2 I‐SIP Certification as it Lacks Enforceable 

Emission Limitations That Ensure Attainment and Maintenance of the NAAQS.

The Commenter asserts that the EPA must disapprove Utah’s SO2 infrastructure SIP 

certification because it lacks enforceable emission limitations that ensure attainment and 

maintenance of the NAAQS. In support, the Commenter cites: CAA section 110(a)(2)(A); 79 FR 

18648 (noting that infrastructure SIPs must contain enforceable emission limit to aid in attaining 

and/or maintaining NAAQS); and CAA section 110(a)(2)(H) (providing for revisions of SIPs 

when the Administrator finds that a plan is “substantially inadequate to attain the [NAAQS] 

which it implements”). The Commenter relies on Motor Vehicle Mfrs. Ass’n v. State Farm Mut. 

Auto Ins. Co., 463 U.S. 29, 43 (1983) and NRDC v. EPA, 571 F.3d 1245, 1254 (D.C. Cir. 2009)

to contend that the EPA must consider the Commenter’s modeling data on Utah EGUs including 
11

the Hunter and Huntington Plants as additional information provided during a rulemaking 

process under administrative law principles. 

Response 7: The EPA disagrees with the Commenter’s statement that EPA must disapprove 

Utah’s infrastructure SIP. Furthermore, the EPA finds that the Commenter’s submitted modeling

is not relevant to the approvability of Utah’s proposed infrastructure SIP for the 2010 SO2

NAAQS for the reasons previously explained. The purpose for which the Commenter submitted 

the modeling—namely, to assert that current air quality in the areas in which those sources are 

located does not meet the NAAQS—is not relevant to the EPA’s action on this infrastructure 

SIP, and consequently the EPA is not required to consider the modeling in evaluating the 

approvability of the infrastructure SIP. Infrastructure SIPs are not required to contain emission 

limitations informed by air dispersion modeling in order to meet the requirements of section 

110(a)(2)(A). As previously discussed, in acting to approve or disapprove an infrastructure SIP, 

the EPA is not required to make findings regarding current air quality status of areas within the 

state, regarding such areas’ projected future air quality status, or regarding whether existing 

emissions limits in such areas are sufficient to meet a NAAQS. The EPA has made no judgment 

regarding whether the Commenter’s submitted modeling is sufficient to show violations of the 

NAAQS.

 

Comment 8: The Plain Language and Legislative History of the Clean Air Act Require that 

Infrastructure SIPs Contain Enforceable Emission Limits that Ensure Attainment and 

Maintenance of the NAAQS.

The Commenter cites two excerpts from the legislative history of the 1970 CAA claiming 

they support an interpretation that SIPs under CAA section 110 must include emissions 

limitations sufficient to show maintenance of the NAAQS in all areas of the state. The 

Commenter also contends that the legislative history of the CAA supports the interpretation that 

infrastructure SIPs under section 110(a)(2) must include enforceable emission limitations, citing 

the Senate Committee Report and the subsequent Senate Conference Report accompanying the 

1970 CAA. 

Response 8: The EPA disagrees with the Commenter’s statement that the legislative history 

provides support for the interpretation of CAA section 110 in the manner that the Commenter 

suggests. As provided in response 1, the CAA, as enacted in 1970, including its legislative 

history, cannot be interpreted in isolation from the later amendments that refined the CAA 

framework and deleted relevant language from section 110 concerning demonstration of

attainment. See also 79 FR at 17046 (responding to comments on Virginia’s ozone infrastructure 

SIP). The two excerpts of legislative history the Commenter cites merely provide that states 

should include enforceable emission limits in their SIPs, and they do not mention or otherwise 

address whether states are required to include maintenance plans for all areas of the state as part 

of the infrastructure SIP. As provided in response to another comment in this rulemaking, the 

proposed rule explains why the Utah’s SIP includes enforceable emissions limitations for SO2.

Comment 9: EPA Regulations Implementing the Clean Air Act Require that Infrastructure

SIPs Contain Enforceable Emission Limits that Ensure Attainment and Maintenance of the 

NAAQS.
12

The Commenter cites to 40 CFR 51.112(a), which provides that ‘‘[e]ach plan must 

demonstrate that the measures, rules, and regulations contained in it are adequate to provide for 

the timely attainment and maintenance of the [NAAQS].’’ The Commenter asserts that this 

regulation requires infrastructure SIPs to include emissions limits necessary to ensure attainment 

and maintenance of the NAAQS. The Commenter states that the provisions of 40 CFR 51.112 

are not limited to nonattainment SIPs and instead applies to infrastructure SIPs which are 

required to attain and maintain the NAAQS in areas not designated nonattainment. The 

Commenter relies on a statement in the preamble to the final rule promulgating 40 CFR 51.112 

which stated that ‘‘[i]t is beyond the scope of th[is] rulemaking to address the provisions of Part 

D of the Act . . .’’ 51 FR 40656, 40656 (Nov. 7, 1986).

Response 9: The EPA disagrees that 40 CFR 51.112 requires infrastructure SIPs to contain 

enforceable emission limits adequate to ensure attainment and maintenance of the NAAQS. As 

an initial matter, the EPA notes that this regulatory provision was initially promulgated and later 

restructured and consolidated prior to the CAA Amendments of 1990, in which Congress 

removed all references to ‘‘attainment’’ in section 110(a)(2)(A). And, it is clear on its face that 

40 CFR 51.112 applies to plans specifically designed to attain the NAAQS. The EPA interprets 

these provisions to apply when states are developing ‘‘control strategy’’ SIPs such as the detailed 

attainment and maintenance plans required under other provisions of the CAA, as amended in 

1977 and again in 1990, such as sections 175A, 181–182, and 191–192. The Commenter 

suggests that these provisions must apply to section 110 SIPs because in the preamble to the

EPA’s action ‘‘restructuring and consolidating’’ provisions in part 51, the EPA stated that the 

new attainment demonstration provisions in the 1977 Amendments to the CAA were ‘‘beyond 

the scope’’ of the rulemaking. It is important to note, however, that the EPA’s action in 1986 was 

not to establish new substantive planning requirements, but rather was meant merely to 

consolidate and restructure provisions that had previously been promulgated. The EPA noted that 

it had already issued guidance addressing the new ‘‘Part D’’ attainment planning obligations. 

Also, as to maintenance regulations, the EPA expressly stated that it was not making any 

revisions other than to re-number those provisions (51 FR 40657(Nov. 7, 1986)).

Although the EPA was explicit that it was not establishing requirements interpreting the 

provisions of new ‘‘Part D’’ of the CAA, it is clear that the regulations being restructured and 

consolidated were intended to address control strategy plans. In the preamble, the EPA clearly 

stated that 40 CFR 51.112 was replacing 40 CFR 51.13 (‘‘Control strategy: SOx and PM 

(portion)’’), 51.14 (‘‘Control strategy: CO, HC, Ox and NO2 (portion)’’), 51.80 

(‘‘Demonstration of attainment: Pb (portion)’’), and 51.82 (‘‘Air quality data (portion)’’). 51 FR 

40657, 40660. Thus, the present-day 40 CFR 51.112 contains consolidated provisions that are 

focused on control strategy SIPs, and the infrastructure SIP is not such a plan.

Comment 10: EPA Interpretations of Section 110 in Other Rulemakings Require that 

Infrastructure SIPs Contain Enforceable Emission Limits that Ensure Attainment and 

Maintenance of the NAAQS.

The Commenter also references a prior EPA SIP disapproval to claim that it shows that 

the EPA relied on section 110(a)(2)(A) and 40 CFR 51.112 to reject the SIP. The Commenter 

points to a 2006 partial approval and partial disapproval of revisions to Missouri’s existing 

control strategy plans addressing the SO2 NAAQS. The Commenter claims the EPA cited section 

110(a)(2)(A) for disapproving a revision to the state plan on the basis that the State failed to 
13

demonstrate the SIP was sufficient to ensure maintenance of the SO2 NAAQS after revision of 

an emission limit. Similarly, the Commenter claims the EPA cited to 40 CFR 51.112 as requiring 

that a plan demonstrates the rules in a SIP are adequate to attain the NAAQS. The Commenter 

claims the revisions to Missouri’s control strategy SIP for SO2 were rejected by the EPA because 

the revised control strategy limits were also in Missouri’s infrastructure SIP, and thus the 

weakened limits would have impacted the infrastructure SIP’s ability to aid in attaining and 

maintaining the NAAQS.

Response 10: The EPA does not agree that the prior Missouri rulemaking action referenced by 

the Commenter establishes how the EPA reviews infrastructure SIPs. It is clear from the final 

Missouri rule that the EPA was not reviewing initial infrastructure SIP submissions under section 

110 of the CAA, but rather reviewing revisions that would make an already approved SIP 

designed to demonstrate attainment of the NAAQS less stringent. The EPA’s partial approval 

and partial disapproval of revisions to restrictions on emissions of sulfur compounds for the 

Missouri SIP in 71 FR 12623 addressed a control strategy SIP and not an infrastructure SIP. 

Nothing in that action addresses the necessary content of the initial infrastructure SIP for a new 

or revised NAAQS.

Comment 11: Supreme and Appellate Court Opinions Hold that Infrastructure SIPs Must 

Contain Enforceable Emission Limits that Ensure Attainment and Maintenance of the 

NAAQS.

The Commenter discusses several cases applying the CAA which the Commenter claims 

support its contention that courts have been clear that section 110(a)(2)(A) requires enforceable 

emissions limits in infrastructure SIPs to prevent exceedances of the NAAQS. The Commenter 

first cites to language in Train v. NRDC, 421 U.S. 60, 78 (1975), addressing the requirement for 

“emission limitations” and stating that emission limitations “are the specific rules to which 

operators of pollution sources are subject, and which, if enforced, should result in ambient air 

which meets the national standards.” The Commenter also cites to Pennsylvania Dept. of Envtl. 

Resources v. EPA, 932 F.2d 269, 272 (3d Cir. 1991) for the proposition that the CAA directs the 

EPA to withhold approval of a SIP where it does not ensure maintenance of the NAAQS, and to 

Mision Industrial, Inc. v. EPA, 547 F.2d 123, 129 (1st Cir. 1976), which quotes section 

110(a)(2)(B) of the CAA of 1970. The Commenter contends that the 1990 Amendments do not 

alter how courts have interpreted the requirements of section 110, quoting Alaska Dept. of Envtl. 

Conservation v. EPA, 540 U.S. 461, 470 (2004) which in turn quoted section 110(a)(2)(A) of the 

CAA and also stated that “SIPs must include certain measures Congress specified” to ensure 

attainment of the NAAQS. The Commenter also quotes several additional opinions in this vein. 

Mont. Sulphur & Chem. Co. v. EPA, 666 F.3d 1174, 1180 (9th Cir. 2012) (“The Clean Air Act 

directs states to develop implementation plans-SIPs-that ‘assure’ attainment and maintenance of 

[NAAQS] through enforceable emissions limitations”). The Commenter cites to Hall v. EPA 273 

F.3d 1146, 1157-61 (9th Cir. 2001) to conclude that “[j]ust as a plan revision must not interfere 

with attainment of the NAAQS under section 110(l), an infrastructure SIP must, in the first place, 

include enforceable limits sufficient to ensure attainment and maintenance of the NAAQS under 

110(a)(2)(A).” Finally, the Commenter cites Mich. Dept. of Envtl. Quality v. Browner, 230 F.3d 

181 (6th Cir. 2000) for the proposition that “EPA’s deference to a state is conditioned on the 

state’s submission of a plan ‘which satisfies the standards of § 110(a)(2)’ and which includes 

emission limitations that result in compliance with the NAAQS.”
14

Response 11: The EPA disagrees with the Commenter’s contention that these cases support the 

proposition that section 110(a)(2)(A) clearly requires infrastructure SIPs to include detailed plans 

providing for attainment and maintenance of the NAAQS in all areas of the state, nor do they 

shed light on how section 110(a)(2)(A) may reasonably be interpreted. With the exception of 

Train v. NRDC, none of the cases the Commenter cites concerned the interpretation of CAA 

section 110(a)(2)(A) (or section 110(a)(2)(B) of the pre-1990 Act). Rather, the courts reference 

section 110(a)(2)(A) (or section 110(a)(2)(B) of the pre-1990 CAA) in the background sections 

of decisions in the context of a challenge to an EPA action on revisions to a SIP that was 

required and approved or disapproved as meeting other provisions of the CAA or in the context 

of an enforcement action. In Train, 421 U.S. 60, the Court was addressing a state revision to an 

attainment plan submission made pursuant to section 110 of the CAA, the sole statutory 

provision at that time regulating such submissions. The issue in that case concerned whether 

changes to requirements that would occur before attainment was required were variances that 

should be addressed pursuant to the provision governing SIP revisions or were “postponements”

that must be addressed under section 110(f) of the CAA of 1970, which contained prescriptive 

criteria. The Court concluded that the EPA reasonably interpreted section 110(f) not to restrict a 

state's choice of the mix of control measures needed to attain the NAAQS and that revisions to 

SIPs that would not impact attainment of the NAAQS by the attainment date were not subject to 

the limits of section 110(f). Thus the issue was not whether a section 110 SIP needs to provide 

for attainment or whether emissions limits to ensure attainment are needed as part of the SIP; 

rather the issue was which statutory provision governed when the state wanted to revise the 

emission limits in its SIP if such a revision would not impact attainment or maintenance of the

NAAQS. To the extent the holding in the case has any bearing on how section 110(a)(2)(A) 

might be interpreted, it is important to realize that in 1975, when the opinion was issued, section 

110(a)(2)(B) (the predecessor to section 110(a)(2)(A)) expressly referenced the requirement to 

attain the NAAQS, a reference that was removed in 1990. 

The decision in Pennsylvania Dept. of Envtl. Resources was also decided based on the 

pre-1990 provision of the CAA. At issue was whether the EPA properly rejected a revision to an 

approved plan where the inventories relied on by the state for the updated submission had gaps. 

The Court quoted section 110(a)(2)(B) of the pre-1990 CAA in support of the EPA's disapproval, 

but did not provide any interpretation of that provision. Yet, even if the Court had interpreted 

that provision, the EPA notes that it was modified by Congress in 1990; thus, this decision has 

little bearing on the issue here. 

At issue in Mision Industrial, 547 F.2d 123, was the definition of “emissions limitation,”

not whether section 110 requires the state to demonstrate how all areas of the state will attain and 

maintain the NAAQS as part of their infrastructure SIPs. The language from the opinion the 

Commenter quotes does not interpret but merely describes section 110(a)(2)(A). The Commenter 

does not raise any concerns about whether the measures Utah relied on in its infrastructure SIPs 

are “emissions limitations” and the decision in this case has no bearing here.9In Mont. Sulphur 

& Chem. Co., 666 F.3d 1174, the Court was not reviewing an infrastructure SIP, but rather the 

EPA's disapproval of a SIP and promulgation of a federal implementation plan (FIP) after a long 

history of the state failing to submit an adequate SIP in response to the EPA's finding under 

 

9 While the Commenter does contend that Utah shouldn’t be allowed to rely on emission reductions that were developed for the 

prior standards (which we address herein), it does not claim that any of the measures are not ‘‘emissions limitations’’ within the 

definition of the CAA.
15

section 110(k)(5) that the previously approved SIP was substantially inadequate to attain or 

maintain the NAAQS. The Court cited generally to sections 107 and 110(a)(2)(A) of the CAA 

for the proposition that SIPs should assure attainment and maintenance of NAAQS through 

emission limitations, but this language was not part of the Court's holding in the case, which 

focused instead on whether the EPA's finding of SIP inadequacy, disapproval of the state's 

required responsive attainment demonstration under section 110(k)(5), and adoption of a 

remedial FIP under section 110(c) were lawful. The Commenter suggests that Alaska Dept. of 

Envtl. Conservation, 540 U.S. 461, stands for the proposition that the 1990 CAA Amendments 

do not alter how courts interpret section 110. This claim is inaccurate. Rather, the Court quoted 

section 110(a)(2)(A), which, as noted previously, differs from the pre-1990 version of that 

provision and the Court made no mention of the changed language. Furthermore, the Commenter 

also quotes the Court's statement that “SIPs must include certain measures Congress specified,”

but that statement specifically referenced the requirement in section 110(a)(2)(C), which requires 

an enforcement program and a program to regulate the modification and construction of new 

sources. Notably, at issue in that case was the state's "new source" permitting program, not its 

infrastructure SIP. 

Two of the other cases the Commenter cites, Mich. Dept. of Envtl. Quality, 230 F.3d 181,

and Hall v. EPA, 273 F.3d 1146, interpret CAA section 110(1), the provision governing 

"revisions" to plans, and not the initial plan submission requirement under section 110(a)(2) for a 

new or revised NAAQS, such as the infrastructure SIP at issue in this instance. In those cases, 

the courts cited to section 110(a)(2)(A) solely for the purpose of providing a brief background of 

the CAA.

Comment 12: The Emission Limitations Relied Upon by the State in Its I‐SIP are 

Insufficient To Attain and Maintain the NAAQS, as Demonstrated by Air Dispersion 

Modeling of the Hunter and Huntington Power Plants — Two Sources Currently 

Permitted to Cause Exceedances of the NAAQS.

Citing section 110(a)(2)(A) of the CAA, the Commenter contends that the EPA may not 

approve Utah’s proposed 2010 SO2 infrastructure SIP because emission limitations fail to 

prevent exceedances of the NAAQS and, therefore, do not provide for implementation, 

maintenance, and enforcement of the 2010 SO2 NAAQS. The Commenter states coal-fired 

electric generating units (EGUs) are large contributors to SO2 emissions but contends Utah did 

not demonstrate that emissions allowed by the proposed infrastructure SIP from such large 

sources of SO2 will ensure compliance with the 2010 1-hour SO2 NAAQS. The Commenter then 

refers to air dispersion modeling it conducted for two EGUs in Utah, including the Hunter and 

Huntington Plants. The Commenter asserts the results of the air dispersion modeling it conducted 

employing the EPA’s AERMOD program for modeling used the plants’ “allowable emissions 

and/or maximum actual hourly emissions and demonstrated that the levels of SO2 emissions 

allowed to be emitted under current regulations and permits allow for exceedances of the 2010 

one‐hour SO2 NAAQS.”

10 The Commenter asserts that the infrastructure SIP fails to include 

adequate enforceable emission limitations for sources of SO2 sufficient to ensure attainment and 

maintenance of the 2010 SO2 NAAQS.

11 The Commenter asserts that the Hunter and Huntington 

 

10 The Commenter asserts its modeling followed protocols pursuant to 40 CFR part 51, Appendix W and EPA’s modeling 

guidance issued March 2011 and December 2013.

11 The Commenter provides a chart in its comments claiming predicted highest fourth high 1‐ hour average SO2 concentration 

due to Hunter units emitting at allowable SO2 emission rates.
16

plant permits have exemptions for periods of SSM and maintenance/planned outages during 

which no specific emission limit applies. The Commenter claims that the limits in Utah’s 

infrastructure SIP are insufficiently protective of the NAAQS and that actual SO2 emissions 

while operating pursuant to the allowable SO2 emission limitations can be expected to cause 

violations of the SO2 NAAQS.12

The Commenter claims that Utah’s infrastructure SIP is inadequate to attain and maintain 

the NAAQS which it implements because emission limits under the laws and regulations cited to 

in the SO2 infrastructure certification allow for exceedances of the NAAQS. The Commenter 

contends that, where infrastructure SIPs are due within the same timeframe as area designations, 

Congress intends states to set forth enforceable emission limitations and other substantive 

measures in their infrastructure SIPs. The Commenter asserts that the EPA “must set forth a 

Federal Implementation Plan (“FIP”) which incorporates necessary and appropriate source‐

specific enforceable emission limitations (preferably informed by modeling) on the Hunter 

Power Plant and the Huntington Power Plant, as well as any other major sources of SO2 pollution 

in the State which are not presently located in nonattainment areas and have modeled 

exceedances of the NAAQS,” and states that emission limits must apply at all times, including 

during periods of start‐ up, shutdown, and malfunction.

Response 12: For reasons explained in response 6, the EPA disagrees with the Commenter that 

the EPA must disapprove Utah’s SO2 infrastructure SIP regarding modeling results and 

insufficient SO2 emission limits. As discussed previously, EPA reasonably interprets section 

110(a)(2)(A) of the CAA to require states to submit infrastructure SIPs that reflect the first step 

in their planning for attainment and maintenance of a new or revised NAAQS. These SIP 

revisions should contain a demonstration that the state has the available tools and authority to 

develop and implement plans to attain and maintain the NAAQS and show that the SIP has 

enforceable control measures. 

As for the AERMOD air dispersion modeling conducted by the Commenter for the 

Hunter and Huntington facilities, as stated in previous responses, the EPA does not find the 

modeling information relevant at this time for review of an infrastructure SIP. While the EPA 

has extensively discussed the use of modeling for attainment demonstration purposes and for 

designations, the EPA has affirmatively stated such modeling was not needed to demonstrate 

attainment for the SO2 infrastructure SIPs under the 2010 SO2 NAAQS. See April 12, 2012 

letters to states regarding SO2 implementation and Implementation of the 2010 Primary 1-Hour 

SO2 NAAQS, Draft White Paper for Discussion, May 2012, available at 

http://www.epa.gov/airqualitysulfurdioxide/implement.html.

The EPA has promulgated a Data Requirements Rule which requires state air agencies to

characterize air quality around SO2 sources through ambient air monitoring, air quality modeling,

or by providing a federally enforceable emission limitation which limits source emissions to less 

than 2,000 tons per year of SO2. 80 FR 51052 (Aug. 21, 2015). The rule includes a lengthy 

discussion of how the EPA anticipates addressing modeling that informs determinations of 

states’ air quality status under the 2010 SO2 NAAQS. 

Finally, the EPA disagrees with the Commenter’s statements that EPA must disapprove 

Utah’s infrastructure SIP submission because it does not establish specific enforceable SO2

 

12 The Commenter provides a chart in its comments claiming the Predicted Highest Fourth High 1‐ Hour Average SO2

Concentration Due to Hunter Units and Huntington Units Emitting at Plantwide Maximum Actual Hourly SO2 Emission Rates 

During 2012 and 2013.
17

emission limits, either for coal-fired EGUs or other large SO2 sources, in order to demonstrate 

attainment and maintenance with the NAAQS at this time.

Comment 13: EPA May Not Approve the SO2 I‐SIP Certification As it Fails to Include 

Enforceable SO2 Emission Limitations With a One‐Hour Averaging Period that Applies at All 

Times.

The Commenter cites to CAA section 302(k) which requires emission limits to apply on a 

continuous basis. The commenter claims the EPA has stated that 1-hour averaging times are 

necessary for the 2010 SO2 NAAQS citing EPA's April 23, 2014 Guidance for 1-Hour S02 

Nonattainment Area SIP Submissions, a February 3, 2011, EPA Region 7 letter to the Kansas 

Department of Health and Environment regarding the need for 1- hour SO2 emission limits in a 

PSD permit, an EPA Environmental Appeals Board (EAB) decision rejecting use of a 3-hour 

averaging time for an SO2 limit in a PSD permit, and the EPA's disapproval of a Missouri SIP 

which relied on annual averaging for SO2 emission rates.13 Thus, the Commenter contends the 

EPA must disapprove Utah’s infrastructure SIP which the Commenter claims fails to require 

emission limits with adequate averaging times.

Response 13: The EPA disagrees that the EPA must disapprove the proposed Utah infrastructure 

SIP because the SIP does not contain enforceable SO2 emission limitations with 1-hour 

averaging periods that apply at all times, as this issue is not appropriate for resolution at this 

stage. The comment does not assert that the SO2 emission limits in the Utah’s SIP are not 

enforceable, instead the comment focuses on the lack of 1-hour averaging times. We do not 

believe, as suggested by the Commenter, that the emission limits are not “continuous” within the 

meaning of section 302(k). As the EPA has noted previously, the purpose of the section 

110(a)(2) SIP is to ensure that the State has the necessary structural components to implement 

programs for attainment and maintenance of the NAAQS.

While the EPA does agree that the averaging time is a critical consideration for purposes 

of substantive SIP revisions, such as attainment demonstrations, the averaging time of existing 

rules in the SIP is not relevant for determining that the State has met the applicable requirements 

of section 110(a)(2) with respect to the infrastructure elements addressed in the present SIP 

action.14 Therefore, because the EPA finds Utah’s SO2 infrastructure SIP approvable without 

SO2 emission limitations showing in-state attainment of the NAAQS, EPA finds the issue of 

appropriate averaging periods for such future limitations not relevant at this time. The 

Commenter has cited prior EPA discussion on emission limitations required in PSD permits (an 

EAB decision and EPA's letter to Kansas' permitting authority) pursuant to part C of the CAA, 

which is neither relevant nor applicable to the present SIP action. In addition, as previously 

discussed, the EPA disapproval of the 2006 Missouri SIP was a disapproval relating to a control 

strategy SIP required pursuant to part D attainment planning, and is likewise not relevant to the 

analysis of infrastructure SIP requirements.

 

13 Sierra Club cited In re Mississippi Lime Co., PSDAPLPEAL 11–01, 2011 WL 3557194, at *26–27 (EAB Aug. 9, 2011) and

71 FR 12623, 12624 (Mar. 13, 2006) (EPA disapproval of a control strategy SO2 SIP).

14 For a discussion on emission averaging times for emissions limitations for SO2 attainment SIPs, see See Guidance for 1-Hour 

SO2 Nonattainment Area SIP Submissions, Stephen D. Page, Director, EPA’s Office of Air Quality Planning and Standards, to 

Regional Air Division Directors Regions 1–10(April 23, 2014). EPA explained that it is possible, in specific cases, for states to 

develop control strategies that account for variability in 1-hour emissions rates through emission limits with averaging times that 

are longer than 1-hour, using averaging times as long as 30-days, but still provide for attainment of the 2010 SO2 NAAQS as long 

as the limits are of at least comparable stringency to a 1-hour limit at the critical emission value. EPA has not yet evaluated any 

specific submission of such a limit, and so is not at this time prepared to take final action to implement this concept.
18

Comment 14: Appropriate Enforceable Emission Limitations in the Infrastructure SIP are 

Necessary to Avoid Additional Nonattainment Designations.

The Commenter states that enforceable emission limits in SIPs or permits are necessary 

to avoid nonattainment designations in areas where modeling or monitoring shows SO2 levels 

that exceed the 1-hour SO2 NAAQS and cites to a February 6, 2013 EPA document, Next Steps 

for Area Designations and Implementation of the Sulfur Dioxide National Ambient Air Quality 

Standard, which the Commenter contends discusses how states could avoid future nonattainment 

designations. The Commenter also quotes the final SO2 NAAQS Rule which states areas will “be 

designated ‘nonattainment’ if either available monitoring data or modeling shows that a violation 

exists, or ‘attainment’ if both available monitoring data and modeling indicate the area is 

attaining.” The Commenter asserts that the EPA must ensure enforceable emission limits in the 

Utah infrastructure SIP to prevent “exceedances” of the SO2 NAAQS. The Commenter claims 

the modeling it conducted for the Hunter and Huntington power plants indicates the areas around 

these plants may be warranted to be designated nonattainment with the 2010 SO2 NAAQS 

without such enforceable SO2 limits. In summary, the Commenter asserts the EPA must 

disapprove the Utah infrastructure SIP and ensure emission limits will not allow large sources of 

SO2 to cause exceedances of the 2010 SO2 NAAQS.

Response 14: While the EPA appreciates the Commenter’s concern with avoiding nonattainment 

designations in Utah for the 2010 SO2 NAAQS, the EPA disagrees with the Commenter’s 

statement that an infrastructure SIP must prevent such future nonattainment designations.

Congress designed the CAA such that states have the primary responsibility for achieving and 

maintaining the NAAQS within their geographic area by submitting SIPs which will specify the 

details of how the state will meet the NAAQS. Pursuant to section 107(d), the states make initial 

recommendations of designations for areas within each state and the EPA then promulgates the 

designations after considering the state’s submission and other information. The EPA

promulgated initial designations for the 2010 SO2 NAAQS in August 2013 for areas in which 

monitoring at that time showed violations of the NAAQS, but has not yet issued designations for 

other areas. EPA will complete the required designations pursuant to the schedule contained in 

the recently entered Consent Decree. EPA will designate additional areas for the 2010 SO2

NAAQS in accordance with CAA section 107 and existing EPA policy and guidance. Utah may, 

on its own accord, decide to impose additional SO2 emission limitations to avoid future 

designations of nonattainment. If additional Utah areas are designated nonattainment, Utah will 

then have the initial opportunity to develop additional emissions limitations needed to attain the 

NAAQS, and the EPA would be charged with reviewing whether the SIP is adequate to 

demonstrate attainment. See Commonwealth of Virginia, et al., v. EPA, 108 F.3d 1397, 1410 

(D.C. Cir. 1997) (citing Natural Resources Defense Council, Inc. v. Browner, 57 F.3d 1122, 

1123 (D.C. Cir.1995) (discussing that states have primary responsibility for determining an 

emission reductions program for its areas subject to EPA approval dependent upon whether the 

SIP as a whole meets applicable requirements of the CAA). However, such considerations are 

not required of Utah at the infrastructure SIP stage of NAAQS implementation, as the 

Commenter’s statements concern the separate designations process under section 107.15 The

 

15 The EPA also notes that in the EPA’s final rule regarding the 2010 SO2 NAAQS, the EPA noted that it anticipates several 

forthcoming national and regional rules, such as the Industrial Boilers standard under CAA section 112, are likely to require
19

EPA disagrees that the infrastructure SIP must be disapproved for not including enforceable 

emissions limitations to prevent future 1-hour SO2 nonattainment designations.

Comment 15. Utah Has Failed to Even Attempt to Satisfy Its Good Neighbor Obligations Under 

CAA Section 110(a)(2)(D)(i).

The Commenter asserts that the EPA must disapprove Utah’s infrastructure SIP because 

it does not include any information relating to the State’s “good neighbor” obligation under

110(a)(2)(D)(i)(I). The Commenter states that Utah’s SO2 NAAQS infrastructure SIP does not 

address or evaluate cross-state impacts due to sources within the state and contends that UDAQ 

incorrectly interprets the EPA’s November 2012 memo addressing the vacatur of the 2011

Cross-State Air Pollution Rule (CSAPR). The Commenter cites to CAA section 110(a)(1) 

claiming that where infrastructure SIPs are due within the same timeframe as area designations, 

states are obligated to address transport in downwind states through their Infrastructure SIP 

submissions.16 The Commenter contends that “Utah’s reliance on a 2012 EPA memorandum in 

which EPA stated that it did ‘not intend to make findings that states failed to submit SIPs to 

comply with section 110(a)(2)(D)(i)(I)’ is improper, as that guidance directly contradicts the 

language of the Clean Air Act.”17 The Commenter asserts that the Supreme Court has 

disapproved the claim that states cannot address section 110(a)(2)(D)(i) until the EPA resolves 

issues related to CSAPR and that there is no “prerequisite” action required before states fulfill 

section 110(a)(2)(D)(i) requirements.18 The Commenter contends that the EPA must disapprove 

Utah’s infrastructure SIP because the State did not include a submittal with respect to section 

110(A)(2)(D)(i)(I) and must “implement a FIP containing source-specific emission limitations 

and other measures to ensure that pollution from Utah is not preventing other states from 

attaining or maintaining the NAAQS.” The Commenter claims that Utah has passed the June 

2013 deadline to submit provisions to meet Good Neighbor obligations and urges the EPA to 

take “immediate action” to disapprove the State’s SO2 infrastructure SIP.

Response 15: EPA did not propose taking any final action with respect to the requirements of 

section 110(a)(2)(D)(i)(I), and is not taking any such action today. We agree with the 

Commenter that Utah’s June 2, 2013 infrastructure SIP submittal for the 2010 SO2 NAAQS did 

not address the requirements of section 110(a)(2)(D)(i)(I). In the NPR, the EPA did not propose 

to take any action with respect to Utah’s obligations pursuant to section 110(a)(2)(D)(i)(I) for the 

June 2, 2013 infrastructure SIP submittal and is not, in this rulemaking action, taking any final 

action on the 110(a)(2)(D)(i)(I) obligations. Because Utah did not include a submission in its

 

significant reductions in SO2 emissions over the next several years. See 75 FR 35520. The EPA continues to believe similar 

national and regional rules will lead to SO2 reductions that will help achieve compliance with the 2010 SO2 NAAQS. If it appears 

that states with areas designated nonattainment in 2013 will nevertheless fail to attain the NAAQS as expeditiously as practicable 

(but no later than October 2018) during the EPA’s review of attainment SIPs required by section 172, the CAA provides 

authorities and tools for the EPA to solve such failure, including, as appropriate, disapproving submitted SIPs and promulgating 

federal implementation plans. Likewise, for any areas designated nonattainment after 2013, the EPA has the same authorities and 

tools available to address any areas which do not timely attain the NAAQS.

16 The Commenter cites In the Matter of Public Service of New Hampshire Schiller Station, Petition No. VI‐ 2014‐ 04 (EAB July 

24, 2014), at 10 (hereinafter “Schiller Station”).

17 The Commenter cites EPA Memorandum, Next Steps for Pending Redesignation Requests and State Implementation Plan 

Actions Affected by the Recent Court Decision Vacating the 2011 Cross-State Air Pollution Rule (Nov. 19, 2012), available at 

https://www3.epa.gov/crossstaterule/pdfs/CSAPR_Memo_to_Regions.pdf. 

18 The Commenter cites EPA v. EME Homer City Generation, 134 S.Ct. 1584, 1600 (2014) (“[T]e CAA sets a series of precise 

deadlines to which the States and EPA must adhere”) and Schiller Station, at 10 (citing Homer City, 134 S.Ct. at 1601.
20

June 2, 2013 SIP submittal to address the requirements of section 110(a)(2)(D)(i)(I), the EPA is 

not required to have proposed, or actually taken, final action under CAA section 110(k) 

approving or disapproving the SIP for this element. In this case, there has been no substantive 

submission for the EPA to evaluate under section 110(k). The EPA interprets its authority under 

section 110(k)(3) of the CAA as affording the EPA the discretion to approve, or conditionally 

approve, individual elements of Utah’s infrastructure SIP submissions, separate and apart from 

any action with respect to the requirements of section 110(a)(2)(D)(i)(I) of the CAA. Discrete 

infrastructure SIP requirements in section 110(a)(2), such as the requirements of 

110(a)(2)(D)(i)(I), are severable from the other infrastructure elements, and the EPA interprets 

section 110(k)(3) as allowing the Agency to act on individual severable measures in a plan

submission. Further, because Utah’s infrastructure SIP submittal did not address the good 

neighbor provision, we disagree with the Commenter’s statement that the EPA currently has a 

mandatory obligation to issue a FIP addressing section 110(a)(2)(D)(i)(I). Under section 

110(c)(1), the EPA’s authority to issue a FIP arises from limited circumstances—either the 

EPA’s disapproval of a required SIP submittal or the EPA’s affirmative finding that a state has 

failed to make a required submittal. Neither of these prerequisites has activated the EPA’s FIP 

authority with respect to Utah’s section 110(a)(2)(D)(i)(I) obligations for the 2010 SO2 NAAQS. 

The EPA acknowledges the Commenter’s concern for the interstate transport of air

pollutants and agrees in general that sections 110(a)(1) and 110(a)(2) of the CAA require states 

to submit, within three years of promulgation of a new or revised NAAQS, a plan containing 

adequate provisions to address interstate air pollution under section 110(a)(2)(D)(i)(I). However, 

in this action, consistent with the proposal, the EPA is only acting on portions of Utah’s 

infrastructure SIP submissions for the 2010 SO2 NAAQS. The EPA intends to address Utah’s 

obligations regarding interstate transport for the 2010 SO2 NAAQS in another rulemaking.

Comments from Western Resource Advocates

Document No. EPA-R08-OAR-2013-0561-0022

Comment 16: The Utah Infrastructure SIP Does Not Meet the Requirements of 110(a)(2)(A) and

110(a)(2)(C) because Excess Emissions Are Exempted from Permit Limitations.

Western Resource Advocates (the Commenter) contends that Utah has director discretion 

and startup, shutdown, and malfunction (SSM) provisions in its state rules that are “contrary to 

Clean Air Act and existing EPA guidance.” The Commenter claims that the EPA confirmed in 

the proposed rule to this rulemaking that “Utah law and practice runs contrary to the [CAA]” and 

therefore cannot ensure emissions will not cause or contribute to a violation of the NAAQS 

through the State’s air permit program. Additionally, the Commenter states that because Utah’s 

minor and major source PSD permits include exemptions resulting from SSM events, Utah’s 

PSD or minor source permit programs cannot ensure emissions will not cause or contribute to a 

violation of the NAAQS or PSD increments. The Commenter points to SSM language in permit 

approval orders for the Huntington, Current Creek, and Intermountain Power Service 

Corporation (IPSC) power plants and claims that these examples indicate a “pattern” in which 

Utah has included exemptions from SSM events in permits it has issued for facilities located 

outside nonattainment areas. The Commenter contends that Utah has not met requirements of 

section 110(a)(2)(C) because permits issued under the State’s minor source and PSD programs 

exempt emissions from permit limitations and are therefore not adequate to protect the NAAQS. 

The Commenter also asserts that “sources cannot demonstrate that their emissions will not 
21

violate the NAAQS pursuant to 110(a)(2)(A)... where their permits authorize essentially 

unlimited emissions.” Finally, the Commenter contends that the EPA is also obligated to 

disapprove prong 3 of 110(a)(2)(D)(i)(II) because it requires states to have adequate PSD 

programs. 

Response 16: The EPA generally disagrees with this comment. As an initial matter, the 

Commenter’s concerns highlight an important distinction between whether an infrastructure SIP 

submission meets the applicable requirements of the CAA on its face (i.e., pertain to the facial 

sufficiency of the state’s SIP), and whether a state is actually complying with the requirements of 

that SIP (i.e., pertain to adequacy of the state’s implementation of the SIP).19 These comments 

implicate the question of the degree to which implementation concerns are relevant in the context 

of acting on a state’s infrastructure SIP. In the context of an infrastructure SIP submission, the 

EPA interprets section 110(a)(1) and (2) to require the Agency to focus on whether the state has 

a SIP that provides the requisite legal framework for implementation, maintenance and

enforcement of the NAAQS. Generally speaking, the EPA’s review of infrastructure SIP 

submissions is limited to whether, pursuant to CAA section 110(a)(2), the submission facially 

meets the requirements of the statutory criteria outlined therein, as applicable (see also response 

1). In the case of section 110(a)(2)(C), for example, the statute requires a state to have a SIP that 

‘‘include[s] a program to provide for . . . regulation of the modification and construction of any 

stationary sources . . . including a permit program as required in parts C and D of this 

subchapter.’’ Thus, the EPA reviews a state’s infrastructure SIP submission to assure that the 

structural elements of the state’s PSD permitting program meets current CAA requirements for 

such programs, e.g., that it addresses GHG emissions. 

This is not to say the EPA has no role in reviewing whether a state is faithfully 

implementing its approved SIP, or otherwise complying with the CAA and its implementing 

regulations. To the contrary, there are multiple statutory tools that the EPA can use to rectify 

problems with state implementation of its SIP, and the existence of these tools is consistent with 

the EPA’s interpretation of section 110(a)(2) with respect to the Agency’s role in reviewing 

infrastructure SIP submissions. For example, as previously described, the CAA provides the 

EPA the authority to issue a SIP call, 110(k)(5); make a finding of failure to implement, id. §§ 

110(m), 179(a)(4); and take measures to address specific permits pursuant to the EPA’s case-bycase permitting oversight. See, e.g., § 505(b). The appropriateness of employing these authorities 

depends on the nature and extent of the particular implementation problems at issue.

With respect to Utah’s infrastructure SIP submission, the EPA analyzed the submission 

itself, and evaluated the text of its provisions for compliance with the relevant elements of 

section 110(a)(2). In the proposal, the EPA explicitly evaluated the State’s submission on a 

requirement-by-requirement basis and explained its views on the adequacy of the State’s SIP for 

purposes of meeting the infrastructure SIP requirements. 

With respect to the requirements related to PSD and minor NSR relevant to this approval 

of the infrastructure SIP submission, the EPA has determined that the State’s SIP as previously 

approved meets the relevant structural requirements for purposes of minor source NSR and PSD 

in sections 110(a)(2)(C) and (D)(i)(II) prong 3. As to the PSD program in particular, these basic 

structural requirements include those provisions necessary for the permitting program to address 

all federally regulated pollutants and the proper sources. The EPA considers action on the 

 

19 See Approval and Disapproval and Promulgation of Implementation Plans; Texas; Infrastructure and Interstate Transport 

Requirements of the 1997 Ozone and the 1997 and 2006 PM2.5 NAAQS, 76 FR 81371 (Dec. 28, 2011).
22

infrastructure SIP submissions required by section 110(a)(1) and (2) to be an evaluation of a 

state’s SIP to assure that it meets the basic structural requirements for the new or revised 

NAAQS, not a time to address all potential substantive defects in existing SIP provisions,

including directors discretion, or language pertaining to SSM exemptions contained in PSD and 

minor source NSR permits. Therefore, the EPA generally considers evaluations of a state’s PSD 

and minor source NSR permits to be outside the scope of an infrastructure SIP review..

With respect to section 110(a)(2)(A), as discussed in our proposal (81 FR 24525, April 

26, 2016), and further explained in the 2013 Guidance Memo,

20 the EPA is not evaluating any 

existing SSM provisions in Utah’s SIP. Although the Commenter cites EPA’s “confirmation” in 

our proposed rulemaking that existing SSM provisions in the Utah SIP, that sentence of the 

proposed rulemaking was a scrivener’s error, as evidenced in part by the fact that it cited a SIP 

call that did not implicate any provisions of Utah law. The EPA is not aware of any existing 

deficiencies in the Utah SIP regarding excess emissions during SSM events at this time. 

However, the EPA has previously addressed SSM provisions in the Utah SIP outside of the 

infrastructure SIP process, with more appropriate tools Congress provided to address such 

problems. Specifically, under the authority of CAA section 110(k)(5), the EPA issued a SIP call 

on April 18, 2011 requiring Utah to revise SSM SIP provisions dating back to 1980 (See 

"Finding of Substantial Inadequacy of Implementation Plan; Call for Utah State Implementation 

Plan Revision," 76 FR 21639). On February 6, 2014, the EPA finalized approval of the State’s 

revisions to Utah rule R307-107, which corrected deficiencies related to the treatment of excess 

emissions during malfunction events, and therefore satisfied the EPA's April 18, 2011 SIP call 

(79 FR 7067). 

As relevant to this action, however, the Commenter has failed to identify a provision in 

Utah’s SIP that grants SSM exemptions in permits and the EPA is unaware of any such 

provision, and we conclude that Utah’s PSD program meets all requirements under Section 

110(a)(2)(C). Additionally, to the extent that the Commenter points to specific permits as 

exempting excess emissions, if this is the case, the EPA agrees that the state should not give such 

exemptions in permits. The EPA also finds that existing SSM provisions in permits should be 

addressed through the permitting review process rather than the SIP rulemaking process because 

it is an implementation issue that is outside the scope of EPA’s review of this infrastructure SIP.

With regard to director’s discretion provisions.(DD) EPA is aware that the state’s EPAapproved SIP contains some DD provisions. EPA reiterates that such existing DD provisions are 

most appropriately addressed outside the scope of EPA’s infrastructure review process. 

However, the EPA is currently working with Utah to correct existing deficient language in its 

 

20 See Guidance on Infrastructure State Implementation Plan (SIP) Elements under Clean Air Act Sections 110(a)(1) and 

110(a)(2), Stephen D. Page, Director, EPA’s Office of Air Quality Planning and Standards, to Regional Air Division Directors 

Regions 1–10, p. 21 (Sept. 13, 2013). 

In summary, the EPA in recent final actions on infrastructure SIP submissions has maintained that the CAA does not 

require that new infrastructure SIP submissions address existing potentially inadequate provisions concerning SSM or 

director's discretion in order to be approved as meeting the CAA section 110(a)(1) and (2) requirements triggered by 

the new or revised NAAQS. The EPA’s stated position has been that it can approve an infrastructure SIP submission, 

even if the infrastructure SIP may incorporate by reference previously approved SIP provisions that are or may not be 

consistent with the EPA’s SSM Policy and its policy on director’s discretion to revise emission limits. The EPA 

articulated this position in a number of infrastructure SIP actions taken in 2011, noting in the preambles for those 

actions that existing provisions for SSM and director's discretion may be dealt with separately, outside the context of 

acting on an air agency’s new infrastructure SIP submission. However, if an air agency submits an infrastructure SIP 

submission that would create a new SIP provision related to SSM that is inconsistent with the EPA’s interpretation of 

the requirements of the CAA, the EPA may disapprove it. We intend to continue this practice and affirm it as part of 

this guidance.
23

SIP through SIP processes outside the context of the State’s infrastructure SIP, such as through 

Utah’s PM10 maintenance plan and PM2.5 attainment plan. 

Comment 17: The Utah Infrastructure SIP Does Not Meet the Requirements of 110(a)(2)(A) and

110(a)(2)(C) Because In Many Instances, Utah Permits Do Not Regulate Condensable PM2.5 and 

PM10.

The Commenter contends that Utah’s PSD and minor source permits do not regulate 

condensable PM emissions in accordance with the CFR and, therefore, the EPA must not 

“approve any aspects of the proposed infrastructure SIP relating to 2012 PM2.5 NAAQS.” The 

Commenter points to language in the Hunter and MagCorp permit approval orders regarding 

condensable PM emissions and compliance demonstration. The Commenter also cites to the 

IPSC approval order and claims there is no limit for PM2.5 and that compliance with the PM10

emission limit is determined by Method 5B or other testing methods approved by the Director. 

The Commenter states that these examples show a pattern in Utah’s permitting practices for not 

regulating condensable PM or requiring monitoring to determine condensable PM. The 

Commenter asserts that the EPA cannot approve Utah’s 2012 PM2.5 NAAQS infrastructure SIP 

for section 110(a)(2)(C) because the State’s PSD and minor source programs do not regulate or 

limit condensable PM emissions nor demonstrate that emissions from a source will not cause or 

contribute to a violation of the NAAQS under section 110(a)(2)(A). 

Response 17: The EPA disagrees with the Commenter that the EPA must disapprove Utah’s

infrastructure SIP for the 2012 PM2.5 NAAQS because some state PSD and minor source permits 

do not regulate condensable PM. For the reasons discussed in response 16, the EPA evaluated 

the State’s submission with respect to the requirements related to PSD and minor NSR relevant 

to this approval of the infrastructure SIP submission and determined that the State’s SIP as 

previously approved meets the relevant structural requirements for purposes of minor source 

NSR and PSD in section 110(a)(2)(A), (C) and (D)(i)(II) element 3. To reiterate, the EPA 

generally considers evaluations of a state’s PSD and minor source NSR permits to be an 

implementation issue that is outside the scope of an infrastructure SIP review, and therefore the

EPA is not at this time evaluating language pertaining to condensable PM in state permit 

approval orders in this action. 

Finally, the EPA addressed the adequacy of Utah’s infrastructure SIP for the purposes of 

meeting CAA requirements for PSD and minor source programs under section 110(a)(2)(C) in 

the proposed rulemaking for this action. In fact, Utah’s PSD program incorporates the 

requirements for condensable PM that were specified in the EPA’s 2008 PM2.5 NSR 

Implementation Rule. 73 FR 28321, 28349 (May 16, 2008) (changes to federal program). The 

Rule was promulgated in 2008, and Utah’s PSD program incorporates by reference the federal 

program in 40 CFR 52.21 as of 2011, including the provision in 52.21(b)(50)(vi) addressing 

condensable PM (78 FR 63883, 63887, Oct. 25, 2013). Utah’s minor source program regulates 

pollutants as necessary to ensure that construction of a minor stationary source or a minor 

modification will not interfere with the NAAQS, including the PM10 and PM2.5 NAAQS. Thus, 

should condensable PM from a minor source have the potential to interfere with these NAAQS, 

Utah can (and should) address the issue in the minor NSR permit. 
24

Comment 18: The Utah Infrastructure SIP Does Not Meet the Requirements of 110(a)(2)(F) 

Because In Many Instances Monitoring Frequency is Inadequate to Show Continuous 

Compliance with Emission Limitations.

The Commenter states that “EPA’s reliance on [Utah Administrative Code] R307-165 is 

ill-founded and its finding of compliance with section 110(a)(2)(F) is improper.” First, the 

Commenter explains that Utah’s emissions testing requirement of “at least once every five years” 

under R307-165-2 is “insufficient to demonstrate that the requirement to limit emissions ‘on a 

continuous basis’ or to show that continuous compliance with an emission limitation has been 

met.” In support, the Commenter cites the definition of “emission limitation” and “emission 

standard” under Section 302(k) of the CAA as well as several other EPA sources21 to conclude 

that states must enforce and monitor emissions standards and limitations “on a continuous basis.” 

The Commenter adds that “even yearly testing is inadequate” unless a state demonstrates how 

yearly testing can show continuous compliance or continuous emissions monitoring, and that 

the“EPA’s reliance on R307-165 is” thus “ill-founded.”

Second, the Commenter states that “[t]he inadequacy of Utah’s monitoring provision is 

further established in [Utah’s permitting] practice.” In support, the Commenter refers to the 

MagCorp approval order which “routinely requires stack testing only once every five years.”

Response 18: The EPA agrees with the Commenter’s statement that emissions limitations must 

be complied with at all times. However, the EPA disagrees with the Commenter’s argument that

the EPA must therefore disapprove Utah’s infrastructure SIP submission for element 

110(a)(2)(F) because Utah’s emission testing requirements under R307-165-1 only requires a 

stack test at least once every five years. Although emission limits must impose continuous 

emission reduction requirements on the affected sources, it does not follow that sources must 

conduct stack tests continuously in order for emission limitations to be continuous so long as the 

state imposes other appropriate requirements on sources sufficient to assure compliance by 

sources.

In the case of Utah, the requirements the state imposes are not restricted exclusively to 

the stack tests contemplated in R307-165-2. This is not the only mechanism the state uses to 

verify compliance with emission limitations in permits. In addition to that requirement, the 

state’s SIP also provides for other forms of compliance assurance such as continuous emissions 

monitoring. For example, R307-170 requires certain large sources to install and maintain 

continuous emission monitors on sources to prove a means to make sure that the emission 

limitations are legally and practically enforceable. Under the Credible Evidence Rule, any of 

these may be used to support enforcement actions against affected sources for violation of 

emission limitations. 

Finally, the EPA acknowledges the commenter’s concern with the adequacy of 

monitoring requirements in practice. However, to the extent that the State has issued approval 

orders for specific sources that contain insufficient monitoring requirements, this is not an issue 

that the EPA is addressing in the context of evaluating infrastructure SIP submissions. As 

explained elsewhere in this response to comments, the EPA has other tools to address problems 

with permits that have been issued under an approved program. 

 

21 Clean Air Act National Stack Testing Guidance, at 14 (April 27, 2009); Definition of ‘Continuous Compliance’ and 

Enforcement of O&M Violations (June 24, 1982); Credible Evidence Rulemaking, 62 FR 8314, 8323 (Feb. 24, 1997).
25

Comment 19: EPA Errs When it Cites SIP Section XVI as Meeting the General Requirements of 

Section 127.

The Commenter states that the EPA’s reliance on Section XVI as meeting the 

requirements of section 127 is improper. First, the Commenter states that “section XVI is 

completely out of date, having been adopted in 1992” and that the phone number that section 

XVI lists no longer works. Second, the Commenter states that “calculation of API [Air Pollution 

Index] is not adequate to let the public know the condition of the air or compliance with the 

NAAQS.” Finally, the Commenter states that “[r]eliance on section XVI’s description of the 

Annual Report is also ill-conceived.” The Commenter explains that an Annual Report that 

provides “only once a year ‘a description of the regulatory, SIP, and public hearing process and 

an indication of the ways the public may participate in these processes in an effort to improve air 

quality’ does not meet section 127 mandates.”

Response 19: The EPA disagrees with the Commenter’s argument that the Utah SIP does not 

meet the requirements of section 127. Among other requirements, section 110(a)(2)(J) of the 

CAA requires states to meet the public notification requirement under section 127. Section 127 

requires a state's infrastructure SIP to contain measures to notify the public upon the exceedance 

of a NAAQS, to advise the public of the health hazards related to such exceedances, and to 

enhance public awareness of measures that can prevent such exceedances and means for which 

the public can participate in efforts to improve air quality. CAA 127; see also 40 CFR 51.285. 

Section 127 further states that "[s]uch measures may include the posting of warning signs on 

interstate highway access points to metropolitan areas or television, radio, or press notices or 

information." As long as the infrastructure SIP meets section 127 requirements, it is largely 

irrelevant when Utah adopted Section XVI. The measures that the State uses to notify the public 

may vary over time. Utah has a phone line which members of the public may call into, and also 

maintains a website that enables Utahans to learn about air quality issues, view a current air 

quality index, review annual reports submitted to the EPA, and access air quality alerts for ozone 

and PM2.5.

22 The site contains sections to enhance public awareness of measures to take to 

prevent exceedance for the NAAQS. The EPA agrees with the Commenter, however, that the 

measures that the SIP identifies to notify the public to meet section 127 requirements should be 

current, including the phone number listed in Utah’s Section XVI (if it no longer functions as the 

Commenter alleges),23 as well as adding the State’s air quality monitoring website. However, 

given the other methods that the State uses to meet the requirements of section 127, we do not 

regard this deficiency to indicate that the SIP as a whole fails to meet those requirements. 

Second, we disagree with the Commenter’s contention that the API inadequately informs 

the public of the condition or compliance status of NAAQS, and note that the Commenter does 

not provide support for its statement. Section XVI of Utah’s SIP requires UDAQ to calculate an 

API on a daily basis. In measuring and reporting its daily API, states are to follow criteria as 

established in Part 58’s Ambient Air Quality Surveillance. Pursuant to Section XVI of its SIP, 

Utah posts API information on a daily basis. Furthermore, we disagree with the Commenter’s 

statement that a once a year Annual Report that provides the public a description of the public’s

potential involvement in improving air quality fails to satisfy section 127 requirements. EPA 

again notes that the Commenter has failed to provide support for its statement. Neither section 

 

22 Available at http://air.utah.gov/.

23 According to Utah DEQ’s air monitoring website at http://air.utah.gov/, the phone forecast number appears to be 

801-536-0072 or toll-free 1-800-228-5434.
26

127 nor any regulations requires the state to provide such information at a greater frequency 

beyond an annual one.