PRECEDENTIAL

UNITED STATES COURT OF APPEALS

FOR THE THIRD CIRCUIT

_____________

No. 19-2562

_____________

SIERRA CLUB,

 Petitioner

v.

UNITED STATES ENVIRONMENTAL PROTECTION 

AGENCY

*PENNSYLVANIA DEPARTMENT OF ENVIRONMENTAL 

PROTECTION,

 Intervenor Respondent

 *(Pursuant to the Court Order dated 8/5/19)

______________

On Petition for Review of Final Agency Action

of the United States Environmental Protection Agency

(EPA-1: EPA-R03-OAR-2017-0290)

______________

Argued May 21, 2020

______________

Before: McKEE, BIBAS, and NYGAARD, Circuit Judges.

(Opinion filed: August 27, 2020)

Zachary M. Fabish, Esq.
2

Sierra Club Environmental Law Program

50 F Street, N.W.

8th Floor

Washington, DC 20001

Charles McPhedran, Esq. [Argued]

Earthjustice

1617 John F. Kennedy Boulevard

Suite 1130

Philadelphia, PA 19103

Mychal Ozaeta, Esq.

Earthjustice

707 Wilshire Boulevard

Suite 4300

Los Angeles, CA 90017

Counsel for Petitioner

Brandon N. Adkins, Esq. [Argued]

United States Department of Justice

Environment & Natural Resources Division

P.O. Box 7611

Ben Franklin Station

Washington, DC 20044

Counsel for Respondent

Robert A. Reiley, Esq.

Pennsylvania Department of Environmental Protection

Office of Chief Counsel

9th Floor

400 Market Street

Rachel Carson State Office Building

Harrisburg, PA 17101

Jesse C. Walker, Esq. [Argued]

Office of Attorney General of Pennsylvania

Bureau of Regulatory Counsel

RCSOB 9th Floor

P.O. Box 8464

Department of Environmental Protection
3

Harrisburg, PA 17105

Counsel for Intervenor

_______________________

OPINION

______________________

McKEE, Circuit Judge.

The Sierra Club petitions for review of the 

Environmental Protection Agency’s approval of new

Pennsylvania National Ambient Air Quality Standards

(NAAQS). The proposed standards govern pollution output at 

coal-burning power plants in the Commonwealth. The Sierra 

Club argues that the standards wrongly claim to reduce

pollution output at Pennsylvania’s most advanced plants while

simply rubberstamping an average of current pollution output

as its supposed new gold standard. Further, the Sierra Club 

criticizes the proposal’s minimum temperature threshold—a 

measure that allows plants to nearly quintuple their pollution 

output when operating below 600 degrees Fahrenheit—as 

unsupported and unsupportable given the technical record 

before the agency. Finally, the Sierra Club claims that the 

approved standards lack enforceable reporting regulations.

Because we agree that the regulatory regime which springs 

forth from these three defining characteristics is neither

supported by adequate facts nor by reasoning found in the 

administrative record, we hold that the EPA’s approval was

arbitrary and capricious. We will therefore grant the petition 

for review and remand to the agency with instructions that it 

develop enforceable pollution controls in accordance with its 

legal obligations.

I.

This dispute is governed by the Clean Air Act which 

gives Circuit Courts of Appeals original jurisdiction to review 

the EPA’s approval of a state’s proposed pollution standards.1

CAA is a model of cooperative federalism. Indeed, that 

1 42 U.S.C. § 7607(b)(1). 
4

philosophy has been described as the Act’s “core principle.”2

Thus, although the EPA is charged with setting the NAAQS,

3

the individual states are afforded discretion in the planning and 

implementation of plans to achieve the EPA’s goals for 

reduction in air pollutants.

4

One such pollutant is ground level ozone, which is not 

a naturally occurring compound. This ozone is the result of a 

chemical reaction that occurs when power plants and industrial 

boilers mix nitrogen oxides (NOx) with the organic 

compounds they are emitting as air pollution.

5

It is similar to 

the process that creates most anthropogenic (i.e., human 

produced) ozone, which primarily arises from the “photolysis 

of nitrogen dioxide by sunlight, occurring in the presence of 

hydrocarbons.”6

A. Relevant standards and history

This dispute has its beginnings in the EPA’s 2008 

revision to its 1997 ozone National Standard. There, the EPA 

tightened the cap on ozone pollution to an average of 75 partsper-billion over an 8-hour period (the previous standards had 

2 Miss. Comm’n on Envtl. Quality v. E.P.A., 790 F.3d 138, 

156 (D.C. Cir. 2015) (quoting E.P.A. v. EME Homer City 

Generation, L.P., 572 U.S. 489, 511 n.14 (2014)).

3 See 42 U.S.C. § 7408(a) (directing the EPA to list “air 

pollutants” whose emissions “cause or contribute to air 

pollution which may reasonably be anticipated to endanger 

public health or welfare”); 42 U.S.C. § 7409(a)-(b) (for such 

listed air pollutants, EPA must set “ambient air quality 

standards the attainment and maintenance of which . . . are 

requisite to protect the public health” with an “adequate 

margin of safety”).

4 42 U.S.C. §§ 7410, 7502.

5 E.P.A., Ground-level Ozone Basics, 

https://www.epa.gov/ground-level-ozone-pollution/groundlevel-ozone-basics.

6 Peter J. A. Rombout, et al., Rationale for an Eight-Hour 

Ozone Standard, 36 J. OF THE AIR POLLUTION CONTROL 

ASSOC. 913, 913 (1986),

https://doi.org/10.1080/00022470.1986.10466130.
5

permitted 80 parts-per-billion7).

8 Seventeen counties around 

Philadelphia and Pittsburgh were unable to achieve the new 

2008 requirements for pollution control.9 Accordingly, the 

Commonwealth was required to design a state implementation

plan (SIP) for its major sources of NOx and volatile organic 

compounds.10 Power plants are one of the most significant 

sources of these pollutants, and were therefore most directly 

impacted by these proposals. 

Pennsylvania’s proposal had to satisfy Reasonably 

Available Control Technology (RACT) requirements.11 RACT

is a technology-forcing standard designed to induce 

improvements and reductions in pollution for existing sources. 

It is a term of art at the foundation of the EPA’s decisionmaking, but is not defined in the Clean Air Act.12 The EPA 

itself originally defined this standard in internal guidance as 

requiring “the toughest controls considering technological and 

economic feasibility that can be applied to a specific situation

. . . [a]nything less than this is by definition less than RACT.”13

7 EPA Proposes New National Ambient Air Quality Standards 

for Ozone, 20 No. 3 AIR POLLUTION CONSULTANT 2.12, 2.13 

(2010).

8 73 Fed. Reg. 16,436 (Mar. 27, 2008). This 8-hour averaging 

period allows for variation in emissions throughout the day. 

Since 1997, the EPA has accepted such 8-hour averages for 

ozone emissions, and has judged compliance based on the 

fourth-highest (i.e., lowest) daily maximum from each 8-hour 

window, averaged over three years. 20 No. 3 AIR POLLUTION 

CONSULTANT at 2.13.

9 Pennsylvania DEP, “Attainment Status by Principal 

Pollutants,”

http://www.dep.pa.gov/Business/Air/BAQ/Regulations/Pages

/Attainment-Status.aspx.

10 See 42 U.S.C. §§ 7511c(a), 7502(c)(1).

11 42 U.S.C. § 7502(c)(1) (imposing the RACT requirement).

12 42 U.S.C. § 7502(c)(1). See also Natural Res. Def. Council, 

Inc. v. E.P.A., 571 F.3d 1245, 1252 (D.C. Cir. 2009) (finding 

“reasonably available control technology” under the Clean 

Air Act to be ambiguous). 

13 Memorandum from Roger Strelow, Assistant Admin. for 

Air and Waste Mgmt., U.S. E.P.A., to Regional Admins., 
6

Because the parties do not dispute this long-standing 

definition, we assume without deciding that the EPA’s 

definition is correct. Therefore, RACT is “the lowest emission 

limitation that a particular source is capable of meeting by the 

application of control technology that is reasonably available 

considering technological and economic feasibility.”14

Pennsylvania calls the SIP’s implementation of that standard

the RACT II Rule, as it is a second generation approach (since

RACT must be reconsidered at each NAAQS revision).15

RACT is not designed to rubber-stamp existing control 

methods. It is a technology-forcing mechanism. When 

originally introducing the standard, the EPA noted that “the 

control agency, using the available guidance, should select the 

best available controls, deviating from those controls only 

where local conditions are such that they cannot be applied 

Regions I - X, at 2-3 (Dec. 9, 1976), 

https://www3.epa.gov/ttn/naaqs/aqmguide/collection/cp2/197

61209_strelow_ract.pdf. 

14 E.P.A., State Implementation Plans; Nitrogen Oxides 

Supplement to the General Preamble for the Implementation 

of Title I of the Clean Air Act Amendments of 1990, 57 Fed. 

Reg. 55,620, 55,624/3 (proposed Nov. 25, 1992); Navistar 

Intern. Transp. Corp. v. E.P.A., 941 F.2d 1339, 1343 (6th Cir. 

1991) (“Since 1976, the EPA has interpreted reasonably 

available control technology to be the lowest emission 

limitation that a particular source is capable of meeting by the 

application of control technology that is reasonably available 

considering technological and economic feasibility.”) 

(internal quotation marks omitted); Washington Envtl. 

Council v. Bellon, 732 F.3d 1131, 1137 (9th Cir. 2013)

(describing same description of the standard adopted into 

state law as part of an EPA-approved SIP).

15 JA38; see also JA247 (“The evaluation or reevaluation of 

what constitutes RACT-level control for affected sources is a 

requirement that must be fulfilled each time the EPA 

promulgates a new NAAQS . . .”). For clarity, given the 

potential for confusion between the general RACT approach 

and Pennsylvania’s specific implementation here, dubbed 

RACT II, we refer to the proposed changes as the SIP 

whenever possible.
7

there and imposing even tougher controls where conditions 

allow.”16

Thus, in order to satisfy RACT, a proposed SIP must 

satisfy both technological and economic feasibility. The EPA 

explains, “[t]he technological feasibility of applying an 

emission reduction method to a particular source should 

consider the source’s process and operating procedures, raw 

materials, physical plant layout, and any other environmental 

impacts such as water pollution, waste disposal, and energy 

requirements.”17 Whereas the economic feasibility “considers 

the cost of reducing emissions and the difference in costs 

between the particular source and other similar sources that 

have implemented emission reduction.”18 When calculating the 

cost, the EPA has previously cautioned: “Economic feasibility 

rests very little on the ability of a particular source to ‘afford’ 

to reduce emissions to the level of similar sources. Less 

efficient sources would be rewarded by having to bear lower 

emission reduction costs if affordability were given high 

consideration. Rather, economic feasibility . . . is largely 

determined by evidence that other sources in a source category 

have in fact applied the control technology in question.”19

A key technological element of this discussion is the 

development of selective catalytic reduction (SCR). SCR 

originated in the 1970s and is currently a preferred method for

limiting coal-fired power plant pollution. More than 300 coal 

power plants in the U.S. feature the technology.20 SCR can, 

potentially, remove up to 100% of the ozone pollution 

produced by a plant. However, most systems are only designed 

for 90% reduction. By comparison, another potential pollution 

control, SNCR, achieves 25-75% reductions.

21 The SCR 

16 Memorandum from Roger Strelow, supra n.10.

17 E.P.A., State Implementation Plans; General Preamble for 

the Implementation of Title I of the Clean Air Act 

Amendments of 1990; Supplemental, 57 Fed. Reg. 18,070, 

18,073 (proposed Apr. 28, 1992) (first introducing RACT as a 

standard to regulate emissions from existing sources).

18 Id.

19 Id.

20 JA108.

21 Id.
8

process involves injecting a substance such as ammonia or urea 

as a catalyst into the post-combustion flue gas. That causes the 

harmful NOx pollution to break down into its component 

nitrogen and water molecules and to be dispersed as vapor.22

Plants that are unable to meet specified pollution limits 

are allowed to average their emissions with other plants of the 

same owner or operator to comply with the limits.23 A plant is

also permitted under section 129.99 of the RACT II Rule to 

request an alternative RACT limit that applies only to its own 

facility. These are called “source-specific RACT limits.”24 It is 

important to stress that the overall RACT limit is therefore not 

a hard cap if certain older plants could not otherwise satisfy the 

requirements.

B. The Pennsylvania proposal

Pennsylvania’s SIP was submitted in May 2016.25 It 

proposed that NOx emission limits for SCR-equipped coalfired power plants operating at 600 degrees or higher be 

required to emit less than 0.12 pounds of NOx per million 

British Thermal Units (MMBtu) (a unit of heat).

26 Yet when 

SCR-equipped boilers operate below 600 degrees Fahrenheit, 

a higher limit between 0/16 and 0.4 lb/MMBtu limit would be

permitted.27 Pennsylvania had originally not offered any 

reduced limit on SCR-equipped facilities but added these 

provisions (and an accompanying temperature exception, 

discussed below) in response to critical feedback from the 

EPA, which suggested a 0.12 lb/MMBtu limit for such plants.28

In March 2018, the EPA provisionally approved

Pennsylvania’s proposal.29 A number of groups opposed it. 

They expressed particular concern over the regulations for 

22 E.P.A., Air Pollution Control Technology Fact Sheet at 3,

https://www3.epa.gov/ttncatc1/dir1/fscr.pdf.

23 JA39. The other plants must be subject to the same NOx 

presumptive limits and be at the same facility or within the 

same nonattainment area. Id.

24 Id.

25 JA26.

26 25 Pa. Code § 129.97(g)(1)(viii).

27 Id. § 129.97(g)(1)(vi)(C).

28 JA330.

29 JA26.
9

coal-fired combustion plants, which generate a large 

percentage of Pennsylvania’s emissions.30 Surrounding states 

opposed Pennsylvania’s proposal and submitted negative 

public comments during the ensuing comment period. 

For instance, New York took issue with the EPA’s 

claim that the Pennsylvania limits were “comparable to NOx 

emission limitations in other states.”31 New York compared its 

own limits to those proposed by Pennsylvania and argued that 

its limits were “more stringent nearly across the board.”

32

According to New York, Pennsylvania was proposing limits 

that were “comparable to limits that were effective in New 

York from 1995 to 2014.”33

New York argued that the EPA’s finding that 

Pennsylvania’s proposal was comparable to New York and 

Connecticut ignored the fact that both states are partway 

through a multi-year emission limit reduction plan. Additional 

substantial reductions are already completed in Connecticut 

and expected in New York by 2023.34 Finally, New York 

criticized the relatively lenient 30-day averaging of pollution 

proposed by Pennsylvania. New York, by contrast, requires a 

24-hour average, which the state claimed prevents emitters 

from relying on the month-long average to balance out days 

when they do not use pollution control mechanisms.35

Maryland also opposed Pennsylvania’s proposal. It 

argued: “all of Pennsylvania’s coal-fired boilers equipped with 

SCR have demonstrated that they can achieve NOx emission 

rates far below 0.12 lb/MMBtu, including hours where the 

SCR inlet temperature may be lower than 600 F.”36 Maryland 

noted that the proposed limits were “on average, nearly 60% 

higher than what they have achieved in the past.”37 The 

submission included data showing that all of Pennsylvania’s 

30 JA47-52.

31 JA351.

32 JA352.

33 Id.

34 Id.

35 Id.

36 JA354.

37 JA355.
10

powerplants were capable of emissions lower than the 

proposed limit, down to as low as 0.043 lb/MMBtu.38

C. Petitioner’s critiques

The Sierra Club offered even more pointed criticism. It 

submitted lengthy comments against the proposal. In 

particular, the Sierra Club used data from the EPA’s own 

sources to demonstrate that at least some of Pennsylvania’s 

plants have historically been able to emit NOx at 50% of the 

proposed limit.39 The Sierra Club also argued that other 

neighboring states have not received a temperature threshold

for their plants. It is therefore not at all clear why it is 

appropriate or reasonable for Pennsylvania to be given one. 

This is particularly important because the Sierra Club provided 

evidence regarding at least one Pennsylvania plant showing 

that it has operated below the proposed limit (600 degrees) in 

the past.40 Lastly, the Sierra Club complained that the 

Pennsylvania proposal failed to require plants to report their 

temperature records. There would be no reliable method for 

monitoring whether plants were even complying with these 

emission limits. Consequently, a plant could explain away 

higher emissions by claiming it was operating below 600 

degrees at the time, without having to substantiate that claim. 

The combination of this lack of mandatory reporting and the 

temperature waiver created a potent loophole for polluters to 

walk through.

41

Despite these concerns, the EPA eventually gave the 

Pennsylvania plan formal approval in 2019.42 Within the 60-

day statutory window to contest that decision, the Sierra Club 

filed the present petition for review.43

38 Id.

39 JA336-41.

40 JA341-45 (modeling temperatures and pollution at the 

Cheswick plant). This data suggests that Cheswick would be 

able to evade the 0.12 lb/MMBtu limit by operating at lower 

temperatures, as it has in the past.

41 JA345-46

42 JA7.

43 See 84 Fed. Reg. 20,274 (May 9, 2019) (JA007); 42 U.S.C. 

§ 7607(b)(1).
11

II.

The EPA had jurisdiction to review and approve 

Pennsylvania’s SIP.44 The SIP is “locally or regionally 

applicable” within the Third Circuit.45 Accordingly, we have 

jurisdiction to review the EPA’s final approval of the 

Commonwealth’s proposal.

A. Standard of Review

We accord due deference to a final EPA action, in light 

of the agency’s expertise. We will remand only when the 

agency’s decision “[i]s ‘arbitrary, capricious, an abuse of 

discretion, or otherwise not in accordance with the law.’”46

But to receive such deference, the agency cannot reach 

whatever conclusion it likes and then defend it with vague 

allusions to its own expertise; instead, the agency must support 

its conclusion with demonstrable reasoning based on the facts 

in the record. When it fails to do so, an agency action is

arbitrary and capricious—examples include the agency 

“entirely fail[ing] to consider an important aspect of the 

problem.”47 Or offering only a “conclusory statement” which 

“failed to articulate a rational basis for its conclusion.”48 Or 

44 JA028; see 42 U.S.C. §§ 7502, 7410(k).

45 42 U.S.C. § 7607(b)(1). 

46 Nat’l Parks Conservation Ass’n v. E.P.A., 803 F.3d 151, 

158 (3d Cir. 2015) (internal citation omitted). This is 

illustrated, for example, in Berks County v. E.P.A., an 

unpublished 2015 decision, where we denied a petition for 

review because we found the EPA had considered all the data 

and made a reasonable decision. 619 Fed. Appx. 179, 184 (3d 

Cir. 2015).

47 Motor Vehicle Mfrs. Ass’n v. State Farm Mut. Auto. Ins. 

Co., 463 U.S. 29, 43 (1983); see, e.g., E. Bay Sanctuary 

Covenant v. Barr, 964 F.3d 832, 857 (9th Cir. 2020)

(remanding an agency action because it “entirely failed to 

consider an important aspect of the problem”) (citing 463 

U.S. at 43); Sierra Club, Inc. v. U.S. Forest Serv., 897 F.3d 

582, 605 (4th Cir. 2018) (same); Genuine Parts Co. v. E.P.A., 

890 F.3d 304, 341 (D.C. Cir. 2018) (same).

48 W.R. Grace & Co. v. E.P.A., 261 F.3d 330, 342 (3d Cir. 

2001).
12

indeed if “cit[ing] no data whatsoever in support of its 

decision.”49 We have held that “courts are ‘not obliged to stand 

aside and rubber-stamp their affirmance of administrative 

decisions that they deem inconsistent with a statutory mandate 

or that frustrate the congressional policy underlying a 

statute.’”50

However, we cannot “substitute [our] judgment for that 

of the agency.”51 We will therefore defer to the agency’s 

expertise if we can discern “a rational connection between the 

facts found and the choice made.”52 Even when “[a]n agency 

has engaged in line-drawing determinations” we review 

primarily to determine whether the result is “‘patently 

unreasonable’ or run[s] counter to the evidence before the 

agency.”53

B. Standing

We briefly consider standing, and find it is satisfied 

here. The Sierra Club asserts that it holds standing based on the 

interests of its members.54 It describes the particular impact 

increased pollution will have on the health and enjoyment of 

its members, who prioritize outdoor activities (and, 

presumably, good health). To have standing in an 

environmental case, “[t]he relevant showing . . . is not injury 

to the environment but injury to the plaintiff.”55 Standing exists 

where “(1) [the plaintiff] . . . has suffered an ‘injury in fact’

that is (a) concrete and particularized and (b) actual or 

imminent, not conjectural or hypothetical; (2) the injury is 

49 Natural Res. Def. Council, Inc. v. E.P.A., 790 F.2d 289,

309 (3d Cir. 1986).

50 Pa. Fed’n of Sportsmen’s Clubs, Inc. v. Kempthorne, 497 

F.3d 337, 347 (3d Cir. 2007) (quoting Nat’l Labor Relations 

Bd. v. Brown, 380 U.S. 278, 291 (1965)).

51 Motor Vehicle Mfrs. Ass’n, 463 U.S. at 43.

52 Prometheus Radio Project v. FCC, 373 F.3d 372, 389–90 

(3d Cir. 2004), as amended (June 3, 2016) (quoting State 

Farm Mut. Auto. Ins. Co., 463 U.S. at 43).

53 Id. at 390 (quoting Sinclair Broad. Grp. Inc. v. FCC, 284 

F.3d 148, 162 (D.C. Cir. 2002).

54 Pet. Br. at 16-18.

55 Friends of the Earth, Inc. v. Laidlaw Envtl. Servs. (TOC), 

Inc., 528 U.S. 167, 181 (2000).
13

fairly traceable to the challenged action of the defendant; and 

(3) it is likely, as opposed to merely speculative, that the injury 

will be redressed by a favorable decision.”56 When, as here, an 

association sues on behalf of its membership, it may do so 

when “the interests at stake are germane to the organization's 

purpose, and neither the claim asserted nor the relief requested 

requires the participation of individual members in the 

lawsuit.”57

The Sierra Club’s claim here is sufficiently 

particularized to satisfy the Supreme Court’s test from 

Laidlaw.

58 There, the Court accepted statements similar to the 

ones Petitioner makes here that the direct interests of its 

members were at stake. The Court held that this imminent harm

was distinct from the theoretical future interest in visiting 

remote destinations threatened with environmental harm 

rejected as insufficient in Lujan.

59 The Sierra Club describes 

the negative impact of ozone pollution on the health and 

recreational opportunities available to its members.60 When, as 

here, the complaint demonstrates such an actual harm that will 

“directly affect[] those affiants’ recreational, aesthetic, and 

economic interests,” standing is satisfied.61

III.

The Sierra Club challenges the EPA’s approval of the 

Pennsylvania SIP on the three grounds described in their public 

comments above. We consider each in turn: the selection of a 

0.12 NOx/MMBtu pollution limit instead of a stricter 

requirement; the 600-degree temperature threshold; and the 

56 Id. at 180-81.

57 Id. at 181 (citing Hunt v. Washington State Apple Advert.

Comm'n, 432 U.S. 333, 343 (1977)).

58 528 U.S. at 183–84.

59 Lujan v. Defs. of Wildlife, 504 U.S. 555, 564 (1992).

60 JA332 (discussing health consequences which particularly 

affect children and those with asthma, and environmental 

damage including visible injury to trees and vegetation).

61 528 U.S. at 184. Cf. Sierra Club v. E.P.A., 754 F.3d 995, 

1000-02 (D.C. Cir. 2014) (finding the Sierra Club lacked 

standing when it alleged merely speculative harm from 

potential future changes to clear air policies).
14

lack of a reporting requirement on power plant inlet 

temperatures. While the reasoning supporting each element is 

questionable individually, joined together they are decidedly 

worse than the sum of their parts. Working in tandem, these 

three elements spawn a pernicious loophole centered on the 

600-degree threshold, one which would easily permit operators 

to exceed the 0.12 NOx/MMBtu cap.

A. 0.12 NOx/MMBtu Limit

The Pennsylvania Department of Environmental 

Protection (DEP) has freely admitted that its requested 0.12 

NOx/MMBtu pollution limit “is not the lowest achievable 

emissions rate (LAER) for this technology.”62 It correctly notes 

that satisfying RACT is not the same thing as meeting LAER.63

This is obvious since LAER applies only to new sources, 

whereas RACT is a technology forcing standard for existing 

polluters.

64 Thus, DEP ignores the obvious possibility that an 

existing source can both fall short of LAER and also fail to 

satisfy RACT.

Nonetheless, the EPA and DEP argue that RACT need 

not be the best possible emissions limit; it must be the best limit 

that is also economically and technically achievable for plant 

operators. That general proposition is certainly correct. 

However, it fails when applied to this record. Here, DEP itself 

analyzed the pollution reduction capabilities of five different 

plants and found that three are already capable of meeting the 

0.12 lb/MMBtu limits with little or no changes.65 One, Homer 

City, has committed to updating its SCR systems to meet that 

standard.66 But a fourth, Cheswick, is currently operating well 

above the limit (from 0.21 to 0.22 lb/MMBtu).67 0.12 

lb/MMBtu was selected as it represents the average pollution 

output of the three plants that are already compliant over the 

62 JA247

63 Id.

64 Nat. Resources Def. Council, Inc. v. Thomas, 838 F.2d 

1224, 1236 (D.C. Cir. 1988) (noting that LAER applies to 

“new sources in nonattainment areas” whereas RACT 

governs “existing sources in nonattainment areas”).

65 JA325.

66 Id.

67 JA329.
15

last five years.68 Suffice to say, an average of the current

emissions being generated by existing systems, will not usually 

be sufficient to satisfy the RACT standard.

69

The EPA seeks to explain this 0.12 lb/MMBtu choice 

by observing that power needs fluctuate between winter and 

summer, so using data from only part of the year is not 

necessarily reflective of the overall pollution possible on a 

yearly basis. But this simply ignores the fact that by averaging 

current emissions over five years, the 0.12 lb/MMBtu result 

already accounts for seasonal variation.

70

Moreover, the DEP data in the record appears to simply 

average the net emissions rate of each plant, without 

considering these facilities’ widely varying actual output of 

pollutants. For example, the DEP data purports to give Unit 2 

at both Keystone (0.09 lb/MMBtu emissions) and Montour

(0.15 lb/MMBtu) equal weighting in its average (for a 30-day

average of 0.12 lb/MMBtu between the two Units). But this 

record suggests that Keystone Unit 2 is normally operating at 

higher capacity than Montour Unit 2—in June 2003, for 

instance, Keystone Unit 2 produced 128.8 tons of NOx 

emissions, whereas Montour Unit 2 produced only 74.9 tons.71

An equal weighting thus distorts the real-world emissions 

rates. In the example above, the correctly weighted average

rate would have been 0.112 lb/MMBtu, below the 

unconvincing 0.12 lb/MMBtu proposal.

Even more disquieting, the EPA ignores its own Air 

Markets Program Data showing that all five Pennsylvania 

power plants noted above have actually achieved much greater 

reductions than 0.12 NOx/MMBtu during at least 150 months 

that Sierra Club identifies (0.07 NOx/MMBtu or lower average 

in those months).72 The EPA claims that other unspecified 

plants may perform worse than these five, but since this 

68 Id.

69 See Navistar Intern. Transp. Corp., 941 F.2d at 1343

(reiterating that RACT must be, “the lowest emission 

limitation that a particular source is capable of meeting . . .”).

70 JA329.

71 JA337.

72 JA336-39.
16

limitation applies only to SCR-equipped plants, the five plants

under consideration (Cheswick, Montour, Keystone, Bruce 

Mansfield, and Homer City) represent the vast majority of the 

regulated sites in Pennsylvania.73 The EPA fails to specify 

whether or how these five units are unrepresentative of 

Pennsylvania’s SCR-equipped coal-fired plants, aside from 

speculating that they may be.

Indeed, the EPA itself acknowledges that the 

Pennsylvania plants are capable of achieving better than 0.12 

NOx/MMBtu. It relies on data from 2011, 2015, and 2016,

when, on average, the year-long average pollution across 

Pennsylvania power plants equipped with SCR was 0.107 

lb/MMBtu.74 While the EPA uses this data to support the 

marginally higher 0.12 lb/MMBtu standard, it provides no 

explanation for setting RACT at a higher level than 0.107 

lb/MMBtu. It has already been shown that the latter lower 

level is readily achievable on a yearly average. 

Furthermore, the Sierra Club demonstrates that the 

EPA’s baseline data from 2011, 2015, and 2016 is not 

necessarily reflective of the lowest possible emissions 

averages. In fact, those non-consecutive chosen years happen 

to be among the highest emission years in recent records.75 For 

example, the modern Seward Generation plant in New 

Florence, PA, which touts itself as the largest waste coal-fired 

power plant in the world and was constructed in 2004,76

produced its highest emission count on record in 2011, and 

nearly equaled that in 2015.77 By contrast, emissions were 

lower by 10% in 2012 (0.092 instead of 0.103 in 2011).78

73 Or. Arg. Trans. at 5-6. Only 14% of large Pennsylvania 

plants are equipped with SCR. JA053. It was also revealed at 

oral argument that this limited number has since fallen 

further: the Bruce Mansfield plant was decommissioned in 

2019. Or. Arg. Trans. at 5.

74 JA55 n.26.

75 JA340.

76 Seward Generation Power Plant, 

https://robindale.energy/seward-generation.

77 JA340.

78 Id.
17

Further, as the Sierra Club stresses, those levels were 

achieved voluntarily. They were not the result of any coercive 

RACT regulations. Absent any regulatory pressure 

whatsoever, the plants were able to operate at limits lower than 

those in Pennsylvania’s SIP.

79 Thus, the EPA’s apparent 

supposition that a limit below 0.12 lb/MMBtu was not feasible 

is not only unsupported by this record, but actually 

contradicted by it. 

The agency suggests that even if the five plants cited 

could achieve a lower limit, other unspecified facilities might 

not be able to. This position is even less compelling after it was 

revealed at oral argument that the SCR-equipped facilities in 

the state are primarily just the five plants under consideration.

80

The EPA’s reliance on the supposed inability of other unnamed 

facilities, for which it has provided no data or details, is not 

helpful. Moreover, even if a RACT standard was unachievable 

by a particular older plant, that plant could take advantage of a 

“source-specific RACT,” which eases requirements for a 

specific facility that is unable to comply with pollution

controls.

81

Finally, the EPA’s technical report on the Pennsylvania 

plan for emissions does provide some guidance for expected 

emissions levels from coal-fired boilers.

82 However, the fact 

that this data is based on EPA research dating back to 1994 is 

relegated to an accompanying footnote, in which the agency 

quietly concedes, “[i]t is possible that further technological 

advancements may have been proven to result in lower NOx 

emissions levels than those reported [here].”83

Given this concession by the agency that technological 

advances may allow for a more environmentally friendly 

standard than the one approved here, reliance on a study that is 

more than two-and-a-half decades old is neither a persuasive 

79 Id.

80 Or. Arg. Trans. at 5-6.

81 JA68-69.

82 JA55.

83 Id. at n.25.
18

nor reasonable basis for adopting the higher standard it is 

urging upon us now.84

Indeed, nearby states’ data demonstrate the progress 

that has been made in the intervening decades. Maryland, for 

instance, requires its SCR-equipped plants to adhere to a 0.09 

NOx/MMBtu limit.85 Further, as noted above, Maryland 

indicates that 0.12 NOx/MMBtu was “nearly 60% higher” than 

the emissions limits Pennsylvania’s plants “have achieved in 

the past.”86

In response, the EPA contends that Pennsylvania’s 

limits are comparable to some other states. They may be, and 

we do not suggest that Pennsylvania must achieve the absolute 

lowest level of emissions that is technologically possible for 

the approved limit to satisfy RACT. However, there is an

important distinction that the agency’s assertion ignores. The 

0.12 lb/MMBtu limit applies only to SCR-equipped plants—in 

other words, the most technologically advanced facilities in the 

state.87 It is therefore simply not reasonable for the EPA to 

attempt to justify its approval of the higher rate by comparing 

it with the general pollution limitations in other states. Those 

other states are regulating all their coal-fired plants, rather than 

separating out their SCR-equipped facilities. This makes 

Pennsylvania’s lax limit of 0.12 lb/MMBtu even less justifiable 

on this record. As we have noted, those more efficient limits 

apply only to a handful of its most modern plants. Thus, the 

EPA’s approval of Pennsylvania’s more lenient pollution 

levels cannot be explained by the fact that that some

unspecified “other” plants may not be able to attain a lower 

limit. This is particularly true since the EPA’s own data clearly 

establishes the contrary for nearly all of the SCR-equipped

plants in the state, and does so in years with higher than 

average emissions.

As the EPA’s own data demonstrates, a lower limit 

would clearly have been practicable. We realize, of course, that 

“mere” data alone may not require a particular result. However, 

84 JA10.

85 JA355.

86 Id.

87 JA56.
19

the EPA is able neither to offer a reasonable justification for 

failing to require a stricter standard, nor to justify the standard 

it endorsed. That standard represents a mere acceptance of the 

status quo.

We confronted a similar challenge to the EPA’s 

approval of a Pennsylvania SIP proposal (brought by a 

coalition of environmental groups, including the Sierra Club) 

in 2015.88 There, the underlying data and analysis conducted 

by Pennsylvania were clearly inadequate. For example, it 

failed to consider the cumulative impact of multiple pollution 

sources, rather than each individually. Moreover, even the EPA 

agreed that the Commonwealth’s proposal contained “systemic 

deficiencies,” and that it should have done more review.89

Despite that very appropriate concession, the agency 

nevertheless approved the SIP. It claimed to have done so 

because the conclusions were at worst harmless error.90

However, approving the proposed standards without sufficient 

explanation was not “harmless” at all. Rather, we stated that 

the error of relying on an admittedly faulty analysis was a 

bridge too far: “the EPA has identified a host of problems with 

Pennsylvania's . . . analysis. What it has not done, however, is 

provide a sufficient explanation as to why it overlooked these 

problems and approved Pennsylvania’s SIP.”91 Despite the 

deference appropriately afforded to agency determinations of 

these issues, we found it necessary to remand “[b]ecause we, 

as a reviewing court, need an agency to show its work before 

we can accept its conclusions . . .”92

The same is true here. Without any basis for justifying 

their selection of a 0.12 lb/MMBtu limit, and evidence that a 

lower limit was practicable, Respondents struggle to meet even 

our deferential standard of review. Our deference to agency 

expertise is not a blank check allowing the EPA to act 

arbitrarily, nor does it give the EPA a pass on having to explain

how its proposed limit is consistent with RACT. Here, the EPA

88 Natl. Parks Conserv. Ass’n v. E.P.A., 803 F.3d 151 (3d Cir. 

2015).

89 Id. at 165–67.

90 Id. at 166.

91 Id. at 167.

92 Id.
20

has failed to adequately explain how and why a 0.12 lb/MMBtu 

limit is permissible on this record. Although it has offered 

vague allusions to the inability of unspecified plants to meet a 

lower standard, the agency has deprived us of the ability to 

review its decision by “show[ing] its work.”93

B. 600-Degree Temperature

Threshold

The EPA’s questionable reasoning above is badly 

compounded by the agency’s simultaneous approval of a 600-

degree threshold for SCR use. Taken together with the 

reporting requirements discussed below, approval of this 

regulatory scheme was clearly arbitrary and capricious.

Regarding the threshold, neither the EPA nor DEP can 

explain why it is necessary at all. It is not a common 

exemption.

94 Moreover, even assuming such a temperature 

threshold were reasonable, the record does not support the 

conclusion that 600 degrees Fahrenheit is the proper limit. The 

EPA instead justifies the threshold by observing that SCR 

controls become increasingly less effective at lower 

temperatures.95 We readily accept that nearly all chemical 

reactions occur with greater efficiency at higher 

temperatures—this is merely a rote application of the 

Arrhenius Equation (which maintains that “reaction rates 

depend on the . . . temperature”96). However, that does not by 

itself justify approving higher pollution levels at cooler 

operating temperatures because the ill effects of running SCR 

at low temperatures are temporary or easily reversed.97 For 

instance, a higher rate of accumulation of the by-products 

(primarily ammonium bisulfate) at an increased rate at lower 

temperatures can be readily reversed when the plant reverts to 

93 Id. The agency should also have specifically analyzed the 

30-day averaging that Pennsylvania’s plan entails, which is 

longer than neighboring states’ averaging periods during the 

ozone season. Response Br. at 32-33.

94 According to the record, other states have not requested 

such a threshold in their SIP proposals. JA343.

95 JA54.

96 JOHN C. KOTZ, ET AL., CHEMISTRY AND CHEMICAL 

REACTIVITY 696 (7th ed. 2009).

97 JA343.
21

normal temperatures during the daytime, or peak hours.98 The 

EPA failed to consider the practicality of such remedies to 

lower temperature operation, despite the fact, as discussed 

below, that SCR controls routinely operate well below 600 

degrees.99

DEP attempts to bolster the threshold requirement by 

pointing to a response it gave during the public comment 

period.100 However, while that response defends a 600-degree 

limit, it is contrary to record evidence. The DEP had noted: 

“While the minimum operating temperature 

varies depending on the type of SCR system, 

typically for the SCR to function at its target 

efficiency rate and optimize the control of NOx 

emissions, the temperature of the EGU flue gas 

entering the SCR must be no less than 600°F. 

When the EGU flue gas temperature falls below 

600°F, less efficient NOx emission reduction 

occurs along with increased ammonia slip and 

increased potential for air heater fouling leading 

to unscheduled outages.”101

The EPA relies upon this to argue “Pennsylvania 

determined that SCR controls cannot result in lower NOx 

emissions rates when operating below the temperature 

threshold.”102 Yet, in making that argument, the EPA fails to 

explain why operating below SCR’s “target efficiency rate,” as 

DEP explains would occur below 600 degrees, means that SCR 

“cannot result in lower NOx emissions.” That inference simply 

does not naturally follow, and the agency impermissibly leaves 

us to puzzle how it reached its conclusion.

98 Id. (citing EPRI, Investigation of Catalyst Deactivation 

from Operation Below the Minimum Operating Temperature 

(abstract), Product ID: 1023928 (Sept. 11, 2012), available at 

https://www.epri.com/#/pages/product/1023928 [link not 

functioning as of 8/14/2020]).

99 JA343.

100 Intervener Br. at 36-39.

101 JA283.

102 Response Br. at 35 (emphasis added).
22

Further, the EPA’s own data demonstrates that DEP’s 

argument, and the EPA’s conclusion drawn from it, is 

incorrect. In selecting the threshold, the EPA found 600 

degrees “consistent with the technical limitations of the 

SCR.”103 However, in the same paragraph of its technical 

summary, the EPA admitted that SCR-based pollution controls 

are used in temperatures ranging from 315 to 698 degrees 

Fahrenheit.104 The EPA also offers a telling chart of SCR peak 

performance, which demonstrates that as the reaction 

temperature declines, the efficiency of NOx reduction also 

falls.105 Although it can operate at over 90% efficiency at 750 

degrees, SCR is reduced to approximately 77.5% efficiency at 

600 degrees and 62.5% efficiency at 550 degrees.106 Yet the 

agency fails to provide any information to support the crucial 

next step of its reasoning: whether and how 77.5% compares 

in terms of economic and technical viability with 62.5% 

efficiency. 

This Court is left to infer that whereas 77.5% efficiency 

is worthwhile, at 62.5% efficiency, SCR controls no longer add 

value to the pollution control process. That is not an impossible 

conclusion, but there is simply no evidence, nor any effort to 

supply such evidence, in this record. Further, it directly 

contradicts the agency’s suggestion that operating below 600 

degrees “cannot result in lower NOx emissions rates.”107

While this shows that efficiency does decline at an 

increasing rate below 600 degrees, the same is true of 650 

degrees, and 700 degrees. Further, nothing in the record before 

the agency demonstrates why the 65% efficiency at 550 

degrees is inadequate or, in the terms of RACT, economically 

or technologically infeasible. The EPA’s case here boils down 

to showing that there is a general connection between setting a 

limit and lower NOx removal efficiency, which the record 

103 JA54.

104 Id.

105 Response Br. at 37 (SCR System NOx Removal Versus 

Temperature).

106 Id.

107 Id. at 35.
23

supports, and then asking us to trust their “technical judgment” 

as to the proper limit.108

While we defer to the agency’s expertise, the agency’s 

decisions must nevertheless be rational and supported by 

record evidence. Here, we have only the agency’s generic 

reliance on “technical expertise” to explain why 600 degrees 

was a rational cutoff.109 Indeed, the EPA points out that 700-

750 degrees is the optimal operating temperature of most SCR 

systems.110 Thus, if the 600-degree cutoff was based upon the 

efficiencies of higher burning temperatures, the selection of the 

cooler, and thus less efficient and “dirtier,” 600 degree

threshold would be an even greater mystery. We would have 

hoped (and the law requires) that the agency would rely upon 

its technical expertise to justify and explain this decision, not

to simply adopt it via ipse dixit authority. Moreover, it is 

important to note that the agency neglected to explain why 

Pennsylvania in particular needs this threshold when 

neighboring states have neither requested nor received one.

Without explaining specifically how the 600-degree threshold 

satisfies RACT, the EPA accepted an arbitrary number 

proposed by PA DEP. 

108 Id. at 38. By contrast, the EPA is on firmer ground when 

the Sierra Club argues that the EPA has failed to justify the 

30-day averaging period by which emissions are produced. 

Pet. Br. at 33. There the EPA did consider the averaging 

periods in neighboring states and concluded that 

Pennsylvania’s fleet of coal-fired plants and the nature of the 

shorter averaging periods elsewhere (active only during ozone

season) did not require a change to the Pennsylvania SIP. 

Response Br. at 32; JA77-78. This careful analysis further 

highlights how much was missing from the agency’s 

approach elsewhere.

109 Response Br. at 38.

110 JA11 (“NOx removal efficiency decreases more drastically 

when temperatures are lower than the optimal operating 

range,” which is “700° to 750° F”). The EPA also explicitly 

acknowledged in its final approval of the plan that “neither 

Pennsylvania nor EPA explained in detail why the minimum 

SCR temperature exemption . . . is adequate for RACT.” Id.
24

The U.S. Court of Appeals for the D.C. Circuit has 

previously rejected similar efforts by the EPA to proceed based 

upon such a “hunch.”

111 In Sierra Club v. EPA, the EPA set a 

130-ppm carbon monoxide output limit on certain industrial 

boilers. That was based on data suggesting that at less than 150 

ppm, the benefits of further reduction were negligible.112

However, the data the EPA used to reach that determination 

had previously been rejected by the agency as unreliable. Thus,

the D.C. Circuit Court held that the proposed standard was 

arbitrary and capricious. The EPA had relied on the data to 

conclude that further reductions would not be helpful.113 The 

court explained, “even if EPA had grounds to conclude that 

there is some nonzero level of CO emissions that marks a point 

below which [pollution] emissions cannot be further reduced, 

it offered no basis for identifying 130 ppm as that level.”114

Likewise, here the data could support establishing a 

threshold limit, but the agency fails to establish why 600 

degrees suffices whereas 550 or 650 degrees does not. Unlike 

the flawed underlying data rejected by the D.C. Circuit, here

the EPA fails to provide any uncontradicted data to support its 

threshold limitation. Instead, it summarily concludes that were 

Pennsylvania to institute a 550-degree limit, “additional NOx 

reductions achieved would be marginal.”115

The threshold limit also serves to eviscerate the 

agency’s already flawed 0.12 lb NOx/MMBtu limit discussed 

above. The evidence here establishes that since the SIP took 

effect, the Cheswick power plant appears to have begun using 

the 600-degree threshold as a loophole to avoid activating its 

SCR system.116 At night, when power needs drop and the plant 

can lower its operating temperatures, the emissions at 

Cheswick have not declined commensurately. On the contrary, 

they have soared—up to 0.35 lb NOx/MMBtu—more than 

111 Sierra Club v. E.P.A., 884 F.3d 1185, 1198 (D.C. Cir. 

2018).

112 Id. at 1195.

113 Id. (“EPA relied on the same data it had elsewhere 

decisively characterized as untrustworthy.”).

114 Id. at 1197.

115 Response Br. at 39; JA12.

116 JA342.
25

three times the daytime emissions. This resulted in the entire 

plant’s average emissions substantially increasing.

117 We 

cannot ignore the fact that this increase in polluting emissions 

only started after implementation of the new SIP standard was 

approved.

118

The EPA tacitly acknowledged the existence of this 

loophole in its public response to the Sierra Club’s concerns. 

There, the agency tried to argue that there was no loophole 

because the plants must still cap emissions at the higher, nonSCR limit of 0.16 lb-0.40 lb/MMBtu, depending on the boiler 

type.

119 The EPA argues it is thus not a “loophole” but the 

natural result of plants lowering their operating temperatures at

night due to reduced demand.120 That argument collapses upon 

itself. It is, in fact, describing what can only be defined as a 

loophole. It should be obvious that a loophole need not allow 

plants to escape regulation entirely. Nevertheless, the 

temperature threshold permits plants to evade the lower SCR 

limits of the Pennsylvania SIP. The EPA is thus flatly wrong 

when it concludes that allegations the threshold constitutes a 

loophole are not “supported in theory or fact.”121 Thus, we 

must remand in order for the agency to develop an alternative 

federal implementation plan.122

C. Reporting Requirement

Finally, the proposed SIP’s lack of a tangible reporting 

requirement is the third chink in the plan’s shoddy enforcement 

regime. In light of this deficiency, the temperature threshold 

exception discussed above becomes even more pernicious. 

Operating in tandem, these two provisions allow plant 

operators to evade the above 0.12 lb/MMBtu limits altogether 

by claiming they were operating below 600 degrees at the time 

117 JA341-42.

118 See JA344-45 (demonstrating the pattern of increased 

emissions after SIP was implemented).

119 JA12.

120 Response Br. at 45.

121 Id. Because these increased emissions started only after the 

SIP’s temperature threshold was implemented, it cannot be 

explained as a necessary byproduct of the plant’s nighttime 

operations.

122 42 U.S.C. § 7410(c)(1).
26

non-compliant emissions occurred. Without a record of inlet 

temperature data at the time of emission, it will be impossible 

to ascertain the validity of such claims.

The EPA and DEP reject the notion that the reporting 

requirements are insufficient. First, they point to the text of the 

Pennsylvania SIP as incorporated into state regulation. They 

then add many additional details regarding how this statutory 

oversight will be enforced that are nowhere to be found in the 

administrative record. “Our review must . . . be based on ‘the 

administrative record [that was] already in existence’ before 

the agency, not ‘some new record made initially in the 

reviewing court’ or ‘post-hoc rationalizations’ made after the 

disputed action.”123 Thus, we can only consider the record as it 

existed when the EPA issued its approval, not any post-hoc 

justifications offered during the course of litigation.

This means that support for the reporting regime must 

be found in the following requirements, which existed at the 

time of approval: 

The owner and operator of an air contamination 

source subject to this section . . . shall keep 

records to demonstrate compliance [with the 

SIP] in the following manner: (1) The records 

must include sufficient data and calculations

to demonstrate that the requirements [of the SIP] 

are met. (2) Data or information required to 

determine compliance shall be recorded and 

maintained in a time frame consistent with the 

averaging period of the requirement.124

The parties dispute whether this SIP requirement that

“sufficient data and calculations” be recorded suffices to 

ensure that temperature records are preserved. The Sierra Club 

argues these terms are too vague to be enforceable. We agree. 

The Clean Air Act requires: “plan provisions shall include 

enforceable emission limitations, and such other control 

123 Christ the King Manor, Inc. v. Sec. U.S. Dept. of Health 

and Human Servs., 730 F.3d 291, 305 (3d Cir. 2013) (quoting 

Rite Aid of Pa., Inc. v. Houstoun, 171 F.3d 842, 851 (3d 

Cir.1999)) (alterations in original).

124 25 Pa. Code § 129.100(d) (emphasis added).
27

measures, means or techniques . . . as well as schedules and 

timetables for compliance, as may be necessary or appropriate 

. . .”125 The Sierra Club also complains that the law allows only 

Pennsylvania to request the records;126 there is no provision for 

public insight into how the plants are operating, and therefore 

no way for interested members of the public, or more crucially, 

the EPA itself, to conduct oversight. The absence of public 

access conditions enforcement upon a given administration’s 

approach to enforcement of state environmental regulations. 

We do not believe that Congress intended to tether 

enforcement of the Clean Air Act safeguards to the vicissitudes 

of those political winds. 

In New York v. E.P.A., the Court of Appeals for the D.C. 

Circuit held that when a state proposal’s lack of sufficient 

reporting requirements prevents the EPA from conducting

enforcement, a given regime thereby fails to comply with the 

Clean Air Act.127 There, the EPA had approved a reporting 

regime that depended on operators self-identifying a 

“reasonable possibility” of experiencing an increase in 

pollution. It left to the independent hands of those operators 

whether, in fact, they matched that description.128 Therefore, 

operators could freely increase their emissions and avoid 

detection simply by claiming that there was no “reasonable 

possibility” that they would have experienced an increase in 

pollution output. The court concluded, “EPA needs to explain 

how its recordkeeping and reporting requirements allow it to 

identify [noncompliant] sources.”129 The court also expressed 

doubt about an enforcement regime’s “reliance on state 

programs to establish minimum recordkeeping and reporting 

standards.”

130 Effective regulation must not depend on the 

candor or veracity of the very entities being regulated. This is 

particularly true under the CAA, where past practices of 

125 42 U.S.C. § 7502(c)(6); see also Reply Br. at 26 (citing 

cases that rejected the EPA’s approval of unenforceable 

standards).

126 25 Pa. Code § 129.100(i).

127 413 F.3d 3, 35 (D.C. Cir. 2005).

128 Id. at 34-35.

129 Id. at 34.

130 Id. at 35.
28

weighing economic factors have historically counseled against 

complete compliance.

The same logic applies here. First, the EPA delegated

recordkeeping entirely to Pennsylvania’s internal procedures. 

This delegation failed to require that records be available to the 

public. Instead, it deferred what “data and calculations” were 

“sufficient” for compliance to an operator’s interpretation. 

That “honor code” approach might suffice in the type of world 

we aspire to. But it is more than a little fanciful to base a 

regulatory enforcement regime upon such aspirations.131

Instead, of requiring a regime that could readily be “policed” 

and enforced, the EPA endorsed an emissions regime with no 

discernible enforcement mechanism.

Anticipating this weakness in their initial argument, the 

EPA and PA DEP offer a second line of justification. They

provide more detail on how the regulatory regime will 

function. In its brief, DEP explains that under existing state 

law, plant operators are required by their operating permits to 

record their operating temperatures and to preserve those 

records for inspection on request of the state.132 In particular, 

the state describes how “major polluters” under Title V (a 

category into which, it assures us, all of the power plants under 

review fall) are required to maintain and make available 

suitable records for public review and inspection. The Title V 

permitting process itself incorporates the RACT requirements, 

131 Moreover, in that aspirational world, regulation would not 

be needed to ensure compliance. As the Founders recognized: 

“[i]f men were angels, no government would be necessary.”

THE FEDERALIST No. 51 (James Madison). Instead, by

requiring a regime that could readily be “policed” and 

enforced, the EPA endorsed an emissions regime with no 

discernible enforcement mechanism.

132 Intervener Br. at 54-55 (citing 25 Pa. Code §§

127.12(a)(3), 127.411(a)(4)(i), 127.12b(c), 127.441, 

127.442). Intervenors direct us to this and other parts of their 

brief in their 28j letter, but the further explication they 

provide was not present in the record when the EPA issued its 

approval of the SIP and is therefore not a valid basis for our 

decision making now. DEP 28(j) letter dated May 28, 2020 at 

1-2.
29

by making each permitee agree to keep suitable records to 

enforce RACT provisions.133

Yet at oral argument, PA DEP conceded that 

temperature inlet data is not specifically included in these Title 

V permit records. Instead, counsel posited that “if the 

Department has the temperature data, citizens are able to 

review that.”134 This tacitly demonstrates that the data’s 

availability is speculative and dependent on the regulated 

entity. Counsel explicitly confirmed this point. When asked, 

“so sometimes it’ll be there, and sometimes it won’t,” PA 

DEP’s counsel admitted, “that’s correct, Your Honor . . . if the 

Department has records, they must be made available to the 

public.”135 It is a strange regulatory system indeed that is based 

on the good faith of the regulated entity to keep records which 

may be prejudicial to its operation and profitability. 

Moreover, the recordkeeping provisions cited by PA 

DEP do not require operators to record temperature inlet 

data.136 Intervenor’s own record cites reveal that PA DEP 

actively removed prior requirements for “how the records shall 

be maintained or in what format[.]”137 And even if this were 

not the case and the EPA had actually submitted after-the-fact 

evidence that temperature inlets were recorded, we would be 

unable to consider that evidence. We are bound to examine 

only “the administrative record . . . already in existence before 

the agency, not some new record made initially in the 

reviewing court or post-hoc rationalizations made after the 

disputed action.”138

Because the SIP’s 600-degree threshold necessarily 

depends upon accurate temperature reporting, the EPA’s 

approval of such inadequate requirements on this record was 

133 Intervener Br. at 55 (citing 25 Pa. Code Chapter 127, 

Subchapter G).

134 Oral Arg. Trans. at 42-43 (emphasis added).

135 Id. at 43 (emphasis added).

136 Intervenor’s Br. at 12, 56 (citing 25 Pa. Code §§ 127.511, 

129.100).

137 JA289.

138 Christ the King Manor, Inc., 730 F.3d at 305 (internal 

quotation marks and citation omitted).
30

arbitrary and capricious. Thus, the reporting requirements must 

be vacated. 

IV.

Therefore, we will grant the petition for review and 

vacate the agency’s action on each of these three provisions of 

the Pennsylvania plan. On remand, the agency must either 

approve a revised, compliant SIP within two years or formulate 

a new federal implementation plan.

139 That proposal must be

technology forcing, in accord with the agency’s RACT 

standard,140 and lack the gaping loophole found in the 

enforcement regime proposed here.

139 42 U.S.C. § 7410(c)(1) (providing two years for the EPA 

to promulgate a federal implementation plan in such 

circumstances); E.P.A. v. EME Homer City Generation, L.P., 

572 U.S. 489, 498 (2014) (acknowledging this timeline).

140 Memorandum from Roger Strelow, supra n.10, at 2.