                                           PRECEDENTIAL


                      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.
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
Harrisburg, PA 17105

             Counsel for Intervenor
               _______________________

                       OPINION
                ______________________


                             2
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
philosophy has been described as the Act’s “core principle.”2
Thus, although the EPA is charged with setting the NAAQS,3

1
  42 U.S.C. § 7607(b)(1).
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

                              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 parts-
per-billion over an 8-hour period (the previous standards had
permitted 80 parts-per-billion7).8 Seventeen counties around

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/ground-
level-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.
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.
                               4
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 decision-
making, 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
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

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.,
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

                                5
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
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


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.
16
   Memorandum from Roger Strelow, supra n.10.
                               6
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
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



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.
22
   E.P.A., Air Pollution Control Technology Fact Sheet at 3,
https://www3.epa.gov/ttncatc1/dir1/fscr.pdf.
                                7
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 coal-
fired 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
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


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.
30
   JA47-52.
                                8
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
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

31
   JA351.
32
   JA352.
33
   Id.
34
   Id.
35
   Id.
36
   JA354.
37
   JA355.
38
   Id.
                              9
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

                              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


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).
44
   JA028; see 42 U.S.C. §§ 7502, 7410(k).
45
   42 U.S.C. § 7607(b)(1).
                              10
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
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


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).
49
   Natural Res. Def. Council, Inc. v. E.P.A., 790 F.2d 289,
309 (3d Cir. 1986).
                              11
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
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

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).
56
   Id. at 180-81.
                                12
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
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


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).
                              13
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
last five years.68 Suffice to say, an average of the current




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.
68
   Id.
                                14
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
limitation applies only to SCR-equipped plants, the five plants
under consideration (Cheswick, Montour, Keystone, Bruce

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.
                                15
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
       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

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.
                              16
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
nor reasonable basis for adopting the higher standard it is
urging upon us now.84



79
   Id.
80
   Or. Arg. Trans. at 5-6.
81
   JA68-69.
82
   JA55.
83
   Id. at n.25.
84
   JA10.
                                17
       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,
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.

85
   JA355.
86
   Id.
87
   JA56.
                                18
        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
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


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.
                               19
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.
                              20
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).
                              21
        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.
                               22
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.
                               23
        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.
                              24
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, non-
SCR 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).
                               25
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).
                                26
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.
                               27
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.
                               28
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).
                               29
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.
                              30
