ORAL ARGUMENT NOT YET SCHEDULED

IN THE UNITED STATES COURT OF APPEALS

FOR THE DISTRICT OF COLUMBIA CIRCUIT

No. 11-1108 (and consolidated cases)

UNITED STATES SUGAR CORPORATION, et al.,

Petitioners,

v.

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY, et al.,

Respondents.

On Petition for Review of Final Action of the

United States Environmental Protection Agency

BRIEF FOR RESPONDENT UNITED STATES

ENVIRONMENTAL PROTECTION AGENCY

SAM HIRSCH

Acting Assistant Attorney General

PERRY M. ROSEN

OF COUNSEL: NORMAN L. RAVE, JR.

SUSMITA DUBEY Environmental Defense Section

Office of General Counsel Environment and Natural Resources Division

United States Environmental United States Department of Justice

Protection Agency P.O. Box 7611

1200 Pennsylvania Ave., NW Washington, D.C. 20044

Washington, D.C. 20460 (202) 616-7568

November 10, 2014

USCA Case #11-1108 Document #1521657 Filed: 11/10/2014 Page 1 of 113
ORAL ARGUMENT NOT YET SCHEDULED

UNITED STATES COURT OF APPEALS

FOR THE DISTRICT OF COLUMBIA CIRCUIT

____________________________________

)

UNITED STATES SUGAR )

CORPORATION, )

)

Petitioner, )

)

 v. ) Docket No. 11-1108

) (and consolidated cases)

UNITED STATES ENVIRONMENTAL )

PROTECTION AGENCY, et al., )

)

 Respondents. )

___________ ________________________ )

RESPONDENTS’ CERTIFICATE OF COUNSEL

Pursuant to Circuit Rule 27(a)(4), counsel for Respondents United States 

Environmental Protection Agency and Gina McCarthy, Administrator (collectively 

“EPA”) submit this certificate as to parties, rulings, and related cases.

(A) Parties and Amici 

(i) Parties, Intervenors, and Amici Who Appeared in the District 

 Court 

This case is a petition for review of final agency action, not an appeal from 

the ruling of a district court.

USCA Case #11-1108 Document #1521657 Filed: 11/10/2014 Page 2 of 113
(ii) Parties to These Cases 

All parties, intervenors, and amici appearing in this court are listed in the 

Brief for Industry Petitioners.

(B) Rulings Under Review

The Agency actions under review are “National Emission Standards for 

Hazardous Air Pollutants for Major Sources: Industrial, Commercial, and 

Institutional Boilers and Process Heaters,” published at 76 Fed. Reg. 15,608 

(March 21, 2011); and “National Emission Standards for Hazardous Air Pollutants 

for Major Sources: Industrial, Commercial, and Institutional Boilers and Process 

Heaters,” published at 78 Fed. Reg. 7,138 (Jan. 31, 2013)

(C) Related Cases

The case on review has not been previously before this Court or any other 

Court. Case No. 13-1256 was severed from the cases consolidated under No. 

11-1108 on October 16, 2013. The Court has coordinated this case with Nos. 

11-1125, 11-1141, and 11-1189, and ordered that they be heard by the same panel. 

Dkt. 1461576.

Respectfully submitted, 

SAM HIRSCH

Acting Assistant Attorney General

ii

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/S/ Norman L. Rave, Jr. 

NORMAN L. RAVE, JR. 

PERRY M. ROSEN

Environmental Defense Section

Environment & Natural Resources Division

United States Department of Justice

P.O. Box 23986

Washington, D.C. 20026-3986

(202) 616-7568

Counsel for Respondents

November 10, 2014

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TABLE OF CONTENTS

TABLE OF AUTHORITIES ....................................................................................iv

GLOSSARY...............................................................................................................x

JURISDICTION.........................................................................................................1

STATEMENT OF ISSUES .......................................................................................1

STATUES AND REGULATIONS ...........................................................................3

STATEMENT OF FACTS ........................................................................................4

A. Statutory Background ...........................................................................4

B. Regulatory Background.........................................................................8

SUMMARY OF ARGUMENT...............................................................................11

A. Industry Petitioners’ Claims................................................................11

B. Environmental Petitioners’ Claims.....................................................14

STANDARD OF REVIEW.....................................................................................17

ARGUMENT...........................................................................................................18

I. EPA ACTED RATIONALLY IN SETTING EMISSION

STANDARDS ON A POLLUTANT-BY-POLLUTANT

BASIS FOR NEW HEAVY OIL-FIRED 

BOILERS AND EXISTING STOKER COAL FIRED BOILERS ..............18

II. EPA DID NOT ACT ARBITRARILY IN SETTING NUMERIC 

CARBON MONOXIDE EMISSION STANDARDS TO CONTROL 

NON-DIOXIN ORGANIC HAPS ................................................................27

A. EPA Did Not Act Arbitrarily in Applying a Numeric Emission 

Standard for Organic HAP Emissions From Coal-Fired Boilers........28

B. EPA Did Not Commit Procedural Error in Addressing the Issue of 

Organic HAP Emission Standards for Coal-Fired Boilers..................33

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III. EPA’S DETERMINATION THAT SECTION 7412 DOES

NOT REQUIRE EMISSION LEVELS DURING MALFUNCTIONS

TO BE TAKEN INTO ACCOUNT IN DETERMINING THE LEVEL

ACHIEVED BY THE BEST PERFORMING SOURCES IS 

REASONABLE AND CONSISTENT WITH THE STATUTE ..................36

A. EPA’S Historic Practice Regarding Malfunctions..............................37

B. There is No Statutory Requirement to Factor Malfunction Emission 

Levels into MACT Numeric Emission Standards..............................39

C. It Was Not Arbitrary and Capricious for EPA to Decide

Not to Create a Work Practice Standard for Malfunction Events.......48

IV. EPA DID NOT ACT ARBITRARILY IN ESTABLISHING

NUMERIC MACT EMISSION STANDARDS FOR HCL ........................ 50

V. EPA’S IMPOSITION OF AN ENERGY ASSESSMENT REQUIREMENT 

AS A BEYOND-THE-FLOOR STANDARD WAS WITHIN EPA’S 

AUTHORITY AND NOT ARIBTRARY OR CAPRICIOUS .....................60

A. The Energy Assessment Fits Squarely Within EPA’s Authority to 

Establish Beyond-the-Floor Standards................................................62

B. Emission Standards Apply to the Major Source, Not Merely to the 

Specific Equipment From Which Hazardous Pollutants are Finally 

Emitted ................................................................................................63

C. The Energy Assessment Complies with All Statutory

Requirements......................................................................................66

VI. EPA REASONABLY USED CARBON MONOXIDE AS

A SURROGATE FOR ORGANIC HAPS....................................................69

VII. THE SUBCATEGORIES IN THE RULE ARE REASONABLE................76

VIII. EPA REASONABLY EXCLUDED CERTAIN UNITS CO-FIRING 

NATURAL GAS FROM ITS MACT FLOOR ANALYSIS........................79

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IX. EPA’S USE OF THE UPPER PREDICTION LIMIT TO ESTABLISH 

STANDARDS IS REASONABLE ...............................................................81

A. Introduction .........................................................................................81

B. Use of the UPL Is Consistent with the Requirements of Section 

7412(d)(3)............................................................................................84

1. The UPL Represents the Average Performance of the Top 

Performing Sources Over Time ................................................85

2. The UPL Represents What the Best Performing Sources 

Achieve Over Time...................................................................88

C. The Standards Are Supported By the Record .....................................90

D. EPA Did Not Change Its Rationale for the UPL

In the Response to the Remand of the Record ....................................93

CONCLUSION........................................................................................................96

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TABLE OF AUTHORITIES

CASES

Alaska Dep't of Envtl. Conservation v. EPA,

540 U.S. 461 (2004)..............................................................................................22

Am. Trucking Ass'ns, Inc. v. EPA,

283 F.3d 355 (D.C. Cir. 2002)..............................................................................92

* Bluewater Network v. EPA,

 370 F.3d 1 (D.C. Cir. 2004) .......................................................................... 70, 72

Cement Kiln Recycling Coalition v. EPA,

255 F.3d 855 (D.C. Cir. 2001)............................................................. 7, 23, 44, 45

Chemical Mfrs. Ass'n v. EPA,

870 F.2d 177 (5th Cir. 1989) ..................................................................................22

Chevron U.S.A. Inc. v. NRDC, Inc.,

467 U.S. 837 (1984)............................................................... 17, 21, 40, 43, 58, 66 

EDF v. Duke Energy Corp.,

549 U.S. 561 (2007)..............................................................................................22

Ethyl Corp. v. EPA,

541 F.2d 1(D.C. Cir. 1976) (en banc)...................................................................92

FCC v. Fox Television Stations, Inc.,

556 U.S. 502 (2009)..............................................................................................58

Huls Am. Inc. v. Browner,

83 F.3d 445 (D.C. Cir. 1996)................................................................................22

Jama v. Immigration & Customs Enforcement,

543 U.S. 335 (2005)..............................................................................................52

* Authorities chiefly relied upon are marked with an asterisk.

iv

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Kennecott Greens Creek Min. Co. v. Mine Safety and Health Admin.,

476 F.3d 946 (D.C. Cir. 2007)....................................................................... 70, 72

McCreary v. Offner,

172 F.3d 76 (D.C. Cir. 1999)................................................................................52

Medical Waste Inst. and Energy Recovery Council v. EPA,

645 F.3d (D.C. Cir. 2011)....................................................................................21

* Mossville Envtl. Action Now v. EPA,

 370 F.3d 1232 (D.C. Cir. 2004) ........................................................... 6, 7, 83, 89

Motor Vehicle Mfrs. Ass'n v. State Farm Mut. Auto. Ins. Co.,

463 U.S. 29 (1983)................................................................................................17

* Nat'l Ass'n of Clean Water Agencies v. EPA,

 734 F.3d 1115 (D.C. Cir. 2013)............................41, 45, 76, 87, 88, 89, 95

Nat'l Cable & telecoms. Ass'n v. Brand X Internet Servs.,

 545 U.S. 967 (2005).....................................................................58

National Lime Ass'n v. EPA,

627 F.2d 416 (D.C.Cir. 1980)........................................................................ 34, 38

Nat'l Lime Ass'n v. EPA,

233 F.3d 625 (D.C. Cir. 2000).................................................... 6,7, 27, 41, 70, 71

Nat'l Mining Ass'n v. EPA,

59 F.3d 1351 (D.C. Cir. 1995)....................................................................... 35, 65

Natural Resources Defense Council v. EPA,

822 F.2d 104 (D.C. Cir. 1987)..............................................................................72

NRDC v. EPA,

859 F.2d 156 (D.C. Cir. 1988)..............................................................................47

NRDC v. EPA,

194 F.3d 130 (D.C. Cir. 1999)..............................................................................32

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NRDC v. EPA,

489 F.3d 1250 (D.C. Cir. 2007)............................................................. 5, 8, 53, 76

NRDC v. EPA,

529 F.3d 1077 (D.C. Cir. 2008)..........................................................................4, 7

NRDC v. EPA,

571 F.3d 1245 (D.C. Cir. 2009)............................................................................21

NRDC v. EPA,

749 F.3d 1055 (D.C. Cir. 2014)..................................................................... 39, 40

Portland Cement Ass'n v. Ruckelshaus,

486 F.2d 375 (D.C. Cir. 1973)..............................................................................35

Reynolds Metals Co. v. EPA,

760 F.2d 549 (4th Cir. 1985).................................................................................72

* Sierra Club v. EPA,

 167 F.3d 658 (D.C. Cir. 1999) .......................................................... 38, 83, 84, 89

* Sierra Club v. EPA,

 353 F.3d 976 (D.C. Cir. 2004)................................4, 24, 27, 29, 70, 71, 72 

Sierra Club v. EPA,

479 F.3d 875 (D.C. Cir. 2007)..................................................... 23, 45, 47, 65, 80

* Sierra Club v. EPA,

 551 F.3d 1019 (D.C. Cir. 2008) ............................................. 9, 36, 37, 40, 44, 81

St. Luke's Hosp. v. Sebelius,

611 F.3d 900 (D.C. Cir. 2010)..............................................................................22

United States v. Mead Corp.,

533 U.S. 218 (2001)..............................................................................................21

Weyerhaeuser Co. v. Costle,

590 F.2d 1011 (D.C. Cir. 1978).......................................................... 45,46, 47, 48

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* White Stallion Energy Ctr., LLC V. EPA,

 748 F.3d 1222 (D.C. Cir. 2014), petition for cert. filed,

 83 U.S.L.W. 3089 (U.S. July 14, 2014) (No.14-46)...................................5,

25, 32, 58, 59

STATUTES

42 U.S.C. § 7411......................................................................................................43

42 U.S.C. § 7411(a) .................................................................................................65

42 U.S.C. § 7412..................................................1, 2, 4, 8, 11, 20, 22, 39, 

................................................................40, 42, 44, 47, 48, 58, 65, 81 

42 U.S.C. § 7412(a)(1).........................................................................................5, 65

42 U.S.C. § 7412(a)(2)......................................................................5

42 U.S.C. § 7412(a)(3).....................................................................65

42 U.S.C. § 7412(c) ...................................................................................... 5, 63, 64

42 U.S.C. § 7412(d)................................. ...1, 6, 18, 23, 50, 51, 57, 65, 76 

42 U.S.C. § 7412(d)(1).........................................................................................5, 76

42 U.S.C. § 7412(d)(2).............................. 5, 6, 14, 18, 21, 52, 57, 62, 63, 66, 67, 81 

42 U.S.C. § 7412(d)(3).............................................. 6, 11, 18, 26, 45, 52, 80, 81, 82 

42 U.S.C. § 7412(d)(3)(A).......................................................................................20

42 U.S.C. § 7412(d)(4)............................................ 51, 52, 56, 57, 58, 59

42 U.S.C. § 7412(f)........................................................................................... 25, 52

42 U.S.C. § 7412(f)(2)(A)........................................................................................52

42 U.S.C. § 7412(h).............................................................. 7, 12, 13, 33, 44, 48, 50 

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42 U.S.C. § 7412(h)(1)...................................................................................... 30, 49

42 U.S.C. § 7412(h)(2).............................................................................................30

42 U.S.C. § 7412(h)(2)(A).........................................................................................8

42 U.S.C. § 7412 (h)(2)(B)...................................................................8

42 U.S.C. § 7412(h)(4).............................................................................................30

42 U.S.C. § 7412(n)(1).............................................................................................59

42 U.S.C. § 7429....................................................................................................8, 9

42 U.S.C. § 7602(k)................................. .......................................81

42 U.S.C. § 7607(b)(1)...............................................................................................1

42 U.S.C. § 7607(d)(6)(B).......................................................................................33

42 U.S.C. § 7607(d)(7)(B)................................................................................ 33, 34

42 U.S.C. § 7607(d)(8).............................................................................................35

42 U.S.C. § 7607(d)(9).............................................................................................17

Pub. L. No. 91-604, §4(a), 84 Stat. 1676 (1970)........................................4

CODE OF FEDERAL REGULATIONS

40 C.F.R. § 63.11237 ...............................................................................................60

40 C.F.R. § 63.7520(d) ............................................................................................81

40 C.F.R. § 63.7575 .................................................................................................78

40 C.F.R. Part 63, Subpart DDDDD..........................................................................5

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FEDERAL REGISTER

61 Fed. Reg. 17,358 (Apr. 19, 1996) .......................................................................21

69 Fed. Reg. 55,218 (Sept. 13, 2004) ........................................................... 8, 37, 52

75 Fed. Reg. 32,006 (June 4, 2010) 51, 53, 54, 55, 56, 60, 61, 62, 63, 64, 66, 68, 77

75 Fed. Reg. 54,970 (Sept. 9, 2010) ........................................................................21

76 Fed. Reg. 15,455 (Mar. 21, 2011).........................................................................9

76 Fed. Reg. 15,554 (Mar. 21, 2011)............................................................ 8, 61, 64

76 Fed. Reg. 15,608 (Mar. 21, 2011).....................10, 20, 24, 26, 32, 34, 37, 38,

..............................39, 41, 43, 46, 50, 54, 60, 63, 64, 68, 76, 78, 83, 86, 90, 93 

76 Fed. Reg. 15,704 (Mar. 21, 2011).......................................................9

76 Fed. Reg. 24,976 (May 3, 2011).................................................................. 31, 32

77 Fed. Reg. 9304 (Feb. 16, 2012)....................................................28, 31

78 Fed. Reg. 7138 (Jan. 31, 2013).....................1, 5, 9, 18, 35, 51, 60, 66, 69, 70, 

..............................................................................71, 75, 76, 78, 91 

LEGISLATIVE MATERIALS

H.R. Rep. No. 101-490, at 328, reprinted in 2 Legislative History of the Clean Air 

Act Amendments of 1990..................................................................80

S. Rep. No. 101-228, (1989), 1990 U.S.C.C.A.N 3385 at *3552, 

3553.......................................................................................23, 25

ELECTRONIC DATABASE

http://en.wikipedia.org/wiki/Prediction_interval.....................................................85

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GLOSSARY

2011 Rule “National Emission Standards for Hazardous Air 

Pollutants for Major Sources: Industrial, Commercial and 

Institutional Boilers and Process Heaters, Final Rule,” 76 

Fed. Reg. 15,608, March 21, 2011

2013 Rule “National Emission Standards for Hazardous Air 

Pollutants for Major Sources: Industrial, Commercial and 

Institutional Boilers and Process Heaters, Final Rule,” 78 

Fed. Reg. 7138, January 31, 2013

CAA Clean Air Act, 42 U.S.C. §7401, et seq.

CO Carbon Monoxide

EGU Electric Generating Unit

EPA United States Environmental Protection Agency

HAP Hazardous Air Pollutant

HCl Hydrogen Chloride

LEAN Petitioners Louisiana Environmental Action Network, et 

al.

MACT Maximum Achievable Control Technology

Major Boilers Rule 2011 Rule and 2013 Rule collectively

MMBtu Million British thermal units

PM Particulate Matter

RTC Response to Comments

tpy tons per year

UPL Upper Prediction Limit

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JURISDICTION

The Court has jurisdiction pursuant to 42 U.S.C. §7607(b)(1).

STATEMENT OF ISSUES

Petitioners challenge various emission standards established by Respondent 

Environmental Protection Agency (“EPA”) under section 112 of the Clean Air Act 

(“CAA” or “the Act”), 42 U.S.C. §7412, for hazardous air pollutants (“HAPs”) 

emitted by industrial, commercial and institutional boilers and process heaters 

(collectively “Boilers”) located at “major” sources. EPA promulgated these 

regulations through two rulemakings: “National Emission Standards for Hazardous 

Air Pollutants for Major Sources: Industrial, Commercial and Institutional Boilers 

and Process Heaters, Final Rule,” 76 Fed. Reg. 15,608, March 21, 2011 (“2011 

Rule”); and EPA’s final action on reconsideration of the 2011 Rule, 78 Fed. Reg. 

7138, January 31, 2013 (“2013 Rule”) (referred to collectively as the “Major 

Boilers Rule.”).

The issues raised by Industry Petitioners are:

1. Is EPA’s longstanding pollutant-by-pollutant approach to setting 

emission standards for each hazardous pollutant regulated under 42 U.S.C.

§7412(d) a rational application of that provision, which expressly requires EPA to 

establish emission standards based on the emission levels actually achieved by the 

best performing source(s), or is Petitioners’ view that EPA must set emission

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standards based on the emission levels achieved by a single source for all HAPs in 

aggregate the unambiguous directive of the statute, even where that single source 

may be the worst performing source for one or more HAPs being regulated? 

2. Did EPA exceed its authority or act arbitrarily in establishing numeric 

emission standards for non-dioxin organic HAPs through the use of the surrogate 

pollutant carbon monoxide (“CO”), rather than establishing a non-numeric work 

practice standard (e.g., equipment tune-up) to govern emissions of organic HAPs?

3. Does 42 U.S.C. §7412 unambiguously require EPA to factor 

emissions that occur during malfunctions, which cannot be predicted as to effect, 

number, length, nature, severity or cause, into emission standards, and is it 

arbitrary and capricious for EPA not to have created a work practice standard for 

malfunctions? 

4. Did EPA exceed its authority or act arbitrarily in refraining from 

exercising its discretion to utilize a health threshold in establishing the emission

standards for hydrogen chloride (HCl) in the face of a lack of data establishing that 

such a threshold would be protective of public health?

5. Did EPA abuse its discretion in establishing a “beyond-the-floor” 

standard requiring major sources to conduct an energy assessment designed to 

identify methods of reducing fuel usage that would thereby reduce the levels of 

HAPs emitted from the regulated source?

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The issues raised by Environmental Petitioners (“LEAN”) are:

6. Did EPA reasonably use CO as a surrogate for non-dioxin organic 

HAP emissions where CO is an indicator of efficient combustion, which is the 

control method for non-dioxin organic HAPs?

7. Is EPA’s creation of subcategories based on the principal fuel that a 

unit is designed to combust consistent with the CAA and reasonable, where EPA 

determined that the principal fuel determines boiler design and affects both 

emission characteristics and applicable emission control methods?

8. Did EPA reasonably determine that certain units co-combusting 

natural gas are not “similar” for determining new source emission standards where 

that is not typical of units in the subcategory?

9. Did EPA reasonably use the Upper Prediction Limit (“UPL”) 

methodology to determine the value that the best performing source(s) would 

achieve 99 percent of the time to account for variability and ensure that the 

resulting standard could be met by the best performing sources over the full range 

of foreseeable operating conditions?

STATUES AND REGULATIONS

Pertinent statutes and regulations appear in Petitioners’ briefs and 

Addendums thereto.

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STATEMENT OF FACTS

A. Statutory Background

Along with two other EPA rules issued on the same day that are also being 

challenged and have been coordinated with this action (see pp. 8-9 infra), the 

Major Boilers Rule regulates the emissions of hazardous air pollutants, in this case

pursuant to CAA §112, 42 U.S.C. §7412. Section 7412 was enacted by Congress 

to regulate the emission of toxic pollutants that are hazardous to public health. 

Consequently, when first enacted, section 7412 required EPA to identify and 

regulate HAPs when they were found to “cause, or contribute to, an increase in 

mortality or an increase in serious irreversible [ ] or incapacitating reversible [ ] 

illness.” Pub. L. No. 91-604, §4(a), 84 Stat. 1676, 1685 (1970), 42 U.S.C. 

§7412(a)(1) (1970). These health-based standards, however, proved exceedingly 

difficult to generate. NRDC v. EPA, 529 F.3d 1077, 1079 (D.C. Cir. 2008). 

In response, Congress substantially amended section 7412 in 1990 to direct 

EPA to regulate HAP emissions utilizing technology-based standards. Sierra Club 

v. EPA, 353 F.3d 976, 979 (D.C. Cir. 2004). First, Congress itself identified the 

pollutants that were deemed to be hazardous, designating 189 HAPs subject to 

regulation. Congress then required EPA to establish emission standards for what it

deemed “major” stationary sources of these hazardous pollutants. Major stationary 

sources are those that emit more than ten tons per year (“tpy”) of any covered HAP 

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or more than twenty-five tpy of any combination of HAPs. 42 U.S.C. §7412(a)(1). 

Sources that emit lower levels of HAPs are classified as “area sources.” Id.

§7412(a)(2). To facilitate the regulation of HAP sources, Congress provided for 

EPA to establish source categories and subcategories. 42 U.S.C. §7412(c). See, 

e.g., 40 C.F.R. Part 63 Subpart DDDDD (covering Boilers), 78 Fed. Reg. at 7142 

(identifying Boiler subcategories). 

Finally, Congress gave EPA specific direction regarding how it must 

promulgate emission standards for major sources. 42 U.S.C. §7412(d)(1); White 

Stallion Energy Ctr., LLC v. EPA, 748 F.3d 1222, 1231 (D.C. Cir. 2014), Petition 

for Cert. filed, 83 U.S.L.W. 3089 (July 14, 2014) No. 14-46. Section 7412 requires 

EPA to establish national emission standards within designated categories and 

subcategories for both new and existing major sources of HAPs that “require the 

maximum degree of reduction in emissions of the hazardous air pollutants subject 

to this section (including a prohibition on such emissions, where achievable)” that 

the Administrator determines is achievable based on existing technology, taking 

cost and other specific factors into consideration. 42 U.S.C. §7412(d)(2). 

Accordingly, section 7412 emission standards are referred to as “maximum 

achievable control technology” or “MACT” standards.

The establishment of MACT standards is essentially a two-step process and 

is different for new sources and existing sources. NRDC v. EPA, 489 F.3d 1250, 

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1254 (D.C. Cir. 2007). Section 7412(d)(3) first specifies the absolute minimum 

level of emissions reductions covered sources must achieve. For new sources, this 

MACT standard “shall not be less stringent than the emission control that is

achieved in practice by the best controlled similar source, as determined by the 

Administrator.” 42 U.S.C. §7412(d)(3). Emission standards for existing sources in 

subcategories with 30 or more sources may not be less stringent than “the average 

emission limitation achieved by the best performing 12 percent of the existing 

sources (for which the Administrator has emission information).” Id. Where there 

are fewer than 30 sources in a category or subcategory, EPA is to set the standard 

based on the best performing 5 sources. Id. This minimum level of emission 

control required for both new and existing sources is called the “MACT floor.” 

Mossville Envtl. Action Now v. EPA, 370 F.3d 1232, 1235 (D.C. Cir. 2004). 

Section 7412(d)(2) then directs EPA, in its discretion, to go beyond the 

minimum stringency requirements of section 7412(d)(3) and set more stringent 

MACT standards, where such standards are achievable. These standards can 

include a broad range of measures that reduce or eliminate emissions of HAPs. In 

setting these “beyond-the-floor” standards, EPA must consider costs and energy 

and non-air related health and environmental impacts to determine if, and how, 

beyond-the-floor standards are to be established for given source categories. 42 

U.S.C. §7412(d); Nat’l Lime Ass’n v. EPA, 233 F.3d 625, 629 (D.C. Cir. 2000).

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EPA has considerable discretion and latitude in determining how to collect 

data relevant to establishing the standards and how such data are to be assessed in 

establishing the standards. NRDC v. EPA, 529 F.3d at 1085-86; Cement Kiln 

Recycling Coalition v. EPA, 255 F.3d 855, 867 (D.C. Cir. 2001). EPA may use 

estimates of emission levels that have been achieved or are achievable and may 

account for variability of a source’s emissions in establishing the emission

standards. Mossville, 370 F.3d at 1240-42. “Floors need not be perfect mirrors of 

the best-performers’ emissions...[but instead are to] reflect a reasonable estimate of 

the emissions ‘achieved’ in practice by the best-performing sources.” Cement 

Kiln, 255 F.3d at 871-72. In regulating HAPs, EPA may use a surrogate (e.g., 

setting a standard for particulate matter (“PM”) that will act to control certain 

hazardous metals), as long as there is a reasonable basis to do so. National Lime,

233 F.3d at 637-40. 

Under 42 U.S.C. §7412(h), if EPA determines that it is “not feasible” to 

prescribe or enforce a numeric MACT standard, it may instead promulgate a 

design, equipment, work practice or operational standard which, in EPA’s 

judgment, is consistent with subsections (d) (“Emission Standards”) or (f) 

(“Standards to protect health and environment”) of Section 7412. These 

alternative standards are referred to as “work practice” standards. While the 

promulgation of a work practice in lieu of a numeric MACT emission standard is 

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wholly within EPA’s discretion, Congress has cabined this authority by narrowly 

defining “not feasible” as limited to situations where EPA determines that (a)

HAPs cannot be emitted through a conveyance to emit or capture such pollutant or 

when any requirement for use of such conveyance would be inconsistent with 

federal, state or local law or (b) when “the application of measurement 

methodology to a particular class of sources is not practicable due to technological 

and economic limitations.” 42 U.S.C. §7412(h)(2)(A),(B).

B. Regulatory Background

EPA initially regulated Boilers through a rulemaking promulgated in 2004. 

69 Fed. Reg. 55,218 (Sept. 13, 2004) (“2004 Rule”). Based centrally on a dispute 

regarding how to define which Boilers would be regulated under section 7412, 

which covers stationary sources generally, versus 42 U.S.C. §7429, which calls for 

emission standards for stationary sources that combust solid waste, in 2007 this 

Court vacated and remanded the emission standards established in the 2004 Rule. 

NRDC v. EPA, 489 F.3d at 1374-75. 

EPA responded to the vacatur of the 2004 Rule by issuing a series of new 

rules, all on March 21, 2011: the “2011 Area Rule,” 76 Fed. Reg. 15,554, 

governing emissions of HAPs from area source boilers; the “2011 CISWI Rule,” 

76 Fed. Reg. 15,704, governing emissions of nine specific pollutants generated by 

commercial and industrial solid waste incineration (“CISWI”) units regulated 

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under 42 U.S.C. §7429; and the Major Boilers Rule that is the subject of 

Petitioners’ challenges in this case. EPA also issued a regulation under the 

Resource Conservation and Recovery Act, defining materials that are solid waste

when combusted for the purpose of determining which units are Boilers and which 

are solid waste incinerators. 76 Fed. Reg. 15,455.1

The Major Boilers Rule establishes MACT floors for 32 subcategories of 

Boilers for five different pollutants: particulate matter (“PM”); hydrogen chloride 

(“HCl”); mercury (“Hg”); carbon monoxide (“CO”); and dioxin/furan, the first 

four generally with numeric MACT standards and dioxin/furan with a work 

practice standard. 78 Fed. Reg. at 7142 (Table 3).2

 Some of these pollutants act as 

surrogates for regulating different HAPs. For instance, non-dioxin organic HAPs

are controlled through emission standards established for CO. 

As explained by this Court, the emission standards established under section 

7412 must apply during all facets of boiler operation, Sierra Club v. EPA, 551 F.3d 

1019, 1026-28 (D.C. Cir. 2008), which include start-up, shut-down, and 

1 Challenges to EPA’s Rule governing area sources are being addressed in No. 

11-1141. Challenges to EPA’s CISWI Rule are being addressed in No. 11-1125. 

Both of these actions, along with No. 11-1189, challenging EPA’s definition of 

solid waste, are coordinated with this case. Dkt. 1461576. 

 

2

 In lieu of a numeric MACT floor, the Major Boiler Rule established a work 

practice standard for all covered HAPs for four of the thirty-two subcategories of 

Boilers. 76 Fed. Reg. at 15,613/1.

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malfunctions. Periods of startup and shutdown are predictable and routine aspects 

of a source’s operations and thus EPA evaluated startup and shutdown conditions 

in establishing emission standards and created a work practice standard to be 

applied during these routine operations. 76 Fed. Reg. at 15,613, 15,618. 

Malfunctions, by contrast, are infrequent, unpredictable, and widely varied 

in scope and impact. Accordingly, EPA does not account for emission levels that 

may occur during malfunctions in setting emission standards. If a source fails to 

meet a given emission standard due to a malfunction, EPA will determine an 

appropriate enforcement response on a case-by-case basis, evaluating, inter alia,

whether the malfunction was “not reasonably preventable” and not “caused in part 

by poor maintenance or careless operation.” 76 Fed. Reg. at 15,613. 

In addition to the numeric and work practice MACT floor standards

established in the Major Boilers Rule, EPA promulgated a beyond-the-floor 

standard for all existing major boilers: a one-time energy assessment. The 

assessment is designed to identify practices and procedures that will reduce fuel 

usage at a source and thereby reduce resultant emissions of hazardous air 

pollutants. 76 Fed. Reg. at 15,613, 15,618.

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SUMMARY OF ARGUMENT

EPA’s arguments on the issues presented by Petitioners can be summarized

as follows:

A. Industry Petitioners’ Claims

1. Petitioners’ assertion that EPA is prohibited from establishing

MACT standards on a pollutant-by-pollutant basis is inconsistent with the statute. 

42 U.S.C. §7412(d)(3) requires that MACT standards for each HAP be no less 

stringent than the level of control achieved by the best-performing source(s). 

EPA’s approach implements this mandate by setting the standards at the lowest 

average emissions level actually achieved for each HAP. In contrast, Petitioners’ 

“unitary-source” approach is based on the lowest common denominator. It would 

require EPA to establish standards for at least some HAPs that are less stringent 

than levels actually achieved in practice, which is facially inconsistent with a 

statute intended to require the maximum achievable control technology. 

Petitioners’ approach would also require EPA to rank pollutants on a risk basis, in 

order to identify sources that are the overall “best” performers for all HAPs. But 

such a process is inconsistent with Congress’ 1990 wholesale modification of 

section 7412 from a program based on subjective determinations of health impacts 

to one based on the control of HAP emissions actually achieved by existing 

sources.

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2. EPA’s decision to establish an emission limit, rather than a 

work practice standard, to control non-dioxin organic HAPs from coal-fired 

Boilers is both reasonable and consistent with the statute. The statute authorizes 

EPA, in its sole discretion, to establish a work practice standard in lieu of a MACT 

numeric standard, and then only if specific statutory requirements for infeasibility 

of a numeric standard are met. 42 U.S.C. §7412(h) (“the Administrator may” 

establish work practice standards if it is “not feasible in the judgment of the 

Administrator” to prescribe or enforce a numeric emission standard). Here, EPA 

found that the statutory requirements for establishing the lack of feasibility for a 

numeric MACT standard were not satisfied because, inter alia, CO concentrations

in the emissions from major source Boilers can be reliably measured and correlated 

with non-dioxin HAP emissions. Petitioners’ assertion that this determination is 

inconsistent with EPA’s use of a work practice in another rulemaking governing 

electric generating units (“EGUs”) is both irrelevant and wrong. This Court has 

made clear that each section 7412 rulemaking stands on its own record and, while 

the record in the EGU rulemaking established that CO could not be reliably 

correlated to emissions of non-dioxin organic HAPs, the record in this case 

establishes the opposite to be true. 

3. EPA had no statutory obligation to either take malfunctions into 

account in setting numeric emission standards or to create a separate work practice 

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standard for malfunctions. Accounting for malfunctions in setting MACT numeric 

emission standards would be wholly impracticable, given the myriad different 

types of malfunctions that can occur across all sources in a category and given the 

difficulties associated with predicting or accounting for the frequency, degree and 

duration of various malfunctions that might occur. Setting alternative work 

practice standards for malfunctions under section 7412(h) presents the same 

inherent problems as setting numerical emission limits, given the varied nature of 

malfunctions. In any event, Petitioners present no evidence that their suggestion to 

create a generic work practice plan that simply calls for minimizing emissions 

during malfunctions would be consistent with the statutory requirements for 

establishing a work practice standard, which require such standards – just like 

numeric emission standards – to reflect the performance of the best performing 

sources. 

4. EPA reasonably determined that it lacked adequate support to 

promulgate an emission standard that is less stringent than the MACT standard for 

HCl based on a health-based risk analysis. Although EPA had promulgated such a 

standard in the 2004 Rule (which was vacated), on the basis of its current analysis 

of the health risks posed by HCl and other acid gases, EPA determined that it 

would be inappropriate to establish anything other than a MACT standard for HCl. 

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This technical, data-driven determination by the Agency is both eminently rational 

and entitled to considerable deference. 

5. EPA’s adoption of an energy assessment requirement as a 

beyond-the-floor standard is wholly consistent with the statute, which requires that 

beyond-the-floor standards be implemented when they will result in the maximum 

degree of reduction in emissions that the Administrator determines is achievable, 

so long as cost and other factors are considered. Because an energy assessment 

may result in more efficient combustion, and thus lower fuel usage, it would 

achieve emission reductions beyond those achieved by post-combustion control 

technologies and would, by definition, do so in a cost-efficient manner, since 

sources will only implement energy saving measures that will pay for themselves 

through lower fuel costs within a reasonable amount of time. An energy

assessment is precisely the type of beyond-the-floor standard contemplated by 

Congress, which directed EPA to implement such standards through all means of 

“measures, processes, methods, systems, or techniques” available to reduce the 

volume of, or eliminate emissions of HAPs. 42 U.S.C. §7412(d)(2).

B. Environmental Petitioners’ Claims

6. EPA reasonably used carbon monoxide as a surrogate for 

non-dioxin organic HAPs. CO is an indicator of efficient combustion, the primary 

control method for these HAPs, and the record demonstrates a strong correlation 

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between CO and non-dioxin organic HAP concentrations. There is no evidence in 

the record to support Petitioners’ assertion that polycyclic aromatic hydrocarbons 

are created post-combustion in Boilers, and the record specifically demonstrates a 

relationship between CO and polycyclic aromatic hydrocarbon emissions. The 

lack of a strong relationship between CO and organic HAPs at low concentrations 

is due to the fact that CO is more difficult to combust than organic compounds and 

thus remains after other compounds have been destroyed.

7. EPA’s creation of subcategories based on combustion system 

and fuel is consistent with the statute. The fuel to be used in a unit dictates its 

design and affects its combustion characteristics and emissions. Thus, units 

designed to burn different fuels constitute different types or classes of sources. 

While operators have some flexibility to alter the mix of fuels combusted in a 

particular unit, that flexibility is significantly constrained by the need for alternate 

fuels to be compatible with the unit’s fuel handling system and by the fact that the 

different heating value and moisture content of different fuels can adversely impact 

the operational characteristics of the boiler.

8. Petitioners’ claims that EPA excluded certain units from 

MACT calculations are not properly before the Court. Furthermore, EPA 

reasonably determined that units co-burning natural gas are not a “similar” unit for 

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determining MACT where not all units in the category are capable of combusting 

natural gas. 

9. EPA’s use of the Upper Prediction Limit methodology to 

account for variability in operating conditions is consistent with the statute. The 

Court has repeatedly recognized that EPA may set MACT standards that can be 

achieved by the best performing source(s) under the full range of foreseeable 

operating conditions. Because the only emissions data available to EPA are

“snapshots” obtained during stack tests, EPA must have some methodology to

account for anticipated variability in setting the emission standards. The UPL does 

this by adding to the average emission result for the best performing source(s) a 

variability factor based on the characteristics of the data set. This is a standard 

statistical technique and provides a prediction of the emission level that the best 

performing source, or the average of the best performing sources, achieves 99 

percent of the time, i.e., over the foreseeable range of operating conditions. Thus, 

the UPL meets the statutory requirement that standards reflect the average 

performance of the best performing sources because it is a prediction of the 

average performance of those sources over time and represents what the sources 

actually achieve, based on actual emission tests and the variability of the data set.

EPA fully complied with the Court’s remand of the record, and there is no 

reason for the Court not to consider EPA’s response. EPA requested an 

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opportunity to explain the methodology it used in this rulemaking, in light of issues 

raised in a decision of this Court that post-dated the rule, and that is what the 

Agency has provided. The UPL methodology described in the remand response is 

exactly the same as in the final rule, and the statutory interpretation embedded in 

the methodology, i.e., that it represents what the average of the best performers 

currently achieve and will achieve over time, is the same as well.

STANDARD OF REVIEW

EPA’s action in promulgating the Major Boilers Rule can be overturned only 

if it is “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance 

with law” or in excess of EPA's “statutory jurisdiction, authority, or limitations.” 

42 U.S.C. §7607(d)(9). “The scope of review under the ‘arbitrary and capricious’ 

standard is narrow and a court is not to substitute its judgment for that of the 

agency.” Motor Vehicle Mfrs. Ass'n v. State Farm Mut. Auto. Ins. Co., 463 U.S.

29, 43 (1983). In interpreting statutory terms, the court applies the familiar 

two-step analysis announced in Chevron U.S.A. Inc. v. NRDC, Inc., 467 U.S. 837 

(1984). Under this standard, the court must apply the language of the statute where 

it reflects “the unambiguously expressed intent of Congress,” but where the statute 

is "silent or ambiguous with respect to the specific issue," the court must defer to 

the agency's interpretation so long as it is "based on a permissible construction of 

the statute." Id. at 842-43.

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ARGUMENT

I. EPA ACTED RATIONALLY IN SETTING EMISSION 

STANDARDS ON A POLLUTANT-BY-POLLUTANT BASIS FOR 

NEW HEAVY OIL-FIRED BOILERS AND EXISTING STOKER

COAL-FIRED BOILERS___________________________________

In establishing emission standards for each subclass of Boiler, EPA must 

require the “maximum degree of reduction in emissions of the hazardous air 

pollutants subject to this section,” which in any case shall “not be less stringent 

than the emission control that is achieved in practice by the best controlled similar 

source.” 42 U.S.C. §7412(d)(2),(3) (emphasis added). Pursuant to this directive, 

EPA set the numeric MACT floor standards based on emission limitations, after 

considering variability, actually achieved by the single best performing unit (and 

best 12 percent of units for existing sources) for each of the covered hazardous air 

pollutants, i.e., on a “pollutant-by-pollutant” basis. Thus, for example, EPA set the 

MACT floor for emissions of PM from new oil units at 0.013 pounds per MMBtu 

because there is an existing oil unit that has actually achieved that level of 

emissions of PM. 78 Fed. Reg. at 7142 (chart). This approach results in MACT 

floor standards that reflect the best emissions performance for each regulated 

pollutant, consistent with the purpose of section 7417(d) to establish stringent 

technology-based emission standards for sources of HAPs. 76 Fed. Reg. at 15622.

According to Petitioners, however, section 7412(d) mandates that EPA set 

the emission standards based on the best-performing single source (or average of 

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the best performing 12 percent of sources for existing sources) for “all” HAPs 

regulated, rather than on the best-performing source(s) for “each” HAP regulated. 

Industry Br. 8. To illustrate, based on emission limitations actually achieved by 

Boilers in the subcategories of new oil units and existing coal-fired stoker units

after considering variability, the Major Boilers Rule sets the following MACT 

floors:

Pollutant Units Emission Limit

New Oil Units Existing Stoker

Particulate Matter lbs. per MMBtu 0.013 0.040

Hydrogen Chloride lbs. per MMBtu 4.4E-04 0.022

Mercury lbs. per MMBtu 4.8E-07 5.7E-06

Carbon Monoxide parts per million 130 160

78 Fed. Reg. at 7142 (chart). 

Under Petitioners’ “unitary-source” theory, in setting these emission 

standards “achieved in practice by the best controlled similar source,” EPA is 

prohibited from actually requiring new heavy-oil and existing coal-fired stoker 

units to meet these enumerated standards which have, in fact, actually been 

achieved by various existing units. Instead, Petitioners assert that EPA must 

identify the single unit within the New Oil subcategory (and 12 percent of units for 

the Existing Stoker subcategory) that comes closest to the emission limitations 

being achieved in aggregate for all HAPs, and then reset each of the standards at 

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the level of emissions of each covered HAP achieved by that single unit (or best 

performing 12 percent of units for existing sources). Industry Br. 29-33. 

Petitioners assert that this unitary-source reading of section 7412 is unambiguous. 

Industry Br. 30. 

Applying this unitary-source theory, Petitioners contend that the standards

for new heavy oil-fired units are invalid because no single source has concurrently 

met the emission standard for all four regulated HAPs. Industry Br. 29-31. 

Similarly, Petitioners assert that the emission standards for existing stoker coalfired units are invalid because, although two sources meet the standards for all 

regulated HAPs, there are over 350 sources in the stoker coal-fired subcategory 

and thus these two sources do not comprise 12 percent of the total sources in that 

subcategory. Industry Br. 33.3 

Nowhere did Congress direct EPA to establish MACT floors based on 

Petitioners’ unitary-source theory. EPA has long recognized that section 7412 is 

3 With regard to existing stoker coal-fired units, Petitioners’ claim is not only 

legally infirm (see discussion, infra) but also factually incorrect. Section 7412 

provides that EPA is to establish the MACT floor for existing sources based on 

“the average emission limitation achieved by the best performing 12 percent of the 

existing sources (for which the Administrator has emissions information)....” 42 

U.S.C. §7412(d)(3)(A) (emphasis added). EPA had emissions information for 24 

sources within the existing stoker coal-fired subcategory and the emissions 

standard established for all four regulated HAPs has been actually achieved by 3 of 

these sources, i.e., 12.5 percent of the 24 sources for which “the Administrator has 

emissions information.” EPA-HQ-OAR-2002-0058-3836. 

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ambiguous with regard to how EPA is to establish MACT floors. 76 Fed. Reg. 

15,621-23. As EPA has explained, given that section 7412(d)(2) mandates the 

“maximum degree of reduction of the hazardous air pollutants subject to this 

section” based on levels actually achieved, the promulgation of emission standards 

for each of the covered pollutants based on what has actually been achieved by 

various sources – rather than on what a single source achieves for all combined 

regulated pollutants – is certainly a reasonable interpretation of section 7412. 

Accordingly, EPA has applied a pollutant-by-pollutant approach for many years in 

its various rulemakings establishing MACT standards. See, e.g., 61 Fed. Reg.

17,386 (April 19, 1996) (lightweight kilns), 75 Fed. Reg. 54,970, 54,998-99 (Sept. 

9, 2010) (Portland cement plants). See also, Medical Waste Inst. & Energy 

Recovery Council v. EPA, 645 F.3d 420, 427 (D.C. Cir. 2011) (“[S]etting floors 

based on the emissions levels achieved by the best performing units with respect to 

each individual pollutant” is the Agency’s “long-standing practice.”).

If a statute is “silent or ambiguous with respect to the specific issue,” the 

court must defer to the Agency's interpretation so long as it is “based on a 

permissible construction of the statute.” Chevron, 467 U.S. at 842-43. Agencies 

are entitled to considerable deference when interpreting a statute they administer, 

particularly one that is complex and within the agency’s area of expertise, United 

States v. Mead Corp., 533 U.S. 218, 227-31 (2001), which is the case here. See

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NRDC v. EPA, 571 F.3d 1245, 1251 (D.C. Cir. 2009). When an agency's action 

involves technical issues or a complex regulatory program, a court applies “an 

extreme degree of deference.” Huls Am. Inc. v. Browner, 83 F.3d 445, 452 (D.C. 

Cir. 1996). See also, St. Luke's Hosp. v. Sebelius, 611 F.3d 900, 904-05 (D.C. Cir. 

2010). Finally, courts “accord particular deference to an agency interpretation of 

‘longstanding’ duration.” Alaska Dep’t of Environtl Conservation v. EPA, 540 

U.S. 461, 487 (2004). See also EDF v. Duke Energy Corp., 549 U.S. 561, 575 

(2007). 

Given the level of deference accorded to EPA on this issue, it is not 

surprising that Petitioners contend that the Court should not reach a Chevron step 

two analysis, instead asserting that section 7412 unambiguously mandates the 

unitary-source approach. But Petitioners’ unitary-source approach is hardly a 

reasonable one, let alone the unambiguous mandate of the statute. 

First, Petitioners fail to cite a single case even questioning EPA’s 

pollutant-by-pollutant approach. Moreover, courts have recognized that a 

pollutant-by-pollutant approach is a reasonable interpretation of requirements to 

apply technology-centric standards under statutory provisions covering multiple 

pollutants. See Chemical Mfrs. Ass’n v. EPA, 870 F.2d 177, 239 (5th Cir. 1989) 

(concluding that basing Clean Water Act best available technology standards on a 

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pollutant-by-pollutant basis was a rational interpretation of EPA’s obligations under 

that statute). 

Petitioners correctly state that MACT floors are to be established based on 

the emission levels that a given source (or top 12 percent of sources) actually has 

achieved. Then, by simply clinging steadfastly to their unitary-source theory, they

assert that in enacting the aforementioned MACT floors, EPA has based those 

standards on hypothetical sources, not an actual source, and on emission levels that 

are “achievable” rather than what has actually been achieved. Industry Br. 32-33. 

But no amount of semantic gymnastics can change the facts. Each of the emission 

standards set forth in the table at p. 19, supra, has actually been achieved by an 

actual source within the given subcategories; and Industry-Petitioners nowhere 

dispute this fact. Quite clearly, a standard is not based on mere achievability if it 

has actually been achieved. 

Petitioners argue that their unitary-source approach is more in line with 

Congressional intent. But again they miss the mark. In enacting the 1990

amendments to section 7412(d), Congress stated that “[t]he technology-based 

standards promulgated pursuant to this authority shall provide for the maximum 

degree of reduction in emissions of each of the listed pollutants released by 

sources in the category.” S. Rep. No. 101-228 at *3553 (emphasis added). As is 

“appropriate” for the “control of extremely harmful air pollutants,” the MACT 

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standards are intended to be more stringent than almost every other technologybased standard in the CAA. Id. at 3552. See also, Cement Kiln, 255 F.3d at 857

(MACT floors are to reflect “the most stringent standards available, even if those 

levels are not achievable by all sources.”); Sierra Club v. EPA, 479 F.3d 875, 881 

(D.C. Cir. 2007). 

Petitioners’ unitary-source approach subverts this Congressional intent 

because it could lead to basing emission standards on sources that are not the best 

achieving source for any covered HAP and may, indeed, be the worst performing 

source for at least some of the covered HAPs. For example, the best performing 

sources for HAP metals might be the worst performing sources for organic HAPs. 

76 Fed. Reg. at 15,622 (describing example). This is not merely fanciful 

conjecture: it would have been the result if a unitary-source approach had been 

adopted in applying MACT to other types of sources. See id. at n.3 (noting that 

Petitioners challenging the pollutant-by-pollutant approach for MACT floors for 

waste incinerators conceded that “the best performers for some pollutants are the 

worst performers for others.”). 

Petitioners assert that EPA could manage the standard-setting process by 

concentrating on the pollutants that are most hazardous to public health in 

identifying the single source on which to base all HAP emission standards. But 

this process would require EPA to prioritize HAPs based on the relative risk to 

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human health of each pollutant, a criterion that has no place in the establishment of 

MACT floors. Sierra Club, 353 F.3d at 979-80 (under section 7412(d)(3), 

“emission standards are to be based not on an assessment of the risks posed by 

HAPs, but instead on the maximum achievable control technology (MACT) for 

sources in each category”); White Stallion, 748 F.3d at 1245 (“[t]he notion that 

EPA must ‘pick and choose’ among HAPs in order to regulate only those 

substances it deems most harmful is at odds with the court’s precedent.”). 

In the 1990 CAA amendments, Congress abandoned a risk-based approach 

to setting MACT floors in favor of a technology-based approach, and reserved 

considerations of health risk for later phases in the standard-setting process. See 

42 U.S.C. §7412(f) (requiring EPA to evaluate the risk remaining after the MACT 

standard is in effect and determine whether more stringent standards are necessary 

to protect public health). Petitioners’ unitary-source approach would reverse this

process, requiring EPA to set initial MACT emission standards based on subjective 

risk-based value judgments not sanctioned by Congress. 

Petitioners attempt to side-step Congress’ mandate not to make health-based 

value judgments by quoting a single sentence from Senator Durenberger. Industry 

Br. 32. Senator Durenberger’s statement, however, mentions nothing about 

utilizing the unitary-source approach. Senator Durenberger merely noted that in 

certain limited circumstances – which are not present in this case – the technology 

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necessary to achieve the lowest emissions levels for one HAP might increase 

emissions for a second HAP. Industry Br. 32. In fact, Congress explicitly 

considered this possibility. S. Rep. No. 101-228, 1st Sess. 168. But rather than 

suggesting that all MACT floors for a source category should be set based on one 

existing source, Congress proposed a different solution: “In cases where control 

strategies for two or more different pollutants are in actual conflict . . . maximum 

protection of human health shall be the objective test.” S. Rep. No. 101-228 at 

(1989) at 3553. See also 76 Fed. Reg. 15,622-23. This indicates that Congress 

expected that MACT floors would be set on a pollutant-by-pollutant basis; 

otherwise there would be no possibility of “conflict” between “control strategies,” 

because all standards would be derived from technologies already used in 

conjunction with each other by one existing source.4

 

Finally, Petitioners resort to dissecting sentence elements to try and pry from 

the statute the meaning they desire. Petitioners point to the phrase “best controlled 

similar source,” 42 U.S.C. §7412(d)(3), and leap to the assumption that the 

“similar source” must be the single source that is considered best performing with 

respect to the entire suite of HAPs. Industry Br. 30. In fact, the phrase “best 

controlled similar source” can just as easily be read to mean the source with the 

4 Petitioners do not claim that there is any such conflict in control technologies in 

the Major Boilers Rule, nor did they provide any information during the public 

comment period demonstrating such a conflict. 76 Fed. Reg. at 15623.

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best emission control for each HAP. Nothing in section 7412(d)(3) specifies how 

EPA is to determine the “best controlled similar source” and it certainly does not 

mandate the unitary-source approach. To the contrary, the full phrase reads “best 

controlled similar source, as determined by the Administrator,” indicating that 

EPA has considerable discretion in determining what is the “best controlled similar 

source.” 

Petitioners insist that EPA has effectively rewritten the statute by setting the 

standards based on the “best controlled source for each pollutant.” Industry Br. 30 

(italicizing the supposed added language). If that is true, then Petitioners have 

done the same, asserting that standards must be based on the “best controlled 

source for all pollutants.” This exercise merely demonstrates that the pertinent 

language is ambiguous. Given the deference accorded EPA based on its long-term, 

consistent interpretation of this ambiguous provision of a technical statute over 

which it has expertise, Petitioners’ challenge to EPA’s establishment of emission

standards on a pollutant-by-pollutant basis should be rejected.

II. EPA DID NOT ACT ARBITRARILY IN SETTING NUMERIC 

CARBON MONOXIDE EMISSION STANDARDS TO CONTROL

NON-DIOXIN ORGANIC HAPS_____________________________

It is undisputed that EPA may use a surrogate to control the emissions of a 

particular HAP, so long as it has a reasonable basis for doing so. Nat’l Lime, 233 

F.3d at 639; Sierra Club v. EPA, 353 F.3d at 984. In this case, EPA used carbon 

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monoxide as a surrogate for establishing the emission standards for non-dioxin 

organic HAPs because CO is an indicator of good combustion, which is a method 

for control of organic HAP emissions. See pp. 68-69, infra. 

Industry Petitioners do not quarrel with EPA’s use of CO as a surrogate for 

organic HAPs for most of the subcategories of Boilers, nor do they challenge the 

appropriateness of using an indicator of good combustion as an emission standard 

to control organic HAPs. Instead, Petitioners assert that EPA should have 

eschewed numeric emission standards for CO solely for the subcategories of 

industrial Boilers that are coal-fired, and instead should have imposed a work 

practice standard (such as requiring a boiler tune-up) to control organic HAP

emissions from this subcategory of Boilers. This challenge, made on both 

substantive and procedural grounds, is meritless.

A. EPA Did Not Act Arbitrarily in Applying a Numeric 

Emission Standard for Organic HAP Emissions From 

Coal-Fired Boilers._________________________________

 Petitioners’ argument is based on the Mercury and Air Toxics Rule, 77 

Fed. Reg. 9304 (Feb. 16, 2012) (“Utility Rule”), governing electric utility steam 

generating units, where EPA adopted a work practice standard rather than a 

numeric CO limit for organic HAPs. Petitioners assert that EPA acted arbitrarily 

by not following the identical practice here. Industry Br. 11-12, 46-48. 

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First, the fact that EPA adopted different standards for the same pollutants 

(organic HAPs) emitted by different industries is irrelevant. EPA may reasonably

choose different regulatory approaches for different industries, as appropriate. 

Petitioners in Sierra Club v. EPA asserted that it was unreasonable for EPA to 

utilize PM as a surrogate for HAP metals for copper smelters when it was not used 

in the rulemaking for hazardous waste combustors and where a different surrogate, 

lead, was used for metals in the lead smelter rulemaking. 353 F.3d at 986. As the 

Court explained, 

[t]his court has adopted an “every tub on its own bottom” approach to 

EPA’s setting of standards pursuant to the CAA, under which the 

adequacy of the underlying justification offered by the agency is the 

pertinent factor – not what the agency did on a different record 

concerning a different industry. [Citation omitted]. 

Id. (explaining that the question of whether EPA acted arbitrarily is to be “decided 

on the basis of information concerning that industry alone.”). As explained below, 

the rationale for promulgating a work practice in the Utility Rule does not apply 

for coal-fired Boilers. 

There are three characteristics associated with applying work practice 

standards in lieu of numeric emission standards: (a) they are to be used only when 

“it is not feasible in the judgment of the Administrator to prescribe or enforce [a 

numeric] emission standard for control of a hazardous air pollutant;” (b) the use of 

a work practice standard is wholly within the discretion of EPA (“[T]he 

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Administrator may, in lieu [of a numeric standard], promulgate a design, 

equipment, work practice or operational standard, or combination thereof”); and 

(c) in choosing to implement a work practice standard, that standard must “in the 

Administrator’s judgment [be] consistent with the provisions of subsection (d) or

(f),” which are the provisions requiring EPA to implement the most stringent 

emission standards possible. 42 U.S.C. §7412(h)(1) (emphasis added). 

In order to determine that a numeric emission standard is not feasible, the 

Administrator must determine that: (a) the HAP cannot be emitted through a 

conveyance designed and constructed to emit or capture that hazardous pollutant or 

it would violate local, state or federal law to do so; or (b) “the application of 

measurement methodology to a particular class of sources is not practicable due to 

technological and economic limitations.” Id. §7412(h)(2). The Administrator’s 

judgment on this issue must be made against the backdrop that numeric emission

standards must be established whenever it is feasible to do so. Id. §7412(h)(4).

As EPA explained in the Utility Rule, it established a work practice for 

emissions of organic HAPs from coal-fired EGUs 

because the significant majority of data for measured organic HAP 

emissions from EGUs are below the detection levels of the EPA test 

methods, even when long duration (around 8 hour) test[s] . . . are 

considered. As such, we consider it impracticable to measure 

emissions from these units. As discussed at proposal, we believe the 

inaccuracy of a majority of measurements, coupled with the extended 

sampling times used, allow a work practice standard under CAA 

section 112(h) to apply to these HAP. . . . We believe that the work 

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practice standard will result in actions being taken that will reduce 

emissions of these HAP.

77 Fed. Reg. at 9369/2. Petitioners assert that the same circumstances are present 

in this case. Industry Br. 45-48. 

In a word, the same circumstances are not present here. In the Utility Rule, 

“the majority of measurements are so low, doubt is cast on the true levels of 

emissions that were measured during the tests.” 76 Fed. Reg. 24,976, 25,040 (May 

3, 2011). More specifically, for non-dioxin/furan organic HAPs, “between 57 and 

89 percent of the run data were comprised of values below the detection level.” Id. 

In contrast, for coal-fired Boilers, EPA had reliable data for about two-thirds of the 

tested units. EPA-HQ-OAR-2002-0058-3830 (emissions database) (JAXXXXX).

Thus, while in the Utility Rule “the majority of emissions of these pollutants are 

below the detection levels of EPA test methods and, therefore, are impractical to 

measure,” 77 Fed. Reg. at 9380/2, the opposite was true with regard to Boilers. 

Petitioners refer to the average and maximum concentrations of

formaldehyde in the two emission datasets for the proposition that “there is no 

meaningful distinction between the datasets” in the Utility Rule and the Major 

Boiler Rule. Industry Br. 47-48. However, EPA is utilizing CO, not 

formaldehyde, as a surrogate for organic HAPs, and therefore the issue in whether 

EPA may utilize a work practice in lieu of a numeric standard is whether CO can 

be effectively measured. Additionally, EPA’s analysis, as explained above, was 

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based on the number of non-detect samples, not the average or maximum 

concentrations. 

As EPA explained, “non-detect values are present in many of the datasets 

from best performing units,” 76 Fed. Reg. at 15,623/2, and EPA must make 

judgments as to when those non-detect levels rise high enough that it merits the 

Administrator making a determination, consistent with the requirements of section 

7412(h) and the strong presumption for establishing numeric standards, that a work 

practice standard is warranted. There have been other instances where EPA found 

significant non-detect levels of HAPs, including organic HAPs, and nevertheless

determined that it could generate reliable numeric standards and that a work 

practice standard was not warranted. See, e.g., 76 Fed. Reg. at 25,040/2

(describing standards set for Portland cement sources). It is certainly reasonable 

for EPA to judge that, while 57 to 89 percent non-detect levels for all organic 

HAPs identified in the Utility Rule made the use of numeric emission standards 

infeasible in that case, that is not the case when the non-detect level is around 33 

percent, which is the case with coal-fired Boilers. EPA-HQ-OAR-2002-0058-3830

(JAXXXX). 

“The ‘arbitrary and capricious’ standard deems the agency action 

presumptively valid provided the action meets a minimum rationality standard.” 

White Stallion, 748 F.3d at 1233, quoting NRDC v. EPA, 194 F.3d 130, 136 (D.C.

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Cir. 1999). Given the discretion afforded to the Administrator under section 

7412(h) to decide whether to establish work practice standards, and the great 

deference to be accorded to the Administrator’s decision on this highly technical 

issue, EPA’s conclusion that a work practice standard was not warranted because it 

had reliable test data from the majority of tested sources was reasonable.

B. EPA Did Not Commit Procedural Error in Addressing the Issue 

of Organic HAP Emission Standards for Coal-Fired Boilers.___

Petitioners raise a procedural issue, asserting that in responding to the 

comments of CIBO and MidAmerican Energy Co. raising the issue of a work 

practice standard, EPA did not provide a “direct” response to those entities and 

instead referred them to EPA’s response to another commenter and otherwise did 

not “enunciate a reason why it did not adopt a §112(h) work practice standard in 

place of a numeric CO limit.” Industry Br. 48-49. 

However, the two comments do nothing more than mention in an off-hand 

manner that a work practice standard could be used, the first in a single sentence 

and the second in a single paragraph. EPA-HQ-OAR-2002-0058-2702 (p.5) 

and -2786 (p. 25). Neither makes the argument Petitioners now raise; that nondetection levels render use of a numeric emissions limit infeasible and therefore 

warrant a work practice standard. 

EPA’s obligation is to provide a response, in whatever form, to “each of the 

significant comments, criticisms, and new data submitted.” 42 U.S.C. 

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§7607(d)(6)(B) (emphasis added). The fact that Petitioners now choose to raise 

this issue to the level that it is included in their brief, does not make the single 

sentence and paragraph submitted by the two commenters significant at the time 

EPA was preparing responses to comments. In any event, EPA explained in detail 

how it was dealing with non-detection levels over several pages in the preamble to 

the 2011 Rule. See Section V.A.3, 76 Fed. Reg. at 15,623-65 (entitled “Treatment 

of Detection Levels”). 

Petitioners further complain that in denying subsequent administrative 

petitions for reconsideration filed in conjunction with the 2013 Rule, EPA 

explained that petitioners had ample opportunity to comment on the work practice 

issue in their original comments (which, as Petitioners note, CIBO and 

MidAmercian did). Petitioners assert that they were entitled to reconsideration 

under 42 U.S.C. §7607(d)(7)(B) because the Utility Rule, which established a work 

practice standard for organic HAPs for a different industry, provides information 

that they “could not have reasonably anticipated” when commenting on the 2011 

Rule. Industry Br. 49. 

EPA had no obligation to address this issue in response to a Petition for 

Reconsideration, or otherwise. EPA’s only obligation is to provide a rational basis 

for establishing the standard it chose and it need not explain why it did not adopt 

the same type of standard it adopted for a different industry. National Lime, 627 

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F.2d at 447, n.108 (“That different industries may be subject to different standards 

and the Administrator need not bear the burden of explaining those differences is 

clear.”); Portland Cement Ass’n v. Ruckelshaus, 486 F.2d 375, 389 (D.C. Cir. 

1973) (“[T]he Administrator is not required to present affirmative justifications for 

different standards in different industries.”).

Moreover, as EPA pointed out in its 2013 Rule, Petitioners had ample 

opportunity to raise this issue in their comments on the 2011 Rule. 78 Fed. Reg. at 

7149-50. Petitioners could have made the identical arguments in those comments

that they make now after issuance of the Utility Rule, asserting that the number of 

non-detect tests rendered establishment of a numeric emission standard infeasible. 

Indeed, in the 2011 Rule EPA promulgated a number of work practice standards 

for various hazardous pollutants for certain subcategories of Boilers. See n.2, 

supra. 

In the end, both of Petitioners’ claims regarding EPA’s purported lack of an 

adequate response to comments raise alleged procedural rulemaking defects. “In 

reviewing alleged procedural errors, the court may invalidate the rule only if the 

errors were so serious and related to matters of such central relevance to the rule 

that there is a substantial likelihood that the rule would have been significantly 

changed if such errors had not been made.” 42 U.S.C. §7607(d)(8). See also, 

Nat’l Mining Ass’n v. EPA, 59 F.3d 1351, 1358 (D.C. Cir. 1995). As outlined 

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above, there is no likelihood that the Major Boilers Rule would have been 

significantly changed if EPA had provided a more robust response to the two 

comments cited on the 2011 Rule or if it performed a reanalysis upon 

reconsideration after the Utility Rule was issued. 

III. EPA’S DETERMINATION THAT SECTION 7412 DOES NOT 

REQUIRE EMISSION LEVELS DURING MALFUNCTIONS TO 

BE TAKEN INTO ACCOUNT IN DETERMINING THE LEVEL 

ACHIEVED BY THE BEST PERFORMING SOURCES IS 

REASONABLE AND CONSISTENT WITH THE STATUTE____

Industry Petitioners assert that EPA must account for malfunctions when 

determining the emissions level achieved by the best performing sources. But this 

view is neither reasonable nor supported by the text of the CAA. Section 

7412(d)(3) requires EPA to set standards that are no less stringent than the 

emission control achieved in practice by the best performing source(s). It also 

requires those standards to apply on a continuous basis, which this Court has 

interpreted to include periods of start-up, shut-down, and malfunction. See Sierra 

Club v. EPA, 551 F.3d at 1027-28 (striking down a general provision that 

exempted start-up, shut-down, and malfunction periods). EPA’s approach both 

accounts for variability associated with a reasonably foreseeable range of operating 

conditions (as explained in section IX, infra) and recognizes that enforcement 

mechanisms can address emission exceedances due to unpreventable equipment or 

process failures. While Petitioners seek greater accommodation for malfunctions, 

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such accommodation is not compelled by the statutory text and EPA’s approach is 

reasonable. 

A. EPA’S Historic Practice Regarding Malfunctions

EPA has acknowledged that start-up and shut-down operations as well as 

malfunctions of a source’s process and pollution control equipment, can sometimes 

result in varying HAP emissions. In fact, EPA had exempted Boilers from having 

to comply with HAP emission standards during start-up, shut-down or 

malfunctions. 69 Fed. Reg. 55,218 (Sept. 13, 2004). In 2008, however, this Court 

struck down an exemption for malfunctions in a different section 7412 regulation, 

finding that it violated the statutory requirement under section 7412 to establish 

emission limitations on a “continuous basis.” Sierra Club v. EPA, 551 F.3d at

1027-28. 

In response to Sierra Club, in the 2011 Major Boilers Rule EPA eliminated 

exemptions for start-up, shut-down, and malfunctions and developed standards that 

apply at all times. Because start-up and shut-down periods are predictable and 

routine aspects of a source’s operations, EPA evaluated start-up and shut-down 

conditions in establishing emission standards and determined that work practice 

standards, which must reflect the emissions achieved by the best performing 

sources, were appropriate for these specific operational periods. 76 Fed. Reg. at

15,613. EPA did not take this same approach for malfunctions.

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Unlike start-up and shut-down, which are foreseeable operations, no one can 

predict the nature, scope, severity, timing, length, number or likely recurrences of 

malfunctions a source may – or may not – experience. Although EPA bases 

emission standards on different manners of operations and circumstances, EPA 

only takes into account conditions that are “foreseeable” and “which can 

reasonably be expected to recur.” Sierra Club, 167 F.3d at 665. See also Nat. 

Lime, 627 F.2d. at 431, n.46. Virtually no malfunction is foreseeable in terms of 

its nature, timing or effect on emission levels and no operator knows when or if a 

malfunction could recur. Moreover, it is difficult to apply the concept of a best 

performing source to sources that are malfunctioning, since the best performing 

sources are likely to operate in a manner that avoids malfunctions. 76 Fed. Reg. at 

15,613/2. 

EPA can use its enforcement discretion to address exceedances of emission 

limits that may be caused by such uncertain, unpredictable events, on a 

case-by-case basis. 76 Fed. Reg. at 15,613, 15,642. If a source is unable to 

comply with emission standards during a malfunction, EPA will consider what 

actions, if any, to take with regard to such exceedance. Id. In making that 

determination, EPA will consider factors such as the source’s efforts to minimize 

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emissions during the malfunction, preventive actions taken, corrective actions 

taken, and root cause analyses. Id.5

According to Petitioners, the case-by-case treatment of malfunction events

will not suffice. Petitioners assert that EPA is required under 42 U.S.C. §7412 to 

factor into its MACT standards the emission levels of HAPs that occur during 

malfunctions. Industry Br. 34-42. Petitioners alternatively assert that EPA acted 

arbitrarily in refraining from exercising its wholly discretionary option to create a 

work practice standard applicable to all malfunction events. Industry Br. 42-44. 

Petitioners’ arguments find no support under either 42 U.S.C. §7412 or the 

decisions of this Court.

B. There is No Statutory Requirement to Factor Malfunction 

Emission Levels into MACT Numeric Emission Standards.

Petitioners identify no language in the statute that even implies that EPA 

must factor into MACT emission standards the emission levels that occur during 

malfunctions. Yet, they assert that 42 U.S.C. §7412 mandates that EPA account 

for malfunctions in establishing every single MACT floor standard or set a 

5 EPA also created an affirmative defense in the Major Boilers Rule with regard to 

imposition of civil penalties for an exceedance during malfunctions. 76 Fed. Reg. 

at 15,613/3. That affirmative defense was recently struck down in another case. 

NRDC v. EPA, 749 F.3d at 1063. In light of this development, the use of an 

affirmative defense for malfunction events for Boilers is the subject of a pending 

petition for reconsideration and is not presently before the Court. See Dkt. 

1511358, severing this issue.

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separate MACT floor standard for malfunctions, so that they reflect higher 

emission levels that might occur during undefined, unidentified malfunction

events. Petitioners appear to rely on the silence of section 7412, which does not 

speak directly to how malfunctions are to be treated to support their view, filling 

the void with their own judgments of how EPA must address such uncertain and 

undefined events.

Of course, where a statute is ambiguous or leaves a gap as to its application, 

the Court must defer to the agency's interpretation so long as it is “based on a 

permissible construction of the statute,” Chevron, 467 U.S. at 842-43, and in 

making this determination under the regulatory HAPs program administered by 

EPA, the Agency is accorded substantial deference. See pp. 21-22, supra. 

Although EPA may have authority to address malfunctions through different 

mechanisms – albeit limited by the Court in Sierra Club v. EPA (striking down 

exemptions for malfunctions) and NRDC v. EPA (striking down an affirmative 

defense for malfunctions) – EPA’s interpretation that it is not required by section 

7412 to address malfunction emissions by resetting MACT numeric standards is 

certainly a rational application of section 7412.

First, Petitioners never explain how setting MACT floors based on emission

levels that occur during various malfunctions might be implemented. As 

Petitioners readily admit, in establishing MACT floors, section 7412 “requires 

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EPA to ground its decisions on data reflecting performance.” Industry Br. 36, 

citing Nat’l Ass’n of Clean Water Agencies v. EPA, 734 F.3d 1115, 1158 (D.C. Cir. 

2013) (“NACWA”). Yet, Petitioners point to no data in the record that could 

arguably form a basis for MACT emission standards that take malfunctions into 

account. This, in fact, would be quite a feat since Petitioners characterize 

malfunctions as any period “when systems are not technologically stable,” an 

extremely broad characterization that could encompass a vast range of 

circumstances. Industry Br. 34.

As this Court has said a number of times, EPA may establish emission 

standards based on information other than actual emissions but only when it results 

in a reasonable estimate of the levels of emissions that will be emitted by the best 

performing source. See National Lime, 233 F.3d at 632 (“EPA’s method of setting 

emission floors must reasonably estimate the performance of the relevant best 

performing plants.”). EPA has accounted for variability among the best 

performing sources’ emissions over the entire range of foreseeable operating 

conditions, as explained in Part IX, infra. But, as EPA determined, it would be 

wholly impracticable for EPA to factor unforeseeable, random malfunction 

incidents into emission standards, 76 Fed. Reg. at 15,613/2, and Petitioners offer 

no roadmap for doing so. To the contrary, Petitioners agree that the process they 

seek is impracticable for numeric standards. Industry Br. 43 (“Commenters 

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asserted, and EPA agreed, that it would be impracticable for EPA to set numeric 

emission standards for malfunctions. [Citation omitted]. This is true for many 

reasons, particularly because malfunctions are infrequent and unpredictable.”). 

In any event, even if incorporating emission levels that occur during 

uncertain, hypothetical, unmeasured malfunction events were theoretically 

possible, there is no statutory basis for requiring EPA to take such action. 

Petitioners assert that 42 U.S.C. §7412 mandates that EPA establish MACT floor 

standards so that they reflect higher emission levels that might occur during 

unidentified, unmeasured malfunction events. Industry Br. 29-37. To support their 

argument, Petitioners assert that a source that experiences a malfunction will not be 

able to achieve the MACT standards established by EPA because they do not 

reflect emission levels that occur during that unknown malfunction. Industry Br. 

34. But a source that suffers worker malfeasance or experiences a hurricane or a 

terrorist event, may also exceed emission standards at certain times. These events, 

like malfunctions, do not magically transform standards based on emission levels 

that actually have been achieved into unachievable standards. Indeed, under 

Petitioner’s reasoning, every MACT floor is forever invalid because it does not 

reflect emission levels that will occur during the next malfunction, act of God, 

strike, malfeasance or other unpredictable event.

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Petitioners seem to contend that malfunctions are somehow different from 

these other unpredictable events by asserting that “EPA expressly acknowledged 

that even the best performers will inevitably experience malfunctions resulting in 

increased emissions.” Industry Br. 37. But EPA did not make this statement, and 

Petitioners cite to no place in the record where it did. Instead, as Petitioners 

explain, EPA stated that even well-maintained equipment “can sometimes fail and 

such failures can sometimes cause an exceedance of the relevant emissions 

standard.” Industry Br. 35, quoting 76 Fed. Reg. at 15,613 (emphasis added).

Hurricanes, strikes, and malfeasance can also occur at well-maintained and wellmanaged sources, but this does not warrant factoring such unpredictable events 

into emission standards. And again, even if malfunctions were inevitable for all 

sources, including the best-performing sources, that does not make it possible to 

take them into account when establishing MACT emission standards, because they 

are still unknown in frequency, length, magnitude and, most importantly, effect on 

emission levels.

In support of their argument, Petitioners cite three cases applying provisions 

of the CAA’s New Source Performance Standards, a separate CAA program under 

42 U.S.C. §7411. Industry Br. 38-40. These cases are not relevant on numerous 

grounds. First, they were all decided decades before the HAP program in its 

present form was even enacted and before Chevron, which requires particular 

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deference to EPA’s interpretation of ambiguous provisions of the CAA. Second, 

these cases did not direct EPA to incorporate emission levels that might occur 

during malfunctions into the applicable standards nor explain how such a task 

could conceivably be accomplished. Third, these cases did not direct EPA to 

implement a work practice standard or consider whether the specific statutory 

requirements for implementing a work practice standard established under section 

7412(h) were satisfied. Fourth, at best, these cases simply suggested that in certain 

limited circumstances EPA could provide an exemption for sources that may not 

be able to reach promulgated emission standards that have been established under 

normal operating conditions. This suggestion, however, has effectively been 

rejected by this Court in Sierra Club, at least with regard to the section 7412 HAPs 

program that is at issue in this case. 551 F.3d at 1027-28.

Petitioners also point to a case decided under section 7412 where the Court 

stated that “industry petitioners may be correct that EPA should have exempted 

HWCs from regulatory limits during periods of startup, shutdown and 

malfunction.” Industry Br. 39, quoting Cement Kiln, 255 F.3d at 872. First, this 

was dicta in a 2001 case (the Court was discussing issues it did not reach). 

Second, as noted, this Court found exemptions to be invalid in Sierra Club. Most

importantly, nothing in Cement Kiln even implies that EPA has a duty to reflect 

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emission levels that might occur during unpredictable malfunction events in its 

numeric or work practice emission standards. 

To the contrary, Cement Kiln cuts to the heart of Petitioners’ argument. The 

fundamental principle of Petitioners’ argument is that due to malfunctions, the 

MACT emission standards, which undeniably have been achieved by Boilers, may 

be “unachievable” if specific sources experience a malfunction. See, e.g., Industry 

Br. 34 (citing Nat’l Lime Kiln and Essex Chem Corp., two New Source 

Performance Standard cases, concluding that “the record does not support the 

‘achievability’ of the promulgated standards for the industry as a whole”). The 

Court in Cement Kiln, however, rejected the notion that because a MACT standard 

may not be achievable by some sources, it is invalid. Cement Kiln, 255 F.3d at 861

(“EPA may not deviate from section 7412(d)(3)’s requirement that floors reflect 

what the best performers actually achieve by claiming that floors must be 

achievable by all sources using MACT technology.”). See also Sierra Club v. 

EPA, 479 F.3d at 878; NACWA, 734 F.3d at 1150 (explaining that the argument 

that a MACT standard is invalid because it is not achievable by all sources at all 

times has been “roundly rejected” by the Court).

In determining that it is appropriate to handle exceedances of emission

standards caused by malfunctions through case-by-case exercise of enforcement 

discretion, EPA relied in part on the reasoning of this Court in Weyerhaeuser Co. 

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v. Costle, 590 F.2d 1011, 1058 (D.C. Cir. 1978). 76 Fed. Reg. at 15,613. As the 

Court there concluded, “[a] line must be drawn as to what is treated in the general 

rule [setting emission standards] and what is handled case-by-case, and we believe 

it appropriate to defer when EPA, in the interest of preserving an enforcement 

system based on straightforward numbers” draws that line. 590 F.2d at 1058.

Petitioners do their best to distinguish Weyerhaeuser, but to no avail. 

Petitioners first assert that Weyerhaeuser should be ignored because it was a Clean 

Water Act case. Industry Br. 32. But, as Petitioners themselves point out, this 

Court has “applied the same approach to technology-based standards under the 

Clean Water Act as it has applied to the CAA.” Industry Br. 38. Petitioners next

assert that Weyerhaeuser only addressed emissions affected by “uncontrollable acts 

of third parties.” Industry Br. 32. In fact, the Court in Weyerhaeuser was 

addressing “unusual events such as plant start-up and shut-down, equipment 

failures, human mistakes, and natural disasters.” 590 F.2d at 1056 (emphasis 

added). Petitioners next assert that the Weyerhaeuser court based its holding on 

the fact that the standards at issue there were technology-forcing. Industry Br. 32. 

While the Court did address this point, it went on to uphold EPA’s case-by-case 

approach because interjecting factors dependent on “murky determinations 

concerning the sequence of events in the plant, whether those events would have 

been avoidable” and similar factors, is inconsistent with the intent of Congress to 

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require numeric emission standards that are measurable and easily enforceable. 

590 F.2d at 1057-58. 

Finally, Petitioners imply that Weyerhaeuser was overruled by another 

Clean Water Act case, NRDC v. EPA, 859 F.2d 156 (D.C. Cir. 1988), citing it for 

the proposition that a technology-based standard must accommodate defects in 

technology. Industry Br. 38. That case was decided in 1988, decades before this 

Court found that accommodations promulgated by EPA (an exemption and an 

affirmative defense for malfunctions) were inconsistent with the requirements of 

the HAPs program under section 7412. Moreover, the discussion of 

technology-based standards was dicta because the issue before the Court was 

whether water quality-based standards must account for malfunctions. In fact, the 

holding in NRDC, that water quality based standards do not need to account for 

malfunctions despite sources’ use of technology for compliance, supports EPA’s 

position in this case. Id. at 207-10. In the present case, although Congress revised 

the HAPs program in 1990 to have technology serve as the core for establishing 

emission standards, those standards are also not strictly control technology-based 

but rather are based on the emission levels actually achieved in practice, which this 

Court has explained goes beyond what can be achieved solely through available 

control technology. See Sierra Club v. EPA, 479 F.3d 875, 882-83 (D.C. Cir. 

2007). 

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Notwithstanding EPA’s reliance on Weyerhaeuser, the establishment of 

emission standards based on foreseeable operations of the best controlled sources, 

and the fundamental impracticality of assessing the effects of unknown, 

unpredictable malfunctions, Petitioners insist that EPA is relying solely on the 

Sierra Club decision that struck down the exemption for malfunctions, which they 

assert does not require EPA to ignore malfunctions in establishing numeric 

emission standards. Industry Br. 40-41. But Sierra Club is not the basis for EPA’s 

treatment of malfunctions, as detailed above. Furthermore, this allegation misses 

the point. The issue is not whether EPA may deal with malfunctions in one form 

or another in establishing MACT standards, it is whether EPA is required under 42 

U.S.C. §7412 to factor emissions occurring during malfunctions into its emission

standards, be they numerical standards or alternative work practices. EPA’s view 

that nothing in the statute contains such a requirement is a permissible reading of 

the statute and, under Chevron, should therefore be upheld.

C. It Was Not Arbitrary and Capricious for EPA to Decide Not 

to Create a Work Practice Standard for Malfunction Events.

Petitioners alternatively assert that EPA’s failure to create a work practice 

standard for malfunctions is arbitrary and capricious. Pet. Br. 42-44. As outlined 

supra, the use of a work practice standard is wholly within the discretion of EPA. 

42 U.S.C. §7412(h) (“[T]he Administrator may, in lieu [of a numeric standard], 

promulgate a design, equipment, work practice, or operational standard, or 

48

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combination thereof.”). In exercising the option to establish a work practice 

standard, that standard must “in the Administrator’s judgment [be] consistent with 

the provisions of subsection (d) or (f).” 42 U.S.C. §7412(h)(1) (emphasis added). 

As outlined above, these subsections make clear that EPA is to base emission

standards on the emission levels already achieved by the best performing sources 

and to ensure that public health is protected. This means that work practice 

standards, although written in non-numeric form, must still approximate the top 

performing source or top 12 percent of sources. See, e.g., Reconsideration 

Response to Comments (“RTC”) at 592 (JAXXXX) (“When establishing work 

practice standards, EPA must ensure that the standard represents the maximum 

achievable control technology.”). 

It is just as difficult to establish a work practice standard for malfunctions

that can approximate the level of emission reduction achieved by the best 

performing sources during malfunctions as it would be to factor emission levels 

that occur during malfunctions into the numeric standards, as discussed supra. 

EPA would have to design a single work practice standard that applies equally to a 

Boiler explosion as it does to a pilot light being extinguished for an hour or 

innumerable types of operator error, computer glitches or a myriad of other 

unknown events, or alternatively create innumerable work practice standards. 

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Petitioners’ generic suggestion to create a work practice standard that merely 

directs sources to have plans to minimize emissions during malfunctions and return 

to system stability as soon as possible, Industry Br. 44, does not present a viable 

solution. Absent any evidence that a mere requirement to have such a plan is 

consistent with EPA’s obligation under section 7412(h) to only establish a work 

practice standard if, in the Administrator’s judgment, it can be done consistent with 

section 7412(d), EPA’s decision not to adopt this suggestion cannot be deemed to 

be arbitrary. In sum, just as it is not arbitrary and capricious for EPA to refrain 

from promulgating a work practice for hurricanes or worker error, it is not arbitrary 

to refrain from creating a work practice for malfunctions. 

Finally, Petitioners appear to assert that EPA did not provide an adequate 

explanation why it did not exercise the work practice option. Industry Br. 44. But 

EPA considered comments calling for such an option and fully explained why it 

did not take malfunctions into account in setting standards and that it would treat 

violations caused by malfunctions on a case-by-case basis through the exercise of 

enforcement discretion. See, e.g., 76 Fed Reg. at 15,613-14, 15,641; 

Reconsideration RTC at 1062-63 (JAXXXX-XX). 

IV. EPA DID NOT ACT ARBITRARILY IN ESTABLISHING 

NUMERIC MACT EMISSION STANDARDS FOR HCL

In the Major Boilers Rule, EPA established numeric MACT emission

standards for hydrogen chloride, which also serves as a surrogate for certain other 

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acid gas HAPs, including chlorine, hydrogen fluoride, and hydrogen cyanide. 75 

Fed. Reg. 32,030/1. As with most of the other emission standards established in 

the Major Boilers Rule, and as required under 42 U.S.C. §7412(d), the emission 

standards for HCl are numeric, technology-based standards generated from the 

emission levels of HCl actually achieved by the best performing single source and 

best 12 percent of sources. 78 Fed. Reg. at 7193-7198 (tables 1 and 2). 

Section 7412(d)(4) does permit EPA, under certain circumstances, to take a 

different approach with regard to pollutants for which a health threshold has been 

established. Section 7412(d)(4) states in full: “With respect to pollutants for which 

a health threshold has been established, the Administrator may consider such 

threshold level, with an ample margin of safety, when establishing emission 

standards under this subsection.” As EPA explained: “This provision is intended 

to allow EPA to establish emission standards other than conventional MACT 

standards, in cases where a less stringent emission standard will still ensure that the 

health threshold will not be exceeded, with an ample margin of safety.” 75 Fed. 

Reg. 32,030/2.

Contrary to Petitioners’ assertion, EPA is not obligated to jettison a 

technology-based MACT standard in favor of a health-based standard for any 

hazardous air pollutant that has an established health threshold. The determination 

of whether to consider health thresholds in establishing an emission standard is, as 

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expressly stated in the statute, wholly within EPA’s discretion (“the Administrator 

may consider such threshold level.”). 42 U.S.C. §7412(d)(4) (emphasis added) 

As a matter of statutory interpretation with regard to an agency’s responsibilities,

except where contrary intent is expressed elsewhere, “may means may.” 

McCreary v. Offner, 172 F.3d 76, 83 (D.C. Cir. 1999). This “connotation is 

particularly apt . . . when ‘may’ is used in contraposition to the word ‘shall.’” 

Jama v. Immigration & Customs Enforcement, 543 U.S. 335, 347 (2005). Here, 

sections 7412(d)(2) and (3) recite that EPA “shall” establish MACT technologybased standards and, where certain requirements are met, beyond-the-floor 

standards for every HAP. The next subsection, section 7412(d)(4), then states that 

the Administrator “may” consider a health threshold when establishing emission

standards. 

Indeed, there are other subsections of section 7412 that require EPA’s 

review and imposition of standards as they relate to health effects. See, e.g., 

section 7412(f), which provides that EPA “shall” promulgate “residual risk” 

standards if it determines that they are required in order to provide an ample 

margin of safety to protect public health. 42 U.S.C. §7412(f)(2)(A). But section 

7412(d)(4), the provision upon which Petitioners rely, contains no such mandatory 

language, nor does it establish any standards or criteria upon which EPA is to 

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exercise its option to implement a health-based standard once a threshold has been 

established.

Petitioners assert that EPA is required to generate emission standards for 

HCl based on health thresholds because it has done so in the past. A decade ago in 

the 2004 Rule, the then-Administrator determined that a health-based emission

standard could be used for HCl emitted from solid fuel Boilers. 69 Fed. Reg. at 

55,227. That Rule, however, was vacated by this Court and thus does not bind the 

Agency. NRDC v. EPA, 489 F.3d at 1261. Vacated or not, the position EPA took 

in 2004 does not constrict its discretion, based on the present state of scientific 

knowledge and technical data, to make a new determination in a new rulemaking 

as to whether the Agency should choose to base HCl emission standards on healthbased thresholds.

In the Major Boilers Rule EPA described in detail its reasoning for not 

exercising its option in 2011 to establish a health-based emission standard for HCl. 

See 75 Fed. Reg. at 32,030-033. Because HCl is an acid gas that is associated with 

chronic respiratory toxicity, a risk threshold was established for this pollutant 

through the establishment of a chronic reference concentration. Id. at 32,031/1. In 

examining whether to establish a health-based emission standard based on this 

threshold, EPA determined that this value tells only a partial story. 

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As EPA explained, there are a number of health factors that were not 

addressed in establishing a health threshold for HCl nor was there adequate data in 

the record relating to these factors. Id. at 32,031. For instance, while the health 

threshold for HCl is based on studies of its chronic effects on respiratory systems, 

“[t]here is a significant body of scientific literature addressing the health effects of 

acute exposure to HCl [but EPA] currently lacks information regarding peak shortterm emissions of HCl from boilers.” Id. (emphasis added). EPA further noted

that there were significant data gaps with regard to the variation of acid gas 

emissions from various subcategories of emitting units. 76 Fed. Reg. at 15,643/3. 

Variation of emissions was important to assessing the peak, short-term effects of 

HCl exposure. EPA also lacked information “addressing the toxicity of mixtures 

of HCl with other respiratory irritants.” Id. EPA also was concerned that while the 

health threshold focuses on respiratory ailments, there is little research regarding 

the carcinogenic effects of HCl. Id. 

This lack of relevant information regarding the types and degree of health 

impacts associated with HCl emissions was of particular concern given that any 

emission standard based on a health threshold must, under the express wording of 

section 7412(d)(4), include an ample margin of safety, 75 Fed. Reg. at 32,031/1, 

and that HCl is the predominant HAP, comprising 69 percent of the hazardous 

pollutants emitted from Boilers. 76 Fed. Reg. at 15,611/1. Accordingly, based on 

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the lack of data on these various health issues, EPA concluded that it did not have 

sufficient information to establish a health-based emission standard for HCl. 75 

Fed. Reg. at 32,031/3. 

In addition to the direct health questions discussed above, EPA also 

examined less direct but equally significant health issues. EPA recognized the 

co-benefits of regulating HCl, as it would significantly reduce emissions of the

other acid gas HAPs listed above. Id. As EPA explained, while this co-benefit is 

present when the technology-based MACT standard is utilized, it disappears if a 

health-based standard is used:

HCl can serve as a surrogate for the other acid gases in a 

technology-based MACT standard, because the control technology 

that would be used to control HCl would also reduce the other acid 

gases. By contrast, HCl would not be an appropriate surrogate for a 

health-based emission standard that is protective against the potential 

adverse health effects from the other acid gases, because these gases 

(e.g., [hydrogen cyanide) can act on biological organisms in a 

different manner than HCl, and each of the acid gases affects human 

health with a different dose-response relationship.

75 Fed. Reg. at 32,030, n.16. Therefore, even if EPA had concluded that it was 

appropriate to establish a health based standard for HCl, numeric standards would 

still be needed for the other acid gases, which are currently regulated through the 

HCl standard.

EPA also explained that establishing the HCl standard based on the health 

threshold ignores the cumulative adverse health effects due to concurrent exposure 

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to other HAPs with similar biological endpoints. Id. at 32,030/3. Furthermore, use 

of the MACT standards for HCl, rather than health-based standards, results in 

significant reductions of non-HAP pollutants, including sulfur dioxide and 

hydrogen bromide. Id. at 32,032/2-3. 

Petitioners assert that it was arbitrary and capricious for EPA to consider 

some of the factors it did, specifically the co-benefits or cumulative impacts 

associated with setting numeric emission standards for HCl. Industry Br. 53-56. 

Petitioners, however, never even address EPA’s stated concern about the direct

health effects of HCl emissions, such as acute (as opposed to chronic) respiratory 

effects and potential carcinogenic effects. These are real, potential direct effects of 

the emissions of HCl, and Petitioners failed to provide any basis to alleviate EPA’s 

concerns about these effects. On this basis alone, EPA’s decision not to implement 

a health-based emission standard for HCl cannot be considered to be arbitrary and 

capricious.

Separately, section 7412(d)(4) mentions nothing about the factors EPA must 

consider in assessing whether to exercise the option of creating a health-based 

standard in lieu of a numeric MACT technology-based standard or, more 

importantly, that EPA is restricted in what factors it may consider. Instead, 

Petitioners assert that restrictions on the factors EPA may consider in deciding 

whether to apply a health-based emission standard under section 7412(d)(4) 

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emanate from section 7412(d)(2). Industry Br. 55-56. However, section 

7412(d)(2) sets forth the parameters for establishing a beyond-the-floor standard, 

which is more stringent than the numerical MACT floor standard. In assessing 

whether to utilize a health-based emission standard, EPA considers whether to alter 

its MACT floor standard, which would create a standard that is less stringent than 

the MACT floor (because EPA has determined that the MACT floor standard is not 

required to protect public health for a threshold pollutant, with a margin of safety). 

The factors to consider in creating a beyond-the-floor standard simply have no 

bearing on creating a health-based MACT standard. 

In the end, Petitioners merely harken back to statements made by EPA in 

conjunction with the promulgation of the 2004 Rule as “evidence” that EPA took 

the view that cumulative impacts or co-benefits were not to be considered. 

Industry Br. 53-56. For instance, Petitioners quote an EPA statement that it did not 

interpret section 7412(d)(4) to require it to consider emissions from other sources 

in establishing health-based standards under this provision. Industry Br. 54. At 

the same time, there is nothing in this provision that precludes EPA from 

considering emissions from other sources, or emissions of other pollutants affected 

by the HAP emission standards used, or the effect on reduction of non-HAP 

pollutants from application of MACT-based standards, or the general 

environmental effects, or other factors. In any event, when the very general 

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language of section 7412(d)(4) is read in the context of the entire section, which 

evidences clear intent to reduce emissions of pollutants to the maximum extent 

possible to protect public health, EPA’s consideration of these factors is clearly 

consistent with the statute and certainly a rational interpretation of section 

7412(d)(4), which does not in any way limit the factors EPA may consider. 

Furthermore, the position EPA took in 2004 with regard to which factors it 

should consider is not germane. As this Court recently explained in another 

challenge to emission standards under section 7412 where EPA reversed its earlier 

view: 

To the extent petitioners’ challenge concerns EPA’s change in 

interpretation from that in 2005, our approach is the same [as a basic 

Chevron analysis] because “[a]gency inconsistency is not a basis for 

declining to analyze the agency’s interpretation under the Chevron

framework.” Nat’l Cable &Telecoms. Ass’n v. Brand X Internet 

Servs., 545 U.S. 967, 981 (2005)[]. That is, “if the agency adequately 

explains the reasons for a reversal in policy, change is not 

invalidating, since the whole point of Chevron is to leave the 

discretion provided by the ambiguities of a statute to the 

implementing agency.” Id. (Internal quotation marks omitted). 

White Stallion, 748 F.3d at 1235. See also, FCC v. Fox Television Stations, Inc., 

556 U.S. 502, 513-14 (2009); Nat’l Cable, 545 U.S. at 981-82 (“An initial agency 

interpretation is not instantly carved in stone. On the contrary, the agency . . . must 

consider varying interpretations and the wisdom of its policy on a continuing 

basis,” Chevron, supra at 863-864 [], for example, in response to changed factual 

circumstances, or a change in administrations.”).

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Indeed, the Court in White Stallion rejected the same type of argument 

Petitioners make here. Under section 7412(n)(1), EPA is directed to study public 

health hazards reasonably anticipated to occur “as a result of emissions by electric 

utility steam generating units.” 42 U.S.C. §7412(n)(1). Petitioners there asserted 

that EPA could not consider cumulative impacts of HAP emissions because they 

were not the direct “result of emissions” from these units. Noting that EPA had 

supported Petitioners’ view in an earlier regulation, this Court found EPA’s present 

view, which considered the cumulative impacts of the HAP emissions, to be well 

within EPA’s discretion. The Court recited EPA’s reasoning for taking a more 

holistic approach, including the fact that “[a]n individual that suffers adverse

health effects as the result of the combined HAP emissions from EGUs and other 

sources is harmed, irrespective of whether HAP emissions alone would cause the 

harm.” White Stallion, 748 F.3d at 1242-43. EPA has taken the same approach 

here in assessing whether to exercise its option under 7412(d)(4). 

The purpose of section 7412(d)(4) is to provide the Administrator with the 

discretion to implement health-based emission standards in situations where the 

Administrator can be reasonably assured that the technology-based MACT 

standards clearly are not necessary to protect public health. This highly technical, 

scientific determination is a decision for EPA, to which this Court grants a high 

degree of deference. Industry-Petitioners have presented no evidentiary basis to 

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conclude that EPA acted irrationally in refraining from creating a health-based 

emission standard and instead, as it is otherwise directed to do by statute, base the 

emission standard for HCl on the emission levels actually achieved by existing 

sources for this predominant hazardous air pollutant. 

V. EPA’S IMPOSITION OF AN ENERGY ASSESSMENT 

REQUIREMENT AS A BEYOND-THE-FLOOR STANDARD

WAS WITHIN EPA’S AUTHORITY AND NOT ARIBTRARY 

OR CAPRICIOUS______________________________________

In addition to the MACT floor standards promulgated in the Major Boilers 

Rule, EPA generated a beyond-the-floor requirement for existing Boilers. These 

sources must conduct a one-time energy assessment which includes, inter alia, a 

review of fuel usage and energy management practices and conservation measures. 

78 Fed. Reg. 7198-99, Table 3. The purpose of the energy assessment is to 

identify processes and practices that will reduce or conserve energy consumption 

because “[i]mprovement in energy efficiency results in decreased fuel use which 

results in a corresponding decrease in emissions (both HAP and non-HAP) from 

the [boiler].” 75 Fed. Reg. at 32,026/2. 

In response to comments about the contemplated breadth of the assessment, 

EPA took special care to limit the energy assessment to the “specific portions of 

the source that directly affect emissions from the affected [boiler].” 76 Fed. Reg. 

at 15,556/1, 15,632. See also, 40 C.F.R. §63.11237 (definitions of “energy 

assessment” and “energy use system”). Thus, EPA is not mandating a general 

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facility-wide energy assessment but rather directing it only to those components 

that directly affect the amount of HAPs emitted from the boilers within the subject 

subcategories. Id. See also, 76 Fed. Reg. at 15,573/2 (Area Rule) (“It is not EPA’s 

intent to require an energy assessment for the entire facility * * * [A]n energy 

assessment is only required for those portions of the facility using the energy 

generated from the affected boiler system.”). 

This beyond-the-floor requirement is limited to an assessment; nothing 

requires a major source to implement pollutant-reducing practices identified in the 

assessment. Instead, because the assessment is designed to identify practices that 

will reduce fuel costs along with emissions of hazardous pollutants, owners and 

operators are expected to voluntarily use the results of the assessment to increase 

the energy-efficiency and cost-efficiency of their boiler system. RTC Vol. 1 at 

1444, 1595 (JAXXXX). The cost of the assessment is minimal (between $2,500 

and $55,000 depending on the size of the source) and that cost would be recaptured 

through implementation of fuel-savings actions. 75 Fed. Reg. at 32,026. Industry

Petitioners’ varied attempts to challenge this beyond-the-floor requirement as 

beyond EPA’s authority are without basis. 

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A. The Energy Assessment Fits Squarely Within EPA’s Authority to 

Establish Beyond-the-Floor Standards.______________________

As Petitioners recognize, the energy assessment requirement is a 

beyond-the-floor standard established under section 7412(d)(2).6

 In enacting 

section 7412(d)(2), Congress made it abundantly clear that EPA was to take 

actions that “shall require the maximum degree of reduction in emissions of 

hazardous air pollutants subject to this section (including a prohibition on such 

emissions, where achievable).” While emissions are generally measured at the 

boiler or other combustion equipment from which hazardous pollutants emanate, 

Congress did not limit EPA’s regulatory authority to that specific combustion 

equipment. To the contrary, section 7412(d)(2) declares that in imposing standards 

designed to achieve the maximum degree of reduction of emissions, EPA shall do 

so through the “application of measures, processes, methods, systems or 

techniques, including, but not limited to, measures which – (A) reduce the volume 

of, or eliminate emissions of, such pollutants through process changes, substitution 

6

 Petitioners alternatively argue that the energy assessment is not a proper work 

practice standard. Industry Br. 28-29. The energy assessment is not, however, a 

work practice standard, and EPA makes no claim that it is. See, e.g., 75 Fed. Reg. 

at 32,030/1 (“An energy assessment is a beyond-the-floor standard being proposed 

for existing facilities.”). Because EPA does not assert that the energy assessment is 

a work practice standard, the Court need not address whether the requirements for 

establishing such a standard have been satisfied. 

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of materials or other modifications.” Id. Thus, Congress authorized EPA to 

address upstream causes of HAP emissions in promulgating emission standards.

As EPA explained, because implementation of measures or process changes 

identified in the energy assessment will inevitably lead to reduction in emissions of 

hazardous pollutants, “an energy assessment, in combination with the MACT 

emission limits will result in the maximum degree of reduction in emissions 

required by CAA section 7412(d)(2).” 75 Fed. Reg. at 32,026/3. EPA is carrying 

out this statutory mandate through the precise mechanisms outlined by Congress: 

“measures, processes, methods, systems or techniques [that will] reduce the 

volume of, or eliminate emissions of, such pollutants, through process changes, 

substitution of materials or other modifications.” And in this case, the energy 

assessment is expressly limited to the specific portions of the facility that directly 

affect emissions from the affected source. 76 Fed. Reg. at 15,632. Accordingly, 

the promulgation of the energy assessment for Boilers cannot be considered to be 

beyond EPA’s authority. 

B. Emission Standards Apply to the Major Source, Not Merely to 

the Specific Equipment From Which Hazardous Pollutants are 

Finally Emitted.________________________________________

Petitioners assert that EPA is confined to regulate only the operations or the 

specific equipment at a facility which fall under the category of sources created 

under 42 U.S.C. §7412(c), which they interpret as only the boiler or process heater 

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and no other equipment that affects emissions from the boiler. Industry Br. 20-23. 

However, Petitioners both overstate the scope of the energy assessment 

requirement and apply an ultra-constrictive view of EPA’s authority to require 

HAP emission reductions from major sources that is not supported by the statute.

EPA directed the energy assessment to a specific portion of the facility: all 

“specific portions of the source that directly affect emissions from the affected 

boiler.” 76 Fed. Reg. at 15,556/1, 15,632 (emphasis added). Therefore, the 

assessment is an exercise of EPA’s authority under section 7412 “over HAPs 

emitted from the boiler and process heater source category.” Cf. Industry Br. at 23.

Congress instructed EPA that it could create “categories and subcategories 

of major sources and area sources . . . of the [hazardous] air pollutants listed.” 42 

U.S.C. §7412(c). As EPA explained, it does so when different types of units have 

different emission characteristics which may affect the feasibility and effectiveness 

of emission control. 75 Fed. Reg. at 32,017/1. There is nothing about the statutory 

language of section 7412(c) that limits EPA’s regulatory authority to specific 

components of a source; it merely states that EPA shall establish emission

standards that are specific to each category or subcategory of source. 

The fact that Congress granted EPA authority to create categories of sources 

to facilitate their regulation does not alter the fact that the entity that is subject to 

potential emission standards, whether MACT floors, beyond-the-floor standards, or 

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work practices, is “any major source.” 42 U.S.C. §7412(d). A “major source” is 

defined as “any stationary source or group of stationary sources located within a 

contiguous area and under common control that emits or has the potential to emit” 

specified quantities of any HAP. 42 U.S.C. §7412(a)(1). Section 7412(a)(3) refers 

to 42 U.S.C. §7411(a) for the definition of a “stationary source,” which defines that 

term as “any building, structure, facility, or installation which emits or may emit 

any air pollutant.” C.f., Nat’l Mining Ass’n, 59 F.3d at 1355 (finding that “all 

portions of a major source are subject to MACT [emission standards] regardless of 

the number of source categories into which the facility is divided.”). Accordingly, 

the regulated entity under section 7412 that is generally subject to MACT 

regulations is the entire facility or installation, not a specific piece of operating 

equipment like a Boiler. And, as noted, in this regulation EPA has carefully 

limited the energy assessment to only those portions of the facility that directly 

affect emissions from the boiler. 

The only case authority cited by Petitioners is a partial quote from Senior 

Judge Williams in his concurrence in Sierra Club v. EPA, 479 F.3d at 885. Judge

Williams explained that the language requiring EPA to establish standards for 

sources in each category is designed to ensure that sources in one category, whose 

technological capabilities may differ from those in another category or who may be 

combusting a different type of fuel, are not held to the standards of other categories 

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of sources. Nothing in Judge Williams’ concurrence even intimates that the 

creation of a category of a major source thereby defines the equipment and 

processes at an individual source that may be subject to regulation.

As outlined above, EPA’s interpretation of its statutory requirements is to be 

upheld so long as it represents a rational application of the statute. Chevron, 467 

U.S. 837 (which itself afforded deference to EPA’s defining the contours of a 

“source” under the CAA). EPA’s interpretation of its mandate as not limited to 

the boiler is clearly a rational interpretation of the directive given by Congress in 

section 7412(d)(2), and is not constricted by the creation of categories of sources 

under section 7412(c).

C. The Energy Assessment Complies with All Statutory 

Requirements._________________________________

Petitioners raise a series of arguments asserting that EPA failed to comply 

with statutory requirements, but those requirements either do not exist, are 

inapplicable to an energy assessment, or have been complied with. Petitioners first 

assert that designation of an energy assessment as a beyond-the-floor standard is 

illegal because “there is no underlying MACT floor determination.” Industry Br. 

24 (Subheading 1). But this is plainly wrong. EPA has established a MACT floor 

or similar standard for every subcategory of existing Boilers. See 78 Fed. Reg. 

7195-7198 (Table 2), setting out the numeric MACT floor standards for each 

subcategory of Boilers. See also 75 Fed. Reg. at 32,026/1 (explaining that it was 

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only after “the MACT floor determinations were done for each subcategory” that 

EPA considered beyond-the-floor standards). 

Petitioners next assert that EPA may not call for an energy assessment as a 

beyond-the-floor standard because EPA did not establish energy assessments as the 

floor. Industry Br. 24. There simply is no authority for the proposition that the 

MACT floor and the beyond-the-floor standard must be of the same type or 

character, and Petitioners cite to no such authority. To the contrary, while MACT 

floors are generally implemented through numeric emission standards, 

beyond--he-floor standards are to consider measures, processes, systems, 

techniques and methods to further reduce HAP emissions, and the energy 

assessment is clearly such a measure. 42 U.S.C. §7412(d)(2). 

Next, Petitioners assert that “EPA did not adequately consider the costs of 

the theoretical beyond-the-floor emissions reductions.” Industry Br. 25 

(Subheading 2). EPA did not impose any “theoretical beyond-the-floor emissions 

reductions” of HAPs through its energy assessment requirement. To the contrary, 

EPA required an analysis of fuel use systems and methodologies that could 

potentially reduce HAP emissions along with analyses of the costs of such systems 

and methodologies. As EPA explained, the energy assessment does not obligate 

operators to implement or modify equipment based on the assessment 

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recommendations, although sources are expected to do so in order to achieve the 

cost savings the measures will provide. RTC Vol. 1 at 1444, 1595 (JAXXXX). 

Petitioners pivot, arguing that the energy assessment itself will cost from 

$2,500 to $55,000 per facility, and because EPA cannot determine if fuel 

management processes should be implemented until the studies show that they are 

useful and effective in further reducing HAPs, EPA has failed to adequately assess 

the costs of its required energy assessment. Industry Br. 25-26. As EPA explained, 

however, lower fuel costs achieved through energy conservation improvements

that are expected to be implemented will offset the costs of such improvements, 

and along with it the $2,500 to $55,000 cost to analyze how best to achieve those 

fuel reductions. 75 Fed. Reg. at 32,026. Indeed, the energy assessment is designed 

specifically to identify only “cost-effective energy conservation measures,” that 

will provide payback of the investment in a short amount of time, otherwise the 

source will not implement such measures. Id.

Finally, Petitioners assert that “EPA failed to consider non-air quality and 

environmental impacts of the energy assessment” and “failed to consider the 

energy requirements of the energy assessment.” Industry Br. 26-27 (Subheadings 3

and 4). As outlined above, however, EPA did consider these factors, explaining 

how they would lead to reduced energy requirements and reduced environmental 

impacts. 76 Fed. Reg. at 15,632-33; Cost Memo, Sec. 5 (JAXXXX). EPA is not 

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required to delineate more specific source-by-source energy and environmental 

impacts, since that is the very purpose of the assessment ordered. 

VI. EPA REASONABLY USED CARBON MONOXIDE

AS A SURROGATE FOR ORGANIC HAPS______

In the Major Boilers Rule, EPA established emission standards for carbon 

monoxide as a surrogate for emissions of non-dioxin organic hazardous air 

pollutants. 78 Fed. Reg. at 7144-45. This approach is based on the demonstrated 

relationship between the combustion process and these pollutants. Combustion, 

such as occurs in the units subject to the Major Boilers Rule, is the process of 

breaking apart the organic (i.e., carbon-containing) molecules in the fuel and 

converting them to carbon dioxide. RTC Vol. 2 at 16-17 (JAXXXX-XX). 

Perfectly complete combustion would convert all of the carbon in the fuel to 

carbon dioxide. Completeness of the combustion process is dependent on several 

variables, including temperature, amount of oxygen, and mixing of the fuel and 

oxygen. Incomplete combustion results in production of partly broken down and 

partially oxidized organic compounds, including CO. Because the conversion of 

CO to carbon dioxide is a difficult step, and the last one in the destruction of 

hydrocarbons, including organic HAPs, it is a good indicator of the completeness 

of combustion. 78 Fed. Reg. at 7145/2. Thus, decreasing levels of CO are 

correlated with increasing destruction of organic compounds until a threshold is 

reached where, because combustion of CO is the last step in combustion, the 

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combustion of organic materials is essentially complete. 78 Fed. Reg. at 7144-45. 

CO concentration is thus an indicator of the level of destruction of organic 

compounds, and accordingly can be used as a surrogate to control the emissions of 

organic HAPs. 

In the Major Boilers Rule, EPA determined that at CO concentrations below 

130 parts per million (“ppm”), there is no more reduction or destruction of organic 

HAPs associated with further reductions of CO concentrations. Id. EPA based this 

conclusion on an analysis of data in the record from emissions tests where both CO

and formaldehyde (a representative organic HAP) had been measured. Id. EPA 

then reviewed the emissions of the best performing sources in each subcategory. 

Where the CO emissions of the best performing source(s), as calculated using the 

Upper Prediction Limit methodology, are above the threshold, the emission 

standard was set at the calculated value. Where the calculated value was below the 

threshold, the emission standard was set at the threshold. Id. at 7145.7

This Court has repeatedly held that EPA can utilize surrogates in regulating 

pollutants, if the use of the surrogate is reasonable. Sierra Club v. EPA, 353 F.3d 

at 984; Bluewater Network v. EPA, 370 F.3d 1, 18 (D.C. Cir. 2004); National 

Lime, 233 F.3d at 637. See also Kennecott Greens Creek Min. Co. v. Mine Safety 

7 Environmental-Petitioners’ challenge to EPA’s use of the 130 ppm threshold as 

the minimum standard for CO has been severed and held in abeyance. Dkt.

1461576.

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and Health Admin., 476 F.3d 946, 954-55 (D.C. Cir. 2007) (“there is nothing 

inherently problematic with an agency regulating one substance as a surrogate for 

another substance.”)

Petitioners’ attempt to apply to this case the standards articulated by the 

Court in National Lime and Sierra Club for determining whether the use of 

particulate matter as a surrogate for hazardous metals is reasonable, LEAN Br. 

22-23, should be rejected because those cases are inapposite. That test is not a 

general one for determining whether the use of a surrogate is reasonable. Rather, 

as stated in Sierra Club, it is specific to determining “whether the use of PM as a 

surrogate for HAPs is reasonable.” 353 F.3d at 984 (emphasis added). That 

analysis is specific to both EPA’s rationale for the use of particulate matter in that 

circumstance (i.e., that the HAP metals are in the form of particulate matter) and to 

the particular challenges made to those standards (i.e., that measures other than 

particulate control were used by the best performing sources to control HAP 

metals). Neither of those circumstances applies here.

Rather, as described above, CO is a surrogate for organic HAPs because it 

is a conservative indicator of the effectiveness of the combustion process in 

destroying organic HAPs. 78 Fed. Reg. at 7144-45; see

EPA-HQ-OAR-2002-0058-2960.1 at C-1 to C-2 (JAXXXX-XX) (comments of 

American Petroleum Institute et al.). This Court has previously upheld the use of 

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surrogates as reasonable without applying the three-part test of Sierra Club. See

Bluewater Network, 370 F.3d at 18 (upholding use of hydrocarbons as a surrogate 

for particulate matter because hydrocarbons contribute to particulate matter 

pollution and control of hydrocarbon emissions serves to control particulate 

matter); Kennecott Greens Creek, 476 F.3d at 954-55 (upholding Mine Safety and 

Health Administration rule using total elemental carbon as surrogates for diesel 

particulate matter). See also Reynolds Metals Co. v. EPA, 760 F.2d 549 (4th Cir. 

1985) (in Clean Water Act context. upholding use of oil and grease as a surrogate 

for control of total toxic organics), cited with approval in Natural Resources 

Defense Council, 822 F.2d at 125.

Petitioners raise two objections to the use of CO as a surrogate for organic 

HAPs. They argue, first, that certain compounds, including polynuclear aromatic 

hydrocarbons, are created downstream of the combustion chamber, and therefore 

are not adequately controlled by maximizing destruction of organics through 

combustion. LEAN Br. 23-24. Second, Petitioners argue that there is not an 

adequate relationship between CO concentration and organic HAP destruction. Id.

at 25-26. 

With regard to the first contention, Petitioners identify no evidence in the 

record showing that polynuclear aromatic hydrocarbons, or any compounds other 

than dioxins and furans, are produced post-combustion in the types of boilers 

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subject to the Major Boilers Rule. Rather, Petitioners rely solely on their own 

comments, id. at 23-24, which in turn rely on general citations to reference works 

on combustion (without identifying specific pages). Clean Air Task Force 

Comments, EPA-HQ-OAR-2002-0058-3187.2, at 18, n.11 (JAXXXX).8

 These 

generalized assertions are not sufficient to overcome the considerable deference 

the Court owes to the Agency’s technical expertise. 

Moreover, contrary to Petitioners’ assertions, the record does contain 

evidence demonstrating a relation between CO and polynuclear aromatic 

hydrocarbons. For example, a study specifically performed to examine that 

relationship found that CO emission levels are a conservative predictor of 

polynuclear aromatic hydrocarbon emissions. EPA-HQ-OAR-2002-0058-3856 at 

3777-78 (JAXXXX-XX). The study authors simultaneously measured emissions 

of CO and polynuclear aromatic hydrocarbons, and found a strong correlation. 

While the relative amount of CO increased at higher boiler temperatures, that only 

makes the use of CO as a surrogate for combustion of hazardous organics more 

8 Moreover, the references cited in the comments do not support Environmental 

Petitioners’ assertion. Warnatz, et al., at 261, state that polycyclic aromatic 

hydrocarbons “are usually formed under fuel-rich conditions (present in rich 

premixed and always in nonpremixed flames),” which is not a condition found 

post-combustion. In addition, Bartok, et al., at 694, state that for cyclic 

hydrocarbons, the “rate-controlling, step in the high-temperature combustion of 

hydrocarbons is the oxidation of CO,” which is exactly EPA’s rationale for the use 

of CO as a surrogate. 

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conservative. Id. Another technical paper in the record examined the combustion 

of wood in boilers, and found that in boilers operating in good combustion 

conditions, lower emissions of CO were correlated with lower emissions of 

hazardous organics, including polynuclear aromatic hydrocarbons. 

EPA-HQ-OAR-2002-0058-0006 at 8-36 to 8-40 (JAXXXX-XX).

That EPA set a separate standard for dioxins and furans is not inconsistent

because EPA has specific data demonstrating that those compounds are formed in 

the air pollution control equipment after the combustion chamber. RTC Vol. 2 at 

16 (JAXXXX). EPA has no such data for other compounds, however, and believes 

that they are adequately controlled by optimizing combustion conditions, which is 

monitored by the CO emissions. See Reconsideration RTC at 336-38

(JAXXXX-XX).

Petitioners’ argument concerning the “break down” of the relationship 

between CO and hazardous organics at low CO concentrations is based on a 

fundamental misunderstanding of the data in the record. For example, Petitioners 

rely on comments submitted by Southern Company. LEAN Br. 24. However, the 

entire point of those comments is that CO is an overly conservative surrogate 

because elevated CO levels can persist when all the organic compounds have been 

destroyed. EPA-HQ-OAR-2002-0058-2741 at 10-12 (JA XXXX-XX). Thus, they 

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do not support Petitioners’ claim that the regulation does not adequately regulate 

hazardous organics.

The alleged “break down” of the relationship is, rather, a reflection of the 

fact that the conversion of CO to carbon dioxide is the last step in the combustion 

process and a particularly difficult one, which means that there is a threshold point 

where essentially all of the organic compounds have been combusted but some CO

remains. RTC Vol. 2 at 34-35 (JAXXXX-XX). This is demonstrated by the 

graphs comparing the concentration of organic compounds versus the 

concentration of CO, which cross the line of zero organics at a point where there is 

still a concentration of CO. Id. In the final rule, EPA took this threshold 

phenomenon into account by setting the CO standard at the higher of the actual CO

concentration achieved by the best-performing sources in a subcategory or 130 

ppm, which EPA determined to be the threshold below which no further 

combustion of organic compounds occurs. 78 Fed. Reg. at 7144-45.

Finally, the fact that there are various ways to reduce the emissions of 

hazardous organics, LEAN Br. 24, does not make the use of CO as a surrogate 

unreasonable. Regardless of the control measure, the boiler’s fuel will be 

combusted, and thorough combustion will be needed to minimize the emissions of 

hazardous organics. CO is an indicator of the completeness of combustion, and 

thus is an appropriate surrogate.

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 VII. THE SUBCATEGORIES IN THE RULE ARE REASONABLE

Section 7412(d) provides that in establishing standards for HAPs, EPA may 

distinguish among classes, types and sizes of sources. 42 U.S.C. §7412(d)(1). 

This Court has recognized that EPA’s exercise of this authority involves an expert 

determination, “placing a heavy burden on a challenger to overcome deference to 

EPA’s ‘articulated rational connection between the facts found and the choice 

made.’” NACWA, 734 F.3d at 1159, quoting NRDC v. EPA, 489 F.3d at 1375. 

Petitioners have not met that burden.

In the Major Boilers Rule, EPA created subcategories based on the fuel the 

boiler is designed to combust and, for some fuel types, the mechanism used for 

feeding the fuel into the boiler. 78 Fed. Reg. at 7144; 76 Fed. Reg. at 15,617-18, 

15,633-37. As EPA explained, the different boiler designs and combustion 

systems affect the emission of pollutants, such as hazardous organics, that are 

associated with combustion conditions and the types of pollution control 

equipment that can be used. 76 Fed. Reg. at 15,617/3; Reconsideration RTC at 

558-64 (JAXXXX-XX). In order to establish a standard based on what the best 

performing units achieve, the units considered must be sufficiently similar to each 

other that the comparison is meaningful. Because the type of fuel a unit is 

designed to burn is a significant factor in determining the level of emission control 

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the unit can achieve, EPA reasonably determined the best-performing sources for 

each type of fuel and combustion system separately.

Petitioners argue that because the subcategories in the rule are defined in 

terms of the fuel that a boiler is combusting, the subcategories do not reflect 

different “classes, types, or sizes.” LEAN Br. 27-29. However, as EPA explained, 

the design, and thus the physical structure of a boiler, is determined by the type of 

fuel it burns. 75 Fed. Reg. at 32,016-17; Reconsideration RTC at 559(JAXXXX). 

The mechanisms for delivering and combusting solid fuels, for example, are 

different from those for gaseous and liquid fuels. Even within these broad 

categories, different types of fuel require different designs. For example, although 

they are both solids, biomass and coal require different combustor designs because 

coal has a higher energy density than biomass. Reconsideration RTC at 559-61

(JAXXXX-XX). Thus, a larger amount of biomass must be combusted to produce 

the same amount of energy, and the combustion system must be designed to 

accommodate that fact. Furthermore, the system must be designed to address the 

higher moisture content of biomass. Id. at 560 (JAXXXX).

Thus, although the subcategories are defined in terms of the fuel being 

burned, each subcategory is characterized by differences in design and 

manufacture that are necessitated by the type of fuel being burned. Furthermore, 

EPA has determined that these differences in design result in differences in 

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emissions. 76 Fed. Reg. at 15,617-18; 78 Fed. Reg. at 7144; Reconsideration RTC 

at 560 (JAXXXX). Thus, in determining the best performing sources, it is 

necessary to look at sources that are comparable in design, which in turn is 

determined by the fuel the unit is designed for.

Furthermore, while the definitions of “unit designed to burn biomass” and 

“unit designed to burn coal” require that the unit derive more than 10 percent of its 

input from biomass or coal, 40 C.F.R. §63.7575, as EPA explained, the differences 

in design between the types of units means that it is generally impracticable for 

units to switch between categories or even to burn such a high percentage of the 

alternative fuel. Reconsideration RTC at 559-63 (JAXXXX-XX). Coal-burning 

units are not designed to handle either the physical form of biomass or its high 

moisture content, which can damage the boiler, and will not be able to operate at 

their designed heat input because of the lower energy density of biomass. Id. at 

560-61 (JAXXXX-XX). Similarly, biomass units may be damaged by the higher 

temperatures resulting from burning coal. Thus, while biomass units may burn 

some coal because of fluctuations in supply of biomass, they are not likely to 

switch to burning high volumes of coal. Id. The subcategories represent units that 

differ structurally and operationally in ways that affect the emissions from the 

units, and thus constitute different classes or types.

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VIII. EPA REASONABLY EXCLUDED CERTAIN UNITS CO-FIRING 

NATURAL GAS FROM ITS MACT FLOOR ANALYSIS________

In calculating the MACT floor for the particulate matter standard for new 

and existing biomass solid suspension burners, the total suspended material 

standard for new wet biomass stoker/sloped grate/other units, and the CO standard 

for new heavy liquid units, EPA did not consider units with the lowest emission 

test value because those units were co-firing natural gas with biomass or heavy 

liquid fuel when the performance test was done. Revised MACT Floor Analysis 

(August 2012), EPA-HQ-OAR-2002-0058-3836, at 4, 8, App. E-9 (JAXXXX, 

XXXX, XXXX).9

 EPA excluded these units because not all units in the 

subcategory are capable of co-firing natural gas as an auxiliary fuel, and therefore

these units are not “similar” sources for the purpose of establishing the MACT 

standard. Id. at 8 (JAXXXX).10

9 Although Petitioners express the issue more broadly, these four standards are the 

only ones for which EPA excluded the top-performing units from a MACT floor 

analysis because the unit was not burning 100 percent of the subcategory-defining 

fuel. Id.

10 While EPA could have gone on creating subcategories ad infinitum to address 

every possible combination of fuels that boilers are capable of combusting, the 

Agency determined it was more appropriate to create subcategories based on the 

primary fuel the boiler is designed to combust and, where necessary, exclude 

anomalous units from the MACT floor calculation.

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This issue is not properly before the Court, regardless of whether Petitioners

raised the issue in comments.11 The challenged standards for the two biomass 

categories were remanded to EPA by the Court’s Order of May 15, 2014 (Dkt.

1493171), and are thus no longer before the Court. See EPA’s Motion for Remand 

(Dkt. 1482091) at 10-12. Petitioners’ challenge to the heavy liquid standard is also 

moot because EPA set the CO standard at the 130 ppm threshold level (see p.70, 

supra), and would have set the same standard if it had used the sources with lower 

emission values.12 

Moreover, EPA’s actions were reasonable. MACT standards for new 

sources must be no less stringent than “the best controlled similar source, as 

determined by the Administrator.” 42 U.S.C. §7412(d)(3) (emphasis added). EPA 

reasonably determined that a unit with an operational feature that is not found in all 

units in the category, i.e., the ability to co-combust natural gas, is not a “similar” 

source. See H.R. Rep. No. 101-490 at 328 (EPA must consider physical 

characteristics and type of operation of a source to determine if it is “similar”).

11 Accordingly, Petitioners’ conditional challenge to EPA’s denial of 

reconsideration, LEAN Br. 31-32, is moot. 

12 As noted above, Environmental Petitioners’ challenge to EPA’s use of the 130 

ppm threshold as the minimum standard for carbon monoxide has been severed 

and held in abeyance.

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Petitioners’ reliance on Sierra Club v. EPA, 479 F.3d 875, is inapposite. In 

Sierra Club, the issue was whether EPA could exclude all units using the 

most-effective emission control technique because it might not be applicable to all 

existing units. Here, EPA is excluding a test result that is unrepresentative of 

typical operations of units in the subcategory, and thus is inappropriate to use in 

establishing the MACT floor.

IX. EPA’S USE OF THE UPPER PREDICTION LIMIT 

TO ESTABLISH STANDARDS IS REASONABLE_

A. Introduction

Emission standards promulgated pursuant to section 7412 must 

simultaneously meet a number of requirements. They must be achievable, 42 

U.S.C. §7412(d)(2); they must ensure continuous regulation of the covered source, 

id. §7602(k); and they must be no less stringent than the level of emission control 

achieved by the best controlled source or sources, id. §7412(d)(3). Sierra Club v. 

EPA, 551 F.3d at 1027 (“there must be continuous section 112-compliant 

standards”).

 In many cases, including this one, EPA must establish those standards on 

the basis of limited data, generally in the form of “stack tests.”13 Because stack 

13 A stack test typically consists of three separate sampling periods of several hours 

each conducted over one or more days. The concentration of the pollutants of 

interest is determined for each sampling event and the result of the test is the 

average of the three values for each pollutant. 40 C.F.R. §63.7520(d).

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tests are time-consuming and expensive, the available data for a source category 

will generally be limited to stack tests that facilities have been required to perform, 

which, in many cases, will be no more than one test per facility. Each stack test is 

a “snapshot” of the facility’s emissions at a particular point in time. Because EPA 

lacks data showing the full emissions performance of the best performing unit or 

units over time, EPA reasonably uses an established statistical methodology in 

order to determine such performance.

When establishing a MACT emission standard, EPA ranks the facilities for 

which it has valid emissions data from the lowest average tested emission level of 

each pollutant to the highest. The Agency then determines the best-performing 

similar sources in accordance with section 7412(d)(3), i.e., the best-performing 

source for establishing standards for new sources and the average of the 

best-performing sources for existing sources. 

Because MACT standards must be complied with at all times under all 

operating conditions, and stack tests only measure emissions at one time and under 

one set of conditions, in establishing MACT standards EPA uses statistical 

techniques to account for the range of variability to be expected in operating 

conditions and measurement accuracy and to set a standard that is achievable for 

the best-performing source or the average of the best-performing sources at all 

times and under the foreseeable range of operating conditions. “EPA’s Response 

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to Remand of the Record for Major Source Boilers,” Dkt. 1502494 (“UPL Remand 

Response”) at 5 (JAXXXX). See also 76 Fed. Reg. at 15,630/1-2. This Court has 

repeatedly held that it is appropriate for EPA to take such variability into account. 

Mossville, 370 F.3d at 1242; Sierra Club v. EPA, 167 F.3d 658, 665 (D.C. Cir. 

1999).

In this case, EPA used a statistical technique known as the Upper Prediction 

Limit. As EPA stated in the preamble to the March 2011 final rule, “The UPL 

calculation is a statistical formula designed to estimate a MACT floor level that is 

equivalent to the average of the best performing sources.” 76 Fed. Reg. at 15,630. 

See also UPL Remand Response at 5 (JAXXXX) (“the UPL predicts the level of 

emissions that the sources upon which the floor is based are expected to meet over 

time, considering both the average emission level achieved as well as emission

variability and the uncertainty that exists in the determination of emission

variability given the available, short-term data.”)

The UPL is a statistical technique that, given the results of a particular 

measurement on a small sample, predicts the range in which all such measurements

will fall with a specified level of certainty, based on prediction of measurements at 

times other than when data is collected. In this case, it predicts the range in which 

the average emissions of the best-performing sources would fall with 99 percent 

certainty on an ongoing basis. It is analogous to the statistical analysis that a 

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manufacturer would perform to determine the range of a particular measurement if 

all units in a large production run were tested based on the results of testing a small 

sample of the production run. For this rule, the existing source UPL was 

calculated by taking the average emissions of the top-performing sources and 

adding to it a variability factor that is calculated based on the characteristics of the 

data set and the desired level of confidence (in this case 99 percent). UPL Remand 

Response at 10-15 (JAXXXX-XX).

 B. Use of the UPL Is Consistent with the Requirements of 

Section 7412(d)(3).__________ ________

EPA uses the UPL to establish emission standards that reflect what the 

average of the top-performing sources achieve over the entire range of operating 

conditions likely to be encountered. The standards are thus consistent with the 

statutory requirements that they be achievable under the foreseeable range of 

operating conditions. Environmental Petitioners nonetheless assert that EPA’s use 

of the UPL is inconsistent with the Clean Air Act’s requirements, claiming that the 

resulting standards do not reflect the average of the top-performing sources and do 

not reflect the level of emission control achieved by those sources. These claims 

lack merit.

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1. The UPL Represents the Average Performance of the 

Top-Performing Sources Over Time.______________

That the emission standards calculated using the UPL reflect the average 

emission control achieved by the top-performing sources is inherent in the formula 

used to calculate the UPL and was stated by EPA both in the rulemaking and in its 

response to the Court’s remand of the record. The formula for calculating the UPL 

determines the value that the average of the best-performing sources will fall 

within 99 percent of the time. The process for calculating the UPL begins with 

calculating the average of the emission levels of the best-performing sources. See

UPL Remand Response at 10 (JAXXXX). (The symbol “xx̅” stands for the average 

of the measured values.) A term is then added to that value, which, using standard 

statistical techniques, predicts how much the average value is likely to vary over a 

range of conditions. Id. at 10-11 (JAXXXX). For a general description of the use 

and calculation of prediction intervals see

http://en.wikipedia.org/wiki/Prediction_interval (“a prediction interval is an 

estimate of an interval in which future observations will fall, with a certain 

probability, given what has already been observed”).

In both the preamble to the final rule and the response to the remand of the 

record, EPA has clearly stated that the purpose of the UPL is to represent the 

expected range of the average emission reductions achieved by the best-performing 

sources. Thus, in the preamble to the March 2011 final rule EPA stated, “The UPL 

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calculation is a statistical formula designed to estimate a MACT floor level that is 

equivalent to the average of the best performing sources.” 76 Fed. Reg. at 15,630 

(emphasis added). Similarly, in its response to the remand of the record EPA 

stated:

EPA interprets the average to mean the average emissions over time, 

based on both the calculated average of all emissions test data from 

the best performing source or sources and the available information 

regarding the variability of emissions. The UPL, which EPA uses to 

account for variability among the best performing sources, reflects an 

upper limit for the emissions of those sources at times other than when 

the emissions test occurred. This not only is a prediction of the 

emissions performance of those sources in tests conducted in the 

future, but is also an indication of the range of current average 

emissions performance of those sources.

UPL Remand Response at 3 (JAXXXX).

Petitioners do not address the way in which the UPL is calculated except to 

make a specious comparison between that calculation and the addition of a string 

of numbers. LEAN Br. 48. As discussed above, the UPL calculation applies a 

standard statistical technique to determine the range of variability in the average

emissions of the best-performing sources that can be expected over time. The 

calculation begins with calculating the average emissions and adds to it a factor 

based on measures of the variability of the data set, such as the size of the data set 

and the range of values. Thus, the UPL, by its nature calculates the expected 

values of the average emissions.

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Petitioners’ further claim that the remaining terms are unrelated to the 

average, LEAN Br. 48-49, is equally spurious and demonstrates a fundamental 

misunderstanding of statistical analysis. Those terms are used to calculate the 

expected variability, represent standard statistical methods, and are determined by 

the nature of the data set. Because the other terms relate to the nature and amount 

of the data, the fact that they are not dependent on the average value does not 

change the fact that what the UPL calculates is the expected value of the average 

emission level. Furthermore, the fact that a smaller data set increases uncertainty, 

and may, as in the example from Sierra Club’s comments cited in NACWA, result 

in a higher value for the UPL, is a basic fact of statistical analysis. If a 

manufacturer tests 10 units out of a run of a million, the extent to which the sample 

represents the range of values found in the entire run is much more uncertain than 

if the manufacturer tested 1000 units. To account for that uncertainty, the 

prediction limit calculated from the 10 tests (which predicts the range of values 

found in the entire run to a specified level of certainty) would likely be higher than 

if 1000 units were tested. The same is true of emission limits. The smaller the 

number of samples, the greater the uncertainty that those samples represent the full 

range of values, which might result in a higher UPL. The calculated value, 

however, still represents a reasonable estimate of the expected values of the 

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average level of control achieved by the best-performing sources based on the 

available data.

2. The UPL Represents What the Best-Performing Sources 

Achieve Over Time.________________________________

Petitioners’ claim that the emission values calculated by the UPL do not 

represent the level of emission control “achieved” by the best performing sources, 

LEAB Br. 36-38, is equally without merit. Petitioners admit that EPA can 

consider variability in establishing MACT standards. Id. at 38. As explained 

above, that is the purpose of the UPL – it starts with the average level and then 

takes variability into account to satisfy the statutory requirement that the standards 

be achievable on a continuous basis during varying operating conditions. 

Petitioners do not address that purpose or the way the UPL is calculated to address 

variability. 

Instead, Petitioners rely solely on a quote taken out of context from EPA’s 

Response to Comments Document. Id. at 37. The comment to which the quoted 

response was made requested that EPA calculate MACT standards by calculating a 

UPL for each individual source, ranking the sources on the basis of the 

site-specific UPL and then basing the standard on a UPL analysis of that set of

numbers. RTC Vol. 1 at 769 (JAXXXX). In explaining why it did not adopt that 

approach, EPA explained that the purpose of the UPL in this rulemaking was not to 

analyze the performance of individual sources, but rather is “a prediction value for 

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the average of test runs from a new observation from the same population.” Id. 

(Emphasis added). There is nothing inconsistent between that statement and the 

fact that the purpose of the UPL is to predict emissions of the best performing 

sources over time. Although Petitioners admit that EPA may consider variability 

in establishing MACT standards, and thus is not required to simply impose the 

mathematical average of the top test results, they do not explain how EPA might 

do that other than by using a statistical technique such as the UPL that predicts the 

range of future performance (which is what the standard governs) based on the 

variability of the test results.

Furthermore, this Court has long recognized that the Clean Air Act does not 

specify how EPA is to determine what the best performing units are achieving, and 

that EPA has considerable discretion in doing so as long as its methodology is 

reasonable. NACWA, 734 F.3d at 1141-42; Mossville. 370 F.3d at 1241; Sierra 

Club v. EPA, 167 F.3d at 661-63. This Court has held that:

EPA would be justified in setting the floors at a level that is a 

reasonable estimate of the performance of the “best controlled similar 

unit” under the worst reasonably foreseeable circumstances. . . . It is 

reasonable to suppose that if an emissions standard is as stringent as 

“the emissions control that is achieved in practice” by a particular 

unit, then that particular unit will not violate the standard. This only 

results if “achieved in practice” is interpreted to mean “achieved 

under the worst foreseeable circumstances.” 

Id. at 665.

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That is exactly EPA’s rationale for using the UPL. As the Agency has 

explained:

It is reasonable to interpret the statutory requirement that the MACT 

floor level reflect the “emission control that is achieved in practice” 

by the best controlled similar source and “average emission limitation 

achieved by” the best performing 12 percent of sources as a level [or] 

the average level the best performers are meeting on a consistent basis 

over time, not just at the single point in time during which emissions 

test data were collected. If EPA were to simply take the average of 

the stack test data from the best performing source or sources, the 

MACT floor would not represent the levels of emissions achieved in 

practice over time because the MACT floors would not reflect 

variations in material inputs (e.g., fuels), control device performance, 

operating unit performance (e.g., changes in combustion conditions 

that impact emissions), and other factors that affect unit performance 

over time. This is demonstrated by the fact that even single three run 

tests, which are performed over a short period of time, typically show 

different emission levels during each individual test run. 

UPL Remand Response at 5 (JAXXXX). See also, 76 Fed. Reg. at 15,630/1-2. 

Since the UPL is designed to set the standard at the level that the average of the 

best controlled units achieve under the worst reasonably foreseeable circumstances 

during operating conditions, it is consistent with both the Clean Air Act and this 

Court’s precedents.

C. The Standards Are Supported By the Record.

EPA’s use of the UPL to set emission standards is supported by the record, 

which demonstrates that emissions from the units covered by the Major Boilers 

Rule are subject to considerable variability that is not due to factors such as 

differences in control measures or operator diligence. This is demonstrated by 

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observed variability in emissions from single boilers, including variability among 

the three sampling events that constitute a single performance test.

Petitioners rely in part on two graphs included in their brief. LEAN Br. 

14-15. The Court should disregard the first graph (on page 14) because it does not 

use the correct emission limit. The filterable particulate matter limit for existing 

wet biomass units is 0.037 lb/MMBtu, 78 Fed. Reg. at 7196, not 0.32 as shown on 

the graph, an error of almost ten-fold.14 If the proper standard were shown on the 

graph, it would fall in the bottommost row, and would be exceeded by several of 

the test runs. While the second graph uses the correct emission limit, the mere fact 

that the limit exceeds the test results from the best performing sources (in this case, 

by approximately 4 millionths of a pound per million Btu), does not render the 

methodology arbitrary and capricious. As shown on the graph, the test results 

show substantial variability, under the controlled conditions of a stack test, and it is 

not unreasonable that the average emissions from these units under the worst 

reasonably foreseeable operating conditions could exceed those levels.

Petitioners also rely on several comments to support their claim that 

variability in test results is not due to statistical variation. LEAN Br. 39-40. None 

of those comments, however, presents any actual data to demonstrate that the 

14 Petitioners appear to have used the MACT floor for dry biomass units, Nov.2011 

Floor MACT Memo at 8 (JAXXXX), which is based on a different data set.

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variability in the test results from design or operational differences between 

boilers, but simply speculate that it may be so. See JAXXXX, XXXX, 

XXXX-XX. Thus, they provide no factual support for Petitioners’ claims. In 

contrast, the record does demonstrate variability in test results at the same unit, 

even within the same 3-run test. 

As this Court has often recognized, it owes considerable deference to EPA in 

the Agency’s exercise of its technical expertise. Ethyl Corp. v. EPA, 541 F.2d 1, 

36 (D.C. Cir. 1976) (en banc) (“[The court] must look at the [agency’s] decision 

not as the chemist, biologist or statistician that [it is] qualified neither by training 

nor experience to be, but as a reviewing court exercising our narrowly defined duty 

of holding agencies to certain minimal standards of rationality.”); Am. Trucking 

Ass’ns, Inc. v. EPA, 283 F.3d 355, 374 (D.C. Cir. 2002). Analyzing the variability 

in emission test results among units in a source category and determining the 

appropriate statistical methodology for establishing standards under the worst 

reasonably foreseeable conditions fall squarely within EPA’s technical expertise. 

The record supports EPA’s determination that the variability in test results can be 

appropriately addressed through statistical methods and the Agency applied a 

well-established statistical technique to the data in the record. The Court should 

accordingly defer to EPA’s exercise of its technical expertise.

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D. EPA Did Not Change Its Rationale for the UPL In 

the Response to the Remand of the Record.____

There is no merit to Petitioners’ claim that EPA’s response to the Court’s 

remand of the record presented a different rationale for EPA’s use of UPL than that 

presented in the original rulemaking. LEAN Br. 41-43.15 To the contrary, while 

the remand response explains EPA’s use of the UPL in more detail, the rationale is 

exactly the same, i.e., EPA uses the UPL to establish emission standards at the 

level that the average of the best controlled unit is achieving under the full range of 

foreseeable operating circumstances. In the March 2011 final rule preamble EPA 

stated, “The UPL calculation is a statistical formula designed to estimate a MACT 

floor level that is equivalent to the average of the best performing sources based on 

future compliance tests.” 76 Fed. Reg. at 15,630. This is no different than what 

the Agency said in its response to the remand of the record: “EPA interprets the 

average to mean the average emissions over time, based on both the calculated 

average of all emission test data from the best performing source or sources and 

the available information regarding the variability of emissions. The UPL, which 

EPA uses to account for variability among the best performing sources, reflects an 

15 There is also no basis to Petitioners’ claim that EPA introduced new data 

contrary to representations in the remand motion. While EPA did use a data set

from the sewage sludge rulemaking to illustrate how the UPL works, that data is 

not presented as substantive support for the Major Boilers Rule.

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upper limit for the emissions of those sources at times other than when the 

emissions test occurred.” UPL Remand Response at 5 (JAXXXX). 

The purpose of the UPL is to determine what the average of the best 

performing sources achieves in the whole range of operating circumstances. It 

applies to the future because that is when the emission standard is effective, i.e., 

sources covered by the Major Boilers Rule must demonstrate compliance with the 

rule by means of emission tests that will occur in the future, but it also represents 

what the average of the best performing sources are currently achieving over time.

Moreover, the method for calculating the UPL is exactly the same in the 

Rule and in the response to the remand. What the UPL represents is inherent in the 

methodology used to calculate it. As described above, in calculating the UPL, 

EPA determines the best performing sources, calculates the average emission level 

of those sources, then calculates a variability factor based on the characteristics of 

the data set and adds it to the average emission value. Thus, the UPL calculates the 

variability of the average of the best-performing sources. Regardless of the 

language used to describe it, EPA’s interpretation of how the UPL is consistent 

with the statutory requirement to base MACT standards on the average of the bestperforming sources is built into the methodology. The methodology provides that 

the UPL-based standards reflect the average emission reductions achieved by the 

best-performing sources.

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Petitioners’ claim that EPA represented to the Court that it would provide an 

explanation of how the average value of a three-run compliance test reflects the 

average of the best-performing sources, LEAN Br. 41, is specious.16 That has 

never been EPA’s view. In the motion for remand of the record, EPA requested 

the remand “in order to provide further explanation of the analysis of variability 

used in setting the numeric standards.” Dkt. 1482091 at 1. That is exactly what 

EPA did. The response to the remand of the record provides a more detailed 

explanation of the analysis that EPA performed. 

Petitioners’ assertion that EPA should instead have made up a rationale for a 

position that the Agency does not hold and has never held is absurd. First, the 

motion sought remand of the record in this case to explain use of the UPL in the 

rule under review in this case, and that is exactly what EPA did. Second, the Court 

in NACWA did not order EPA to provide an explanation of “how the average value 

of a three-run compliance test reflects the average of the best-performing sources,” 

but rather ordered EPA “to clarify issues related to its upper prediction limit and 

variability analysis.” NACWA, 734 F.3d at 1161. Again, that is exactly what EPA 

did. Finally, even if the NACWA Court erroneously believed that EPA was 

16 As noted above, the standard protocol for a stack test requires three separate 

sampling periods with emission levels calculated for each period. Compliance is 

determined by the average of the levels measured in each period. The average of 

the three periods constitutes a single compliance test.

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equating the average of a three-run compliance test with the average of the best 

performing sources, the Court would surely have expected EPA on remand to 

explain what it actually did, rather than to make up an explanation for a position it 

has never taken.

Finally, the Court has already rejected Petitioners’ claim that the remand of 

the record required notice and comment when it granted EPA’s motion over that 

objection by the Petitioners. That holding is therefore the law of the case and 

cannot be revisited here. Petitioners’ arguments concerning the validity of EPA’s 

use of the UPL, LEAN Br. 43-51, are addressed above. 

CONCLUSION

The petitions for review should be denied.

Respectfully submitted, 

SAM HIRSCH

Acting Assistant Attorney General

November 10, 2014 /S/ Perry M. Rosen

PERRY M. ROSEN

NORMAN L. RAVE, JR. 

Environmental Defense Section

Environment & Natural Resources Division

United States Department of Justice

P.O. Box 7611

Washington, D.C. 20044

(202) 616-7568

Counsel for Respondent

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Of Counsel:

SUSMITA DUBEY

Office of General Counsel

U. S. Environmental Protection Agency

1200 Pennsylvania Ave., NW

Washington, DC 20460

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CERTIFICATE OF COMPLIANCE WITH WORD LIMITATION

Pursuant to Federal Rule of Appellate Procedure 32(a)(7)(C), I hereby 

certify that the foregoing Brief of Respondent EPA contains 22,314 words as 

counted by the Microsoft Office Word 2013 word processing system, and thus 

complies with the applicable word limitation.

/S/ Norman L. Rave, Jr.

Norman L. Rave, Jr.

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CERTIFICATE OF SERVICE

I hereby certify that on November 10, 2014, the foregoing Brief of 

Respondent was served electronically through the Court’s CM/ECF system on all 

registered counsel.

/S/ Norman L. Rave, Jr. 

Norman L. Rave, Jr.

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