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Chapter 13

Startup, Shutdown and Malfunction

Contents

13.1 General................................................................................................................................. 2

13.2 Treatment of Malfunctions and Affirmative Defense.......................................................... 6

13.3 Startup and Shutdown........................................................................................................ 16
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13.1 GENERAL

Comment 13.1-1: Commenter 10681 agreed with the EPA's proposed approach to include all 

emissions during startup, shutdown, and partial load in determining the emissions rate. The 

commenter referenced Washington's greenhouse gas emission performance standard regulation 

(WAS 173-407, Part II) requirements.

Response 13.1-1: The EPA acknowledges the commenter’s support. The EPA’s final action 

establishes standards that apply at all times. In establishing the standards, the EPA has taken into 

account emissions during startup and shutdown periods. Specifically, startup and shutdown 

periods are included in the compliance calculation as periods of partial load.

Comment 13.1-2: Commenter 9512 noted that the proposed rule is incomplete and inadequate 

with respect to SSM provisions of proposed subparts Da and KKKK. Commenter 9512 stated, 

"EPA's intended approach to startup, shutdown, and malfunction events, as described in the 

preamble to the Proposed Rule and discussed in the foregoing comments, is only reflected fully

in proposed subpart TTTT. The proposed alternative additions to subpart Da do not make any 

changes with respect to the way malfunctions are addressed under other, existing provisions of 

subpart Da and under subpart A. In contrast, the proposed alternative additions to subpart KKKK 

exempt the proposed CO2 provisions from portions of subpart A that address SSM events (see 

proposed Table 3, 79 Fed. Reg. 1510, stating that sections 60.8 and 60.11 do not apply to the 

CO2 emission standards), but no affirmative defense language has been proposed." Commenter 

9512 further stated, "If EPA decides to address CO2 emissions at new and modified EGUs 

through revisions to subparts Da and KKKK, EPA must re-propose those revisions for public 

comment with clear and unambiguous indications of how SSM events will be addressed under 

the proposed rules."

Response 13.1-2: As explained in section III.B of the final rule preamble, the EPA is combining 

the steam generator and combustion turbine categories into a single category of fossil fuel-fired 

electricity generating units for purposes of promulgating standards of performance for GHG 

emissions. The standards of performance for CO2 emissions will be codified in a new 40 CFR 

part 60, subpart TTTT. Because this comment regards the SSM provisions associated with the 

co-proposed approach of codifying the standards of performance in the 40 CFR part 60, subparts 

Da and KKKK, which the EPA is not finalizing, further response is not provided. 

Comment 13.1-3: Multiple commenters (7977, 9471, and 9512) stated that the EPA has not 

sufficiently supported its treatment of emissions during startup, shutdown, and malfunction 

periods in the rulemaking.

Commenter 7977 expressed "serious and significant concerns regarding the practical ability to 

monitor emissions during periods of startup, shutdown, and malfunctions." 

Commenter 9471 noted that "during periods of startup and shutdown, although weighted mass 

emissions are low, the emission rate based on the ratio of mass emissions to electric generation 

can easily exceed the 1,000 lb/MWh standard."

Commenter 9512 stated that "EPA has failed to account adequately for emissions that occur 

during SSM periods, consistent with the language and intent of CAA NSPS."
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Response 13.1-3: EPA disagrees that it has not adequately explained the basis for its decision to 

promulgate standards that apply at all times, including during SSM events. See section X.A and 

J.1 of the final rule preamble for the EPA’s response to these comments.

Comment 13.1-4: Commenter 9512 noted that it can be "unclear whether a condition that leads 

to excess emissions should be characterized as a startup or shutdown event or a malfunction 

event. Without a clear demarcation (both in EPA regulations and in practice), the EPA may be 

analyzing data sets that exclude events that were treated as malfunctions, but that the EPA would 

say should be included in calculating average performance as startup or shutdown conditions."

Response 13.1-4: The terms “startup,” “shutdown,” and “malfunction” as defined in section 60.2 

of 40 CFR part 60, subpart A (General Provisions), enable sources subject to subpart TTTT to 

determine whether specific periods of operation are periods of startup, shutdown, normal 

operation or malfunction. See also section X.A of the final rule preamble.

Comment 13.1-5: Commenter 9512 stated that the EPA has not "justified its rejection of relief 

from numerical emission limitations that it has provided in NSPS for decades." Commenter 9512 

noted the following:

 "court decisions both before and after the Clean Air Act Amendments of 1977...have 

affirmed the appropriateness of including special SSM provisions in standard issued 

under section 111"

 "an emission limitation that applies during SSM events does not meet the requirement of 

CAA section 111(a)"

 courts have reached similar conclusions in Clean Water Act decisions

Response 13.1-5: EPA acknowledges that in the past it addressed emissions during SSM events 

differently in regulations it issued pursuant to CAA section 111, CAA section 112, and CAA 

section 129. As noted by the commenter, the General Provisions applicable to NSPS have 

historically not required sources to meet the same emission limits during SSM events as during 

other periods of operation, unless otherwise specified in the applicable standard. (See, 40 CFR 

section 60.8(c)). Likewise, EPA acknowledges that some prior court decisions support the 

general proposition that emission limitations must be reasonable and appropriate, including 

limits that apply to emissions during modes of source operation such as startup and shutdown. 

(See, e.g., Portland Cement Ass’n v. Ruckleshaus, 486 F.2d 375 (D.C. Cir. 1973)). EPA does 

not, however, agree with the commenter’s extrapolation from these past rulemakings and 

decisions that emission limitations promulgated under CAA section 111 must contain 

exemptions or other special treatment for emissions during SSM events. The D.C. Circuit’s 

decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008) vacated the SSM exemption 

contained in 40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1). Since that decision, EPA’s proposed 

approach to emissions during SSM periods has been used consistently in CAA section 112, CAA 

section 111, and CAA section 129 rulemaking actions. (See, e.g., National Emission Standards 

for Hazardous Air Pollutants From the Portland Cement Manufacturing Industry and Standards 

of Performance for Portland Cement Plants, 75 FR 54970 (Sept. 9, 2010); Standards of 

Performance for New Stationary Sources and Emission Guidelines for Existing Sources: Sewage 
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Sludge Incineration Units; Final Rule, 76 FR 54970 (March 21, 2011) National Emission 

Standards for Hazardous Air Pollutants from Coal- and Oil-fired Electric Utility Steam 

Generating Units and Standards of Performance for Fossil-Fuel-Fired Electric Utility, IndustrialCommercial-Institutional Steam Generating Units; Final Rule, 77 FR 9304 (February 16, 2012)).

Under this approach, EPA sets emission standards that apply at all times, including during 

predictable modes of operation such as startup and shutdown. See also Preamble section X.A.

Comment 13.1-6: Commenter 9512 stated that EPA is wrongly interpreting the court’s decision 

in Sierra Club v. EPA concerning the requirement for continuous emission limitations in a 

NESHAP under section 112 to apply to an NSPS under section 111. The commenter noted that 

the court’s decision only addressed the issue of exemptions for emissions during SSM events for 

sources in regulations pursuant to section 112, not section 111. In addition, the commenter stated 

that the court’s decision only held that a blanket exemption in the General Provisions for 

NESHAPS was inconsistent with the requirements of section 112. The commenter thus asserted 

the court’s decision has no bearing on the requirements of section 111.

Response 13.1-6: EPA disagrees that the Sierra Club v EPA decision has no bearing on section 

111 standards. EPA believes the reasoning of the D.C. Circuit’s decision in Sierra Club v. EPA 

applies not only to standards EPA promulgates under section 112, but also to standards under 

section 111. As explained in the proposal for this action, the D.C. Circuit’s decision vacated the 

SSM exemptions in the General Provisions applicable to many NESHAP in 40 CFR section 

63.6(f)(1) and 40 CFR 63.6(h)(1), holding that under section 302(k) of the CAA, emission 

standards or limitations must be continuous in nature and that the exemption for emissions 

during SSM events violated the CAA requirement that some section 112 standard apply 

continuously. EPA believes that the logic of the court applies with equal force to the 

requirements of section 111. Section 111 requires EPA to impose a “standard of performance” 

on affected sources, and section 111(a)(1) specifically defines “standard of performance” as a 

standard “which reflects the degree of emission limitation” achievable through BSER. Similarly, 

section 111(b)(B) directs EPA to revise a NSPS when “emission limitations . . . beyond those 

required by the standards” are achieved in practice. Both provisions define a standard of 

performance based, in part, on the key requirement that it constitute an “emission limitation.” 

Section 302(k) explicitly defines the term “emission limitation” to be a requirement “which 

limits the quantity, rate, or concentration of emissions on a continuous basis, including any 

requirement relating to the operation or maintenance of a source to assure continuous emission 

reduction.” Consistent with the decision of the D.C. Circuit in Sierra Club v. EPA, EPA 

interprets section 111 to require NSPS that impose standards that apply to affected sources at all 

times, during all modes of source operation without exemptions. This interpretation is further 

supported by section 111(h) which authorizes EPA, under appropriate circumstances, to impose 

“a design, equipment, work practice, or operational standard, or combination thereof, which 

reflects the best technological system of continuous emission reduction.” The definition of the 

term “technological system for continuous emission reduction” in section 111(a)(7)(B) includes 

“a technological system for continuous reduction of the pollution generated by a sources before 

such pollution is emitted into the ambient air.” In both of these provisions, the statute explicitly

describes the standard as “continuous.” Thus, even if an NSPS were composed of different limits 

or forms of control, section 111(h)(1) requires that the standard must reduce emissions on a 

“continuous” basis. Even if section 111 were ambiguous on this point, EPA believes it is 
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reasonable to interpret section 111 to preclude any exemptions from NSPS for emissions during 

SSM events, just as the D.C. Circuit interpreted section 112 to preclude such exemptions.

To the extent that the commenters argue that the Sierra Club v. EPA court vacated the 

General Provisions applicable to emissions during SSM events because they were based 

on a “general duty” clause rather than a continuously applicable section 112 standard, 

EPA agrees that the court found that the “general duty” was not a section 112-compliant

standard. EPA does not claim that the Sierra Club case constrains its authority to 

prescribe standards under section 111 that impose different numerical limits or different 

forms of controls during different modes of source operation, under appropriate 

circumstances. Section 111(h)(1) expressly authorizes such an approach, under certain 

conditions, so long as the resulting standard applies continuously and meets the relevant 

stringency requirements for a standard of performance under section 111. As explained 

in section V.J.1 and section X.A of the Preamble, however, EPA has determined that it 

is not appropriate to set alternative standards for emissions during startup and shutdown, 

nor is it appropriate to include an exemption or other special treatment for emissions 

during malfunctions.

Comment 13.1-7: Commenter 9512 noted that CAA section 302(k) “defines ‘emission 

limitation’ and ‘emission standard’ to be not solely a numerical limit on the quantity, rate, or 

concentration of emissions of an air pollutant on a continuous basis, but rather ‘a requirement’ 

which ‘limits the quantity, rate, or concentration of emission of air pollutants on a continuous 

basis.” The commenter thus asserted that “the statute does not say that ‘requirement’ must be 

expressed as a single, numerical, not-to-be exceeded-at-all times limitation.” The commenter 

also argued that “a ‘requirement’ that limits emissions ‘on a continuous basis’ does not have to 

impose the same limitation at all times. Nor does the form of the limitation have to always be 

the same.”

Response 13.1-7: EPA agrees, in general, that the definition of emission limitation in CAA 

section 302(k) does not require that all standards must be set only as a numerical limit, or at the 

same numerical limit applicable at all times. EPA likewise agrees, in general, that an emission 

limitation may be comprised of a numerical limit or limits combined with specific control 

technologies or work practices that apply during certain modes of source operation. So long as 

all components of such a continuously applicable emission limitation meet applicable stringency

requirements and are legally and practically enforceable, such an emission limitation may be 

appropriate. Section 111(h) explicitly authorizes EPA to impose standards that may include 

different levels or forms of controls that, in combination, provide for continuous emissions 

control at the level of stringency required for purposes of section 111. In some circumstances 

specific alternative numerical limits or control requirements applicable to for periods of startup 

and shutdown as part of an emission limitation may be appropriate. In the case of this action, 

however, EPA has determined that it is not appropriate to promulgate standards that impose 

different numerical limits, or different forms of controls, for specific modes of operation such as 

startup and shutdown. Moreover, EPA does not agree with the commenter’s arguments that 

because an emission limitation could include a combination of different numerical limits, 

technological controls, or work practices, that an NSPS can include an exemption for emissions 

during startup, shutdown, malfunctions, or any other mode of operation. EPA has concluded that 

the court’s decision in Sierra Club v. EPA concerning the term “emission limitation” precludes
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the type of SSM exemptions for which the commenter advocates. Finally, EPA disagrees with 

the commenters’ characterization of the legislative history for section 302(k). Contrary to the 

commenters’ view, EPA does not interpret the statutory language to apply only to “intermittent” 

controls, nor does the legislative history support such a narrow reading. Congress was concerned 

that emission limitations be continuous so that they achieve the requisite emission reductions and 

be capable of effective enforcement. See also section X.A of the final rule preamble.

13.2 TREATMENT OF MALFUNCTIONS AND AFFIRMATIVE 

DEFENSE

Comment 13.2-1: Multiple commenters (9660, 9666, and 10100) cited NRDC v. EPA, 749 f.3d 

1055 (D.C. Cir. 2014) and asked that the EPA re-evaluate its decision to provide an affirmative 

defense for violations during malfunctions. . Commenters took issue with the specific wording 

of the affirmative defense, the narrow circumstances under which the affirmative defense would 

be available, and the fact that an affirmative defense would not be allowed given the recent 

decision of the D.C. Circuit in NRDC v. EPA. Commenters used these arguments in support of 

their preferred approaches that would provide either an exemption for emissions during all 

malfunctions or a numerical limit sufficiently high that it would encompass emissions during all 

malfunctions.

Response 13.2-1: The EPA is not including a regulatory affirmative defense provision in the 

final rule. See section X.A of the final rule preamble for the EPA’s response to this comment.

Comment 13.2-2: Multiple commenters (10098 and 10239) stated that the DC Circuit's decision 

in NRDC v. EPA need not affect the affirmative defense in this rulemaking.

Commenter 10098 stated that the "parties' deadline to seek further review has not yet passed" 

and "as the D.C. Circuit recognized, id. at 18, n.2, the decision appears to be inconsistent with 

Fifth Circuit's decision in Luminant Generation Co. v. EPA, 714 F.3d 841 (5th Cir. 2013), which 

affirmed the inclusion of an affirmative defense in a state implementation plan." Commenter 

10098 urged EPA to include the defense.

Commenter 10239 asserted that an affirmative defense for violations during malfunctions is 

warranted and stated that they "do not believe that the EPA is bound by any judicial precedent 

that would prohibit it from including in a final rule an affirmative defense for malfunctions."

Response 13.2-2: EPA disagrees with commenters who stated that the decision in NRDC v. 

EPA, 749 F.3e 1055 (D.C. Cir. 2014) has no bearing on this rulemaking. In that decision, the 

court vacated the comparable affirmative defense that EPA had provided for violations due to 

emissions during malfunction events. The DC Circuit explicitly held that EPA has no authority

to alter the jurisdiction of the federal courts granted by Congress pursuant to sections 113 and 

304. That decision did not turn upon the specific provisions of section 112 and is equally

applicable to standards promulgated by EPA under section 111. Sections 113 and 304 address 

jurisdiction of the courts for judicial enforcement for violations of all CAA requirements, 

including judicial enforcement actions for violations of NSPS. Similarly, EPA does not agree 

that footnote 2 in the NRDC v. EPA decision noting the existence of a 5th Circuit decision 

pertaining to an affirmative defense in a SIP provision has any bearing upon this action. 
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Contrary to the belief of the commenters, EPA does not interpret that footnote to indicate any 

decision by the DC Circuit that an affirmative defense is valid in a SIP provision. EPA has 

separately taken action on a petition for rulemaking to address the issue of affirmative defenses 

in SIP provisions. (See, “State Implementation Plans; Response to Petition for Rulemaking; 

Restatement and Update of EPA’s SSM Policy Applicable to SIPs; Findings of Substantial 

Inadequacy; and SIP Calls To Amend Provisions Applying to Excess Emissions During Periods 

of Startup, Shutdown and Malfunction; Final Rule,” 80 FR 33840 (June 12, 2015)). 

Accordingly, the EPA is not including a regulatory affirmative defense provision in the final 

rule. See section X.A of the final rule preamble for the EPA’s response to this comment.

Comment 13.2-3: Multiple commenters (9425, 9591, 10048, 10098, and 10105) agreed with 

specific aspects of the proposed affirmative defense provision.

Commenters 9425 and 9591 agreed with the EPA's decision to remove the requirement to notify

EPA within two days of a malfunction.

Commenters 10048 and 10098 supported the EPA's creation of an affirmative defense for 

excursions caused by a malfunction of control equipment.

Response 13.2-3: Comments supporting aspects of the proposed affirmative defense provision 

are no longer germane to this action. The EPA is not including an affirmative defense provision 

in the final rule. See section X.A of the final rule preamble for the EPA’s explanation for that 

decision. .

Comment 13.2-4: Multiple commenters (3862, 9423, 9512, 9666, and 10098) asked for 

clarification of or changes to affirmative defense language.

Commenter 3862 asked that the word "violation" be replaced with "prohibition" in the 

affirmative defense language.

Commenter 9423 asked that the rule be revised to "allow state rules for affirmative defense that 

are EPA-approved as part of a SIP to be used in lieu of the federal procedures."

Commenter 9512 asked that the requirement in section 60.5530(b) be changed from 45 days to 

90 days.

Commenter 9512 stated that "it is not even clear what the affirmative defense 

covers." Commenter 9512 further noted, that the "affirmative defense is 'to civil penalties that are 

caused by malfunctions.' (See, e.g., 79 Fed. Reg. at 1449, 1450.) Is the term 'civil penalties,' 

which is not defined in the Proposed Rule, intended to apply as well to a 'civil administrative 

penalty' imposed by EPA under CAA section 113(d)? (The term 'civil penalty' in other contexts 

means only penalties imposed by a court.) Does the affirmative defense apply to 'noncompliance 

penalties' under CAA section 120 (which apply, inter alia, to noncompliance with a section 111 

NSPS)? To meet the purported purpose of the affirmative defense, which is to provide relief 

from emission limitations that cannot be met at times even with equipment that is properly

designed and maintained (see id. at 1449), the affirmative defense would need to apply to civil 

and administrative penalties, including noncompliance penalties."
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Commenter 9512 also asked how the affirmative defense would apply to enforcement actions by 

state and local governments, or to private citizen enforcement actions under CAA section 304. 

Commenter 9512 asked for an explanation for why the affirmative defense would not apply to 

injunctive relief. (See 60.5530)

Commenter 9512 asked that affirmative defense be redefined to state that a source "'will not be 

deemed in violation of' the NSPS for excess emissions or other deviations from the standards, 

associated with a startup, shutdown, or malfunction event, unless the event, and the source's 

response to the event, do not meet the criteria spelled out in the regulations." Commenter 9512 

noted that, "Configured in that way, this provision for malfunction events should be considered 

something other than an 'affirmative defense,' such as an 'alternative standard for SSM 

events.'" Commenter 9512 offered that, "By allowing these SSM considerations and issues to be 

addressed by an 'alternative standard,' EPA would also circumvent any possibility that its use of 

the affirmative defense to the SSM provisions in this and other rulemakings could be vacated by

a court as beyond the scope of EPA's authority."

Commenter 9512 asked that 60.5530(a)(6) be changed to exclude the language "if at all possible" 

because it differs from section 60.2, which uses the qualifier "to the extent practicable."

Commenter 9512 noted that 60.5530 lists items "which may be appropriate considerations in 

determining whether excess emissions during a malfunction should be considered a violation, but 

which ought not to be listed as mandatory criteria, all of which have to be met in order for an 

exceedance to be excused. For example, proposed section 60.5530(a)(1)(i) requires that the 

excess emissions must have been 'caused by a sudden, infrequent, and unavoidable failure of air 

pollution control and monitoring equipment, process equipment, or a process to operate in a 

normal or usual manner'. There is no apparent reason why a 'sudden' and 'unavoidable' 

equipment failure or process upset leading to emissions greater than the NSPS should be 

considered a violation of the standards if it is not 'infrequent,' even though it is 'not part of a 

recurring pattern indicative of inadequate design, operation, or maintenance' and '[c]ould not 

have been prevented through careful planning, proper design or better operation and maintenance 

practices.' See 60.5530(a)(1)(ii) and (iv)."

Commenter 9512 objected to the use of phrases that are subject to a wide range of 

interpretations:

 "How will the enforcement authority, or a judge, determine whether 'proper design' or 

'better operation and maintenance practices' could have prevented a malfunction (section 

60.5530(a)(1)(ii))

 "whether a recurring malfunction is a result of 'inadequate design' (section 

60.5530(a)(1)(iv)), 

 "whether repairs were made 'as expeditiously as possible' (section 60.5530(a)(2)), 

 "whether the source took 'all possible steps' to minimize the impact of the excess 

emissions (section 60.5530(a)(5)), and 
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 "whether emissions monitoring and control systems 'were kept in operation if at all 

possible' (section 60.5530(a)(6))?"

Commenter 9666 asked that the following changes be made:

 in sections 60.3350(a)(2) and (7), replace the term "violation" with "malfunction"

 in sections 60.3350(a)(3), (4), and (5), replace the term "violation" with "emissions"

Commenter 9666 asked that the following sections be clarified:

 In section 60.5530(a)(5), a source must prove that "all possible steps were taken to 

minimize..." 

 In section 60.5530(a)(8), the source must show that "at all times, the affected source was 

operated in a manner consistent with good practices..."

 In section 60.5530(a)(9), the source must submit a written report to the Administrator 

"with all necessary supporting documentation..."

For section 60.5530(a)(5), commenter 9666 stated that the affirmative defense is more "absolute 

and extreme" than the CAA. According to Commenter 9666, the CAA specified a level below 

which further reductions are not required (Sections 112(d) and (f).

For section 60.5530(a)(5), commenter 9666 also asked how this language differs from section 

60.5530(a)(3) which requires the frequency, amount, and duration of excess emissions "were 

minimized to the maximum extent practicable." Commenter 9666 asked that unless EPA 

"explains what additional showing would be needed by section 60.5530(a)(5), it should be 

removed from the rule.

For section 60.5530(a)(8), commenter 9666 noted that "affected source" is broader than "affected 

facility" as defined in 40 CFR 60.2. Commenter 9666 asked that EPA cite the statutory authority

that allows them "to shift the focus" of the NSPS from the "apparatus subject to the NSPS to the

plat as a whole." Commenter 9666 cited 40 CFR 60.74a(a)(8) was changed from "affected 

source" at proposal to "affected facility" at final.

For section 60.5530(a)(9), commenter 9666 states that it is "inefficient and burdensome for both 

sources and regulators, to require a complete justification of the affirmative defense before the 

enforcement authority has indicated any need for further investigation."

Commenter 10098 asked that EPA include a "procedure to address the affirmative defense 

through a declaratory judgment/settlement process" so that facilities can "obtain a measure of 

administrative certainty.

Response 13.2-4: Comments seeking specific clarification of, or revisions to, the proposed 

affirmative defense provision are no longer germane to this action. The EPA is not including a 
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regulatory affirmative defense provision in the final rule. See section X.A of the final rule 

preamble for the EPA’s response to these comments.

Comment 13.2-5: Multiple commenters (5537, 9512, 9666, and 10031) stated that the EPA must 

account for malfunctions when setting standards under section 111 and must include emissions 

attributable to malfunctions in the standards.

Commenter 5537 stated that "an affirmative defense to civil penalties for malfunctions is not 

appropriate under either a 12 operating month standard or a potential 84 operating month rolling 

average compliance option." Commenter 5537 noted "for equipment to 'malfunction' long 

enough to affect compliance with either a 12-month or 84-month standard suggests an 

extraordinarily long period of malfunctioning time, and could encourage poor operational 

practice."

Commenter 9512 noted that the standards are not achievable during malfunctions. Commenter 

9512 suggested that EPA "obtain and analyze [deviation reports or malfunction reports from 

state agencies], in order to assess what type of requirement might reasonably apply to the subject 

emission units during malfunctions.”

Commenter 9512 also asserted that the EPA has not provided a "factual analysis supporting its 

new conclusion that NSPS need not include the allowances for malfunctions that were included 

in dozens of NSPS issued over the past 40 years [Transactive Corp. v. United States, 91 F.3d 

232, 237 (D.C. Cir. 1996)] (agency must provide a 'reasoned analysis' to support departing from 

prior practice)." 

Commenter 9666 stated, "although the Sierra Club decision may draw into question the Agency's 

ability to exempt periods of malfunction for CAA section 111 standards, it did not authorize EPA 

to ignore malfunctions in the setting of achievable standards."

Commenter 9666 disagreed that an 84 operating month averaging period would be sufficient to 

compensate for emissions during a malfunction.

Commenter 9666 noted that EPA must address challenges to the achievability of the standard at 

the rulemaking stage [Duquesne Light Co. v. EPA, 698 F.2d 456, 469 n.14 (D.C. Cir. 1983).

Response 13.2-5: A number of commenters argued that providing an affirmative defense 

provision applicable to emissions during malfunctions was insufficient and that EPA is required 

to set standards of performance that either exempt emissions during malfunctions or incorporate 

emissions that occur during malfunctions as part of the numerical standard. In support of this 

premise, commenters relied on a series of court decisions that stand for the proposition that EPA 

must set reasonable emission limitations on sources (e.g., Portland Cement Ass’n v. 

Ruckleshaus, 486 F.2d 375 (D.C. Cir. 1973); Essex Chem. Corp. v. Ruckleshaus, 486 F.2d 427 

(D.C. Cir. 1973); and Nat’l Lime Ass’n v. EPA, 233 F.3d 625 (D.C. Cir. 2000)). According to 

the commenters, these decisions compel EPA to account for emissions during malfunctions in 

order to set “achievable” NSPS. EPA believes that these decisions are distinguishable on 

numerous grounds, not least of which is that they predate substantial revisions to the CAA in 
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1990, including revisions to sections of the statute that pertain to emissions limitations such as 

section 302(k). At bottom, however, these prior cases stand for the more general principle that 

EPA should set standards that are achievable by appropriately designed, operated and maintained 

sources, and do not suggest that is required to set standards that exempt emissions during 

malfunctions. As explained in detail in section X. A of the Preamble, nothing in section 111 or 

in case law requires EPA to consider malfunctions when determining what standards of 

performance reflect BSER and EPA does not consider it appropriate to do so given the facts in 

this action. EPA has promulgated standards that appropriately address variability for emissions 

from affected sources. In addition, EPA is not finalizing the proposed 84-operating-month 

compliance period option because the final standard of performance for newly constructed 

sources is less stringent than the proposed standard so that a protracted compliance period to 

provide for variable performance is unnecessary, and because, as discussed in section V of the 

final preamble, EPA is identifying alternative compliance pathways for new steam generating 

EGUs that also would not need such an extended comment period to account for variable 

performance. EPA specifically disagrees with commenters who argued that EPA has not 

provided an adequate explanation for why it has “departed from prior practice” and will not 

include “allowances” for emissions during malfunctions (i.e., exemptions like those previously 

provided in 40 CFR section 60.8(c)). As EPA explained in the proposal, recent decisions of the 

D.C. Circuit have indicated that emission limitations under the CAA must impose continuous 

controls and cannot contain exemptions for emissions during malfunctions. EPA explained the 

basis for its changed interpretation of the relevant statutory provisions in the proposal. EPA has 

authority to revise its prior interpretation of the CAA when further consideration indicates to 

EPA that its prior interpretation of the statute is incorrect. (See, e.g., White Stallion Energy

Center LLC v. EPA, 748 F.3d 1222, 1235 (D.C. Cir. 2014)). See section X.A of the Preamble 

for additional response to these comments.

Comment 13.2-6: Multiple commenters (9382, 9425, 9734, 9666, and 10023) asked that 

malfunctions be excluded from compliance calculations.

Commenter 9425 asked that the EPA "exempt emissions associated with malfunctions from 

being factored into the compliance calculation."

Commenter 9382 and 9734 noted that "Section 60.8 of the NSPS regulations provides that unless 

specified otherwise in an applicable standard, excess emissions during SSM period shall not be 

considered a violation of the applicable emission limit."

Response 13.2-6: EPA disagrees with commenters who argued that emissions during 

malfunctions should be excluded from compliance calculations. EPA acknowledges that 40 CFR 

section 60.8 provides that emissions during SSM events malfunctions shall not be considered a 

violation of the applicable emission limit, unless otherwise specified in the applicable standard. 

As explained in the proposed action, however, EPA interprets the reasoning of the court in the 

D.C. Circuit’s decision in Sierra Club v. EPA to apply to NSPS under section 111. The 

commenters advocate that emissions during SSM events be excluded from compliance 

calculations and treated as exempt. Such an approach is impermissible in light of the 

requirements of the CAA and the reasoning of the court in Sierra Club v. EPA concerning the 

statutory requirement for continuously applicable emission limitations. See also section X.A of 

the final rule preamble for the EPA’s response to these comments.
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Comment 13.2-7: Multiple commenters (9512, 9666, and 10100) suggested that work practice 

standards should apply during periods of malfunctions instead of the otherwise applicable 

standard of performance.

Commenters 9512 and 9666 noted that EPA has authority under CAA section 111(h) to 

promulgate a "design, equipment, work practice, or operational standard" where it is not feasible 

to set or enforce a numerical emission limit. 

Commenter 9512 also referred to the "flexibility accorded by CAA section 302(k)" to "address 

emissions during malfunction events through operational requirements, rather than by applying 

the same limits on pollutant concentrations in exhaust gases that apply during normal 

operations."

Commenter 10100 asked that the phrase, "[a]ll possible steps were taken to minimize the impact

of the violation on ambient air quality, the environment and human health. . ." be excluded from 

the work standards.

Response 13.2-7: EPA has authority under section 111(h)(1) to include a design, equipment, 

work practice, or operational standard, or a combination thereof, as part of a continuously

applicable emission standard where that is appropriate and consistent with section 111(h)(2). In 

this case, however, EPA has determined that it is not appropriate to create alternatives such as a 

work practice. In particular, EPA has determined that no such treatment is appropriate in the 

case of emissions that result from malfunctions. Even if the conditions of section 111(h)(2) were 

met, creation of a work practice for malfunctions presupposes that it is feasible to predict all 

possible forms of malfunctions and to devise a work practice that would adequately address 

emissions in a broad array of such events. By definition, malfunctions are neither predictable 

nor routine. By definition, they are sudden, infrequent, and not reasonably preventable failures 

of emissions control, process or monitoring equipment. Under these circumstances, EPA has 

concluded that excusing sources from the otherwise applicable emission standards during 

malfunctions is not the correct approach to imposing limits that will most effectively control 

emissions and provide incentive for compliance. Instead, EPA has concluded that it is feasible to 

prescribe and enforce a standard of performance that applies at all times, including during 

malfunctions. Given that compliance with the emission standard is determined on a 12-

operating-month rolling average basis, the impact of periods of malfunctions on the total average 

over a 12-operating-month period is expected to be minimal. The 12-operating-month rolling 

average period provides sources the ability to accommodate intermittent periods of minor 

malfunctions and small spikes in emissions. See section X.A for additional explanation for why 

EPA is not promulgating a work practice for emissions related to malfunctions.

Comment 13.2-8: Commenter 9512 stated that the EPA's explanation of the availability of the 

affirmative defense for violations due to excess emissions during malfunctions contradicted 

EPA’s explanation of the burdens of the affirmative defense in connection with the Paperwork 

Reduction Act. The commenter asserted that "Either EPA has offered an unrealistically low 

accounting of the paperwork burden of the affirmative defense, or it has claimed that the 

affirmative defense supports the rationality of the proposed CO2 NSPS when, in fact, the Agency

believes the affirmative defense will not play any role at all. Either way, the Proposed Rule does 
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not contain a rational statement of the basis for EPA's proposed action, rendering the proposal an 

inadequate solicitation of public comment and in violation of the Paperwork Reduction Act."

Response 13.2-8: EPA disagrees that its burden estimates for sources seeking to use the 

proposed affirmative defense were inconsistent with its proposed affirmative defense. As 

explained in the proposal, EPA intended the affirmative defense to be available to sources only 

in appropriate circumstances that met the applicable requirements. EPA’s interpretation of the 

CAA at the time of the proposal was that affirmative defense provisions were only consistent 

with statutory requirements if they were very narrowly drawn and limited to monetary penalties. 

In any event, the commenter’s concerns are irrelevant at this juncture because the EPA is not 

including a regulatory affirmative defense provision in the final rule. 

Comment 13.2-9 Multiple commenters (8964, 8969, 8970, 8973, 8995, 9318, 9512, 9514, 9666, 

9671, 9672, 9736, 10023, 10392, 10606, and 10876) stated that the proposed affirmative defense 

provisions are unlawful, indefensible, or contrary to section 111.

Multiple commenters (8964, 8969, 8970, 8973, 8995, 9318, 9671, 9672, 9736, 10392, and 

10876) stated that the provisions place the burden of proof on the unit owner/operator and 

therefore "will only add to the hesitancy that utilities already have regarding their willingness 

to [build] new units (thus potentially threatening system reliability) at this time."

Response 13.2-9: The EPA is not including a regulatory affirmative defense provision in the 

final rule. See section X.A of the final rule preamble for the EPA’s response to this comment.

Comment 13.2-10: Multiple commenters (9512, 9779, 10098, and 10554) asked that EPA 

include an affirmative defense provision for excess emissions during other modes of source 

operation..

Commenters (9512 and 10098) asked that an affirmative defense be available for excess 

emissions during startup and shutdown.

Commenter 10554 asked that the affirmative defense be expanded and that a new section be 

added that includes an affirmative defense against both "civil and criminal liability during an 

energy emergency as defined in CAA section 110(f) or when required to operate under an order 

of the Department of Energy (DOE) issued under the Federal Power Act (FPA) or when RTO 

may require the power for grid reliability reasons."

Commenter 9779 asked that the EPA add grid emergency as event for which there is an 

affirmative defense.

Response 13.2-10: The EPA is not including a regulatory affirmative defense provision in the 

final rule. See section X.A of the final rule preamble for the EPA’s response to this comment.

Comment 13.2-11: Commenter 7990 asked that the proposed affirmative defense be structured 

so that "an operator makes a prima facie demonstration that an unavoidable failure occurred, the 

burden of proof be shifted to EPA to show that the event was not a malfunction."
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Response 13.2-11: The EPA is not including a regulatory affirmative defense provision in the 

final rule. See section X.A of the final rule preamble for the EPA’s response to this comment.

Comment 13.2-12: Multiple commenters (9382, 9512, and 9734) stated that the requirements to 

satisfy the proposed affirmative defense provision are too stringent. 

Commenters 9382 and 9734 stated, "For instance, the rule could be interpreted as requiring 

sources to use off-shift and overtime labor to repair malfunctioning equipment in order to claim 

the defense. One of the conditions for the affirmative defense is that the affected source is 

operated in a manner consistent with good practices for minimizing emissions at all times. By

definition, malfunctions are not easily foreseeable problems that can be planned for in advance. 

The NSPS regulations define a malfunction as 'any sudden, infrequent, and not reasonably 

preventable failure of air pollution control equipment, process equipment, or a process to operate 

in a normal or usual manner.' Because unforeseen malfunctions often result in excess emissions, 

this requirement should be removed."

Commenter 9512 noted that the affirmative defense is "unreasonable and 

impracticable." Commenter 9512 stated that "Proposed section 60.5530(a)(4) would preclude a 

facility from taking advantage of the affirmative defense if the malfunction involved bypassing 

control equipment or a process and the bypass was not 'unavoidable to prevent loss of life, 

personal injury, or severe property damage.' Commenter 9512 stated that it may be "difficult or 

impossible for a source to demonstrate that it met this criterion, even though bypassing the 

control equipment or the process was an appropriate exercise of good air pollution control 

practices."

Commenter 9512 offered the following example, "a bypass can constitute the best air pollution 

control practice in response to an upset in order to prevent excess emissions, e.g., to avoid 

fouling of pollution control equipment media that in turn would result in reduced pollution 

control equipment efficiency or increased pollution control equipment downtime. There can be 

substantial room for disagreement about what constitutes 'severe' property damage. Also, what 

degree of injury to employees must the bypass avoid in order to qualify as avoiding 'severe' 

personal injury? Besides the unclear and subjective nature of these criteria, there is nothing 

inherent to standards of performance under CAA section 111 that requires a source to avoid 

bypassing control equipment to such a degree. Lastly, it is not apparent at all why the CAA 

would disfavor bypassing 'a process'-as opposed to pollution control equipment-in this way."

Response 13.2-12: The EPA is not including a regulatory affirmative defense provision in the 

final rule. See section X.A of the final rule preamble for the EPA’s response to this comment.

Comment 13.2-13: Commenter 9591 noted that the EPA only proposed the affirmative defense 

language under subpart TTTT and asked that the affirmative defense language be included under 

the GHG provisions as well.

Response 13.2-13: The EPA is not including a regulatory affirmative defense provision in the 

final rule. See section X.A of the final rule preamble for the EPA’s response to this comment.
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Comment 13.2-14: Commenters stated that the proposed standards would violate the 

Constitutional rights of affected sources because sources remain liable for violations due to 

excess emissions during malfunctions and the proposal only provided a limited affirmative 

defense applicable to monetary penalties for such violations. Commenters asserted that 

providing an affirmative defense was insufficient. Commenters further noted that the legal 

validity of any such affirmative defense had been called into question by the decision of the D.C. 

Circuit in the NRDC v. EPA case. 

Commenter 9666 stated that "the imposition of penalties for 'unavoidable' and, therefore 

innocent, conduct also would infringe on substantive due process principles under the Fifth 

Amendment” to the U.S. Constitution.

Two commenters (9666 and 10023) stated that the proposed rule would violate the Eighth 

Amendment to the U.S. Constitution because it would impose liability for emissions they

claimed are beyond the control of sources. Commenter 10023 stated that "Imposition of penalties 

for any conduct that is 'unavoidable' violates basic constitutional protections guaranteed by the 

Eighth Amendment and substantive due process. Commenter 9666 asserted that even with an 

affirmative defense, the proposed standards would violate the “Excessive Fines Clause and the 

Cruel and Unusual Punishments Clause” by potentially subjecting a source to penalties for 

“unavoidable” conduct. The commenter suggested that imposition of any penalties for violations 

due to “unavoidable” behavior per se “would not be proportional to the ‘offense’ committed.”

Response 13.2-14: EPA notes that the commenters objected to the proposed rule on the grounds 

that it included only an affirmative defense to liability for violations due to emissions during 

malfunctions and they argued that was insufficient to shield sources from liability for such 

conduct. As explained in section X.A of the Preamble, EPA is not including an affirmative 

defense provision in the final rule. Even without an affirmative defense provision, however, EPA 

does not agree with the premise of the commenters that the CAA requires EPA to provide 

sources with exemptions from liability for emissions during malfunctions or alternatively 

requires EPA to set emission limitations at levels that functionally exonerate all emissions during 

malfunctions in order to meet Constitutional requirements. As the commenters acknowledged, 

the court’s decision in Sierra Club v. EPA forecloses exemptions for emissions during 

malfunctions (or in their view, “calls into question” the legality of any such exemptions). EPA 

interprets section 111 to require continuous emissions limitations with no exemptions for 

emissions during any mode of source operation, including during malfunctions. Section 111 also 

does not require EPA to set standards that account for emissions during malfunctions. 

Accordingly, EPA is establishing standards that sources must meet on a continuous basis. As 

explained in Section X.A of the Preamble, EPA believes that the enforcement structure of the 

CAA already addresses the concerns of the commenters. EPA and other parties can exercise 

enforcement discretion in the event of violations due to malfunctions. Sources retain the ability

to raise any appropriate legal or equitable defenses in the event of an enforcement action. Courts 

have discretion to determine whether the conduct at issue should result in liability and, if so, the 

appropriate amount of penalty for a violation. The commenter’s arguments appear to be that any 

penalty assessed for a violation of an NSPS due to a malfunction would per se be excessive or 

constitute cruel and unusual punishment. The thrust of these comments suggests that the existing 

CAA enforcement provisions are facially unconstitutional. EPA disagrees. The CAA does not 

mandate that a penalty is automatically assessed for a violation. Rather, the CAA establishes a 
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maximum civil penalty in section 113(b) but then expressly provides in section 113(e) the 

criteria that EPA or the courts (as appropriate in administrative or judicial enforcement) “shall 

take into consideration (in addition to such other factors as justice may require).” These criteria 

explicitly include consideration of “good faith efforts to comply.” Thus, the CAA on its face 

does not mandate the imposition of any penalty automatically, much less one that is per se 

excessive. To the contrary, EPA believes that the existing provisions of the CAA assure due 

process consistent with the requirements of the 5th Amendment and preclude “excessive” or 

“cruel and unusual” penalties consistent with the 8th Amendment. In the event that a source feels 

that the penalties rise to such a level, they have the ability to appeal the penalties as has occurred 

in notable cases such as State Farm Mut. Auto Ins. Co v. Campbell (See, 538 U.S. 408 (2003)). 

Finally, EPA notes that this view of the enforcement provisions of the CAA is consistent with 

that expressed by the DC Circuit in the NRDC v. EPA decision, in which the court noted that the 

absence of an affirmative defense provision for violations due to malfunctions does not preclude 

sources from raising comparable facts and arguments in the context of an enforcement action, 

consistent with the provisions of sections 113 and 304.

13.3 STARTUP AND SHUTDOWN

Comment 13.3-1: Commenter 10619 agreed that emissions during startup and shutdown are 

negligible, "particularly averaged over a rolling 12-operating month period."

Response 13.3-1: The EPA agrees and acknowledges the commenter’s support.

Comment 13.3-2: Commenter 10392 noted that the EPA "fails to recognize the fact that unit 

operation is not always within the control of unit owners/operators due to the nature of today's 

competitive electricity markets, including operations in response to RTO-declared emergency

situations."

Response 13.3-2: Given that the duration of startup or shutdown periods is expected to be small 

relative to the duration of normal operation and that the fraction of power generated during 

periods of startup or shutdown is expected to be very small, the impact of periods of startup and 

shutdown on the total average over a 12-operating-month period is expected to be minimal. A 

new fossil fuel-fired steam generating EGU – if constructed – would, mostly likely, be built to 

serve base load power demand and would not be expected to routinely start-up or shutdown or 

ramp its capacity factor in order to follow load demand. Thus planned start-up and shutdown 

events would only be expected to occur a few times during the course of a 12-operating-month 

compliance period. Moreover, compliance on a 12-operating-month rolling average period basis 

provides sources the ability to accommodate startup and shutdown instances such as those 

pointed out by the commenter. 

Comment 13.3-3: Multiple commenters (8944, 8952, 9423, 9425, 9665, 9777, 9779, 10242, 

10554, 10606, and 10965) recommended that emissions during startup and shutdown be 

exempted from the standards in the rule.

Commenters 8944 and 8952 asked that the EPA exempt startup/shutdown and load operation 

below 50% of nameplate rated output or Original Equipment Manufacturer (OEM) rated output.
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Commenters 8944 and 8952 stated that an exemption from startup and shutdown will "support a 

rapidly growing installed base of non-dispatchable renewable generation."

Commenter 9423 asked that the EPA "withdraw or delay the adoption of the rule until an 

appropriate standard or method for evaluating compliance during SSRL [startup, shutdown, and 

reduced load] operation has been provided." 

Commenter 9425 noted that combustion turbines operate "essentially as a simple cycle machine" 

during startup and thus these periods should be exempt.

Commenter 9665 asked for an exemption from startup and shutdowns and also for part load 

operation below 75 percent of OEM rated output.

Commenter 9777 noted "EPA lacks sufficient data and understanding of how full-scale CCS 

units function to assess operations during startup and shut down."

Commenter 10242 noted that "the proposed standard for CO2 is in terms of lb/MWh which is not 

truly an appropriate metric during startup and shutdown."

Response 13.3-3: It is legally impermissible not to have some standard for startup and

shutdown conditions. See preamble section X.A and Sierra Club v. EPA, 551 F.3d 1019 (D.C. 

Cir. 2008) (under section 302(k) of the CAA, emissions standards or limitations must be 

continuous in nature and that the SSM exemption violates the CAA's requirement that some 

CAA section 112 standards apply continuously) Furthermore, separate startup and shutdown 

standards are inappropriate for coal-fired fossil fuel-fired units for the reasons stated in comment 

13.3.2 above.

Comment 13.3-4: Commenter 10606 asked that the EPA "establish an optional, alternate CO2

standard that is based on heat input" during startup and shutdown events.

Response 13.3-4: See response 13.3-2 above.

Comment 13.3-5: Multiple commenters (8964, 8969, 8970, 8995, 9194, 9318, 9396, 9425, 

9512, 9665, 9671, 9672, 9736, 9779, 9780, 10100, 10392, 10500, 10554, 10618, and 10876) 

asked that the EPA allow for work practice standards to minimize emissions during startup and 

shutdown periods.

Commenters 9425 and 9779 noted unintended consequences if the rule does not allow for work 

practices during startup and shutdown periods. 

Commenters 9425, 9779, and 9780 gave the following example, If an NGCC unit is requested by

an Independent System Operator to run on an intermittent basis with frequent startup and 

shutdowns, or even at low capacity factors, causing CO2 emissions to be high, it would put the 

unit at risk of not being in compliance with the NSPS. Rather than risk noncompliance, a utility

would be likely to "withhold a unit from the market, or only offer it into the market at times 

when the unit could be dispatched at high loads." Commenter 9425 and 9779 noted that such 

practices could distort electricity markets and increase consumer costs.
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Commenter 9512 stated, "EPA cannot, consistent with CAA sections 111 and 302(k), simply

ignore the possibility of using some type of work practice, etc. standard during SSM events."

Commenter 9512 noted that Section 111(h)(2) allows EPA to determine that it is "'not feasible to 

prescribe or enforce a standard of performance' because it is not feasible to capture the pollutant 

and emit it through a particular conveyance, or because it is not practicable to measure emissions 

'due to technological and economic limitations.'" 

Response 13.3-5: See response 13.3-2 above explaining why no separate startup and shutdown 

standard is necessary. In addition, commenters failed to explain their theory as to why a work 

practice would comply with section 111 (h)(2). The EPA knows of no credible basis for finding 

that is not economically or technically practicable to measure emissions during startup and 

shutdown, and it certainly is feasible to capture and measure CO2 emitted during startup and 

shutdown.

Comment 13.3-6: Multiple commenters (8973, 9512, 9665, and 10100) dispute the assumption 

that CO2 emissions during partial load are consistent with CO2 emissions during startup and 

shutdown.

Commenter 9665 noted that this assumption is flawed because "periods of startup and shutdown 

are demonstrably different from partial load periods. Partial load operation is limited to levels 

that achieve emission compliance for all criteria pollutants, including NOx and carbon monoxide 

(CO). When operating at part load, the plant equipment, including emission control equipment, is 

thermally soaked at operating temperature and combustion is within a stable steady state regime 

capable of maintaining rated emission performance. Start-up events, however, begin from a stand 

still, no load condition and include operation at loads below the emission compliant level. 

Further, the equipment is experience rapid temperature changes which induce additional transient 

factors contributing to the variability of start emissions while inducing thermal stresses and 

thermal soaking requirements to achieve full operating conditions."

Response 13.3-6: See sections V.J.1 and X.A. of the preamble.

Comment 13.3-7: Multiple commenters (7990, 8957, 9425, and 9512, and 10105) noted that the 

calculation of the standard must include emissions during startup and shutdown if startup and 

shutdown are not exempted from the standard. Commenters agreed that these emissions were 

understated in the EPA's analyses. Commenter 9512 recommended deferring promulgation until 

such data are obtained.

Commenter 8957 recommended that the EPA use a calculated value for the electrical load 

instead of dividing by zero during startup and shutdown events. Commenter 8957 stated, "a 

possible approach that EPA could use is to assume 100% of the useful thermal energy generated 

at startup and shutdown is converted into an electrical load value of MWh until the end of startup 

and shutdown."

Commenter 9425 stated, "failing to account for lower utilization rates and more frequent SS 

periods punishes NGCC units for the flexibility for which they are regularly designed and built. 
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EPA should increase the proposed NSPS standard for new units to accommodate actual usage 

and emissions data from the full range of NGCC unit operations."

Commenter 9512 noted several reasons why emissions data from startup and shutdown are not 

readily available:

 performance testing during SS are not allowed

 concentrations during SS may exceed the span of the monitor

 monitoring system QA/QC parameters may not be met during SS

Commenter 9512 recommended analyzing CO2 CEMS data specific to startup and shutdown 

events form multiple facilities and also study operational logs to ensure that the averaging period 

is sufficiently long so that typical startups and shutdowns would not cause the unit to be out of 

compliance.

Commenter 10105 noted that the proposed rule could deter renewable generation due to the 

increased number of startups and shutdowns inherent in accommodating renewable generation 

sources.

Response 13.3-7: See sections V.J.1 and X.A. of the preamble.