MEMORANDUM

Subject: Response to Public Comments on Proposed Standards of Performance for 

Stationary Compression Ignition Internal Combustion Engines 

From: Jaime Pagán, SPPD - Energy Strategies Group 

To: EPA Docket EPA-HQ-OAR-2005-0029 

On July 11, 2005, EPA proposed standards of performance for stationary compression 

ignition (CI) internal combustion engines (ICE) in 40 CFR part 60, subpart IIII. The 

purpose of this document is to present a summary of the public comments that EPA 

received on the proposed standards and the responses developed. This summary of 

comments and responses serves as the basis for revisions made to the standards between 

proposal and promulgation. 

EPA received 47 public comments on the proposed rule. A listing of all persons 

submitting comments, their affiliation, and the Document ID for their comments is 

presented in Table 1. The comments can be obtained online from the Federal Docket 

Management System at http://www.regulations.gov. The docket number for this 

rulemaking is EPA-HQ-OAR-2005-0029. In this document, commenters are identified 

by the last three digits of the Document ID of their comments. 

1
Table 1. List of Commenters on the Proposed Standards of Performance for Stationary 

Compression Ignition Internal Combustion Engines 

Document ID1 Commenter/Affiliation

EPA-HQ-OAR-2005-0029-0214 

Jon D. Beddington 

Senior Engineer/Supervisor 

Earthtech 

EPA-HQ-OAR-2005-0029-0217 

Stephanie R. Meadows 

Upstream Coordinator 

American Petroleum Institute 

EPA-HQ-OAR-2005-0029-0218 Gordon Gerber 

Caterpillar, Inc. 

EPA-HQ-OAR-2005-0029-02192 The Engine Manufacturers Association (EMA) 

EPA-HQ-OAR-2005-0029-0220 

Dr. Roger Saillant 

President and CEO 

Plug Power 

EPA-HQ-OAR-2005-0029-0223 Robert D. Haggard 

Washington Group International 

EPA-HQ-OAR-2005-0029-0224 

Stephen W. McCluer 

Project Engineer 

American Power Conversion Corporation 

EPA-HQ-OAR-2005-0029-0225 

Jerry D. Ogan 

Director Facilities Services & Safety Officer 

St. Francis 

EPA-HQ-OAR-2005-0029-0226 Miratech Corporation 

EPA-HQ-OAR-2005-0029-0227 

EPA-HQ-OAR-2005-0029-0228 

Andrew Wallo 

Director 

Department of Energy 

EPA-HQ-OAR-2005-0029-0229 

Robert Rosner 

Director 

Argonne National Laboratory 

EPA-HQ-OAR-2005-0029-0233 

Kurt Fredriksson 

Commissioner 

Alaska Department of Environmental Conservation 

EPA-HQ-OAR-2005-0029-0234 Alfred K. Bohn, PE 

HMH Consulting, LLC 

EPA-HQ-OAR-2005-0029-0235 The European Association of Internal Combustion Engine 

Manufacturers (EUROMOT) 

EPA-HQ-OAR-2005-0029-0236 

W. Thomas Schipper 

President 

American Society for Healthcare Engineering (ASHE) 

EPA-HQ-OAR-2005-0029-0237 Duplicate comment, see OAR-2005-0029-0236 

2
Document ID1 Commenter/Affiliation

EPA-HQ-OAR-2005-0029-0238 

James Ralston, P.E. 

Director, Bureau of Air Quality Planning Division of Air Resources 

New York State Department of Environmental Conservation 

EPA-HQ-OAR-2005-0029-0239 National Diesel Corporation 

EPA-HQ-OAR-2005-0029-0240 

Joseph L. Sucheki, Director, Public Affairs 

Timothy A. French, Legal Counsel 

The Engine Manufacturers Association (EMA) 

EPA-HQ-OAR-2005-0029-0241 

Kirk J. Thomson 

Director, Environmental Affairs 

The Boeing Company 

EPA-HQ-OAR-2005-0029-0242 

Phil Karris 

Vice President 

Energy Alternatives 

EPA-HQ-OAR-2005-0029-0243 

Environmental Defense – Dr. Jana Milford and Janea Scot 

Natural Resources Defense Council – Rick Kassel 

Izaak Walton League of America – Mr. William Grant 

American Lung Association of Metropolitan Chicago – Brian 

Urbaszewski 

Wyoming Outdoor Council – Bruce Pendery 

Galveston-Houston Association for Smog Prevention (GHASP) – 

John D. Wilson 

Southern Alliance for Clean Energy – Anne Gilliam 

San Juan Citizen Alliance – Dan Randolph 

EPA-HQ-OAR-2005-0029-0244 

Dale McKinnon 

Executive Director 

Manufacturers of Emission Controls Association 

EPA-HQ-OAR-2005-0029-0245 

Also supports comments of 240 

Richard A. Bishop 

Environmental Compliance John Deere Power Systems 

John Deere Product Engineering Center 

EPA-HQ-OAR-2005-0029-0246 Anonymous commenter 

EPA-HQ-OAR-2005-0029-0247 

John F. Kuterbach 

Manager 

State of Alaska Department of Environmental Conservation 

Division of Air Quality Air Permits Program 

EPA-HQ-OAR-2005-0029-0248 

John Whitney 

VP Engineering 

Clarke Fire Protection Products, Inc. 

EPA-HQ-OAR-2005-0029-0249 

Joe Jobe 

Executive Director 

National Biodiesel Board 

EPA-HQ-OAR-2005-0029-0250 

Valerie Ughetta 

Director of Stationary Sources 

Alliance of Automobile Manufacturers 

3
Document ID1 Commenter/Affiliation

EPA-HQ-OAR-2005-0029-0251 

Donald R. Schregardus 

Deputy Assistant Secretary of the Navy (Environment) Department 

of the Navy 

EPA-HQ-OAR-2005-0029-0252 Duplicate comment, see OAR-2005-0029-0242 

EPA-HQ-OAR-2005-0029-0253 

David Hansell 

Sr. Environmental Engineer, P.E. 

EM-Assist, Inc. 

EPA-HQ-OAR-2005-0029-0254 

Also supports comments of 264 

Aaron Kleinbaum 

Assistant General Counsel and Director of Environmental, Safety 

and Health 

William F. Lane 

Counsel 

Ingersoll-Rand Company 

EPA-HQ-OAR-2005-0029-0255 

Eric P. Yould 

Executive Director 

The Alaska Power Association (APA) 

EPA-HQ-OAR-2005-0029-0256 

Thomas R. Weeks 

Chief, Engineering 

San Diego Air Pollution Control District 

EPA-HQ-OAR-2005-0029-0257 Duplicate comment, see OAR-2005-0029-0256 

EPA-HQ-OAR-2005-0029-0258 

Bradley C. Thomas 

Sr. Environmental Engineer 

Alyeska Pipeline 

EPA-HQ-OAR-2005-0029-0259 

Stephanie R. Meadows 

Upstream Coordinator 

The American Petroleum Institute (API) 

EPA-HQ-OAR-2005-0029-0260 

Patti Krebs 

Executive Director 

The San Diego Industrial Environmental Association 

EPA-HQ-OAR-2005-0029-0261 

Lisa S. Beal 

Director, Environment and Construction Policy 

The Interstate Natural Gas Association of America (INGAA) 

EPA-HQ-OAR-2005-0029-0262 

Leonard N. Helms 

Air Program Manager 

Tetra Tech 

EPA-HQ-OAR-2005-0029-0263 

Daniel E. Donohue 

Chief, Emissions Assessment Branch, Stationary Source Division 

California Air Resources Board 

EPA-HQ-OAR-2005-0029-0264 

Also supports comments of 219 

Herb Whittall 

EGSA Technical Advisor 

The Electrical Generating Systems Association (EGSA) 

4
Document ID1 Commenter/Affiliation

EPA-HQ-OAR-2005-0029-0265 

William O’Sullivan, P.E. 

Director 

The State of New Jersey Department of Environmental Protection 

Air Quality Permitting Program 

EPA-HQ-OAR-2005-0029-0266 

Liz Moyer 

TI ESH Manager 

Texas Instruments Incorporated 

EPA-HQ-OAR-2005-0029-0267 Bryan Brendle 

The National Association of Manufacturers 

EPA-HQ-OAR-2005-0029-0268 Richard Huth 

National Diesel Corporation 

EPA-HQ-OAR-2005-0029-0269 Anonymous commenter 

EPA-HQ-OAR-2005-0029-0270 

(late public comment) 

Mason Griffin 

Director, Environmental Health and Safety 

Bell South 

EPA-HQ-OAR-2005-0029-0271 

(late public comment) Robert L. Greene, Ph.D. 

1

EPA-HQ-OAR-2005-0029-0215, 0216, 0221, 0222, 0230, 0231, and 0232 are non-comment items 

submitted to the docket. 

2

Comments submitted by EPA-HQ-OAR-2005-0029-0219 are included in EPA-HQ-OAR-2005-

0029-0240.

5
 Summary of Public Comments and Responses

The summary of public comments and responses is organized as follows: 

1.0 Applicability/Effective Date 

2.0 Modeling Mobile Source Program 

2.1 Foreign Strategy to Stationary Sources 

2.2 Size Threshold 

2.3 Useful Life 

2.4 Other 

3.0 Testing and Maintenance Restrictions for Emergency Engines 

4.0 Fuel Requirements 

4.1 General 

4.2 Alaska 

4.3 Engines with a Displacement of ≥30 Liters per Cylinder 

4.4 ULSD and Older Engines 

4.5 Add-on Controls 

5.0 Test Methods 

6.0 Flexibility/ABT 

7.0 Compliance 

7.1 Following Manufacturer’s Instructions 

7.2 Pre-2007 Model Year Engines and Engines that Conduct Performance 

Testing 

7.3 Load 

7.4 Engines with a Displacement of ≥30 Liters per Cylinder 

7.5 Startup, Shutdown, and Malfunction 

8.0 Add-on Controls 

9.0 Research and Development 

10.0 Definitions 

10.1 Emergency 

10.2 Stationary Internal Combustion Engine 

11.0 Rule Structure 

12.0 Labeling 

13.0 Recordkeeping and Reporting 

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13.1 Certification Records 

13.2 Hour Meter and Other Compliance Requirements for Emergency Engines 

13.3 Notifications 

14.0 Fire Pumps 

15.0 Prior Tier Certification Requirements 

16.0 Emission Standards 

16.1 Emergency Engines 

16.2 Engines >750 hp 

16.3 Engines <75 hp 

16.4 Engines with a Displacement of <30 Liters per Cylinder 

16.5 Engines with a Displacement of ≥30 Liters per Cylinder 

17.0 Peak Shaving 

18.0 Need for Regulation 

19.0 Costs 

20.0 Health/Environmental Impacts 

21.0 Other 

21.1 Public Comment Period Extension 

21.2 Corrections Needed 

21.3 Format of Standards 

21.4 Military Training Engines 

21.5 Replacement Engines 

21.6 Temporary Engines 

21.7 Adjustments 

21.8 Biodiesel 

21.9 Dual-Fuel 

21.10 SI NSPS 

21.11 Test Cells 

1.0 Applicability/Effective Date 

1.1 Comment: One commenter (240) said that EPA is proposing to impose regulatory 

requirements on pre-2007 model year (MY) engines as of April 1, 2006, a date that is 

expected to precede the publication of the final rule. This undermines and is inconsistent 

with the notice and comment requirements of the Administrative Procedures Act, as well 

7
as the Clean Air Act (CAA) section 111(b)(1)(B). Rule requirements before the 

finalization of the New Source Performance Standards (NSPS) are inherently 

problematic. The commenter stated that by imposing regulatory requirements on engine 

manufacturers, entities that centrally produce products at manufacturing facilities that are 

separate and distinct from where such engines may later be installed and operated, EPA 

has acted in contravention of manufacturers’ fundamental rights to administrative due 

process. The commenter specifically objected to the violation of the notice and comment 

requirements of Federal law that is inherent in the proposal. 

Response: EPA worked with industry and the commenter, Engine Manufacturers 

Association (EMA), was directly involved in the rulemaking process. Regarding the 

comment that requirements begin as of April 1, 2006, the rule will not be effective until 

after it is published in the Federal Register. Manufacturers and others have had a full 

opportunity for notice and comment. It is true that certain requirements will apply to 

engines manufactured prior to the publication date. This is fully consistent with the 

specifications in section 111(b)(1)(B), which requires EPA to promulgate standards of 

performance for new sources in listed categories of stationary sources, and section 

111(a)(2), which defines “new source” to mean “any stationary source, the construction 

or modification of which is commenced after the publication of regulations (or, if earlier, 

proposed regulations), prescribing a standard of performance under this section which 

will be applicable to such source.” [emphasis added]. There can be no question that an 

engine manufactured after April 1, 2006, was constructed or modified after the 

publication of the proposed regulations, which were published on July 11, 2005. 

8
Moreover, the requirements for engines manufactured prior to the 2007 MY do not even 

apply to manufacturers, but apply solely to owners and operators, who can meet such 

requirements either through purchase of an engine that meets the requirements or through 

actions taken when placing the engine into service. EPA also met with EMA several 

times prior to proposal and EPA was informed by EMA that the standards that would be 

proposed for pre-MY 2007 engines were feasible in the timeframe provided. 

 Regarding the comment that EPA has acted in contravention of manufacturers’ 

due process rights, EPA disagrees. First, as noted above, no entity is subject to the 

regulations until after publication of the final rule and manufacturers in particular are not 

subject until the 2007 MY. It is not clear how manufacturers were not afforded due 

process or how the proposal violated notice and comment requirements. EPA allowed for 

full notice and comment and EMA in particular was provided numerous opportunities to 

provide input into the rulemaking process. Nor does EMA provide any justification for 

stating that by imposing requirements on manufacturers, we have violated their rights to 

due process. Manufacturers have been regulated for many years under various EPA 

requirements and there is no question they are subject to regulation under the CAA. 

EMA does not claim that section 111 prevents regulation of manufacturers. As EPA 

noted in the proposal, section 111 provides broad authority for EPA to promulgate new 

source performance standards and EPA believes that applying such standards to engine 

manufacturers is reasonable in this instance. Indeed, EMA has expressed on several 

occasions that it is in general agreement with EPA that it is appropriate to regulate new 

stationary CI engines by adopting similar requirements that apply to nonroad mobile 

source engines through a certification program. EMA has stated that this ensures 

9
technologically feasible and cost-effective emissions reductions from stationary CI 

engines. EPA believes it is appropriate to impose regulatory requirements on engine 

manufacturers and also thinks that this is technologically feasible and provides the most 

cost-effective approach for reducing emissions from stationary CI engines. As stated in 

the proposal, a large majority of stationary CI engines are consumer products produced in 

mass quantities. EPA believes that the knowledge gained by manufacturers through a 

certification program for nonroad CI engines can be applied to implement an equally 

successful program for stationary CI engines. This also reduces burden on the individual 

owner and operator. 

1.2 Comment: One commenter (258) expressed that the applicability of the rule to 

engines manufactured before 2007, but permanently installed in a facility between July 

11, 2005 and 2007 is unclear. The commenter asked what is the practical (or emission 

limitation) significance of the date July 11, 2005. It seems the rule has no requirements 

for engines installed, modified, or reconstructed between July 11, 2005 and April 1, 2006, 

according to the commenter. The commenter further noted that it is true that the rule will 

require engines modified or reconstructed after July 11, 2005 to comply with emission 

standards applicable to new engines of the same MY, but the substance of this 

requirement is not clear. The commenter could find no emission standards in the rule for 

engines of MY preceding April 1, 2006. The commenter requested that the rule be 

clarified in this regard or, perhaps explicitly simplified to require nothing of engines 

manufactured prior to April 1, 2006. 

10
Response: The rule applies to owners and operators of engines that are modified or 

reconstructed after the date the rule was proposed, i.e., July 11, 2005. Therefore, the rule 

does have requirements for engines modified or reconstructed between July 11, 2005 and 

April 1, 2006. The rule applies to owners and operators of new engines that are 

constructed after July 11, 2005, but not if the new engines were manufactured prior to 

April 1, 2006. Therefore, it is true that the rule has no requirements for engines that are 

constructed between July 11, 2005 and April 1, 2006. The significance of the date July 

11, 2005 determines when modified and reconstructed engines become subject to the 

rule. Engines that are modified or reconstructed must meet the emission standards for the 

MY in which the engine was manufactured. For example, if a 1999 MY engine is 

modified or reconstructed after July 11, 2005, this engine would have to meet the 

emission standards that would apply to the 1999 MY engines under this rule, i.e., the pre2007 MY emission standards in table 1 of the proposed rule. EPA agrees with the 

commenter that it would be appropriate to clarify the applicability of the rule and has 

made this clarification in the final rule. 

1.3 Comment: Two commenters (234, 258) said that the word “install” is not specifically 

defined in §60.4216 of the proposed rule. Commenter 234 said that the word “install” in 

§60.4208 of the proposed rule should be replaced by the more accurate term “commenced 

construction” consistent with the regulatory definition in 40 CFR 60.2 and 40 CFR 

52.21(8) and (9) and that this will eliminate any ambiguities for regulatory agencies and 

owners/operators.

11
Response: EPA does not believe it is appropriate to use the term “commenced 

construction” instead of “install” in §60.4208 of the rule, and has retained the term 

“install” in the final rule. The purpose of this provision is to ensure that older engines 

meeting less stringent standards are no longer installed by owners and operators after a 

reasonable period of time has elapsed once engine manufacturers begin making cleaner 

engines. In §60.4208 of the final rule, EPA is providing up to 24 months for owners and 

operators to install stationary engines produced in a previous model year that do not meet 

the applicable requirements for that particular model year (see comment 1.4). 

Commencing construction has been defined in the General Provisions to include 

commencing a contract to build, which would cause the requirements of this section to be 

delayed even further, and would also be more difficult to enforce. For that reason, EPA 

believes it is more appropriate to use the term “install” rather than “commenced 

construction.” We believe 24 months is enough time for an owner or operator to install 

an engine that is not a clean as engines being manufactured at that time. For the purposes 

of this rule, the term “install” refers to the date the engine is installed at the operator site. 

EPA believes that using the term “install” is clear to owners and operators complying 

with the rule and eliminates confusion with respect to the General Provisions. 

1.4 Comment: One commenter (240) expressed that the 6-month installation date 

deadlines in §60.4208 of the proposed rule are problematic and unworkable. The period 

of time between the manufacture of a stationary CI engine and its installation is regularly 

in excess of 6 months. The NSPS should incorporate the relevant anti-stockpiling from 

the nonroad rule (40 CFR 89.1003(b)(4)) instead. 

12
Another commenter (248) said that §60.4208(a) of the proposed rule does not exclude 

fire pumps (emergency CI ICE), but §60.4208(c) through (f) of the proposed rule does. 

A 6-month time limitation will become problematic, the commenter said. Due to 

construction project complexities, size and delays, National Fire Protection Association 

(NFPA) certified fire pump engines may not be installed for as long as 1 year after the 

date of sale by the NFPA certifier. The NFPA certified fire pump engines are typically 

not purchased for inventory, and therefore, are self regulated by the date of manufacturer. 

The commenter stated that fire pump engines should be exempt from this fixed time 

restriction. 

Response: EPA agrees with the commenters that the 6-month deadline for installing 

engines of a previous tier is not long enough to allow for the time that typically can 

elapse between order and installation of an engine and may prevent engine manufacturers 

from using up existing inventories of engines. Therefore, EPA increased the time limit to 

24 months after the beginning of the calendar year coinciding with the applicable MY. 

EPA has also included anti-stockpiling provisions similar to those used for nonroad 

engines to prohibit stockpiling of previous tier engines in the final rule. Also, EPA was 

concerned about imports of non-compliant stationary CI engines and has made it clear in 

§60.4208 of the final rule that the limitations of that section apply to imports of engines 

with a displacement of less than 30 liters per cylinder also. Engines with a displacement 

greater than or equal to 30 liters per cylinder are not included in this provision since 

compliance with the emission standards for those engines can only be demonstrated 

13
through on-site stack testing. Finally, EPA has exempted stationary emergency fire pump 

engines from the deadlines in §60.4208(a) and (b) of the final rule to account for the fact 

that fire pumps have different timing requirements for the emission standards they have 

to meet. 

1.5 Comment: One commenter (258) said that it maintains several engines for use at 

various locations. It is conceivable that the commenter may opt to permanently install 

one of these engines at one of its facilities in the future. The rule would seem to prohibit 

this, even though the engine was in the company’s possession long before the rule was 

drafted. One reason for concluding this is that §60.4208(a) of the proposed rule states 

that “owners and operators may not install pre-2007 MY stationary CI ICE after June 30, 

2007.” The commenter could find no explanation for this and stated that such a ban is 

excessively restrictive. The commenter requested that the rule allow flexibility for 

owners/operators to install engines it already owns even after 2007. If EPA is opposed, 

the commenter asked that EPA please provide an explanation in the final rule preamble. 

Response: EPA contacted the commenter for clarification on this comment. The 

commenter indicated that it has nonroad engines that may remain in one location for 

more than 1 year, in which case these engines would be considered stationary engines. 

The commenter was referring to engines it already possesses and uses. It appears that 

this commenter misunderstood the provisions in §60.4208 of the proposed rule and was 

under the impression that those provisions would apply to any pre-2007 MY engine, not 

just pre-2007 MY engines that are subject to the rule, i.e., new engines that are 

14
manufactured after April 1, 2006 and engines that are modified or reconstructed after July 

11, 2005. If the engine in question is manufactured prior to April 1, 2006, it would not be 

subject to the rule and subsequently not subject to the requirements in §60.4208 of the 

proposed rule unless it is modified or reconstructed. Moreover, §60.4208(g) explicitly 

exempts modified and reconstructed engines from the requirements of that section. 

Additionally, it was not EPA’s intention to apply the restrictions in §60.4208 to engines 

that had been previously used and reinstalled in a different location. EPA has clarified 

this issue in the preamble and regulations in the final rule. 

1.6 Comment: One commenter (258) requested clarification on what is meant in all 

references to “pre-2007” or “pre-2008,” etc., in the proposed rule. Given the bans in 

§60.4208 of the proposed rule, the commenter requested that EPA specify how this 

paragraph and any other similar paragraphs would even apply after June 30, 2007. 

Response: A “pre-2008” MY engine is an engine that has a MY of 2007 or earlier. 

Similarly, a “pre-2007” MY engine is any engine that has a MY of 2006 or earlier. EPA 

feels that this is clear in the rule and no further clarification is necessary. The rule applies 

to pre-2007 MY engines that are manufactured after to April 1, 2006 or modified or 

reconstructed after July 11, 2005. 

1.7 Comment: One commenter (238) was of the opinion that the deadlines for 

purchasing engines produced in a previous MY may be too restrictive and counterproductive. If an engine from a previous MY is in compliance with the limits for the 

15
current MY engines, with or without post-combustion control, there is no reason to ban 

the purchase of such engine. If the limits are based upon the date operation commences 

(the approach proposed in a distributed generation rule being developed by the New York 

Department of Environmental Conservation (NY DEC) (6 NYCRR part 222) anticipated 

to take effect on May 1, 2006), §60.4208 of the proposed rule would be unnecessary. 

Response: EPA believes that it is appropriate to base the limits on the MY of the engine. 

This is consistent with the approach used for nonroad engines and helps to make the 

process for certifying stationary engines easier for engine manufacturers, since many 

engines are used for both stationary and nonroad applications. The proposed limits on 

purchasing and installing previous MY engines were limited to specific situations when 

new emission standards would come into effect in the new MY. As discussed above, 

EPA is revising the language in §60.4208 to provide more time for owner/operators to 

install older engines and to prohibit manufacturers from stockpiling older engines when a 

new set of emission standards is coming into effect. EPA agrees with the commenter that 

if an engine from a previous MY is in compliance with the limits for the current MY 

engines it can be installed. EPA has modified the language in the final rule to 

accommodate this. 

1.8 Comment: One commenter (264) was concerned with the inadequate lead time that 

the proposed NSPS affords nonvertically integrated equipment manufacturers. In the 

commenter’s experience, it takes a minimum of 18 months from the time an equipment 

manufacturer receives a prototype engine to incorporate the engine into a final 

16
marketable product. The commenter noted that in the nonroad rules, EPA has provided 

flexibility provisions that ease the transition for equipment manufacturers when new 

emission standards take effect. However, the proposed NSPS does not include any 

flexibility for equipment manufacturers. The commenter believed that the NSPS 

standards should take effect 18 months after promulgation of the final NSPS or 18 

months after the effective date of the corresponding nonroad standards, whichever is 

later. 

Response: The regulations for stationary CI engines do not apply to equipment 

manufacturers directly. The only possible effect is on owners and operators downstream. 

However, the emission standards are directed to MYs, which are determined at the time 

of engine manufacture, so any lag time is irrelevant. The only exception is in §60.4208 

of the final rule, where EPA has provided additional time. The commenter refers to 

prototype engines. Prototypes are usually developed well before an engine is actually 

manufactured. The important criterion is the MY of the engine, not when the prototype is 

built. Regarding the comment about lead time, the initial standards for stationary CI 

engines are less stringent than current nonroad standards for CI engines and do not apply 

to engine manufacturers, but to owners and operators. The standards that begin with 

2007 MY engines are applicable to engines beginning approximately 18 months after the 

regulations were initially proposed and are identical to (or less stringent than) standards 

for comparable nonroad engines and equipment. Consequently, equipment 

manufacturers have been provided considerable lead time to design equipment 

compatible with the certified engines. Again, however, EPA is not putting any 

17
requirements on equipment manufacturers, so they are under no time constraints except 

the one that apply to their suppliers and customers. These constraints contain sufficient 

lead time and flexibility to deal with lag time between design of engine prototypes and 

manufacture of equipment. The issue of incorporating the equipment flexibilities in the 

nonroad engine regulations is discussed in response to comment 6.2, which concludes 

that EPA believes that equipment manufacturers do not need those flexibilities in this rule 

because they are not regulated by this rule. 

1.9 Comment: One commenter (265) recommended that the NSPS regulate any nonemergency generator sets greater than 50 horsepower (hp). Distributed generation is 

becoming more common, and proliferation of small high emitting electric generators that 

are used in non-emergency situations should be avoided, the commenter said. 

Response: EPA is regulating all new stationary engines, whether greater or less than 50 

hp, and whether emergency or non-emergency. 

1.10 Comment: One commenter (247) requested that the rule exempt area sources from 

the requirement to have a title V permit solely because of the presence of an affected 

engine. 

Response: Section 502(a) of the CAA specifies the sources that are required to obtain 

operating permits under title V. These sources include (1) any affected source subject to 

the acid deposition provisions of title IV of the CAA, (2) any major source, (3) any 

18
source required to have a permit under parts C or D of title I of the CAA, (4) “any other 

source (including an area source) subject to standards under section 111 (new source 

performance standards) or 112 (national emissions standards for hazardous air 

pollutants),” and (5) any other stationary source in a category designated by regulations 

promulgated by the Administrator. 

 Section 502(a) of the CAA also provides that the Administrator may “promulgate 

regulations to exempt one or more source categories (in whole or in part) from the 

requirements of this subsection if the Administrator finds that compliance with such 

requirements is impracticable, infeasible, or unnecessarily burdensome on such 

categories, except that the Administrator may not exempt any major source from such 

requirements.” EPA has exempted many area sources subject to section 111 or 112 

standards from title V requirements in prior rulemakings, in particular see a recent final 

rule, 70 FR 75320, December 19, 2005, that provides additional background information 

and rationale for such exemptions for a large number of area sources subject to CAA 

section 112 standards. 

 In the case of affected stationary CI engines located at area sources, EPA believes 

compliance with permit requirements under title V would be impracticable, infeasible and 

unnecessarily burdensome for the reasons explained below. 

First, title V permits would be unnecessarily burdensome for area sources subject 

to this final rule because title V would not result in significant improvements to 

compliance with the CAA section 111(b) standard for the area sources. (The term “title 

V permits” used here refers to permits issued under 40 CFR parts 70 or 71 by either a 

State or local agency or EPA.) For a great number of these area sources, these engines 

19
are the only emission source and the owner/operator (often a hospital or a school) will not 

be at all familiar with the requirements for permits. To demonstrate compliance with 

these section 111(b) standards, the final rule requires the owner or operator of the area 

source to purchase a certified stationary CI engine. Certification that the engine meets 

the emission reduction requirements of this final rule is done by the manufacturer of the 

engine, rather than the area source that owns or operates the engine. This strategy places 

a significant amount of responsibility for compliance with the standard on the 

manufacturer, compared to many other emission standards that place the compliance 

responsibility on the owner or operator. EPA believes this strategy is the most effective 

way to ensure that the standard is met during the useful life of the engine. Also, title V 

would not result in significant improvements to compliance with the standard for these 

area sources because the section 111(b) standard itself contains adequate compliance 

requirements for these area sources, consistent with the CAA, without relying on title V. 

Second, title V would impose certain burdens and costs on area sources subject to 

this final rule that EPA does not believe are justified when compared to the potential for 

title V permits to improve compliance with the CAA section 111(b) standards for such 

sources. This is so because EPA believes the costs and burdens of title V permits for the 

typical area sources subject to this final rule would be significant. This assessment is not 

based on any particular empirical data or study but on a review of the types of standalone area sources that would be subject to this final rule, for example, small farming 

operations using diesel engines for irrigation purposes and small businesses and 

residential homeowners using diesel engines for back-up electrical power generation. 

(See current ICR for 40 CFR part 70, EPA ICR # 1587.06 and OMB control number 

20
2060-0243 for EPA’s best estimate of the burdens and costs of title V for sources subject 

to 40 CFR part 70 on a national, aggregate basis.) Also, as explained above, EPA’s 

judgment is that requiring operating permits for these area sources would not result in 

significant improvements to compliance over that already required by this final rule. 

Thus, the burdens and cost of title V permits for these area sources would be significant, 

and in any case, they will be unnecessary and not justified, when compared to the low 

potential for title V permits to improve compliance, consistent with the “unnecessarily 

burdensome” criterion of section 502(a) of the CAA. 

The strategy of this final rule, requiring the manufacture of cleaner burning 

emission sources (manufacturer-based controls), has been employed in other CAA 

section 111 standards, for example, the NSPS for new residential woodstoves (subpart 

AAA of 40 CFR part 60). We exempted area sources subject to the woodstove NSPS in 

the final rule for 40 CFR part 70 (57 FR 32250, July 21, 1992) for reasons similar to 

those we describe today for stationary CI IC engines. (40 CFR 70.3(b)(4) and 40 CFR 

71.3(b)(4).) 

 Thus, we have decided to exempt area sources subject to this final rule from title 

V operating permit requirements under 40 CFR part 70 and 40 CFR part 71, and we have 

changed the applicability language in the final regulations to specify this. Under this 

approach, title V exemptions are allowed for an area source, provided the area source is 

not required to obtain a permit under 40 CFR 70.3(a) or 40 CFR 71.3(a) for another 

reason, such as when the source becomes a major source. Also note that this exemption 

only affects whether an area source is required to obtain an operating permit, it has no 

bearing on any other requirements of this final rule. 

21
2.0 Modeling Mobile Source Program 

2.1 Applying Strategy to Stationary Sources 

2.1.1 Comment: One commenter (240) stated that it supports the alignment of nonemergency stationary CI engine standards with the corresponding nonroad and marine CI 

engine standards. As a general matter, the commenter supports and agrees with the 

emission standards and effective dates set forth in the proposal. Those proposed 

standards appropriately recognize that non-emergency stationary CI engines are derived 

from corresponding nonroad or marine CI engines, depending on their power ratings and 

displacement. The commenter also expressed support for the proposal’s recognition of 

the relevant differences between the use and emissions capabilities of non-emergency 

engines, on the one hand, and emergency engines and fire pump engines, on the other. 

Accordingly, the commenter also endorses those elements of the proposal that will: 

(i) align the emission standards for 2007 MY and later non-emergency stationary 

CI engines less than or equal to 3,000 hp and a displacement less than 10 liters per 

cylinder (l/cyl) with the Tier 2 through Tier 4 nonroad diesel engine standards; 

(ii) align the emission standards for 2011 MY and later non-emergency stationary 

CI engines greater than 3,000 hp and a displacement less than 10 l/cyl with the 

Tier 4 nonroad diesel engine standards; 

22
(iii) align the emission standards for pre-2007 MY stationary CI engines with a 

displacement less than 10 l/cyl with the Tier 1 nonroad diesel engine standards; 

(iv) align the emission standards for 2007-2010 MY non-emergency stationary CI 

engines greater than 3,000 hp and a displacement less than 10 l/cyl with the Tier 1 

nonroad diesel engine standards; 

(v) align the emission standards for 2007 MY and later non-emergency stationary 

CI engines having a displacement greater than or equal to 10 l/cyl and less than 30 

l/cyl with emission standards applicable to new marine CI engines; and 

(vi) ensure that emergency stationary CI engines are not subject to emission 

standards (e.g., Tier 4-type standards) that would necessitate the installation and 

use of emissions aftertreatment systems. 

The commenter stated that each of the foregoing elements of the proposal is a vital 

component of any rulemaking pertaining to stationary CI engines. Engine manufacturers 

do not separately design and produce non-emergency CI engines for stationary 

applications. Instead, non-emergency stationary CI engines are derived from CI engines 

that are designed and manufactured to comply with the relevant nonroad and marine CI 

engine emission requirements that EPA has established. The net result is that a nonemergency stationary CI engine is, in essence, nothing more than either a nonroad CI 

engine or a marine CI engine that is installed and operated in a stationary application. 

23
Because of this fundamental aspect of the non-emergency stationary CI engine industry, 

the relevant benchmarks for the “best demonstrated technology” must be the emission 

standards that EPA has determined as setting the benchmarks of technological feasibility 

for nonroad and marine CI engines within the relevant range of power ratings and 

displacements. The commenter stated that the proposal is, at its core, guided by this basic 

principle, and so it is, at its core, a well-reasoned and sound rulemaking proposal. 

Response: EPA generally agrees with the comments provided and has continued to align 

the standards in the final rule with nonroad CI engine standards, as appropriate. 

2.1.2 Comment: Two commenters (259, 261) stated that the proposed standard layers 

mobile source requirements with similar 40 CFR part 60 requirements. These mobile 

legacy provisions, such as the General Provisions and testing requirements for nonroad 

engines, are foreign to stationary source operators. Two commenters (259, 260) said that 

a rule modeled after mobile standards is unnecessarily complex and includes 

requirements that are inconsistent with the legacy of stationary sources affected under 40 

CFR part 60. One commenter (261) was concerned that an array of unforeseen 

implementation issues could arise in translating the mobile source criteria to stationary 

sources. 

One commenter (238) said that the limits are based upon the engine MY and could lead 

to confusion. Limits for stationary sources have in the past been based upon the date of 

construction or operation. Two adjacent facilities may install identical engines 

24
manufactured by different companies and are of different MYs. These engines could be 

subject to different limits. The facility that is subject to the more stringent limits may 

challenge the fairness of the limits and the cost to comply with the more stringent limits. 

This can be avoided by establishing limits based upon the date a source commences 

operation. The commenter added that compliance with NSPS limits is primarily based 

upon manufacturer guarantees. This is a new regulatory strategy for stationary sources. 

The NY DEC issues permits to facility owners/operators, which are contracts whereby 

the permittee agrees to comply with all applicable provisions. Manufacturers are not 

parties to permits issued by the NY DEC. Any violation of a permit condition is, 

therefore, the responsibility of the permittee. Any enforcement action initiated by the NY 

DEC would be against the permittee, not the manufacturer. The NY DEC’s distributed 

generation rule (6 NYCRR part 222) is structured in this way. If an engine is not in 

compliance with the limits, the owner/operator may have legal recourse against the 

manufacturer depending upon the conditions of a warranty. The NY DEC, not being a 

party to a warranty, would not have legal recourse against the manufacturer. This 

commenter recommended that the owner/operator be responsible for compliance with 

emission limits under the NSPS. 

Response: EPA disagrees with these commenters on certain issues. EPA agrees that 

aligning the NSPS with mobile standards and placing significant responsibility with 

manufacturer is somewhat unusual, but it is not an unprecedented regulatory strategy for 

stationary sources (40 CFR part 60, subpart AAA, Standards of Performance for New 

Residential Wood Heaters). EPA has determined that it is appropriate to develop a 

25
regulatory strategy for internal combustion engines that is generally directed towards 

engine manufacturers. EPA recognizes that the proposed approach is different than the 

strategy typically followed in NSPS rulemaking for stationary sources, which is often 

aimed at the owners and operators of stationary sources. However, EPA has worked with 

engine manufacturers throughout the rule development process, and it was determined 

that developing a rule that will affect engines at the manufacturing level, will achieve the 

best system of emission reduction while taking into account the cost of achieving such 

reductions. The certification of nonroad diesel engines is a well-established program that 

engine manufacturers are familiar with. Engine manufacturers have indicated that they 

often design and manufacture the same engines for nonroad use as for stationary use. As 

mentioned in the preamble to the proposed rule, the vast majority of stationary CI engines 

are consumer products produced in mass quantities. Internal combustion engines have 

traditionally been regulated through the manufacturer for purposes of meeting mobile 

source regulations. Manufacturers have extensive experience with complying with such 

standards. It is also simpler, more reliable, and comparatively inexpensive to regulate 

stationary CI engines employing the same approach as for mobile sources than to create a 

new approach based on testing by every owner and operator. 

 Moreover, EPA believes this method of regulation will be much easier for owners 

and operators (represented by the commenters) than a set of regulations aimed primarily 

at owners and operators. The commenters note that the proposed standards layer mobile 

source requirements on 40 CFR part 60 requirements, but EPA’s mobile source 

regulations are directed towards manufacturers, so they will not substantially affect 

owners and operators. In general, owners and operators will be required to purchase 

26
certified engines, which are likely to be the only new engines available, since 

manufacturers will not be able to sell uncertified engines. This would seem to be 

preferable from an owner/operator’s perspective than having to individually test all of its 

new engines initially and periodically thereafter to show compliance with the standards, 

and to engage in all of the other compliance procedures normally required for stationary 

sources. While EPA acknowledges that this approach is one with which stationary source 

owners and operators may not be accustomed, EPA believes that this approach will 

provide less burden to owners and operators than a more standard NSPS approach. 

Regarding the comments from NY DEC, EPA believes that because the owner/operator 

will be purchasing certified engines, it will know prior to purchase and installation the 

emission limits and costs for the engine. A manufacturer would not be selling identical 

engines for different model years unless the engine met the standards for both model 

years, so there would be no increased cost for the user. Unlike in other regulations, the 

emission-related costs are known from the outset, because they are inherent in the cost of 

the certified engine. The NSPS should have no effect on the manner in which NY DEC 

ensures compliance with its distributed generation rule. However, as discussed below, 

owners and operators do have responsibilities under the NSPS, compliance with which 

can be readily determined. EPA agrees that it would be appropriate to specify what parts 

of the General Provisions apply to engines subject to subpart IIII of 40 CFR part 60. In 

the final rule, EPA has included a table listing which General Provisions from 40 CFR 

part 60, subpart A, apply to stationary CI engines subject to this subpart. 

2.2 Size Threshold 

27
2.2.1 Comment: Three commenters (259, 260, 261) said that the rule proposes regulation 

of equipment much smaller than typical for 40 CFR part 60 standards. Two of these 

commenters (259, 261) were of the opinion that other than for manufacturer certification, 

engines 500 hp or less should be exempted and a size threshold should be added. 

Commenter 259 said that the rule, as proposed, regulates all stationary CI engines 

regardless of size, which is inconsistent with established NSPS. Rationale must be 

provided for including smaller units and EPA must state its regulatory intentions. 

Response: EPA is required to regulate all sources in a source category unless there is a 

basis for not addressing all size units. During the rule development process, EPA 

determined that it would be appropriate to regulate all units. As stated in the preamble to 

the proposed rule, EPA estimates that approximately 81,500 new stationary CI ICE will 

become affected by the rule in the year 2015. Of these, more than 72,000 are below 500 

hp and represent more than 50 percent of the total emissions emitted from new stationary 

CI engines. These engines, or engines similar to these engines, have already been 

regulated in the context of regulation of mobile sources and there is no reason not to 

regulate these engines here. Owners and operators of these engines, particularly smaller 

engines, are not subject to onerous requirements. In fact, after stationary CI engines are 

required to be certified, owners and operators will have minimum compliance 

requirements beyond purchasing a certified engine. Owners and operators of certified 

engines would have to operate the engine according to the manufacturer’s instructions to 

demonstrate continuous compliance. Some owners would have additional monitoring 

28
requirements, such as recording the hours of operation, which is not a burdensome 

requirement and many sources may already be recording this information for other 

purposes. Thus, the burden on owners and operators is comparatively minimal under 

these regulations; however, as EPA must assure that certified engines are actually being 

installed and used, we must have some level of requirement on owners and operators. 

The commenter speculates that State and local agencies may institute further 

requirements on owners and operators, but State and local agencies have always had the 

ability to regulate these engines, and some have done so. The actions of these agencies 

should be judged on their own merits. The commenters provide no substantive reason to 

exclude smaller engines, including those engines 500 hp or less, from this regulation, or 

to completely exempt owners and operators from any responsibility in assuring that 

certified engines are purchased and operated according to manufacturer specifications. 

2.2.2 Comment: Two commenters (259, 260) stated that without a size threshold, title V 

permitting at major sources may require consideration of applicable requirements for 

very small units. The commenters suggest that no permitting requirements other than 

manufacturer certification be required for these engines. 

Response: As discussed under comment 1.10, the final rule exempts area sources 

from title V permit requirements but it does not exempt major sources. Section 502(a) of 

the CAA requires all major sources to obtain title V operating permits and it does not 

allow any major source to be exempted from title V. Also, 40 CFR 70.3(c)(1) and 40 

CFR 71.3(c)(1) require permits for major source to include all applicable requirements, 

29
and any requirements of today’s final rule that applies to a major source are applicable 

requirements and must be included in the permit. Additionally, it should not be a big 

burden on major sources to add these engines to their permits, given that they already 

have to fill out the permits. Thus, we disagree with the commenter and we have not 

made the suggested change. 

2.3 Useful Life 

2.3.1 Comment: One commenter (238) noted that the manufacturer’s guarantees are 

good for the “useful life” of the engine. The useful life of engines, as defined in 40 CFR 

parts 94 and 1039, range from 3 to 10 years. The useful life of a stationary CI engine can 

last for decades. The NY DEC estimates that approximately 25 percent of the demand 

response sources in NY City and on Long Island are more than 25 years old. The oldest 

such engine is nearly 50 years old. Clearly, the useful life of an engine, as defined by the 

nonroad rules is too short. Stationary engines must be maintained such that they are in 

compliance with applicable emission standards for as long as they are in use in order to 

maintain compliance with permits. 

Three commenters (259, 260, 261) note the introduction of mobile source concepts such 

as “useful life.” Two commenters (259, 261) state that useful life, “includes time limits 

related to mobile operation that suggests inappropriate limitations for engines in 

stationary applications.” One commenter (259) states that this also raises questions about 

ongoing compliance certification for stationary engines operating beyond their “useful 

30
life.” States and local agencies may be compelled to institute additional compliance 

requirements for units that exceed their useful life. Since the proposal is silent on the 

issue of longer term compliance, it leaves open the possibility that disparate requirements 

will expand across the U.S. 

Response: EPA acknowledges that stationary diesel engines can last beyond the useful 

life as defined in §60.4219 of the proposed rule. It is true that stationary diesel engines 

can last more than the 3 to 10 years given in 40 CFR parts 94 and 1039. The useful life 

period is designed to represent the time during which the engine manufacturer is 

responsible for the engine meeting the emission standards as long as the owner operates 

the engine according to the manufacturer’s specifications. After the useful life of the 

engine, it is the owner or operator’s sole responsibility to ensure that the engine continues 

to meet the emission standards. EPA expects that owners and operators will continue to 

operate regulated engines in a manner that provides for continued emissions control. 

Throughout the life of the engine, the owners and operators must operate and maintain 

the stationary CI engine and control device according to the manufacturer’s written 

instructions (or procedures developed in cooperation with the engine manufacturer). The 

engine must also be installed and configured according to the manufacturer’s 

specifications. As noted above, State and local agencies are authorized to regulate these 

engines beyond EPA’s NSPS requirements. If State and local agencies wish to institute 

additional compliance requirements for certified engines that operate beyond their useful 

life that is their prerogative and such requirements should be judged on their merits. 

31
2.4 Other 

2.4.1 Comment: One commenter (240) expressed that it generally agrees with the 

emission standards and effective dates of the proposal. The proposed standards 

appropriately recognize that non-emergency stationary CI engines are derived from 

corresponding nonroad or marine CI engines, depending on their power ratings and 

displacement. The commenter also supported the proposal’s recognition of the relevant 

differences between the use and emissions capabilities of non-emergency engines and 

emergency and fire pump engines. The commenter further expressed that as a general 

matter, the rule should not pull ahead any requirements derived from nonroad engine 

regulations in advance of the applicability of those requirements to the corresponding 

nonroad engines. Specifically, none of the requirements of new 40 CFR part 1068 should 

be applied to any stationary CI engines in advance of the applicability of the Tier 4 

standards to such engines. The requirements of 40 CFR part 89 (not 40 CFR part 1068) 

should be applied to stationary CI engines that are subject to compliance with the Tier 1 

through Tier 3 nonroad emission limits. Otherwise, several of the regulatory 

requirements developed in the context of Tier 4 nonroad engines will end up being pulled 

ahead and imposed on stationary CI engines in advance of the applicability of the 

underlying Tier 4 emission limits, even to the corresponding nonroad engines. Such a 

pull ahead would be contrary to the basic premise of the NSPS proposal, which is to 

apply nonroad engine requirements to stationary engines only as or after they are being 

phased in for nonroad engines and no earlier and would therefore be inherently 

unreasonable. 

32
Response: EPA proposed that all engines should meet part 1068 because EPA believed 

that the provisions in that part were generally the same as those for the other parts. 

However, manufacturers have provided several examples of differences in the 

requirements in these parts and EPA believes that it is consistent with the intent of this 

rule that stationary engines meet the same compliance requirements as comparable 

nonroad engines. Therefore, EPA is finalizing provisions that subject only part 1039 

engines to part 1068; the engines subject to other parts will meet the compliance 

requirements applicable to engines subject to those parts. EPA has clarified this in the 

final rule. 

2.4.2 Comment: One commenter (243) stated that EPA’s overall approach of adopting 

Tier 4 equivalent engine standards implemented through a manufacturer certification 

program is appropriate and well-justified, and that promulgation of standards not as 

rigorous as Tier 4 would be arbitrary and capricious. 

Response: EPA agrees with the commenter’s view that using a manufacturer certification 

approach, and requiring Tier 4 equivalent standards, is appropriate and well justified, 

though EPA does not necessarily believe that failure to do so would have been arbitrary 

or capricious. 

2.4.3 Comment: One commenter (259) was of the opinion that phase-in dates for lower 

emission standards should be preceded by a technology review to ensure that the 

33
proposed requirements are technically and economically feasible. The commenter 

specifically refers to the issue of fuel availability in rural portions of Alaska. The initial 

phase of regulation should be associated with 2007 certified engines. 

Response: EPA has thoroughly reviewed the feasibility of the proposed standards in the 

context of previous nonroad engine rules. EPA firmly believes that these standards can 

be achieved based on known demonstrated technology. For example, the particulate 

matter (PM) standards that will be implemented in 2011 are based on the use of 

particulate filters that are currently in use in some applications and will likely be used by 

much of the on highway diesel industry when new standards for such engines take effect 

in 2007. The low sulfur diesel fuel necessary to meet these standards will be fully 

available by the time these later standards take effect. Indeed, ultra low sulfur diesel 

(ULSD) fuel will represent the vast majority of diesel fuel refined and distributed in the 

U. S., as a result of rules promulgated under title II of the CAA. EPA is planning to 

conduct a technology review in 2007 to address technology issues warranting such a 

review for nonroad engines below 75 hp. It is expected that the findings of this review 

will apply to stationary engines as well. During the 2007 review, EPA will evaluate 

which long-term standards for PM are appropriate for engines below 25 hp. Long-term 

NOx standards for engines below 75 hp will also be reviewed to determine if more 

stringent standards are appropriate. Further information regarding EPA’s future plans to 

conduct a technology review can be found in the material related to the 2004 nonroad CI 

engine rulemaking. Regarding the particular issue of rural Alaskan villages, please see 

the discussion in section 4.2 below. Regarding the suggestion that this rule should not be 

34
implemented until the certification requirements begin in 2007, the CAA requires that 

engines constructed after proposal of this regulation are covered by the regulation. Given 

the difficulty of beginning a certification program without sufficient time to change 

manufacturing processes, there was a certain period where engines would be covered by 

standards, but engines certified to those standards would not necessarily be available. 

However, EPA has set the standards for these interim engines at levels that are easily met 

with existing technologies and has provided numerous methods of compliance with these 

standards that should ease the burden on owners and operators during this interim period. 

EPA believes this interim program provides needed emission reductions without unduly 

burdening owners and operators during this period. 

2.4.4 Comment: One commenter (264) was concerned with incorporating Tier 4 

requirements into the NSPS. Because aftertreatment technologies are still in the 

developmental stage, the commenter did not believe that those systems qualify as the best 

demonstrated technology (BDT) for NSPS. The commenter urged EPA to modify the 

NSPS. For engines less than 19 kilowatt (kW) (25 hp) the ultimate tier of standards 

should be Tier 4 standards that do not require aftertreatment controls. For engines rated 

between 19 and 37 kW (25 and 50 hp), the interim Tier 4 standards should apply. 

Finally, for engines greater than 37 kW (50 hp), the ultimate tier of standards should be 

Tier 3. 

Response: EPA believes that the proposed emission standards are appropriate and that 

the aftertreatment technologies that are the basis for the majority of the Tier 4 emission 

35
standards are suitable as BDT for this NSPS. As noted above, the standards are based on 

technologies that have been demonstrated to be effective in reducing emissions to 

necessary levels. Manufacturers have indicated that for the most part, emission standards 

that are based on aftertreatment controls are achievable. The final tier of standards for 

stationary CI engines less than 19 kW (25 hp) do not rely on the use of aftertreatment 

controls. EPA does not agree that the interim Tier 4 standard should act as the final 

emission standard for non-emergency engines between 19 and 37 kW (25 to 50 hp). The 

final Tier 4 standard should be the final tier of standards for these engines. However, for 

emergency engines between 19 and 37 kW, the final emission standards are not based on 

aftertreatment controls. In general, for non-emergency engines greater than 37 kW (50 

hp), the final tier of standards is Tier 4. For emergency engines greater than 37 kW (50 

hp), the final tier of standards is the most stringent tier (usually Tier 3) prior to the tier 

that requires aftertreatment. The commenter did not provide any rationale supporting 

these requests and EPA believes the emission standards, as proposed, are appropriate. 

2.4.5 Comment: One commenter (265) supported the proposed standards for stationary 

diesel engines being at least as stringent as for nonroad diesel engines. The commenter 

added that it believed that the proposed standards for stationary sources can be more 

stringent than for mobile source engines because add-on controls are not restricted by the 

space limitations of mobile sources. The commenter recommended a limit of 0.15 grams 

per horsepower-hour (g/hp-hr) of NOx for all stationary diesel engines starting in 2011, 

36
after ULSD becomes available nationally. The commenter provided their State of the Art 

manual1

, which provides justification for this new source emission level. 

Response: EPA must consider several aspects when developing emission standards for 

stationary engines, such as technical feasibility and cost of requirements, and EPA’s 

considerations are not limited to space concerns. EPA believes that the NOx emission 

standards in the proposed rule, which are generally based on the emission standards for 

nonroad diesel engines in 40 CFR parts 89 and 1039, are appropriate for stationary CI 

engines. Furthermore, since the rule relies in large parts on manufacturer certification, 

and considering that engine manufacturers often produce the same engines for nonroad 

and stationary use, requiring the same or similar emission standards for stationary 

engines that are required for nonroad engines is appropriate. 

 

1

 Section 3.13 State of the Art (SOTA) Manual for Reciprocating Internal Combustion Engines. Effective 

Date: 2003. State of New Jersey Department of Environmental Protection Division of Air Quality. 

Internet: http://www.state.nj.us/dep/aqpp/downloads/sota/sota13.pdf. 

37
3.0 Testing and Maintenance Restrictions for Emergency Engines 

3.1 Comment: Several commenters (218, 223, 224, 225, 228, 234, 236, 238, 240, 241, 

242, 246, 248, 250, 251, 253, 255, 256, 259, 261, 263, 264, 270) said that the testing and 

maintenance allowance for emergency engines in the proposed rule is not sufficient. 

Multiple commenters (218, 223, 228, 240, 241, 242, 250, 253, 259, 261, 270) 

recommended revising the definition of emergency engines to be consistent with 40 CFR 

part 63, subpart ZZZZ for stationary reciprocating internal combustion engines (RICE). 

Two commenters (256, 263) suggested following the California Airborne Toxic Control 

Measure (ATCM), which allows, depending on PM emissions, the California air districts 

to approve up to 50 hours per year or more for emergency engine maintenance and 

testing. Engines emitting higher levels of PM are given less hours (up to 20) for 

maintenance and testing. Commenter 263 said that if the above request cannot be 

accommodated in the NSPS, an alternative would be to allow the Air Resources Board 

(ARB) stationary ATCM in California to meet the requirements of the NSPS.2

 One 

commenter (248) suggested adding “or documented engine repair” to the end of the last 

sentence of §60.4211(e) of the proposed rule. One commenter (223) requested that the 

rule be changed to either match wording in 40 CFR part 63, subpart ZZZZ for stationary 

RICE or be revised as follows: “Emergency stationary internal combustion engines may 

be operated for the purpose of maintenance checks and readiness testing, provided that 

the tests are recommended by the manufacturer, the vendor, engineering standards, or the 

insurance company associated with the engine. Maintenance checks and readiness testing 

 

2

 EPA contacted the commenter for clarification on this request and the CA ARB recommends that the 

NSPS state that if an engine meets the California ATCM then it meets the NSPS. 

38
of such units is limited to 30 hours per year or to durations permitted through regulatory 

agency issued orders of approval.”

One commenter (224) recommended a minimum of 8 hours per month or 96 hours per 

year. 

One commenter (225) noted that it runs its emergency generators approximately 70 hours 

each year to meet hospital code requirements, which could double if troubleshooting is 

required. The commenter also said that it intends to off-load power to the grid to avoid 

real time pricing penalties and that it has run over 100 hours on each machine when 

committed to that task. This commenter encouraged EPA to either exempt hospitals, 

categorically from the restrictions, or apply a reasonable allowance of combined total 

operations of all emergency generators per hospital facility to 2,000 hours per year. 

Four commenters (234, 236, 251, 255) recommended that EPA specify 100 hours per 

year instead, as a maximum for maintenance and readiness testing. Commenter 234 

recommended as an alternative that delegated regulatory agencies could more adequately 

determine facility specific limits to readiness testing under the title V permit program or 

other State Implementation Plan (SIP) based program. Commenter 236 recommended 

allowing hospitals to petition for an exemption raising the limit beyond 100 hours as: a) 

a permanent exemption for the largest, most complex systems based on a substantiated 

need for additional testing (submit design and operational data) and b) a one-time 

exemption to exceed 100 hours based on extraordinary circumstances such as initial 

39
testing and commissioning, extensive repair or expansion of existing system, extended 

time without normal utility power. Commenter 255 recommended as an alternative that 

regulatory agencies could establish site-specific limits for maintenance checks and 

readiness testing. Commenter 251 recommended the last sentence of §60.4211(e) of the 

proposed rule be revised to read: “There is no time limit on the use of emergency 

stationary ICE in emergency situations or during training for, or simulation of, such 

emergency situations.” 

One commenter (238) recommended 500 hours per year for the use of emergency 

engines. If EPA decides to keep a limitation for maintenance and testing, the commenter 

recommended that such activities be limited to 78 hours per year. 

One commenter (264) said that the operation of an emergency engine should be at the 

discretion of the owner or operator, based on the engine manufacturer’s recommendations 

and any applicable health and safety codes. The commenter believed this requirement is 

unnecessary because non-emergency engines will be allowed to operate without any 

hourly limitations. The commenter added that utilities ask the owners of standby 

generator sets to use those sets to lower the owner’s electrical requirements on the utility 

during the utilities peak usage times. The usage amounts to less than 100 hours per year 

on average, according to the commenter. This helps the utility to keep its costs down 

because the utility does not have to build more generating capacity, and is a win-win 

situation for the owner, the utility and the general public. The commenter stated that the 

30 hour limit will cause utilities to build more power plants. 

40
Response: As summarized in this document, EPA received several comments on the 

issue of maintenance and testing of stationary emergency engines. EPA proposed to limit 

the time emergency engines spend during maintenance and testing to 30 hours per year, 

based on information available at the time of proposal indicating that 30 hours per year 

would be sufficient to address operation for such activities. For example, NFPA 

requirements stipulated 30 minutes per week (27 hours per year) for maintenance and 

testing purposes to ensure that the engine would respond properly in the event of an 

emergency. A survey conducted by the CA ARB indicated that emergency engines spend 

on average of about 30 hours per year for all operation. The proposed limit of 30 hours 

per year for maintenance and testing for stationary emergency CI engines was also 

consistent with the CA ATCM. Since the proposal of the rule, CA increased the 

maintenance and testing limit based on new information it had received, which indicated 

that more frequent testing was required by certain healthcare regulatory bodies. Local air 

districts in CA are allowed to approve additional hours of operation for maintenance and 

testing beyond 30 hours per year, and the ATCM also includes a sliding scale based on 

the PM levels the engine emits, of up to 100 hours per year. Considering the extent to 

which commenters provided information indicating that the proposed 30 hours per year 

allowance was not sufficient for most emergency engines, EPA has determined that it is 

appropriate to allow emergency engines to operate 100 hours per year during 

maintenance and testing. It is crucial to allow owners and operators of emergency 

engines to sufficiently test and maintain their emergency engines to ensure the engines 

will respond properly and as expected during an emergency situation. The engines must 

respond without failure and without lengthy periods of startup and adequate testing and 

41
maintenance must therefore be performed. Based on the comments received, EPA 

believes that 100 hours per year is a sufficient amount to ensure readiness of emergency 

engines in most cases. The final rule has been written to limit operation of emergency 

engines to 100 hours per year during maintenance and testing operation. In addition, 

EPA believes that there may be cases where it is necessary for an owner or operator of 

emergency engines to operate their emergency engines beyond 100 hours per year to 

ensure their engines will respond as needed during an emergency. Additionally, Federal, 

State or local safety standards may require maintenance and testing beyond 100 hours per 

year. Therefore, EPA has incorporated a provision into the final rule that allows anyone 

to petition the Administrator for approval to operate their emergency engines for more 

than 100 hours per year for maintenance and testing purposes. If a sufficient case is 

presented, the Administrator may approve such petitions for additional time to conduct 

maintenance checks and readiness testing to ensure that emergency engines can be used 

for their intended application during emergency situations. A petition is not required if 

an owner or operator can show that operation beyond 100 hours is required by regulation 

such as State or local requirements. EPA does not believe it is generally appropriate to 

allow unlimited hours for maintenance and testing, or hours well in excess of 100 hours, 

as suggested by some commenters, given the substantial emissions that can occur from 

these engines during their operation and the ability of owners and operators to meet their 

maintenance and testing needs under the final provisions. The California ARB presented 

in Table IV-1 of their Staff Report from 2003 that PM and NOx emissions from 

emergency standby engines in 2002 were 0.3 and 6.4 tons per day, respectively. The 

maintenance and testing allowance in the final rule would include training for and 

42
simulation of emergency situations and EPA believes the 100 hours per year would be 

sufficient to account for such operation. Documented engine repair would also be 

considered maintenance and testing and the change from 30 to 100 hours per year should 

provide enough hours to make necessary repairs. Finally, peak shaving is not considered 

emergency use and EPA has clarified this in the definition of emergency engine in the 

final rule. EPA responds to the issue of peak shaving in section 17 of this document. 

3.2 Comment: One commenter (228) said that the 30 hour restriction does not make 

allowance for the manufacturer-recommended break-in period for new engines. If EPA 

retains a fixed hour limitation for maintenance and testing, EPA should include an 

explicit, allowable number of hours for a manufacturer-recommended break-in period. 

Response: Engine manufacturers have told EPA that they do not have engine break-in 

requirements after the engine is delivered to the customer site. This information is 

included in the docket to the final rulemaking. The engines are shipped from the 

manufacturing facility ready for normal use, according to the manufacturers. Therefore, 

EPA does not feel that it is necessary to include an allowance for a break-in period for 

engine owners and operators. Additionally, the final rule provides 100 hours of operation 

per year for maintenance and testing of emergency engines, instead of the proposed 30 

hours. Owners and operators of emergency engines could use the 100 hours per year that 

is designated for testing and maintenance for engine break-in, if necessary. 

43
3.3 Comment: One commenter (238) stated that pursuant to §60.4211(e) of the proposed 

rule, emergency engines would be allowed to run an unlimited amount of time during an 

emergency. Without an annual limit of operation, the potential emissions of these 

engines must be calculated over an entire year (8,760 hours). This may result in an 

owner/operator of emergency engines being required to install costly controls (which 

may not work based on the operating parameters of emergency engines) in order to 

comply with New Source Review regulations. 

Response: EPA does not believe it is appropriate to limit the operation of emergency 

engines during emergencies. The operation of emergency engines during emergency 

situations varies widely and it is impossible to determine a one-size-fits-all limitation on 

the operation during emergencies. The operation of emergency engines is crucial to be 

able to support equipment needed during emergencies, which could potentially be lifethreatening in cases of fire, flood, or power outages at healthcare facilities, and it is 

inappropriate to restrict the hours emergency engines can spend supporting such 

equipment. The only operation of emergency engines that EPA is restricting is the 

operation during maintenance and testing, which is limited to 100 hours per year. 

3.4 Comment: One commenter (246) requested an exemption from the 30 hour operating 

limitation for emergency engines for nuclear power plants. The commenter suggests the 

following language: This regulation does not apply to engines under the regulation of the 

Nuclear Regulatory Commission (NRC), as long as the engines are run only to satisfy the 

NRC requirements. The commenter said that 1) For public safety reasons upon loss of 

44
power, the NRC requires these emergency engines to be running and the generators 

loaded within a very few seconds. 2) All buildings and equipment associated with safety 

operation require design and construction to withstand seismic events. (Reference: 

Appendix A of 10 CFR 50). 3) Engines with the role of public safety require a prudent 

approach to changes (References: Appendix B of 10 CFR 50 Criterion III Design 

Control and Criterion XI Test Control; NRC Regulatory Guide 1.9, Rev 3). Changes to 

the operating characteristics of the engine are not allowed. For other changes the normal 

methodology is to verify through testing of similar equipment that hp ratings, exhaust 

backpressure and other important parameters are negligibly affected prior to 

implementing a change. Additionally, these engines have passed a rigorous NRC 

qualification process. Due to the age and variety of engines in the nuclear industry, test 

run data from similar engines is not necessarily available in these size engines, e.g., 6,000 

hp. This coupled with the above make verification of emission compliance difficult. 4) 

Engines with the role of public safety are run only for mandated reliability testing. These 

engines have minimum required maintenance operation schedules that total more than 30 

hours per year. The NRC mandated engine run hours also increase dramatically if 

surveillance test failures occur, which require an increased frequency of retesting. These 

requirements suggest that exemption from the hour limitation is the best alternative. 

Response: EPA addressed the issue of maintenance and testing in response to comment 

3.1. As stated in response to that comment, owners and operators can operate their 

emergency engines for maintenance and testing purposes up to 100 hours per year. EPA 

believes that 100 hours per year is a sufficient amount to address the majority of 

45
emergency engines; however, owners may petition the Administrator for approval of 

additional hours, if necessary. Owners and operators may operate more than 100 hours 

per year without a petition, if required by Federal, State or local law or regulation to 

maintain and test their emergency engines more than 100 hours per year. EPA believes 

these provisions satisfy the commenter’s concerns. 

4.0 Fuel Requirements 

4.1 General 

4.1.1 Comment: One commenter (228) expressed that the proposed fuel requirements 

would be burdensome to some facilities that store and use large inventories of diesel fuel. 

To comply with the proposed fuel requirements, an owner/operator of stationary CI 

engines with large fuel inventories may have to dilute/blend existing diesel fuel 

inventories with fuel that is virtually sulfur-free prior to each compliance date in 

§60.4207 of the proposed rule, and sample/analyze the blended fuel for sulfur content, 

and cetane index or aromatic content to document compliance with the fuel content 

requirements. Sources with large fuel inventories may require dilution quantities that 

exceed the existing storage tank capacities, and diluting/blending would be an expensive 

task. Diluting/blending fuel to meet these requirements would require the procurement of 

diesel fuel that has a sulfur content and cetane index or aromatic content that would be 

much more stringent than the specified fuel sulfur content standards. As an alternative, 

owners/operators would have to deplete existing diesel fuel inventories completely prior 

to each compliance date and then purchase fuel that meets the requirements of 40 CFR 

46
§80.510(a) and (b) for just-in-time fuel delivery prior to each compliance date. This 

alternative is not reasonable for owners/operators that operate 24 hours a day. Also, 

depleting inventories to zero potentially would cause owners/operators to have to 

clean/remove tank bottoms to prevent fouling of fuel lines and equipment, and to have to 

dispose of off-specification diesel fuel, producing additional costs. The commenter 

requested that EPA include a grandfather clause that would allow owners/operators to 

continue to use up existing fuel inventories after October 1, 2007, and October 1, 2010. 

Alternatively, EPA could revise §60.4207(a) and (b) of the proposed rule by replacing the 

word “use” with “purchase.” 

Response: EPA believes it is providing sufficient time for owners and operators to 

switch to using lower sulfur fuel. Substantial amounts of fuel meeting the fuel 

requirements will be available in the years and months prior to implementation of the fuel 

requirements. However, EPA understands that there may be cases where sources may be 

unable to use up existing non-compliant fuel inventories prior to the fuel compliance 

dates of the rule. EPA does not think it would be appropriate to include an open-ended 

provision allowing owners and operators to use up existing non-compliant fuel 

inventories after October 1, 2007 and October 1, 2010. Also, EPA does not believe it 

would be appropriate to use the word “purchase” instead of “use” in §60.4207 of the rule. 

A more reasonable provision, which takes into account that there may be varying 

volumes of existing fuels from site to site, would be for the owners and operators to 

petition the Administrator for additional time beyond the schedule set in the final rule to 

use up existing non-compliant fuels. EPA believes that a case-by-case approach to 

47
dealing with existing fuel inventories is more appropriate and will incorporate the 

uniqueness of each source’s fuel inventory situation. EPA has incorporated a provision 

into the final rule that allows owners and operators that have stationary CI engines 

subject to the rule to petition the Administrator for additional time to use up existing noncompliant fuel inventories. If approved, the petition is valid for a period of up to 6 

months. If additional time is needed beyond that, the owner or operator would have to 

submit another petition to the Administrator. Also, EPA does not believe such a 

provision should be included for engines built after 2011 as these stationary CI engines 

will require the use of ULSD in order to operate properly. Therefore, the final rule 

includes the provision to petition the Administrator to use up existing non-compliant fuel 

for a period of 6 months only for pre-2011 MY stationary CI engines. 

4.1.2 Comment: One commenter (238) concurred with EPA’s decision to require lower 

sulfur diesel fuel. However, the commenter believed ULSD will be available in 

sufficient quantities by fall 2006 to supply stationary engines. 

Response: As discussed in EPA’s nonroad diesel Tier 4 rule, EPA believes there is a 

need for a period of lead time prior to implementation of the 15 ppm sulfur requirement. 

Given the significant actions that are required for refiners to meet the 15 ppm standard, it 

would not be possible to require 15 ppm fuel in the same time frame as the 500 ppm 

sulfur requirement. While 15 ppm sulfur diesel fuel will be available by 2006, due to the 

requirements applicable to highway diesel fuel, EPA cannot be certain enough 15 ppm 

fuel will be available in all locations to accommodate the additional needs of stationary 

48
engines. Therefore, we believe that phasing the 15 ppm requirement in at the same time 

as it becomes applicable to the nonroad market will allow for a more feasible and 

reasonable transition for stationary engines. 

4.1.3 Comment: One commenter (265) supported a requirement of meeting a fuel sulfur 

content limit of 0.0015 percent by weight as a practical and efficient way to minimize 

sulfur dioxide (SO2) emissions and allow the use of catalyzed diesel particulate filters 

(CDPF) and NOx adsorbers to achieve maximum levels of emission reduction. 

Response: No response is needed. 

4.1.4 Comment: One commenter (238) stated that §60.4207(b) of the proposed rule cites 

40 CFR 80.510(b), which specifies 15 parts per million (ppm) sulfur content for nonroad 

diesel fuel, and 500 ppm sulfur fuel content for locomotive and marine diesel fuel. The 

sulfur limit that would apply for stationary engines is unclear, although it is assumed that 

EPA intends to require 15 ppm sulfur fuel. The commenter suggested that EPA either 

change the reference to 40 CFR 80.510(c), or write §60.4207(b) of the proposed rule to 

read: “...must use diesel fuel that meets the requirements of 40 CFR 80.510(b) for 

nonroad diesel fuel.”

Response: EPA acknowledges that the sulfur limit that would apply to stationary engines 

was unclear in the proposal. It would not be accurate to cite to the fuel requirements in 

40 CFR 80.510(c). Those fuel requirements begin on June 1, 2012 and are inconsistent 

49
with EPA’s intent for fuel requirements for stationary CI engines. It is EPA’s intent to 

require 15 ppm sulfur fuel starting October 1, 2010. EPA has clarified this and has 

included “...for nonroad diesel fuel.” in §60.4207(b) of the final rule. 

4.2 Alaska 

4.2.1 Comment: One commenter (233) noted that EPA’s past mobile source rulemakings 

have provided the necessary flexibility for Alaska to transition to ULSD, in recognition 

of Alaska’s unique fuel distribution circumstances. The proposed rule may significantly 

and disproportionately increase the cost of power in rural Alaska and possibly increase 

home heating fuel cost. The commenter recommended eliminating the requirement to 

use 500 ppm sulfur fuel between October 2007 and October 2010 in rural Alaska. 

Phasing fuel in different stages, as proposed, would create an unnecessary logistical and 

financial hardship for rural Alaska communities for a relatively small environmental gain. 

A one step transition to ULSD in 2010 will reduce adverse effects to Alaska and provide 

several benefits. 

The commenter recommended that EPA perform Alaska specific cost benefit analyses 

and participate in a rural diesel health assessment. The substantive air quality benefits of 

the proposed rule will not be realized for decades since it relies on diesel engine turnover 

and newer engines being equipped with post-combustion control. Due to uncertain cost 

and health concerns, Alaska cannot support the proposed rule without additional Alaska 

specific cost benefit analyses. The commenter recommended specific costs and health 

50
benefits analyses for rural Alaska. The commenter believed that two types of 

assessments will be necessary for rural communities to make decisions on fuel choices, 

storage tanks and marine transport of those fuels. These are: 1) an economic assessment 

of the fuel cost differential for ULSD as delivered to rural communities including 

amortized infrastructure costs, and 2) whether emissions from existing technology 

engines and fuels cause significant health risks for rural residents. 

Two commenters (234, 255) expressed that the fuel requirements in the proposed rule are 

incompatible with the requirements of 40 CFR 69.51(a) and (b) for Alaska sources. The 

final rule must be written to incorporate the exemptions in 40 CFR 69.51, or separate 

rulemaking should be undertaken that includes the Alaska exemption that takes effect at 

the time subpart IIII becomes final. 

Two commenters (234, 255) said that it is common practice for owners/operators in 

remote locations of Alaska to economically dispose of on-specification used oil by 

mixing it with diesel fuel and burning it in CI engines. In some cases, it is the only way 

to dispose of used oil. The fuel requirements and PM limitations in §§60.4201 and 

60.4202 of the proposed rule will eliminate the ability of an owner/operator to burn used 

oil/diesel blends. There is no economic or environmentally safe alternative to 

blending/burning in most remote locations in Alaska. 

Two commenters (234, 255) stated that the standards need to be revised to allow 

manufacturers to provide engines that can operate intermittently on used oil/diesel blends 

51
without meeting stringent PM or fuel sulfur standards. Alternatively, delegated 

regulatory agencies could more adequately determine facility specific limits for 

combustion of used oil/diesel blends under the title V program or other SIP based 

program. 

Response: EPA issued a proposal in October of 2005 (70 FR 59690), which proposed to 

delay the nonroad fuel requirements to 2010 for rural areas of Alaska. That proposal 

applies to stationary engines covered by the NSPS as well. The proposal would delay 

low sulfur fuel requirements for new stationary engines in areas of Alaska not supported 

by the Federal Aid Highway System until December 1, 2010, but requires 2011 and later 

MY engines located in rural areas of Alaska to comply with the 15 ppm sulfur 

requirements. EPA believes this addresses the commenters’ concerns regarding timing 

and phasing of fuel requirements. EPA believes that it is most appropriate to finalize the 

delay of the stationary engine fuel requirements for rural areas of Alaska in the same rule 

as the finalization of the nonroad fuel delay, because it is appropriate that fuel issues for 

rural Alaska be handled in a single rule where all related issues can be reviewed and 

resolved. EPA has included a section in this final rule that refers parties to 40 CFR part 

69 to find out the fuel requirements for areas of Alaska not supported by the Federal Aid 

Highway System until December 1, 2010. 

Commenter 233 appears to say that further measures, like retrofits that cannot be 

compelled in this regulation, may be appropriate. The commenter is free to pursue such 

actions if it believes it is appropriate. The commenter also states that the costs for rural 

52
Alaskans will be unique, because they rely to a greater extent on such engines. While 

this is true, the health benefits for rural Alaskans can be much greater than the costs, 

especially given the usage of these engines. The commenter does not provide evidence 

that the costs and benefits of this in rural Alaska are so different from the cost and benefit 

analyses performed for this rule, in particular, the comparisons of benefits to costs, are 

inapplicable to such engines. 

In response to commenter 233’s recommendation that EPA should assist Alaska in a rural 

diesel health assessment, such help, if available within EPA’s own budget constraints, 

may be helpful and appropriate, but such assistance is not part of this rulemaking. The 

commenter has noted that most rural villages use one community tank for all fuel, and 

about 5 percent of the fuel is for mobile sources and another 25-45 percent for power 

production, with the rest for heating fuel. The issue of how to handle the introduction of 

ULSD fuel, either having to purchase new storage facilities, or to purchase only low 

sulfur diesel fuel, or take steps to reduce the need for ULSD fuel for as long as possible 

(through use of older engines) is one that villages will need to deal with as a result of the 

nonroad engine Tier 4 rule as well as this rule. Again, EPA recognizes that rural 

Alaskans have some unique costs associated with this fuel change, and EPA is taking 

steps to reduce them, but the emission reductions from this rule can bring substantial 

health benefits for these communities that outweigh the costs of the program. To address 

Alaska’s concerns, the final regulations include language that allows Alaska to submit for 

EPA approval through rulemaking process, by no later than 18 months after publication 

of the final rule, an alternative plan for implementing the requirements of this regulation 

53
for public-sector electrical utilities located in rural areas of Alaska not accessible by the 

Federal Aid Highway System. The alternative plan must be based on the requirements of 

section 111 of the Clean Air Act including any increased risks to human health and the 

environment and must also be based on the unique circumstances related to remote power 

generation, climatic conditions, and serious economic impacts resulting from 

implementation of 40 CFR Part 60 Subpart IIII. 

Regarding the comment related to mixing used oil with diesel fuel and burning it in CI 

engines, EPA disagrees. Engines that are built after 2011 cannot use any diesel fuel other 

than 15 ppm diesel fuel. Engines built after 2011 must use 15 ppm sulfur diesel fuel or 

the engine can be severely damaged. Used oil cannot be used in these engines and will 

have to be disposed of in other ways, perhaps by being burned for heat. EPA believes it 

would be reasonable to allow pre-2011 MY engines located in remote areas of Alaska to 

burn such fuels on a case-by-case basis. The final regulation includes a provision in 

§60.4207 that allows owners and operators of pre-2011 MY engines located in areas of 

Alaska not accessible by the Federal Aid Highway System to petition the Administrator 

for approval to use fuels mixed with used lubricating oils. The petition must include 

information that shows that the owner has no other place to use the oil, and if the petition 

is approved, it is valid for a period of up to 6 months. 

In response to the comment requesting revised emission standards, EPA disagrees. 

Emission standards are set at certification so no new standards are required. However, 

owners and operators must operate the engine according to the manufacturer’s 

54
specifications. This may, or may not allow (and for post-2011 engines, certainly will not 

allow) blending with used oil. For pre-2011 MY engines located in remote areas of 

Alaska, the final regulation has been written to allow some amount of relief from the 

sulfur specifications if the owner or operator can show that there is no way to avoid 

blending with used oil, as discussed in the previous paragraph. 

4.3 Engines with a Displacement of ≥30 Liters per Cylinder 

4.3.1 Comment: One commenter (235) stated that no operating experience currently 

exists for engines with a displacement of greater than or equal to 30 l/cyl with 15 ppm 

sulfur fuel, and therefore, an alternative should be worked out. The use of ULSD may 

have impacts on safety, reliability and durability of the stationary engine. At the current 

stage of technology, engine manufacturers will not be able to guarantee an engine 

operating exclusively on ULSD. According to the European Union (EU) Directive 

1999/32/EC, the maximum sulfur content of heavy fuel oil is a maximum of 1 weight 

percent (10,000 ppm) from January 1, 2003, and in gas oil a maximum of 0.1 weight 

percent (1,000 ppm) from January 1, 2008. These fuels can be used in stationary CI 

engine plants without installed flue-gas desulfurization. According to the EU 

2001/80/EC Directive, a maximum of 0.5 weight percent sulfur (850 milligrams per 

Normal (273.15 °Kelvin, 101.3 kilo Pascal (kPa)) cubic meters (mg/Nm3

) SO2 at 3 

percent oxygen (O2) and 280 mg/ Nm3 SO2 at 15 percent O2) fuel oil can be used in 50 to 

100 megawatt (MW) boiler plants. Large CI engines are designed to operate on heavy 

fuel oil and the use of ultra clean light fuel oils (with different density, viscosity, etc., 

55
properties) may cause operation problems. The commenter requested that for large 

engines the requirement should be equivalent to 500 ppm after 2010 on the U.S. 

mainland. The commenter also stated it was reasonable for EPA to exempt Guam, 

American Samoa and the Commonwealth of the Northern Mariana Islands from fuel 

limits. 

Another commenter (240) expressed that additional time may be necessary to phase in 

the use of ULSD with respect to new engines with a displacement of 30 l/cyl or greater. 

Response: EPA requested comments on whether owners and operators of stationary CI 

engines with a displacement of greater than or equal to 30 l/cyl should be required to use 

ULSD fuel. There is no information regarding the effect of burning 15 ppm sulfur fuel in 

stationary CI engines with a displacement of greater than or equal to 30 l/cyl and 

operators of these engines have expressed concerns with burning such fuel. 

Manufacturers of engines with high displacement have told EPA that there is a large 

variety of fuels used in these engines and that the fuel used can contain a high sulfur 

content. The fuels used in large displacement engines are of a different grade than the 

fuels used in nonroad engines. Information EPA has received indicates that engines with 

a displacement of greater than or equal to 30 l/cyl are often designed to operate on 

residual fuels containing up to 5 percent sulfur, but that these engines can also operate on 

fuels with lower fuel content. Further information on this subject can be found in the 

docket (EPA-HQ-OAR-2005-0029-0146). EPA believes it would be inappropriate to 

require owners and operators of these engines to use ULSD as the impacts of using such 

56
fuel are unknown. However, EPA does believe it is appropriate to require these engines 

to utilize fuel containing 500 ppm sulfur or less, consistent with the commenter’s 

statement. The final rule has been written to require owners and operators of stationary 

CI engines with a displacement of greater than or equal to 30 l/cyl to use 500 ppm sulfur 

fuel starting October 1, 2007. Owners and operators of stationary CI engines with a 

displacement of greater than or equal to 30 l/cyl are not required to use 15 ppm sulfur 

fuel, but must use 500 ppm fuel from October 1, 2007, and beyond. 

4.4 ULSD and Older Engines 

4.4.1 Comment: One commenter (240) said that the requirement that owners/operators of 

all stationary IC engines must use ULSD as of October 1, 20073, could cause problems 

for certain engine installations that were not designed to operate on ULSD (e.g., older 

engines with high injection pressures). This suggests that retroactive application of a 

ULSD requirement in this context needs further investigation. 

Another commenter (264) believed the requirement to use ULSD and low sulfur diesel 

(LSD) will cause considerable hardship for owners/operators of stationary engines. 

Standby generator sets have a useful life of over 20 years due to their low hours of usage 

per year. The fuel systems of many engines built in the year 2000 and before have fuel 

systems that will seize up if used with low sulfur fuels. The cost to replace these engines 

will be astronomical compared to their small amount of emissions per year. The 

commenter urged EPA not to adopt a fuel sulfur requirement for existing engines. 

 

3

 EPA contacted the commenter and clarified that the commenter meant 2010. 

57
Response: The fuel requirements in the rule apply only to owners and operators of 

stationary CI engines subject to the rule. The fuel requirements do not apply to existing 

engines, unless the engines are modified or reconstructed after the date of proposal, 

which would make these engines subject to the rule. EPA believes that, with regard to 

those rare internal combustion engines that are modified or reconstructed, the level of 

change needed to become subject to those provisions is such that any engine becoming 

subject to those provisions will likely be changed to a degree that refurbishing the engine 

to ensure ability to use ULSD will not cause significant problems. EPA has made it clear 

in the final rule that the fuel requirements of §60.4207 apply only to those engines that 

are covered by the rule, as specified in the applicability section of the rule §60.4200. 

4.5 Add-on Controls 

4.5.1 Comment: One commenter (244) stated that less than 15 ppm diesel is absolutely 

essential for meeting EPA’s proposed PM standards for stationary engines rated from 25 

to above 750 hp. Sulfur affects CDPF performance by inhibiting the performance of 

catalytic materials upstream of or on the filter. This phenomenon not only adversely 

affects the ability to reduce emissions, but also adversely impacts the capability of these 

filters to regenerate and there is a direct trade-off between sulfur levels in the fuel and the 

ability to achieve regeneration. Sulfur also competes with chemical reactions intended to 

reduce pollutant emissions and creates PM through catalytic sulfate formation. The 

availability of less than 15 ppm sulfur fuel will enable these filters to be designed for 

58
improved PM filter regeneration and emission control performance, as well as to 

minimize any increase in sulfate emissions. Diesel fuel with a sulfur content of less than 

15 ppm is absolutely essential to commercializing NOx adsorber systems that can 

function effectively. At higher sulfur levels, a NOx adsorber quickly becomes ineffective 

as the sulfur attaches to the sites meant to “trap” the NOx. The sulfur remains attached to 

these sites until high temperature, rich conditions, which are not characteristic to normal 

diesel engine operation, are met. Also, while a sulfur regeneration mode or 

desulfurization cycle will need to be employed in any case, the frequency of 

desulfurization must be minimized to avoid substantial fuel economy penalties and 

perhaps a degradation of the NOx adsorber performance that, in turn, will require an even 

more frequent desulfurization. As the sulfur level increases, the frequency, as well as the 

severity, of regenerations needed increases. 

The commenter added that the effectiveness of selective catalytic reduction (SCR) and 

lean NOx catalyst technology would greatly benefit from the use of less than 15 ppm 

sulfur fuel in terms of improved emission control performance and minimization of the 

sulfate formation when precious metals are used. Although diesel oxidation catalysts will 

function effectively with less than 500 ppm fuel, the availability of 15 ppm will improve 

overall PM control efficiency by reducing the sulfate production and will enable the 

utilization of more active catalyst formulations that could provide greater reductions in 

toxic hydrocarbons (HC) and the soluble organic fraction of the PM emissions, according 

to the commenter. The commenter supported the proposal of extending the 15 ppm 

59
sulfur limit to diesel fuel sold for use by all stationary diesel engines, including engines 

with a displacement of 30 l/cyl or greater. 

Response: EPA agrees with the commenter with regard to engines with displacement 

below 30 l/cyl. However, as discussed above, EPA does not have enough data regarding 

the use of 15 ppm sulfur fuel in engines above 30 l/cyl to require 15 ppm sulfur fuel for 

such engines. The commenter provided no data on this issue supporting its request to 

extend the 15 ppm requirement to these engines. 

5.0 Test Methods 

5.1 Comment: One commenter (240) stated that the field test methods to be utilized 

under the NSPS also will need to be fully aligned with and equivalent to the nonroad 

engine certification test methods. 

Response: EPA believes the test methods as proposed are consistent with those required 

for nonroad diesel engines. EPA references the nonroad test regulations in the NSPS 

regulations. 

5.2 Comment: Two commenters (259, 261) expressed support for inclusion of EPA 

Method 19 and EPA Method 7E in the proposed rule, but other test methods should also 

be included and allowed, such as ASTM Method D6522-00 and extractive Fourier 

Transform Infrared Spectroscopy (FTIR). Extractive FTIR test methods and portable 

analyzers have proven effective for measuring emissions from combustion equipment, 

60
and associated test methods have been included in other recent EPA regulations, e.g., 

proposed subpart KKKK for stationary combustion turbines and 40 CFR part 63, subpart 

ZZZZ for stationary RICE. EPA should allow the use of FTIR and portable analyzer test 

methods in the CI NSPS. For portable analyzers, ASTM Method D6522-00 has been 

developed based on validation testing conducted by GRI and an independent peer review 

and approval through ASTM. The method has been accepted by EPA for other standards 

such as 40 CFR part 63, subpart ZZZZ for stationary RICE and the stationary combustion 

turbines NSPS proposal (40 CFR part 60, subpart KKKK). Two test methods have been 

commonly applied for FTIR testing and have also been included in other regulations for 

measurement of exhaust species from combustion equipment. The final rule should 

include both FTIR methods: EPA Method 320 and ASTM Method D6348. 

Response: EPA has retained EPA Methods 10 and 7E in the final rule. EPA agrees with 

the commenter that FTIR is appropriate and has included FTIR as an acceptable option in 

the final rule. The final rule has been written to include EPA Method 320 and ASTM 

Method D6348-03. EPA does not believe that it is appropriate to include ASTM D6522-

00 in the final rule. This method is a test method for portable analyzers for natural gas 

fired engines and may not be appropriate for diesel fired stationary engines. EPA has not 

included ASTM D6522-00 as an alternative to Method 10 or Method 7e for CO or NOx 

measurement in the final rule because ASTM does not represent this method for sources 

other than natural gas-fired combustion sources (refer to Section 1.1.1 of ASTM D6522-

00 and title of same). 

61
5.3 Comment: One commenter (235) said that in Europe, the PM measurement method 

used is in principal similar to EPA Method 17. Comparison has shown that different 

methods have given different results, e.g., when comparing EPA Method 17 and EPA 

Method 5, it has been noted that EPA Method 5 usually gives much higher measurement 

results. In a CIMAC (International Council on Combustion Engines) recommendation4

, 

it is recommended to use PM measurement methods principally similar to EPA Method 

17 instead of a method where exhaust gas has to be cooled dramatically leading to a nonreproducible sampling. 

Response: EPA has noted the commenter’s concerns. However, EPA Method 5 (versus 

EPA Method 17) is thought to be the only appropriate test method since it requires the 

filter temperature to be held at a near constant temperature ( 120 ± 14 °C ( 248 ± 25oF ) ), 

and therefore results are more reproducible. EPA Method 17 does not control filter 

temperature so there is a good chance of extremely variable results, depending on the 

exhaust temperature. Therefore EPA does not believe it is appropriate to allow EPA 

Method 17, but feels that EPA Method 5 is the appropriate test method to use to measure 

the concentration of PM from the stationary CI engine exhaust. 

6.0 Flexibility/ABT 

6.1 Comment: One commenter (238) made the point that the average, banking, and 

trading (ABT) provisions of the proposed NSPS are not compatible with the NY DEC’s 

 

4

 CIMAC Recommendation – Standards and Methods for sampling and Analysing Emission Components 

in Non-automotive Diesel and Gas Engine Exhaust Gases – Marine and Land Based Power Plant Sources. 

CIMAC Working Group on Exhaust Emissions. February 2005. The document can be ordered from: 

http://www.cimac.com/services/Index1-techpaperdatabase.htm. 

62
regulatory approach for stationary sources in which the owner/operator is responsible for 

complying with all applicable emission limits. 

Response: As stated in more details in the preamble to the proposed rule, EPA believes 

the proposed ABT provisions are appropriate for this regulation. The ABT provisions are 

important elements in establishing a manufacturer-based certification program that will 

be feasible for stationary CI engines. Engine manufacturers are familiar with ABT 

provisions from the nonroad engine program, and many of those same manufacturers 

produce stationary engines affected by this rule. As stated in the preamble to the 

proposed rule, the proposed ABT provisions are essential elements in EPA’s 

determination that the proposed standards reflect BDT. There are many benefits and 

advantages of including an ABT program in the rule, as described in the preamble to the 

proposed rule. The ABT program also provides engine manufacturers flexibility in 

producing certified engines that meet the standards of this rule. For these reasons, and as 

explained in further details in the preamble to the proposed rule, EPA believes it is 

justified to include ABT provisions in the final rule. 

6.2 Comment: One commenter (240) strongly agreed that the inclusion of a fully 

integrated ABT program (as well as flexibility provisions) is critically important to the 

feasibility of the proposed NSPS. The commenter added that in addition to incorporating 

the ABT program as currently applies in the nonroad rule, the final rule needs to 

incorporate and allow for the fully-integrated application of flexibility provisions allowed 

under the nonroad rule (see 40 CFR §89.102(d); 40 CFR §1039.625). Without this 

63
necessary flexibility, cost-effective integration of stationary engines and equipment will 

be hampered (if not precluded), and significant product shortages and dislocations could 

result (given the growing number of regulatory demands for current-Tier nonroad 

engines). The NSPS provisions need to adopt and incorporate by reference all of the 

relevant nonroad ABT provisions, including the ABT calculation provisions (see 40 CFR 

§§1039.701-1039.740). 

Response: As proposed, EPA is including the ABT program from the nonroad road 

provisions into the final rule. EPA does not believe it is necessary to cite the specific 

nonroad ABT provisions in the final rule; it is clear in the regulation that EPA is 

incorporating them. Regarding equipment manufacturer flexibility, the provisions of 

1039.625 (and 89.102) are designed to help equipment manufacturers, who are not being 

regulated in this rule. Equipment manufacturers have flexibility under this rule to take 

actions not permitted under the nonroad regulations because they are not directly 

regulated by this rule. In addition, engine manufacturers have not shown that the 

considerations for integrating engines into new equipment that motivated these provisions 

are applicable to stationary applications. 

6.3 Comment: Two commenters (259, 261) were of the opinion that EPA must ensure 

that flexible options such as emissions averaging are retained in the rule for all categories 

of engines, e.g., large units that are subject to owner/operator compliance requirements 

are not afforded the same flexibility. EPA has previously considered flexible approaches 

for engines under the NOx SIP Call Phase II Rule. The approach for the Phase II Rule is 

64
based upon achieving a tonnage reduction target rather than engine-specific technology 

performance. Commenter 259 believed that a variety of flexible options are available 

that are appropriate for inclusion in an NSPS, e.g., a compliance plan developed by the 

operator could be used, as recommended in the Phase II guidance. 

The commenter recommended that EPA retain the flexible approaches available for 

certification and also include approaches such as emissions averaging for all engines that 

will be affected by the NSPS. 

Response: EPA is required to set emission standards that are based on BDT. For engines 

that are required to be certified, BDT includes the ABT program, which is necessary and 

crucial to the success of the certification program. It would not be appropriate to include 

emissions averaging for engines not included in a certification program by an engine 

manufacturer and it is outside EPA’s authority under this action to incorporate such 

flexibility. For owners and operators, the rule is flexible in that owners and operators that 

do not purchase certified engines have several ways of demonstrating compliance with 

the rule, as specified in §60.4211. In addition, owners and operators who conduct 

performance tests to demonstrate compliance with the emission standards have to show 

that exhaust emissions from their stationary CI engines meet not-to-exceed (NTE) 

standards, as opposed to the certification emission standards. The NTE standards which 

owners and operators have to comply with if they decide to test their engines are higher 

than the certification standards, which provides owners and operators flexibility in 

meeting the standards in the field. Also, EPA is allowing owners and operators in 

conjunction with the engine manufacturer to develop site-specific operating and 

65
maintenance procedures that must be followed at all times, thereby incorporating a 

certain level of flexibility in the continuous compliance requirements for owners and 

operators. 

66
7.0 Compliance 

7.1 Following Manufacturer’s Instructions 

7.1.1 Comment: One commenter (261) expressed concern that the requirement that 

owners/operators must follow manufacturer operating and maintenance (O&M) 

provisions is onerous. Operators of engines often have existing O&M practices that may 

differ from the vendor recommendations, but are designed to address the specific 

challenges and rigor of the application. The commenter recommended that 

owners/operators be allowed to follow an O&M procedure based upon manufacturer 

recommendations and/or operator defined procedures. 

One commenter (253) stated that the proposed rule requires owners/operators to operate 

their engines in accordance with the engine manufacturer’s written instructions over the 

entire life of the engine and operate and maintain the stationary CI engine and control 

device according to these instructions. These provisions do not provide facilities any 

flexibility. Flexibility is critical to many facilities, especially those with non-standard 

operations that may not be addressed by the manufacturer’s written instructions. In 

addition, modified and reconstructed engines will require modifications to the original 

manufacturer instructions. However, as the facility modifying or reconstructing the 

engines would not be considered a manufacturer as defined under §60.4216 of the 

proposed NSPS, modifications to the instructions would not be allowed. Modifications to 

these instructions would be necessary to ensure that the proposed CI ICE emission limits 

continue to be met. To provide flexibility for facilities and ensure that the emission limits 

67
of the rule are met, the commenter recommended that EPA replace §§60.4206 and 

60.4211(a) of the proposed rule with the following provision from 40 CFR part 63, 

subpart ZZZZ for stationary RICE: “If you must comply with emission limitations and 

operating limitations, you must operate and maintain your stationary RICE, including air 

pollution control and monitoring equipment, in a manner consistent with good air 

pollution control practices for minimizing emissions at all times, including during startup, 

shutdown, and malfunction.” 

One commenter (258) stated that the language that owners/operators must operate and 

maintain their stationary CI ICE according to the manufacturer’s “written instructions” 

over the entire life of the engine can be vague and confusing. The commenter asked what 

“written instructions” EPA is referring to. The commenter said that manufacturers often 

develop stock manuals that can be very conservative. Others may develop, at the request 

of the purchaser, site-specific operation and maintenance instructions. The commenter 

asked which set of instructions would apply. The facility, in consultation with the 

manufacturer, might develop its own O&M instructions. This happens often in Alaska 

due to the extreme climatological conditions and the remoteness of many facilities. Since 

the instructions are the result of a joint effort, the commenter asked if these could be 

considered manufacturer’s written instructions with which a facility can elect to comply. 

The commenter suggested modifying the rule (perhaps by defining “manufacturer’s 

written instructions”) permitting owners/operators the flexibility with manufacturer’s 

written instructions as discussed above. There are also cases where manufacturers may 

fold, relocate, or otherwise change in a manner that makes updating of their instructions 

68
excessively difficult though such updating may be absolutely necessary due to conditions. 

A facility, in this case, may have to unilaterally modify the instructions and this would 

leave them vulnerable to charges of violating the rule. The commenter suggested 

including language that allows owners/operators to change instructions so long as 

consultation with EPA occurs. 

One commenter (259) requested that EPA revise the provisions that require 

owners/operators to follow manufacturer O&M procedures. Engine operators should be 

allowed to use O&M practices that have been developed by the owners/operators to 

address the specific challenges, rigor, and accessibility of their application. The 

commenter cited two State permits (in Alaska and Colorado) that allow this for stationary 

engines. For example, the following example text is included within Alaska title V 

permits: 

Good Air Pollution Control Practice 

The Permittee shall do the following for Emission Unit ID(s) [insert ID number]: 

a. perform regular maintenance considering the manufacturer's or the operator's 

maintenance procedures; 

b. keep records of any maintenance that would have a significant effect on 

emissions; the records may be kept in electronic format; 

c. keep a copy of either the manufacturer's or the operator's maintenance procedures. 

In addition, text from a Colorado permit references a maintenance plan and indicates: 

69
• These engines shall be operated and maintained in accordance with the 

manufacturer’s recommendations, Company’s internal policies, and industry 

standards. Maintenance activities are typically performed based on the number of 

“fired hours” or as indicated by engine analysis results. 

• Records of all maintenance and overhauls performed on the engines will be 

maintained. 

This example indicates that on-site inspection and analysis, i.e., on-site factors unknown 

to the vendor is integral to maintenance decisions. Both of these examples provide the 

owner the necessary control over operational decisions that should not reside solely with 

the manufacturer, while ensuring that proper procedures are followed and significant 

maintenance activities are documented.

Response: EPA disagrees that the requirement for owners and operators to follow the 

manufacturer’s instructions is onerous. EPA believes the requirement is justified and 

appropriate, especially in the absence of a requirement to conduct performance testing. 

EPA does not believe that operating and maintaining an engine and control device, 

according to established written instructions by the manufacturer, is a burdensome 

requirement. This requirement provides a reasonable level of assurance that the emission 

standards continue to be met during engine operation in the field, in the absence of any 

emission limits applicable to the owner and operator. However, EPA recognizes that 

there may be instances where an owner or operator may tweak or alter the manufacturer’s 

typical guidelines, to address site-specific conditions. In such case, a site may have a 

different set of instructions to follow during operation and maintenance that vary from 

70
the original manufacturer recommendations. EPA believes it is acceptable to allow 

owners and operators to follow instructions that were developed to address needs not 

covered in the manufacturer stock manual. However, the modified operation and 

maintenance instructions must have been developed in conjunction with the engine 

manufacturer and both parties must have agreed to the modified set of written 

instructions. During the useful life of the engine, it is ultimately the engine manufacturer 

who is responsible for meeting the limits. Therefore, it is extremely important that the 

procedures followed are supported by the engine manufacturer. EPA has specified in the 

final rule that owners and operators must operate and maintain their stationary CI engines 

in accordance with the manufacturer’s written instructions, or according to procedures 

developed by the owner or operator that are approved by the engine manufacturer. 

 

7.1.2 Comment: One commenter (266) cited section III.E.3.a of the preamble to the 

proposed rule, which contains the proposed standards for owners/operators of stationary 

CI engines with a displacement of less than 30 l/cyl. The commenter stated that the 

owners/operators are required to perform maintenance on the engines as recommended 

by the manufacturer, which should be sufficient to ensure the emission standards are met 

over the entire life of the engine. It should not be necessary for the owners/operators to 

validate with additional testing the emission standards if the engine is maintained. 

Response: The section that the commenter is referring to discusses the proposed 

standards for stationary CI engines with a displacement less than 30 l/cyl. The owners 

and operators of these engines are not required to conduct testing in order to demonstrate 

71
compliance with the emission standards. Testing is one option for demonstrating 

compliance. However, other options are available, such as purchasing a certified engine 

or keeping records of data from the engine manufacturer. Once the 2007 MY begins and 

all such engines are required to be certified by the manufacturer, there are no testing 

requirements for owners and operators. 

7.1.3 Comment: One commenter (267) suggested that an engine manufacturer is best 

suited to make recommendations with respect to the maintenance of its product, and that 

additional maintenance requirements should not be imposed on those customers by EPA 

or any other agency. The manufacturer recommendations would apply to the entire life 

of the engine, as drafted in the proposal. It would be unnecessary for the 

owners/operators to validate those requirements with additional testing and emission 

standards, so long as the engine is maintained pursuant to the recommendations of the 

manufacturer. 

Response: EPA is not imposing additional maintenance requirements beyond those 

recommended by the engine manufacturer or those developed by the owner/operator in 

cooperation with the engine manufacturer. 

72
7.2 Pre-2007 Model Year Engines and Engines that Conduct Performance 

Testing 

7.2.1 Comment: One commenter (240) stated that all that should be necessary to 

demonstrate compliance for owners/operators of pre-2007 MY engines is that the 

manufacturer provide access to the original parent engine certification data and related 

engine model listings on request. The commenter stated that this issue needs to be 

resolved (perhaps through issuance of EPA guidance) well in advance of April 1, 2006, 

and prior to issuance of the final NSPS, since requirements pertaining to pre-2007 MY 

engines will take effect on April 1, 2006. 

Response: In the proposed rule at §60.4211(b), several options were provided for owners 

and operators of pre-2007 MY engines to demonstrate compliance with the emission 

standards. One of these options was to keep records of engine manufacturer data 

indicating compliance with standards (§60.4211(b)(3)). These provisions have been 

retained in the final rule. EPA does not believe it would be a significant effort for owners 

and operators to maintain records of this information and does not agree with the 

commenter that it is sufficient for the engine manufacturer to provide access to the 

information. Original parent engine certification data would be acceptable information to 

show compliance, consistent with EPA’s regulations regarding engine families; however, 

the owner or operator must maintain a copy of this information in order to comply with 

the regulation. 

73
7.2.2 Comment: One commenter (240) expressed that any potential initial performance 

testing of stationary CI engines to assess compliance with the nonroad not-to-exceed 

(NTE) standards (see §§60.4211(b)(3)5 and 60.4212(b) of the proposed rule) should not 

be required until the NTE standards begin to take effect for nonroad engines under 40 

CFR part 1039. 

Response: EPA believes that it is appropriate to require that owners and operators of 

stationary CI ICE with a displacement of less than 30 l/cyl who conduct testing to 

demonstrate compliance be required to demonstrate compliance to NTE standards. The 

NTE standards are less stringent than the standards that apply to certified engines, to 

allow for the fact that testing may occur over different use conditions than the specific 

conditions required for certification testing. Engines subject to 40 CFR parts 89 and 94, 

in addition to pre-2007 MY engines, must meet NTE requirements if the owner or 

operator conducts testing. Alternatively, these engines may be tested using the provisions 

specified for engines with a displacement of greater than or equal to 30 l/cyl. This 

change is reflected in the final rule. The final rule does not require any owner/operator 

testing for certified engines, including, for engines with displacement of less than 30 

l/cyl, all model year 2007 and later engines and those pre-2007 model year engines that 

are certified. For those engines that are not certified, no other testing is required for such 

engines, so performance testing is justified. In the proposed §60.4212, EPA intended to 

include engines subject to 40 CFR part 94 and this correction has been made to the final 

rule. Engines subject to 40 CFR part 1039 must meet the NTE requirements of that part. 

EPA has clarified in §60.4212(b) of the final rule that the requirements of that section 

 

5

 EPA contacted the commenter and clarified that the commenter meant §60.4211(b)(5) and not (3). 

74
will start when NTE requirements take effect for nonroad diesel engines under 40 CFR 

part 1039. 

7.2.3 Comment: One commenter (258) asked that EPA clarify the applicability of 

§60.4214(a) through (c) of the proposed rule. As written, it appears the paragraphs can 

be construed to cover engines manufactured prior to April 1, 2006. The commenter 

suggested that one way to rectify this is to modify the definition of stationary internal 

combustion engine to exclude those manufactured prior to April 1, 2006. 

Response: Section 60.4212 of the proposed rule applies to owners and operators of 

stationary CI engines with a displacement of less than 30 l/cyl that are subject to this 

subpart that conduct performance tests to demonstrate compliance with the rule. Based 

on the applicability in §60.4200 of the proposed rule, it is possible that engines 

manufactured prior to April 1, 2006 could be subject to the requirements in §60.4212, but 

only if the engines commence modification or reconstruction after July 11, 2005. New 

engines that commence construction after July 11, 2005, but that are manufactured prior 

to April 1, 2006, would not be affected by this rule. EPA has clarified the applicability 

language in §60.4200 of the final rule. 

7.3 Load 

7.3.1 Comment: Two commenters (259, 261) requested that for performance tests 

conducted by the owners/operators, EPA should specify that the NOx emission standards 

only apply at full load and that performance testing shall be conducted at 90 to 100 

75
percent of site rated maximum load or maximum attainable load. The commenters did 

not specify which particular performance testing requirement they were referring to, but 

provided, as an example of required performance testing, the annual performance test 

requirement for engines with a displacement of greater than or equal to 30 l/cyl. 

The commenters also had concerns that since certification is only valid for the “useful 

life” and the operating life for stationary engines may far exceed the “useful life” based 

upon mobile source standards, that additional testing requirements will be instituted at the 

State or local level. Thus, it is important that engine operating conditions for 

performance tests be identified, according to the commenters. 

Response: The commenters did not provide any data supporting the claim that 

performance testing should be conducted at high load. The in-use testing (NTE) 

requirements specify that engines be run as they are run in actual use, so that if an engine 

only runs at full load it will be tested at full load, but if it runs on other loads, it can be 

tested at other loads. State and local agencies are not prevented from providing 

additional regulations beyond these regulations and such agencies may institute 

additional testing requirements independent of EPA related actions. EPA believes that 

the reference to the nonroad testing regulations for engines with a displacement below 30 

l/cyl is an appropriate guide for other regulatory entities. For engines with a 

displacement of greater than or equal to 30 l/cyl, EPA agrees with the commenter that 

performance testing should be conducted at high load. These engines are required under 

the rule to conduct performance testing. For similar regulations, EPA specified that 

performance testing to demonstrate compliance should be conducted at high load, e.g., 40 

76
CFR part 63, subpart ZZZZ and 40 CFR part 60 subpart KKKK, for stationary engines 

and turbines, respectively. EPA believes it is appropriate to specify that performance 

testing for engines greater than or equal to 30 l/cyl should be conducted at high load. The 

emissions performance data that EPA reviewed and used to establish the final emission 

limits are based on operation at full load. In addition, although the performance of 

controls devices may be different at lower loads, EPA expects that if the emission 

limitations are achieved at high load, then the technology will be operating appropriately 

and will also operate appropriately at lower loads. The final rule has been written to 

specify that performance testing of stationary CI ICE with a displacement of greater than 

or equal to 30 l/cyl must be conducted within 10 percent of 100 percent peak (or the 

highest achievable) load. 

77
7.4 Engines with a Displacement of ≥30 Liters per Cylinder

7.4.1 Comment: One commenter (234) expressed that requiring annual source testing for 

non-emergency engines with a displacement of greater than or equal to 30 l/cyl is an 

exceptionally costly requirement. In Alaska, these costs are exacerbated by the 

remoteness of some of the installed engines. Even simple source tests require several 

days of travel by air to remote areas with all required test equipment. Some equipment 

cannot even be shipped by air, such as compressed calibration gases used for Relative 

Accuracy Test Audits of NOx continuous emission monitoring systems (CEMS). These 

gases and other chemicals may require shipping by barges, which only seasonally serve 

remote areas in Alaska. The commenter suggested that the applicable regulatory agency 

determine the source testing requirements that consider location, costs, intended 

operation of the unit and the agency’s ability to assure continuous compliance with 

applicable standards. 

Response: EPA disagrees with the commenter and believes it is appropriate to require 

annual source testing from non-emergency stationary CI engines with a displacement of 

greater than or equal to 30 l/cyl. These engines are not certified engines like the majority 

of new CI engines covered by this rule would be. For that reason, it is necessary to 

include requirements that will ensure that the emission standards are met. Source tests 

are the best way to demonstrate compliance with the emission standards. EPA is 

requiring other smaller CI engines to conduct source testing to demonstrate compliance 

with standards, e.g., engines subject to standards under 40 CFR part 63. Other units with 

high displacement located in Alaska are subject to source testing to show compliance 

78
with emission limits, e.g., engines operating at the Nome Joint Utility System Snake 

River Power Plant. Regarding the comment relating to the cost of source testing, EPA 

reviewed information the commenter submitted containing the technical analysis report 

for the Snake River Power Plant (available from the rulemaking docket). The annual 

operating cost estimate in that analysis presented total annual source test costs for three 

Wartsila 12V32 engines of $31,500 per year. Per engine, this equates to about $10,000 

per year. This cost is consistent with other cost information EPA has received from a 

testing firm indicating that to test one engine for PM and NOx (and other pollutants) 

using EPA methods and conducting three 1-hour test runs at three different operating 

loads would cost $15,000. Based on source test costs EPA has available, EPA does not 

believe the costs are exceptionally high. EPA understands that engines located in rural 

areas may be at a disadvantage compared to engines located in non-rural areas. The 

commenter stated that testing is an exceptionally costly requirement (and can be 

exacerbated by the remoteness of some engines), but did not provide any information 

demonstrating that the costs are particularly high. In the absence of specific cost 

information, EPA does not believe it is appropriate to discount the cost information in the 

record based solely on a statement made by the commenter. Manufacturers of high 

displacement engines have told EPA that an initial performance test followed by annual 

performance tests are appropriate (see comment 7.4.3). The requirement to conduct 

annual performance testing to demonstrate compliance with the emission limits for nonemergency engines with a displacement of greater than or equal to 30 l/cyl has been 

retained in the final rule. 

79
7.4.2 Comment: One commenter (240) stated that §60.4211(d)(3) of the proposed rule 

should be revised to make it clear that annual performance tests will only be required for 

non-emergency engines with a displacement of greater than or equal to 30 l/cyl. 

Response: EPA has made it clear in §60.4211(d)(3) of the final rule that the requirements 

of that section apply to non-emergency CI engines with a displacement of greater than or 

equal to 30 l/cyl. 

7.4.3 Comment: One commenter (235) said that the proposed rule requires that 

owners/operators of engines with a displacement of greater than or equal 30 l/cyl 

demonstrate compliance by first conducting an initial performance test and then 

establishing parameters to be monitored on a continuous basis. Performance tests are to 

be conducted on an annual basis. This is a logical approach, according to the commenter. 

The commenter provided a reference to a document6 that lists some process parameters 

such as intake air humidity recording for NOx indication, etc., which will support the 

proposed approach. 

Response: No response is necessary. 

7.4.4 Comment: Two commenters (259, 261) were of the opinion that the requirement 

that units with a displacement of greater than or equal to 30 l/cyl petition EPA for 

 

6

 The commenter referred to appendix 4, chapter 3, “Alternative approach to CEMS” of CIMAC 

Recommendation – Standards and Methods for Sampling and Analysing Emission Components in Nonautomotive Diesel and Gas Engine Exhaust Gases – Marine and Land Based Power Plant Sources, CIMAC 

Working Group on Exhaust Emissions, February 2005, available from 

”http://www.cimac.com/services/Index1-techpaperdatabase.htm. 

80
parameter monitoring requirements is onerous and should be replaced with reasonable 

monitoring requirements, such as periodic testing. 

Response: EPA does not agree and believes it is appropriate to require parameter 

monitoring for stationary CI engines with a displacement of greater than or equal to 30 

l/cyl. Affected units are very large power plants and EPA does not think that parameter 

monitoring requirements would be onerous for such sources. In fact, commenter 235 

agreed with this approach. Periodic testing is also required for non-emergency engines 

on an annual basis. However, to ensure that the emission standards are being met on a 

continuous basis, EPA believes that parameter monitoring is a reasonable and not a 

burdensome requirement. Once parameters to be monitored have been established, 

recording the information would require minimum effort, and is not an onerous 

requirement for the owner or operator. EPA decided not to specify which specific 

parameters to monitor because the appropriate parameters may be different for each 

engine. Allowing owners and operators to petition for their own specific parameters to 

monitor provides flexibility and allows sources to determine the most appropriate 

indicators of emissions performance. The most appropriate parameters to monitor may 

differ based on factors such as engine size, location of the engine, fuels, and controls 

used. EPA has retained this requirement in the final rule. 

7.4.5 Comment: One commenter (234) said that the requirement for owners of units 

greater than or equal to 30 l/cyl to petition the Administrator for approval of operating 

parameters will produce hundreds of petitions from Alaska alone. Petitioning the 

81
Administrator will cause considerable delay in obtaining approval, and adequacy of the 

compliance plan is not easily deduced from the proposed rule. The commenter 

recommended reducing the number of parameters to be considered to fuel input, power 

input, a curve or linear equation of urea injection rate vs. either of the previous 

parameters (SCR), catalyst temperature (SCR), particulate trap delta P and electrostatic 

precipitator (ESP) voltage/sparkover rate (if ESP can be made “available”). Then, the 

commenter recommended that EPA require the owner to keep records of these parameters 

on file and available for review by the appropriate local regulatory agency. Section 

60.4211(d)(2) of the proposed rule is especially inappropriate for emergency engines. 

Compliance with engine emission standards is least important when considering 

emergency operation. The most important factors are the ability to start up and respond 

quickly when needed and operate reliably. The commenter suggested delegating 

authority for the rule to the applicable regulatory agency to determine source-specific 

requirements consistent with the title V or SIP program that considers location, costs, 

intended operation of the unit to assure continuous compliance with applicable standards. 

Response: The commenter did not provide any information to support the claim that 

owners of units greater than or equal to 30 l/cyl petitioning the Administrator for 

approval of operating parameters will produce hundreds of petitions from Alaska alone. 

It is EPA's understanding that there are just a handful of these units in the U.S. 

Therefore, EPA does not understand how this requirement can produce hundreds of 

petitions from only Alaska. The commenter also did not provide any data to support 

having fuel input, power input, a curve or linear equation of urea injection rate vs. either 

82
of the previous parameters (SCR), catalyst temperature (SCR), particulate trap delta P 

and electrostatic precipitator (ESP) voltage/sparkover rate as the only parameters that 

should be monitored. Therefore, EPA cannot respond to this comment. EPA does not 

agree that §60.4211(d)(2) of the proposed rule is especially inappropriate for emergency 

engines, because there are not likely to be many, if any, emergency engines of this large 

size, and any such engines will, when operational, be significant emitters. 

7.5 Startup, Shutdown, and Malfunction

7.5.1 Comment: One commenter (253) stated that the proposed rule appears to require 

compliance with the emission limitations at all times including periods of startup, 

shutdown, and malfunction (SSM). Most of the NESHAP and NSPS emission limits do 

not apply during SSM, e.g., 40 CFR part 60 subpart Dc, which does not require the 

owner/operator to comply with PM standards during periods of SSM (see 40 CFR 60.43c 

(d)). Consistent with other EPA regulations, EPA should clearly specify in the NSPS that 

the emission limits do not apply during periods of SSM. At a minimum, EPA should 

replace §60.4206 of the proposed rule with the following provision from 40 CFR 

§63.6605 of the NESHAP for stationary RICE: “You must be in compliance with the 

emission limitations and operating limitations in this subpart that apply to you at all 

times, except during periods of startup, shutdown, and malfunction.” 

Response: It is correct that the regulation requires compliance at all times for the 

majority of engines. This approach is reasonable considering the main structure of this 

rule, which is a certification program through engine manufacturers. Owners and 

83
operators must operate and maintain the stationary CI engines in accordance with the 

manufacturer’s written instructions or procedures developed in conjunction with and 

approved by engine manufacturers, as specified in §60.4211(a) of the final rule. EPA 

does not believe that this requirement should not apply during periods of startup, 

shutdown, and malfunction. The written instructions should be followed by the owner 

and operator at all times to ensure compliance with the emission standards of this rule. 

However, for engines with a displacement of greater than or equal to 30 l/cyl, consistent 

with previous regulatory decisions such as the NESHAP for stationary RICE, these 

engines are not required to meet the emission standards during periods of SSM. The final 

rule has been revised accordingly. Although these engines are exempt from meeting 

emission standards during periods of SSM, the engines must, at all time, including 

periods of SSM, operate in a manner consistent with good air pollution control practice 

for minimizing emissions. This requirement is consistent with §60.11(d) of the General 

Provisions. 

84
8.0 Add-on Controls 

8.1 Comment: One commenter (226) said that the statement on page 147

 that CDPF 

require ULSD in order to achieve 90 percent reduction of PM, carbon monoxide (CO), 

and non-methane hydrocarbons (NMHC) is incorrect. Sulfur tolerant coatings are 

available for both particulate filters and oxidation catalyst. The commenter added that 

the statement on page 228

 that NOx adsorber technology is a lower cost than SCR 

technology is questionable. According to the commenter, NOx adsorbers have a high 

initial cost due to the high platinum content, have not yet been proven durable in field 

applications, and have an associated fuel penalty due to the requirement for regeneration. 

Delivery and storage of urea for stationary applications is much less of an issue than for 

mobile applications. The commenter said that NOx adsorbers also are not sulfur tolerant. 

The commenter further stated that the use of ESP for PM reduction on large bore engines 

(displacement greater than or equal to 30 l/cyl) will not be as effective as using diesel 

particulate filters (DPF). They will not be very effective for any size diesel engines. 

Problems with collection of unburned fuel and lube oil which can foul the ESP elements. 

This fouling is very difficult to clean. The size of diesel particles can make the design 

and operating costs for an ESP high. The main reason DPF cannot be used in marine 

applications is due to the poor quality fuel used on ships. This will be corrected soon as 

the fuel quality for inland marine applications (ferries, barges, tugs, and dredging 

equipment) is quickly improving. For stationary applications in the U.S. this should not 

be an issue. If the exhaust temperature is too low for regeneration, an inline duct burner, 

 

7

 EPA believes the commenter is referring to page 14 of the Word Perfect version of the proposed rule, and 

not the Federal Register notice, which would be page 39872. 

8

 EPA believes the commented is referring to page 22 of the Word Perfect version of the proposed rule, and 

not the Federal Register notice, which would be page 39874. 

85
electric heating element, or supplemental fuel injection across an oxidation catalyst can 

be employed to periodically raise the exhaust temperature. 

Response: The commenter did not provide any data to support the claims made in the 

comment. EPA is following the approach for nonroad diesel engines as much as possible 

to ensure consistency between rules. Manufacturers have indicated that they often 

produce the same engine for nonroad and stationary use. EPA, therefore, believes it is 

important that the requirements are as similar as possible to reduce the burden on engine 

manufacturers and to prevent delays. Regarding the claims about sulfur tolerant coatings, 

the commenter provides no information supporting its claim. On the other hand, there is 

voluminous information, including information used to support EPA’s on highway and 

nonroad diesel engines rules and this rule, that indicate that levels of sulfur beyond 

ULSD levels can interfere with regeneration and can cause clogging of catalyzed PM 

filters. The commenter also notes the adverse effect sulfur in fuel would have on NOx 

adsorber technology. Higher sulfur levels in fuel will also increase levels of sulfur 

dioxide and sulfate particulate in the exhaust. See also the comments of commenter 244 

on this issue. Regarding the relative benefits of SCR technology compared to NOx 

adsorber technology, EPA does not dictate which control technologies to use to comply 

with the emission standards. Engine manufacturers are free to apply the type of control 

they believe is appropriate that will achieve the required reductions and emission 

standards. The NOx adsorber technology is just one technology that can be utilized to 

meet the emission standards; other technologies such as SCR could potentially be used to 

meet the standards as well. EPA agrees that both technologies are available for use to 

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meet the standards in this rule. For engines with a displacement of greater than or equal 

to 30 l/cyl, EPA is not requiring that owners and operators use ESP to comply with the 

standards. EPA is not prohibiting the use of CDPF to meet the emission reduction and 

limit; indeed, EPA would welcome the use of such technology if it is shown to be 

feasible and dependable for such engines; however, the numerical standards are based on 

the use of ESP. It is up to each individual owner or operator to determine which 

technology it believes would be best suited for their specific application that would meet 

the standards, and owners and operators are free to use CDPF if they prefer, as long as 

the emission standards are met. 

 

8.2 Comment: Two commenters (259, 261) disagreed with EPA that SCR is technically 

and economically feasible for application to engines. The application of SCR to engines 

has been limited in scope and only limited testing has been conducted for engines with 

SCR. The efficiency of SCR was another aspect the commenters were in disagreement 

with EPA on. The commenters could not find any support in the docket for a 90 percent 

NOx reduction with SCR. The commenters referred to other EPA related actions where 

EPA had presented different conclusions regarding SCR applicability. The commenters 

recommended that EPA provide proper context regarding SCR application (i.e., baseload 

operation) for this standard and consider the potential deleterious effects from technology 

issues such as robust control of the reagent feedrate in a varying exhaust. The 

commenters said that EPA should revise the SCR-based NOx standard for units with a 

displacement of greater than or equal to 30 l/cyl. 

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Response: Regarding SCR, EPA believes, based on information reviewed, that it is a 

technically and economically feasible control technology for stationary CI engines. 

Several successful installations of SCR have been documented on stationary CI engines 

as documented in the rulemaking docket. In a meeting with European manufacturers, 

EPA was presented with a list of SCR applications to large displacement engines in 

several locations. Nearly all these engines cited NOx emission reductions of at least 90 

percent (EPA-HQ-OAR-2005-0029-0146). EPA evaluated the cost of SCR control per 

ton of NOx removed and determined that the cost per ton was reasonable. More 

information on this analysis can be found in the rulemaking docket in the memorandum 

entitled “Emission Standards for Engines with a Displacement of >30 Liters Per 

Cylinder.” The commenters stated in their letters that source tests included in the docket 

showed that performance testing conducted on two engines equipped with SCR showed 

one engine achieving 85.0 to 86.5 percent reduction and the other achieving 90.7 to 94.2 

percent reduction for NOx. The engines that were tested were Cummins QSK60-G6 

diesel engines (rated at about 2,700 hp). The correct citation for this test report is EPAHQ-OAR-2005-0029-0043. However, there are also source tests in the docket for several 

Caterpillar 3516B diesel engines with SCR (EPA-HQ-OAR-2005-0045). Test results 

from two of these engines equipped with SCR showed NOx reduction efficiencies 

ranging from 91.1 to 91.8 percent reduction for one engine, and 93.1 to 95.2 percent 

reduction for another engine. Engine manufacturers and control technology vendors have 

also indicated that NOx reduction of 90 percent with SCR on diesel engines is possible 

(EPA-HQ-OAR-2005-0029-0036, 0038, 0044 and 0055). In early 2004, catalyst vendor 

Miratech indicated that is had installed between 70 to 80 SCR systems on stationary 

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engines in the U.S., and more than 1,000 installations worldwide (EPA-HQ-OAR-2005-

0029-0051). For the final nonroad CI engine rule, EPA stated that there are several 

stationary diesel generator sets currently using SCR (69 FR 38979). In addition, EPA 

stated in the Final Regulatory Analysis for nonroad CI engines that SCR can reduce NOx 

emissions by more than 90 percent.9

 This was supported by a test program conducted by 

the Manufacturers of Emission Controls Association (MECA) conducted on a 1998 12.7 

liter Detroit Diesel 400 hp Series 60 engine.10 As summarized in the below comment 

from commenter 244, the commenter discussed real life successful experience with SCR 

on stationary engines. Commenter 244 indicated in the comment letter that SCR is a 

proven technology and has recently been applied to mobile sources such as trucks, marine 

vessels, and locomotives. The technology is expected to be used on mobile CI engines in 

Europe to meet European NOx emission standards. Commenter 244 stated in their 

comment letter that since the mid-1990s, SCR technology using urea-based reductant has 

been used on various marine applications in Europe including installations such as 

ferries, cargo vessels, and tugboats totaling more than 100 systems on engines ranging in 

size from 450 to 10,400 kW. The commenter also stated in their comment letter that in 

2001, a gantry crane powered by a 850 kW diesel engine was equipped with SCR and 

DPF in California. The combined control system was expected to reduce PM by 85 

percent and NOx by 90 percent. In addition, commenter 244 stated that a similar 

combination system has been installed on stationary diesel power production engines in 

 

9 Final Regulatory Analysis: Control of Emissions from Nonroad Diesel Engines. Environmental 

Protection Agency, Office of Transportation and Air Quality. EPA420-R-04-007. May 2004.

10 Demonstration of Advanced Emission Control Technologies Enabling Diesel-Powered Heavy-Duty 

Engines to Achieve Low Emission Levels. Final Report. Manufacturers of Emission Controls Association. 

June 1999. 

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Southern California. These engines were Caterpillar 3516B engines. The commenter 

also cited a 2004 announcement by Volvo, which stated that the company has launched a 

combined SCR/DPF system on their diesel transit buses to meet European emission 

limits. Similar applications have also been employed in the U.S., according to 

commenter 244. Further details can be found in the commenter’s letter to EPA. A recent 

article published in Power, stated that diesel engines routinely achieve 90 percent NOx 

reduction; sometimes higher reductions are possible (EPA-HQ-OAR-2005-0029-0203). 

Commenter 265 indicated in their state-of-the-art (SOTA) manual that NOx reductions of 

90 to 98 percent are possible with SCR. EPA is finalizing a NOx emission standard for 

engines with a displacement of greater than or equal to 30 l/cyl of 1.6 g/kW-hr (1.2 g/hphr). EPA believes the proposed NOx standard of 0.40 g/kW-hr (0.30 g/hp-hr) was too 

stringent. EPA is also finalizing the proposed NOx percent requirement of 90 percent. A 

source must meet either of these requirements, but need not meet both. EPA explains its 

reason for changing the emission standard and the appropriateness of increasing the NOx 

standard for large displacement engines in the responses to comments in section 16.5. 

Regarding the comment related to other EPA related actions, which occurred several 

years ago, newer information EPA has obtained indicates that SCR is a viable control 

strategy for these engines. As discussed in this response to comment and demonstrated 

by several successful installations, SCR is a technology that is feasible on stationary CI 

engines, and EPA strongly believes that SCR is BDT for engines with a displacement of 

greater than or equal to 30 l/cyl and as summarized here and as documented in the 

docket, 90 percent reduction with SCR is clearly possible. 

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8.3 Comment: One commenter (244) provided summaries including capabilities and 

experience for a variety of emission control technologies including DPF, SCR, NOx 

adsorbers, lean NOx catalysts, exhaust gas recirculation, and diesel oxidation catalyst 

(DOC) and crankcase emission control technologies. 

Response: EPA appreciates the detailed discussion of control technologies provided in 

this comment. EPA agrees that DPFs are commercially available today and have already 

been used in numerous applications, including stationary applications. EPA agrees that 

SCR technology is a proven NOx control strategy for stationary sources and for diesel 

engines in general. EPA also agrees with comments related to DOCs, NOx adsorbers, 

lean NOx catalysts, exhaust gas recirculation, and crankcase emission controls. 

9.0 Research and Development 

9.1 Comment: One commenter (229) requested that EPA exempt stationary CI engines 

used solely for the purpose of testing, research, and development from the requirements 

of the rule. 

Another commenter (262) said that there are certain circumstances in which the 

owner/operator of stationary CI ICE must deviate from the engine manufacturer’s 

recommended operating and maintenance parameters in order to perform research related 

to a variety of issues. Commenter 262 requested that a provision be included that 

exempts engines used in various types of research studies. This commenter added that 

the number of engines utilized for these purposes is small when compared to the total 

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number of stationary CI ICE currently in use. These engines are also smaller engines in 

most cases, typically less than 500 hp, and are not normally operated on a 24-hour per 

day, 7 day per week basis. Therefore, such an exemption would have a negligible impact 

on the expected emission reductions that will be achieved by the proposed changes. 

Response: EPA agrees with the commenters that it is appropriate to exempt stationary CI 

engines used for research and development purposes. A provision exempting such 

engines is already included for the nonroad regulations parts 89 and 1039. In those 

provisions, the engines are referred to as test engines. EPA refers to various parts of the 

nonroad regulations and the specific sections of the nonroad regulations that address 

research and development engines are 89.905 and 1068.210 apply to stationary engines 

covered by this rule. 

10.0 Definitions 

10.1 Emergency 

10.1.1 Comment: One commenter (236) said that because there is no time limit on the 

use of an emergency CI engine in emergency situations, it will be critical that both the 

operators of these emergency generators, and the authority having jurisdiction enforcing 

this rule, both have a common understanding of the term “emergency situation.” In the 

healthcare community, an emergency situation is an unplanned event that requires a rapid 

response to minimize the negative impact to patient care outcomes. In addition to power 

outages, hospitals are highly susceptible to power fluctuations, which can cause erratic 

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operation of computer based diagnostics, therapeutic, and patient monitoring equipment. 

In response to fluctuating power conditions hospitals must manually start their 

generator(s) and transfer critical loads to maintain power reliability. During high power 

demand days hospitals may be requested by the local utility to run their generators to 

curtail (lessen) their reliance on utility power thereby stabilizing the power grid serving 

the community. The commenter urged that EPA clarify “emergency situation” with 

provisions for these scenarios. Hospital emergency generator systems are extremely well 

maintained so as to meet their charge of continuous standby operation. 

Another commenter (243) stated that EPA must provide an adequate definition of what 

constitutes an “emergency.” Suggested elements of the definition of and “emergency” 

and “emergency generator” are provided in the comments. 

Another commenter (238) was of the opinion that the definition of emergency engines is 

incomplete. This definition does not adequately describe emergency situations or allow 

facilities that produce their own power to use emergency engines if their own power 

generation sources go off-line or down. The commenter recommended the following 

definition: “A stationary internal combustion engine that operates as a mechanical or 

electrical power source only when the usual supply of power is unavailable, and operates 

for no more than 500 hours per year. The 500 hours of annual operation for the engine 

include operation during emergency situations, routine maintenance, and routine 

exercising (e.g., test firing the engine for one hour a week to ensure reliability). 

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Stationary internal combustion engines used for peak shaving generation are not 

emergency power generating stationary internal combustion engines.” 

One commenter (267) said that EPA should include fire and other situations that would 

call for interruption of power and necessitate ancillary generator operation in the 

definition of emergency engines. Vague regulatory language not only compromises 

environmental quality and the public, but it adds to the operation costs of facilities. 

Vague regulatory language also spawns litigation when interested parties begin to dispute 

the meaning of a given rule. Legal disputes hinder environmental protection and add 

more costs to doing business, by causing delays in implementation and creating a climate 

of investment uncertainty. 

One commenter (269) assumed that a generator (at a manufacturing facility) is considered 

an “emergency” generator if its primary purpose is to handle: 1) Power 

outages/interruptions to allow continued operation of emergency lights, fire protection 

systems, water supply pumps, computers, etc., 2) Testing activities to test periodically to 

ensure the unit is still operational, and/or 3) Pending power losses when generators are 

operated to avert an imminent power loss or power spike resulting from poor weather 

conditions (i.e., approaching storm). However, would EPA still consider these same 

units “emergency” generators if they ALSO were on occasion, used to operate for peak 

shaving, the commenter asked. Peak shaving occurs during poor weather conditions such 

as extremely hot summer days or cold winter days where the facility will voluntarily, or 

at the request of the utility company, curtail energy usage. Since operation of these 

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generators for peak shaving is: 1) not its primary function, 2) triggered by unforeseeable 

conditions such as weather, and 3) an abnormal situation that does not occur on a regular 

basis, the commenter asked if the unit still is considered an “emergency” generator. 

One commenter (251) said that the discussion in section III.C.7 of the preamble to the 

rule should also include, as an example of an emergency situation, the use of emergency 

engines as critical backup operations for satellite tracking stations. Department of 

Defense standard operating procedures require the operation of standby generators during 

initial launches of satellite systems. These emergency stationary CI ICE ensure 

continuous critical communications that are necessary to prevent loss of facilities and 

flight hardware in case of a failure in the prime source of power. The use of CI ICE as 

critical backup operations for satellite tracking stations should be considered an 

“emergency situation” and, in accordance with §60.4211(e), the rule should not limit 

their use in these operations. The commenter proposed the following language be 

included under section III(C)(7) of the preamble to the final rule: “Examples of 

emergency operation also include backup power for initial launch tracking of U.S. 

Department of Defense flight hardware (in parallel with grid power), where the loss of 

normal power would cause damage to or loss of government facilities and/or flight 

hardware.” 

Another commenter (266) believed that site or facility related interruptions such as an onsite fire or other situations should be included in the definition of emergency engines and 

recommended that “a site or facility-specific interruption occurs” be added to the 

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definition of emergency engines. It should be specified that the maintenance checks and 

readiness testing should include those that are required by the NFPA. 

Response: EPA believes it has provided an adequate definition of emergency stationary 

internal combustion engine. EPA feels that it is not necessary to include more examples 

of emergency operation. To cover all possible scenarios that would constitute an 

emergency in the definition would be nearly impossible. EPA notes that fire pumps are 

already listed as an example of emergency engines, and engines that operate only during 

fires and other onsite emergencies would obviously qualify as emergency engines. 

Regarding power fluctuations, EPA understands there may be crucial needs at e.g., 

hospitals, to ensure power reliability. EPA agrees that power fluctuations would be 

considered an emergency situation. Also, it would not be appropriate to limit the time 

allowed to be spent during emergency operation (see discussion in section 3.0 of this 

document). EPA believes it would be appropriate to consider facilities that generate their 

own power in the definition of emergency engine and has revised the definition to add 

“or the normal power source, if the facility runs on its own power production,” to account 

for facilities which do not rely on power from the local utility. Consistent with other 

regulations for stationary engines, peak shaving is not considered emergency use. This 

issue is discussed in response to comments in section 17.0 of this document. Peak 

shaving is a relatively planned activity performed for basic energy generation during peak 

periods, not for unplanned emergencies like fires, floods, or natural disasters. In addition, 

peak shaving involves income generation, which is not an emergency activity. Further, 

engines can certainly be used for peak shaving, but if so, they are not considered 

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emergency engines and would not be exempt from meeting the more stringent 

requirements applicable to non-emergency engines. EPA has revised the definition of 

emergency engine to specifically state that engines used to supply power to an electric 

grid or that supply power as part of a financial arrangement with another entity are not 

considered emergency engines. EPA agrees with commenter 243 that any operation that 

is intended to supply power for distribution to the electric grid would not be emergency 

operation, like peak shaving, peaking powers units, or standby units. EPA believes that 

the definition of emergency engine is reasonably clear on this point. In response to the 

comment related to engines used for Department of Defense satellite launch backup 

purposes, these are likely to be exempt under national security exemptions in parts 89 and 

1068, which EPA refers to in the rule for stationary engines. EPA believes this addresses 

the commenter’s concern regarding engines used for such purposes. EPA agrees that 

maintenance should be included in the definition. This is consistent with §60.4211(e) of 

regulation and EPA has incorporated this change into the definition of emergency engine 

into the final rule. 

10.2 Stationary Internal Combustion Engine 

10.2.1 Comment: One commenter (247) said that the definition of stationary internal 

combustion engine is confusing. The proposed §60.4216 says that a stationary ICE is one 

that is not mobile. It further states that a stationary ICE is not a nonroad engine as 

defined by 40 CFR 1068.30. The definition in 40 CFR 1068.30 contains two paragraphs: 

paragraph (1) describing engines that are nonroad engines and paragraph (2) describing 

exceptions. Paragraph (2)(ii) of 40 CFR 1068.30 excludes an engine subject to NSPS. 

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Thus an engine is excluded from the proposed NSPS as long as it is not subject to the 

proposed NSPS. 

The commenter wanted the part that says a stationary ICE is not a nonroad engine as 

defined by 40 CFR 1068.30 clarified to explain how to interpret the sentence in the 

nonroad engine definition in 40 CFR 1068.30 that says that an engine that is regulated 

under an NSPS is not a nonroad engine. Must engines described under paragraph (1)(iii) 

of the definition of nonroad engines in 40 CFR 1068.30 comply with the proposed NSPS 

and thereby lose their status as nonroad engines, the commenter asked. 

Response: A stationary internal combustion engine is any stationary internal combustion 

engine, except combustion turbines, that converts heat energy into mechanical work and 

is not mobile. Stationary ICE differ from mobile ICE in that a stationary internal 

combustion engine is not a nonroad engine as defined at 40 CFR 1068.30, and is not used 

to propel a motor vehicle or a vehicle used solely for competition. EPA agrees with the 

commenter that the definition in the proposal is somewhat unclear in that there appears to 

be mutual exclusions in the definitions of nonroad and stationary engines. EPA has 

revised the definition of stationary engine to exclude the reference to paragraph 2(ii) of 

the definition of nonroad engine. Thus, any engine meeting the substantive definition of 

a nonroad engine in part (1) of that definition, and not excluded under part (2)(iii) of that 

definition, would not be considered a stationary engine. Engines described under 

paragraph (1)(iii) of the definition of nonroad engine in 40 CFR 1068.30, and not 

excluded under section (2)(iii) of that definition, would be considered nonroad engines 

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and would not have to comply with the CI NSPS, which applies to stationary engines 

only. EPA believes this response addresses the commenter’s concerns. 

10.2.2 Comment: One commenter (265) recommended that the definition of stationary 

internal combustion engines be revised to include portable electric generating engines, 

which are connected to the commercial power grid for any time period. Some power 

companies have sought to use diesel generators for peak summer electric demand 

periods, trying to fit within the definition of nonroad engine. Any engine connected to 

the power grid should be considered a stationary source, whether or not it is moved prior 

to the time period specified within the definition of nonroad engine. The proposed 

definition appears to exempt all portable or transportable equipment remaining on site for 

less than 12 consecutive months, even if connected to the commercial power grid. 

Response: As stated in 40 CFR 1068.30(1)(iii), nonroad engine means that, by itself or in 

or on a piece of equipment, is portable or transportable, meaning designed to be and 

capable of being carried or moved from one location to another. Indicia of 

transportability include, but are not limited to, wheels, skids, carrying handles, dolly, 

trailer, or platform. Portable electric generating engines that remain in one location for 

less than 12 consecutive months are considered nonroad engines and are subject to 

requirements for nonroad engines. This definition is consistent with how EPA has treated 

nonroad and stationary engines in the past, and EPA does not believe it would be 

appropriate to alter the definition of a stationary engine to include engines that are 

portable that remain in one location for less than 12 consecutive months. 

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11.0 Rule Structure 

11.1 Comment: One commenter (238) made the comment that the layout of the proposed 

rule is hard to follow. The commenter recommended the rule be structured in the same 

manner as other NSPS rules, where the first section of the rule deals with applicability 

issues, the second deals with definitions, etc. The emission limits should be included in 

the rule in a clear and concise manner. It is not fair to the public to have to refer to other 

EPA regulations to determine which standards and provisions apply in any given 

situation. To the extent practicable, all provisions that are to apply to CI engines must be 

expressly presented in the NSPS. Placing the standards explicitly in the NSPS will avoid 

the risk of inadvertently incorporating something that works well for the manufacturerbased compliance and enforcement of mobile source regulations, but would not be 

compatible with permittee-based compliance enforcement for stationary regulations. 

E.g., mobile regulations contain tampering provisions that prohibit modification of 

emission control systems, even if the modification leads to lower emissions. This is 

incompatible with stationary source permitting where the source has a compliance 

responsibility and may need to upgrade the emission control system at some point during 

the life of the engine. For the same reasons, emission control systems upgrades cannot 

void manufacturer’s warranties. 

Another commenter (240) said that EPA should provide a summary chart in the final rule 

setting forth all the applicable emission standards and effective dates for emergency 

engines. 

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One commenter (264) urged EPA to clarify the emission standards contained in 

§60.4202(a) of the proposed rule. The proposed language consists of one extremely long 

sentence that incorporates several provisions from EPA’s Tier 3 and Tier 4 nonroad rules 

for diesel engines. This approach is very confusing and the commenter urged EPA to 

summarize the applicable requirements in a table. 

Response: EPA believes the structure of the rule is appropriate and is in general 

consistent with the layout of other NSPS rules. EPA has kept the references to other 

rules at a minimum, but certain references are necessary since those are the standards and 

requirements that stationary CI engines will have to comply with. The nonroad engine 

regulations generally require several separate sets of emission standards to be met, and 

there is little reason to copy them into a new part of the CFR. EPA wishes to limit 

repeating standards that can be found elsewhere. Furthermore, engine manufacturers, 

who for the most part will be the party subject to the emission standards are already 

familiar with the requirements in the regulations for nonroad diesel engines. Also, by 

referring to the emission standards in the nonroad rules (and marine rules) eliminates the 

need of having to potentially revise the NSPS rule should changes be made to the 

nonroad and/or marine rules. EPA intends to keep the stationary and nonroad diesel 

engine requirements consistent. Also, EPA is limiting repeating language and 

requirements that are already established in other parts. EPA has included as many 

provisions explicitly in the rule as possible to minimize referring to other rules and 

believes the references as proposed are necessary. EPA has included the emission 

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standards in the proposed rule for some engines where the emission standards may be 

different than those that apply for nonroad diesel engines. EPA agrees that §60.4202(a) 

of the proposed rule (specifying emission standards for emergency engines) could be 

difficult to understand. EPA has restructured §60.4202(a) in the final rule and believes 

that the requirements as written in the final rule can be clearly understood. EPA notes 

that EPA has generally enforced the tampering provisions of the CAA only when the 

modifications would tend to lead to increased emissions. 

11.2 Comment: One commenter (238) expressed that the limits for NOx + NMHC need 

to be amended to separate emission limits for NOx and NMHC or just establish a NOx 

limit. The key factor in determining what type of a permit a facility should apply for and 

what regulations may apply to a facility is a facility’s potential NOx emissions. In order 

to properly estimate the NOx emissions from CI engines, the NOx emission rate from 

these sources must be known. The term “HC” is not defined in table 1 of the proposed 

NSPS. 

Response: EPA does not agree with the commenter that there should be separate 

emission limits for NOx and NMHC. The combined NOx + NMHC limit is consistent 

with the limits for nonroad diesel engines, which helps to facilitate the certification 

program for stationary engines. In addition, NMHC is an ozone precursor and emissions 

of NMHC should therefore be regulated. Because NOx and NMHC are both regulated as 

ozone precursors and there can be an inverse relationship between reductions in NOx and 

NMHC, EPA believes that having a combined standard provides needed flexibility to 

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reduce total emissions of the two pollutants. Estimating the potential NOx emissions 

from a source for permitting purposes is outside the scope of this rulemaking and having 

a combined emission limit does not prevent sources from estimating their NOx 

emissions. EPA does not feel that it is necessary to define the term “HC” in table 1 of the 

proposed rule. 

12.0 Labeling 

12.1 Comment: One commenter (238) said that the label restricting certain engines to 

emergency use only could lead to confusion in cases where such engines are equipped 

with post-combustion pollution control equipment that meets all applicable standards. 

The wording on such labels needs to be flexible enough to account for this possibility. 

Response: The provisions in §60.4210(f) of the proposed rule were included because 

emergency engines are not required by the rule to meet emission standards that are based 

on the use of aftertreatment, so EPA expects that the majority of emergency engines will 

comply with the emission standards that do not require aftertreatment. Therefore, 

separate labeling of these engines is necessary to distinguish them from non-emergency 

engines. EPA understands that it may be possible that emergency engines may be 

equipped with aftertreatment controls. The provisions in §60.4210(f) of the proposed 

rule also account for this possibility. There is nothing in §60.4210(f) of the proposed rule 

that restricts an emergency engine to emergency use only if the engine meets the 

emission standards for non-emergency engines in §60.4201 of the proposed rule, and in 

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such case, a permanent label stating that the engine is for emergency use only is not 

required, as stated in §60.4201(f) of the proposed rule. 

12.2 Comment: One commenter (240) stated that the labeling requirements need to be 

fully coordinated and aligned with the labeling requirements under the nonroad and 

marine engine rules. In that regard, a single, uniform label should be utilized whenever 

feasible. Certification-type labeling of Tier 1 (or other prior Tier) engines should not be 

required. The proposal to make the labeling requirements of 40 CFR part 1068 

applicable to stationary engines in advance of Tier 4 requirements is inconsistent with the 

nonroad and marine engine rules (where the 40 CFR parts 89 and 94 labeling provisions 

will continue to apply to Tier 2 and Tier 3 engines) and so will create unique, inconsistent 

and unworkable labeling requirements for stationary engines. The commenter provided a 

chart summarizing certain principal labeling inconsistencies at issue under the pending 

proposal. 

Response: EPA generally agrees that the labeling requirements for stationary CI engines 

should be consistent with the nonroad and marine engine rules and that a single label is 

preferable whenever feasible. EPA agrees that labeling of certified engines meeting 

current part 89 or part 94 standards should meet the labeling requirements in those parts. 

EPA has revised the labeling requirements in part 1068 for non-certified engines or 

engines certified to earlier tiers and has clarified the labeling requirements in the final 

rule pursuant to discussions with the commenter . 

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13.0 Recordkeeping and Reporting 

13.1 Certification Records 

13.1.1 Comment: One commenter (250) said that it does not make sense for EPA to 

require owners/operators to obtain and keep the certification records as required in 

§60.4214(a)(2)(iii) of the proposed rule. The Office of Transportation and Air Quality 

(OTAQ) has the certification data for all certified nonroad diesel engines. Section 

60.4214(a)(1) of the proposed rule would require an owner/operator to submit an initial 

notification with the make, model, engine family, serial number, etc. Thus, EPA would 

have more than enough information from which to identify and access the certification 

information at OTAQ related to the particular stationary CI ICE, without requiring an 

owner/operator to obtain and maintain this information. 

Response: EPA disagrees with the commenter’s statement that it does not make sense for 

engine owners/operators covered by this requirement to keep documentation that the 

engine is a certified engine. EPA does not think that this is an unreasonable burden for 

engine owners and operators and also it allows other enforcing agencies such as States to 

have access to the information. EPA is not requiring that all certification data be kept, 

only that documentation of certification be kept. Also, §60.4214(a) of the proposed rule 

only applies to a limited number of engines and not all engines covered by the rule are 

subject to this requirement. In fact, the vast majority of engines will not be required to 

keep this information. Also, many of the engines covered by this requirement will not be 

certified (e.g. engines with displacement greater than 30 l/cyl and uncertified pre-2007 

105
engines), so the information regarding certification is relevant and important for engines 

subject to this requirement. 

13.2 Hour Meter and Other Compliance Requirements for Emergency Engines 

13.2.1 Comment: One commenter (238) was of the opinion that the owner/operator of 

emergency engines should be required to keep records of all situations, including 

emergency situations, when the engine is used, in order to determine compliance with an 

annual cap on the hours of operation. 

Another commenter (243) stated that if EPA promulgates different requirements for 

“emergency” engines, EPA must impose enforceable limits so these engines are used 

only in clearly defined emergencies. By exempting “emergency” operation from the 

reporting requirements, allowing emergency engines to run for an unlimited number of 

hours during “emergencies,” and failing to provide a definition of what constitutes an 

“emergency” situation, the proposed rule leaves a highly problematic loophole. To 

ensure compliance with the rule, EPA must require reporting for all operation of 

emergency engines, emergency situations as well as required testing. Many states require 

reporting of both emergency and non-emergency use, e.g., the California ATCM requires 

a monthly log of all operation by emergency engines. To ensure that reporting is required 

of the entire class of emergency engines, EPA must require that all emergency engines be 

registered with the Agency. The additional registration and reporting requirements will 

greatly enhance EPA’s ability to enforce the new rules and will discourage owners and 

106
operators from illegally purchasing engines that are certified only for emergency use, but 

operating them in non-emergency situations. 

One commenter (236) stated that thorough documentation of operating hours and 

operating conditions is currently maintained at hospitals. In recognition of this “already 

in place” practice of documentation, the commenter urged EPA to allow hospitals to 

document the “emergency situation” entire run conditions utilizing current logs, with no 

further data collection requirements (e.g., climatic data reports, service tickets, letters 

from utility companies, etc., are not required). 

Another commenter (266) stated that additional recordkeeping (above what is already in 

place) should not be required. 

Response: EPA is revising its recordkeeping requirements to require that an owner or 

operator of an emergency engine keep records of all operation of the emergency engine. 

This will ensure that there is documentation that the engine was operating in emergency 

situations when it was running beyond the annual limits permitted for maintenance and 

testing. There is no annual cap on the hours of operation during an emergency situation, 

but it is important to have documentation that such operation was indeed for emergency 

purposes. Commenters indicate that owners and operators of emergency already keep 

documentation of when and why such engines were operated. EPA’s recordkeeping 

requirement requires no more than this. EPA does not believe it is appropriate to require 

reporting (as opposed to recordkeeping) for emergency engines and believes requiring 

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such reporting would be a burdensome and unnecessary requirement. Given the number 

of emergency engines purchased each year (EPA estimates that more than 65,000 new 

stationary CI emergency engines will be sold in 2015) and the level of their usage, EPA 

believes that requiring reporting will create needless paperwork that will not result in 

substantial further enforcement. EPA believes the requirement for recordkeeping and the 

requirement for an hour meter will serve as a significant deterrent and a sufficient 

compliance tool. EPA is including an additional requirement in the final rule that owners 

and operators log all periods in which the emergency engine was used for emergency 

purposes and the nature of the emergency. If the owner or operator already keeps such 

information, which EPA believes (and commenters say) may often be the case, no more 

information would be needed to indicate emergency use. EPA does not believe it is 

appropriate to require registration of all emergency engines put into operation after the 

rule is in place. EPA believes that this would be a paper exercise of monumental 

proportions, given the number of engines that would need to register, with little practical 

result. EPA notes that State and local authorities may require more substantial 

compliance requirements in areas where such authorities believe it is appropriate. 

13.2.2 Comment: One commenter (240) stated that §60.4209(a) of the proposed rule 

should be revised to account for the fact that a non-resettable hour meter will not be able 

to distinguish between engine operation during maintenance and readiness testing, and 

engine operation during actual emergencies when hour limits on operation do not apply. 

The rule should simply require that the owner/operator keep records of engine operation 

during non-emergency situations utilizing a non-resettable hour meter. 

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One commenter (264) stated that it is not aware of a method that will accurately track the 

non-emergency hours of operation of an emergency engine. The non-resettable hour 

meter required in §60.4214(b) of the proposed rule cannot distinguish between 

emergency and non-emergency service. The commenter urged EPA to delete this 

provision from the rule. 

One commenter (259) recommended removing the requirement for an hour meter for 

emergency engines. Manual records will still be required to differentiate between 

emergency and non-emergency service, so a manual log of non-emergency run time is 

adequate. 

Response: EPA is not implying that the hour meter is capable of distinguishing between 

emergency and maintenance and testing operation. EPA expects that an operator or 

technician would be the one to distinguish between emergency and non-emergency hours 

and would record the hours of operation during non-emergency operation. The hour 

meter would have to be read prior to the start of maintenance and testing activities and at 

the conclusion of such activities, and the total hours spent during non-emergency 

operation would be recorded. This is what the rule requires to ensure that the 100 hours 

per year limit during non-emergency operation is not exceeded. EPA believes that it is 

appropriate to require that an hour meter be installed and does not agree with the 

commenter who recommended not including this requirement. Most stationary CI 

engines come equipped with an hour meter and EPA believes that requiring an hour 

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meter will not be a burdensome requirement. The use of the hour meter will ensure that 

the recorded hours are as accurate as possible and will eliminate the need to manually 

track the exact hours of operation. 

13.2.3 Comment: One commenter (250) made the comment that the requirement to keep 

records of the operation of the emergency engine in non-emergency service is 

inconsistent with how EPA regulates other new/reconstructed emergency stationary 

engines under 40 CFR part 63, subpart ZZZZ for stationary RICE. In that rule, EPA does 

not require new/reconstructed emergency RICE to meet any of the reporting and 

recordkeeping requirements of subpart ZZZZ or the General Provisions except for initial 

notification. Moreover, there is no provision in subpart ZZZZ of 40 CFR part 63 to 

maintain records of the non-emergency use of this equipment. The commenter did not 

see the environmental benefit to including this requirement in the CI NSPS. 

Response: The NSPS for stationary CI engines and the 40 CFR subpart ZZZZ for 

stationary RICE are completely separate rules. In subpart ZZZZ there is no time limit on 

the use of emergency engines for maintenance and testing, so therefore there is no need to 

require owners and operators to maintain records of this use. Furthermore, emergency 

engines do not have to meet any emission standards in that rule. However, in this rule, 

EPA is limiting the hours of operation during maintenance and testing, and to ensure that 

the non-emergency hours of operation limit is not exceeded, EPA is requiring that owners 

and operators record the hours spent during maintenance and testing and maintain these 

records. Clearly, this requirement yields environmental benefits since it will limit the 

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likelihood that sources subject to the rule that operate emergency engines would exceed 

the 100 hour annual non-emergency limit. In the absence of monitoring and 

recordkeeping requirements, this requirement would not be enforceable. For these 

reasons, EPA believes the requirement as proposed is appropriate. 

13.2.4 Comment: One commenter (267) strongly urged EPA to provide clear and 

reasonable recordkeeping requirements with respect to maintenance of stationary engines 

in order to reduce business costs, and assure consistency in the maintenance of stationary 

engines. The proposed rule caps engine testing at 30 hours per year, and 

owners/operators should not be required to keep records for testing beyond the amount of 

time specified within the proposal. 

Response: The commenter did not specify what provisions of the recordkeeping 

requirements are unclear or unreasonable, or how these requirements would increase 

business costs or lead to inconsistency in the maintenance of stationary engines. 

Therefore, EPA does not have any basis for addressing the commenter’s concerns. 

Regarding the commenter’s statement that owners/operators should not be required to 

keep records for testing beyond the amount of time specified within the proposal, EPA is 

unclear on what type of records the commenter is referring to. 

13.2.5 Comment: One commenter (243) claimed that EPA’s proposal failed to establish 

policies that enforce any meaningful distinction between emergency and prime engines. 

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The commenter states that the Federal and State regulators have extremely limited 

resources to track an engine’s use throughout its life in the stream of commerce. 

 

Response: EPA disagrees strongly with the commenter. EPA is imposing enforceable 

clear labeling requirements limiting emergency engines to emergency use only, if the 

engine is not certified to Tier 4 emission standards. This requirement is included in 

§60.4210(f) of the final rule. In addition, as noted above, EPA is requiring owners and 

operators to keep records of all operation of the emergency engines, and requires an hour 

meter to provide further verification. This requirement is intended to make records 

available to enforcing agencies to ensure that owners and operators do not operate outside 

of acceptable usage. EPA is also clarifying the regulations to state explicitly in section 

60.4211(e) that any operation other than emergency operation, and required maintenance 

and testing, is prohibited. EPA understands that, given the number of emergency engines 

in the country, it will be impossible to ensure that all engines always operate according to 

the regulations. This is true with regard to any regulation. However, the regulations 

provide considerable ability for enforcement agencies to check operation and the 

regulations, including the labeling requirement, provide ample warning that operation 

outside emergency conditions, other than required maintenance and testing, is prohibited. 

Given the penalties for violation of the NSPS, the requirements for recordkeeping, and 

the manner in which these engines are normally used, EPA does not believe that 

substantial nonconformance is likely. In addition, EPA has included a requirement in the 

final rule that engine manufacturers must specify in the owner’s manual that operations 

for emergency engines are limited to emergency operations and required maintenance 

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and testing. This will ensure that the engine is used appropriately and EPA believes that 

in most cases the engine manufacturers already include this. EPA also notes that 

emission reductions will be realized by emergency engines meeting Tier 2 and Tier 3 

emission standards, and it is not unlikely that some emergency engines will be certified to 

Tier 4 emission standards. Indeed, State and local authorities are not preempted from 

requiring emergency engines to meet more stringent standards, or more stringent 

compliance requirements, in areas where the local authority believe such regulation is 

appropriate. 

13.3 Notifications 

13.3.1 Comment: One commenter (259) questioned the necessity of the notification 

requirement. EPA solicited comment on notification for engines in addition to those 

specified in §60.4214 of the proposed rule, and the commenter believed that the 

notification requirements should not be extended beyond the units currently proposed. 

The commenter recommended deleting the notification requirements in §60.4214 in the 

proposed rule for all engines. The commenter did not understand the need for any 

notification requirements, as the owner/operator bears responsibility to conform to the 

requirements of the standard. In addition, other State or Federal programs will likely 

require a permitting action for larger engines that are also subject to subpart IIII. In 

response to EPA comment solicitation, at a minimum, the commenter recommended that 

notification requirements not be extended any further than currently proposed.

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Response: EPA proposed notification requirements for certain stationary CI engines in 

§60.4214(a) of the rule. As explained in the preamble to the proposed rule, an initial 

notification requirement is appropriate for those engines because many of those engines 

will not be certified engines. Certified engines are warranted by the engine manufacturer 

that it will achieve the certified engine emission levels for the useful life of the engine. 

Engines that have not been through the certification process will be required to 

demonstrate compliance with the emission standards in other ways. Owners and 

operators of non-certified engines will have to keep records indicating that their engine 

meets the emission standards. The initial notification requirement for these engines is 

intended to alert State and local agencies of the presence of these non-certified engines. 

Similarly, EPA felt that an initial notification requirement would be appropriate for very 

large engines, even if certified, because enforcing agencies may want to track these 

engines individually. Finally, engines with a displacement of greater than or equal to 30 

l/cyl are not required to be certified, therefore, an initial notification requirement for these 

engines is also appropriate. The initial notification requirement is not a burdensome 

requirement and EPA estimates that minimal effort would be involved in preparing and 

submitting an initial notification. The notification requirements remain as proposed in 

the in the final rule. 

14.0 Fire Pumps 

14.1 Comment: One commenter (239) said that the transition period which allows 

manufacturers the time necessary to have the Tier 3 units approved by Underwriters 

Laboratories and Factory Mutual is an excellent proposal. However, in the interest of the 

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environment, the commenter suggested that current production engines should be 

regulated to a minimum of Tier 1 standards, as this technology already exists. Pump 

manufacturers build vertical turbine, and horizontal split case pumps for fire pump 

service. They have the technology and are building today multi-stage vertical turbines 

and dual-stage split case pumps, which would supply the high pressures needed when 

using lower revolutions per minute (rpm) Tier 3 engines. High speed engines are not 

necessary for emergency fire pump duty. High speed Tier 3 engines already exist and are 

being manufactured by more than one major engine supplier. This can be confirmed by 

looking at the product availability from Deutz, Iveco, Caterpillar and others. It is the 

commenter’s opinion that the additional 3 year extension requested by commenter 248 is 

a marketing ploy, not in the interest of protecting the environment. The extension would 

allow commenter 248 to continue manufacturing their substandard engines for the next 6 

years, as commenter 248 knows that this commenter, and other corporations, will not be 

able to sell Tier 0, 1, and 2 engines since only Tier 3 engines will be manufactured and 

available from the engine suppliers. Commenter 248 would subsequently enjoy a 

monopoly in the marketplace on high speed engines because of the lower cost of building 

Tier 0 and Tier 1 engines. This commenter agreed with the intent of the proposal, but 

questions the motives behind the 3 year extension. 

Response: In response to the comment stating that EPA should regulate current 

production engines to a minimum of Tier 1 standards, as this technology already exists, 

EPA is regulating emergency fire pump engines to emission standards equivalent to Tier 

1 emission standards starting with engines manufactured on July 1, 2006. This means 

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that prior to complying with Tier 3 emission standards, all emergency fire pump engines 

will have to meet currently achievable emission standards. Regarding the comments 

pertaining to high speed emergency fire pump engine, information available from the 

rulemaking docket (see Document ID Number EPA-HQ-OAR-2005-0029-0098) shows 

that at least one commenter (248) uses high speed engines for certain emergency fire 

pump applications, and in fact, the commenter has indicated that it imports some engines 

from Italy for this purpose. While EPA believes that it may be possible for all fire pump 

engines to not be high speed, EPA does not have sufficient evidence at this time to 

promulgate regulations based on this belief. EPA does not disagree that there may be 

high speed Tier 3 engines available, but these are not designed for fire pump applications. 

EPA believes it is appropriate to allow additional time for high speed fire pump engines 

to reach compliance with Tier 3 emission standards and feels the emission standards and 

compliance dates are appropriate as proposed. 

14.2 Comment: One commenter (240) supported the two-prong approach proposed for 

fire pumps. The proposal recognizes that some fire pump engines are nonroad engines 

and others are specifically developed as fire pump engines. For those fire pump engines 

that are also nonroad engines, the maximum engine power is the power listed in the 

application for certification and the NFPA nameplate power is 10 percent less than the 

certified power. For those engines that have specifically developed fire pump ratings, the 

proposal calls for testing and certifying these engines to their NFPA nameplate power, 

while recognizing that the maximum power available during dynamometer testing is 10 

percent higher than this power. The commenter agreed with this approach. To utilize 

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this option, EPA proposes requiring that the engine manufacturer “certify that the engine 

will not be used in any application that allows higher hp and provided that the engine is 

not modified following testing.” Engine manufacturers are not able to control how the 

engine is used; the manufacturer can only inform the customer on how the engine is 

intended to be used. Furthermore, the last part of the sentence in the proposal is not 

needed since the modification of the emissions characteristics of any certified engine, fire 

pump or not, is not allowed. Thus, the commenter recommended that the last sentence of 

§60.4210(g) of the proposed rule be changed to read as follows: “Fire pump engines may 

test at the NFPA certified nameplate hp, provided that the engine is labeled as “Fire 

Pump Applications Only”.” This approach is similar to that used when an engine 

manufacturer certifies an engine for use as a constant speed engine using the D-2 test 

cycle. 

Another commenter (248) expressed that it disagreed with §60.4210(g) of the proposed 

rule. Manufacturers can only confirm the customers declared intended use for an engine. 

It is impossible for an engine manufacturer to control the use of engines after they have 

been sold, therefore impossible to certify such. The requirement for this certification 

effectively leaves this test method unusable. The language here should be changed to 

“the engine manufacturer shall, as part of the emission label, restrict the use of the engine 

to fire pump application.” This correctly places the burden of conformance on the 

owners/operators. 

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Response: EPA understands that engine manufacturers are not able to control how the 

engine is used, but can only instruct the customer of how the engine is intended to be 

used. EPA agrees that the last part of §60.4210(g) of the proposed rule, which states 

“and provided that the engine is not modified following testing,” is not needed since the 

modification of a certified engine is not allowed. EPA believes the suggestion that the 

commenters have provided regarding this section of the rule is appropriate and has 

written the final rule to incorporate the commenters’ suggestions. The last sentence of 

60.4210(g) is written as “Fire pump engines may test at the National Fire Protection 

Association (NFPA) certified nameplate hp, provided that the engine is labeled as “Fire 

Pump Applications Only”.” 

14.3 Comment: One commenter (245) supported EPA recognition of the unique aspects 

of fire pump engines and notes that fire pump engines are produced in very low volumes 

to provide vital life and property protection functions, and need greater lead time than 

other engines. The commenter supported the following specific provisions as being 

necessary for fire pump engines: 

a. A July 1, 2006 implementation date for the interim program, in which the 

owner/operator must demonstrate compliance with the Tier 1 standards,

b. Implementation of the Tier 3 standards 3 years after the Tier 3 effective date for 

nonroad engines,

c. No requirements for aftertreatment (Tier 4 levels) on fire pump engines, 

d. Provisions for certification of fire-pump-only engines at the NFPA nameplate 

power, and

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e. Optional testing of fire pump engines on a special test cycle. 

The commenter did not support the requirement that fire pump engines be certified to 

Tier 1 levels starting on January 1, 2007. This will result in a significant cost to 

manufacturers, with very low sales volumes over which to recover those costs, and it will 

not result in any environmental benefit. Some fire pump engine ratings are unique and 

have not been previously certified. The owners/operators will have available emissions 

data demonstrating that the engines can meet Tier 1 (per the requirements of 

§§60.4200(b) and 60.4205(c) of the proposed rule). But it will be time consuming and 

expensive to actually certify these engines, according to the commenter. Furthermore, 

the fuel flow rate of some of these fire pump engines is such that the fire pump rating 

would be the parent engine of the nonroad family. This would lead to the need for a new 

certification test, adding to the cost. The commenter recommended that EPA modify 

table 2 of the proposed rule to delete the first row of standards (the Tier 1 standards) 

associated with each power category. The remaining row of the table (currently the 

second row) would then be the first (and only) standards to which fire pump engines 

would need to be certified. Section 60.4202(e) of the proposed rule should be similarly 

modified to read: “Stationary CI internal combustion engine manufacturers must certify 

their fire pump stationary CI ICE to the emission standards in table 2 of this subpart, for 

all pollutants, for the applicable MY and maximum engine power.” 

One commenter (248) stated that regarding §60.4202(e) of the proposed rule, which 

contains the emission standards for fire pump engines, the commenter disagreed. 

Considering the very low contribution fire pump engines make to the pollution of the 

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atmosphere there is no justification to burden this industry and the end user with the 

expense of dollars and utilization of personnel resources to certify engines that were 

already required to be compliant in §60.4200 and 60.4200(b) of the proposed rule. The 

emission limits for this phase in some power categories are less than the Tier 1 of the offroad rule, in other power categories additional elements are being regulated relative to the 

off-road rule. The commenter states that few if any of the old Tier 1 certifications would 

apply for this set of limitations. The first level of emission limitations for fire pump 

engines, for each power category as defined in table 2 of the proposed rule, should be 

enforceable via §60.4211(b)(3) of the proposed rule until that power category transitions 

to the next lower set of emission limits. The commenter also suggests changing the word 

“certify” in Table 2, notes 1, 2 and 3 to “provide” in light of its comments regarding 

§60.4202(e). 

One commenter (268) was in agreement with commenters 245 and 248’s opinion that 

certifying engines that have already been proven to be compliant with Tier 1 standards is 

an unjustified expense as it will not result in any benefit to the environment. The 

commenter asked if the engines must meet Tier 1 standards as of June 2006, what would 

be the purpose of having engine manufacturers bear the expense of certifying each engine 

in January of 2007. 

One commenter (240) agreed with the proposal recognizing that additional leadtime is 

required for certification of fire pump engines. Fire pump engines must go through 

extensive extra safety testing and certification, so the additional 3 year leadtime is well 

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reasoned and appropriate. The commenter stated that for fire pumps required to meet the 

Tier 1 standards, EPA should establish no certification requirements of any kind. Under 

the proposal, manufacturers are required to maintain data starting on July 1, 2006, 

showing that their fire pumps comply with Tier 1. Thereafter, as of January 1, 2007, 

manufacturers would be required to “certify” their fire pumps to those same Tier 1 

standards. There is no purpose that will be served by imposing this certification burden 

for such a limited number of engines when the relevant Tier 1 standards will not have 

changed. Instead, manufacturers should simply be held to the requirement that will take 

effect as of July 1, 2006. All that should be necessary is that manufacturers maintain 

sufficient data showing that their fire pumps comply with Tier 1 standards. Any 

requirements beyond that will only serve to engender burdens and costs without any 

corresponding environmental benefit. 

Response: EPA acknowledges the commenters’ concerns on the issue of certifying 

emergency fire pump engines starting with the 2007 MY. The majority of engines are 

already meeting Tier 1 levels; some are meeting even more stringent levels. EPA 

understands that requiring certification so quickly for fire pump engines, which must go 

through more significant development and lead time, will be burdensome, especially 

given that owners and operators will already be required to show that these engines meet 

Tier 1 standards. EPA therefore agrees that manufacturers may start certification to the 

second row of standards in table 2 of the rule. However, EPA will need to keep all of the 

Tier 1 standards in Table 2, because owners and operators will still need to show 

compliance with such standards until certification of such engines is required. Also, EPA 

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will need to revise requirements for owners and operators of fire pump engines that are 

not certified beginning in MY 2007, in order to ensure that such owners and operators 

can show compliance with Tier 1 emission standards. Commenters 245 and 268 do not 

appear to object to the requirement to certify engines once more stringent standards go 

into effect. Commenter 248’s comments are unclear on this, but EPA believes that 

following the initial lead time provided for Tier 1 engines, there is no reason why engine 

manufacturers should be exempted from certifying fire pump engines. The certification 

requirements are a key element of this rule and its effectiveness. EPA does not believe 

the certification of emergency fire pump engines to emission standards beyond Tier 1 

will be a significant burden, and the comment provides no reason to exempt fire pump 

engine manufacturers from such requirements. As EPA will continue to require 

certification of post-Tier 1 engines, it will not change the word “certify” to “provide” in 

notes 1, 2, and 3 of Table 2. 

14.4 Comment: One commenter (248) said that the regulation of emissions from 

emergency CI fire pumps is unwarranted in light of the very low population of these 

engines, and their continual inherent emission reduction as derivatives of emission 

controlled engines results in insignificant overall emissions from these engines as a 

group. Thus, the low environmental benefits from regulation compared to the substantial 

costs for compliance and adverse impact on the reliability of such engines is unjustified. 

If EPA is going to regulate fire pump engines, the commenter asked that EPA not 

regulate them to emission limits lower than those proposed for MY 2007 in table 2 of the 

proposed rule, which are off-road limits. These limits are achievable without extreme 

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complexities being added to the engines, according to the commenter. The commenter 

also noted that emissions from its fire pump engines have already decreased in the last 

decade due to improvements in the emissions characteristics of the base engines upon 

which the fire pump engines are derived. 

One commenter (268) wished to state that, in contrast to the comments of commenter 

248, it is very much in favor of emission regulation and is willing to do its part to help 

EPA achieve its goal. 

Response: EPA generally disagrees with commenter 248. EPA is required to regulate all 

sources under the NSPS and there is no technical reason why emergency fire pump 

engines should not be regulated. EPA does believe it is appropriate to exempt fire pump 

engines, and all emergency engines, from meeting standards that require the use of addon controls, for reasons described in the preamble to the rule. However, EPA does not 

see any reason why fire pump engines should not be able to achieve the emission 

standards that do not rely on the use of aftertreatment. The emission standards that EPA 

is requiring for emergency fire pump engines are appropriate and achievable, and in fact, 

the commenter provided information to EPA which indicated that fire pump engines are 

capable of meeting the limits imposed by EPA (see Document ID Number EPA-HQOAR-2005-0029-0109). Neither commenter 245 nor commenter 268, both of whom 

make fire pumps engines, provide any indication that these standards were problematic, 

especially given the requirement that all other CI engines used in the U.S. will by such 

date be required to meet those standards or more stringent standards. As previously 

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stated, special provisions have been provided for emergency fire pump engines to allow 

for sufficient time for pump manufacturers to design and assemble units that comply with 

all relevant standards. Additionally, as stated, emergency fire pump engines are only 

subject to standards that do not require the use of aftertreatment controls, and EPA is not 

aware of any technical reasons why these engines should not be able to comply with the 

emission standards. See the comment and response to 14.8 regarding the effect of these 

regulations on reliability of fire pumps. 

14.5 Comment: One commenter (248) stated that the current language in §60.4202(e) of 

the proposed rule may be confused to include the 10 percent additional power fire 

engines have and requested that EPA replace “maximum” with “NFPA nameplate.” 

Prior to fire pump engines being emission certified by the engine manufacturer as defined 

by the rule beginning in MY 2007, the commenter asked if the date that the engine is 

built into a certified NFPA fire pump engine be considered the date of manufacture. This 

will be necessary to process conforming engines manufactured before July, 1 2006 and 

NFPA certified after July 1, 2006. With the proposed date of MY 2007 for certified fire 

pump engines to be available from the engine manufacturers, fire pump engine certifiers, 

such as the commenter, will have a problem with carryover inventory that is compliant 

but not certified. The commenter asked what language can be provided in the rule to 

allow for the sell out of 2006 compliant inventory in 2007. 

Response: EPA agrees with the first comment regarding §60.4202(e) and believes that it 

is appropriate to replace “maximum” with “NFPA nameplate.” This change is reflected 

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in the final rule. For emergency fire pump engines, the manufacturing date is the date the 

engine is built into a certified NFPA fire pump engine. EPA has clarified this in the final 

rule. As far as including additional special provisions for fire pump engine certifiers with 

respect to carryover inventory that meets the emission standards but is not certified 

equipment, EPA worked with the commenter to arrive at an applicability date that would 

be workable. The applicability date of July 11, 2006, as specified in §60.4200, already 

accounts for this issue and fire pumps have been given more time than other engines. 

The commenter has also been aware of this applicability date for some time and EPA 

does not expect there to be issues with existing inventory. Furthermore, as proposed, if 

the engines are pre-2007 MY engines, these engines will not be required to be certified, 

but owners and operators of these engines can maintain information from the 

manufacturer, which shows that the engine meets the emission standards. In the final 

rule, EPA has expanded this flexibility for all Tier 1 fire pump engines. For these 

reasons, EPA does not believe it is necessary to provide additional time, beyond the extra 

time provided, for sell out of existing fire pump engines. 

14.6 Comment: One commenter (266) cited III.E.4 of the preamble to the proposed rule, 

which contains the requirements for owners/operators of emergency fire pumps. The 

commenter stated that it should be specified that the manufacturers should meet the 

emission standards and the owners/operators should maintain the engines to ensure the 

emission standards are met. 

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Response: EPA regulations require owners and operators to be obligated to meet 

appropriate standards; however, in the owner-operator compliance provisions of 

§60.4211(a) of the final rule, EPA specifies that owners and operators who must comply 

with emission standards must operate and maintain the stationary CI internal combustion 

engine and control device according to the manufacturer’s written instructions. This 

provision applies to all stationary engines subject to emission standards under this rule, 

including emergency fire pump engines. EPA requires that owners and operators of 

uncertified engines demonstrate compliance through methods such as keeping records 

from manufacturers or vendors showing compliance. EPA also requires in §60.4211(c) 

that owners and operators of 2007 MY and later engines must comply by purchasing an 

engine that is certified. EPA will be allowing manufacturers of fire pumps engines to 

sell, and allowing owners and operators to buy, uncertified fire pump engines beyond the 

2007 MY until standards more stringent than Tier 1 standards take effect. 

14.7 Comment: One commenter (268) referred to correspondence between Sims Roy of 

EPA and John Whitney of Clarke Fire Protection Products on June 2, 2005, available 

from the rulemaking docket, where it is mentioned that emergency fire pump engines 

with a rated speed of greater than 2,650 rpm have an additional 3 years to meet Tier 3 

standards if a high speed engine that meets Tier 3 standards is not available for the MY. 

The commenter asked if it can understand this to mean that if it manufactures emergency 

fire pump engines with an rpm of greater than 2,650 that do meet Tier 3 standards, the 

regulation would no longer allow the additional 3 years for the industry. 

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Response: The emission standards for emergency fire pump engines are given in table 2 

of the rule. Footnotes 1 through 3 allow certain high speed fire pump engines to certify 

to less stringent emission standards for some model years. This provision is not 

contingent upon high speed engines that meet Tier 3 emission standards being available. 

14.8 Comment: One commenter (240) said that additional investigation may be 

warranted to assess whether the stricter emission standards to be imposed on fire pumps 

under the proposed NSPS (which will necessitate advanced electronic controls and other 

engine design changes) could adversely affect the reliability of fire-pump engines. 

One commenter (248) said that regarding EPA’s request for comments on the impact on 

reliability of fire pump engines as a result of this proposed rule the commenter stated that 

it is impossible to quantify the reduction in reliability the additional complexities 

necessary to conform to the proposed emission limitations will cause. For sure, the most 

reliable system is the simplest system, and these new technologies are not simple. It does 

not surprise the commenter that not one engine manufacturer will go on record that it has 

doubts about the reliability of its future fire pump engines. That would be marketing 

suicide. The commenter’s experience with fire pump installers is that they will install the 

fire pump package presented to them, but the commenter did not believe they would have 

an understanding of technologies involved to achieve the emission reductions proposed. 

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One commenter (268) wished to state that in its opinion, improving efficiency will 

increase reliability as cleaner and more complete combustion will produce less byproducts and deposits, increasing useful engine life. 

Response: EPA does not believe additional investigation, as suggested by commenter 

240, is necessary prior to completion of this rule. EPA stated in the preamble to the 

proposed rule that fire pump engine manufacturers and installers have indicated that the 

provisions of the rule will not reduce the reliability of fire pump engines. EPA also 

requested comment on this issue and it was one commenter’s opinion that improving 

efficiency will increase reliability as cleaner and more complete combustion will produce 

less by-products and deposits, increasing useful engine life. EPA has provided fire 

pumps additional time to comply with the emission standards and the extra time provided 

should be sufficient time for emergency fire pump manufacturers to resolve any issues 

there may be related to reliability. EPA has also exempted emergency fire pump engines 

from meeting Tier 4 emission standards that rely on the use of add-on controls. Finally, 

no information has been submitted to EPA indicating any reliability issues. 

15.0 Prior Tier Certification Requirements 

15.1 Comment: One commenter (240) stated that the rule should not impose any new 

type of certification requirements with respect to any Tier 1 standards. Since the Tier 1 

standards are no longer “current” in the nonroad engine context, nonroad engines are no 

longer capable of being “certified” to those Tier 1 standards. The language of §§60.4201 

and 60.4202 of the proposed rule should be revised to delete any requirement to “certify” 

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engines to any expired nonroad engine standards. Instead, a simple carry-over 

mechanism should be established to address those stationary CI engines that will be 

manufactured to comply with the emission standards applicable to prior-Tier nonroad 

engines. In such cases, the commenter recommended that EPA issue one “master” 

certification form listing all of a given manufacturer’s stationary CI engine families and 

ratings that are carry-overs of previously-certified, prior-Tier nonroad engines. This type 

of mechanism would greatly simplify the “certification” process of prior-Tier engines, 

while also alleviating the workload that otherwise would fall on EPA personnel (with no 

corresponding environmental benefit). 

Response: EPA disagrees with the commenter. The certification procedures carried over 

from the mobile source regulations require that engine families be certified every year. 

This is necessary even with regard to engine families that are not subject to new, more 

stringent, standards. It is needed to ensure that any changes in design to any engine 

family do not cause the engine family to exceed applicable standards. This is equally true 

for stationary engines. Regarding the desire for a simplified carry-over mechanism for 

engines meeting previous tier standards, EPA’s regulations already contain simplified 

procedures for certifying engine families that have not changed appreciably from one 

year to the next and that are not subject to new standards. However, the commenter is 

incorrect to presume that merely because an engine family does not need to meet new 

standards, the engine will not change appreciably from year to year. Engine 

manufacturers are often redesigning engines and creating new engines to meet the needs 

of their customers, as well as regulatory requirements. EPA cannot merely assume that 

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all such engines will meet existing standards. Nor can owners and operators of engines 

presume that such engines meet these emission requirements. Given that the structure of 

this rule is intended to allow owners and operators to rely on the certification of engines 

to avoid more onerous compliance requirements, EPA believes that requiring certification 

of these engines is appropriate. Additionally, with regard to meeting Tier 1 standards, 

the proposal only required fire pump engines and engines above 3,000 hp with 

displacement below 10 l/cyl to certify to Tier 1 standards that no longer applied to 

nonroad engines. As discussed above in section 14 of this document, in the final rule, 

EPA is not requiring certification for Tier 1 fire pump engines, due to particular issues 

concerning fire pumps. The commenter provides no evidence that certification of Tier 1 

engines above 3,000 hp with displacement below 10 l/cyl is at all burdensome. On the 

other hand, the comment refers to emergency engines that are not required to meet final 

nonroad Tier 4 standards. For such engines, the last set of standards required under the 

rule (either Tier 2, 3 or interim Tier 4 standards) are the final standards that these engines 

are required to meet into the future. Unless EPA promulgates more stringent standards in 

the future, these engines will be required to meet these standards for many years to come. 

EPA cannot presume that merely because the engine emission standards are not 

changing, that the engines themselves will not change. Therefore, it is critical for EPA to 

continue to require certification into the future for these engines. While the commenter 

refers to these standards as “prior-Tier” standards, it is important to remember that such 

standards will be the currently-applicable standards for these engines (which represent 

most of the diesel stationary engine population) and thus EPA must insure that such 

engines are meeting these standards. 

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16.0 Emission Standards 

16.1 Emergency Engines 

16.1.1 Comment: One commenter (240) stated that EPA’s treatment of emergency 

engines separately from non-emergency engines was necessary and appropriate. 

Emergency engines perform vital life-saving functions when regular power supplies have 

been disrupted, and so must be configured in ways that do not jeopardize their start-up 

capabilities and reliability. Emergency engines typically operate less than 50 hours per 

year, and so inherently have little overall impact on air quality or emissions inventories. 

Response: EPA agrees with the comment. 

 

16.1.2 Comment: One commenter (240) believed that interim Tier 4 NOx standards 

should not be applied to emergency engines, which will not be required to be equipped 

with PM aftertreatment. Manufacturers could have to undertake separate and unique 

design and manufacturing efforts for emergency engines to meet Tier 4 NOx standards 

(with PM aftertreatment). That would be cost-prohibitive and unworkable. The Tier 3 

standards generally should be the final standards for all emergency engines greater than 

or equal to 37 kW (50 hp). For engines less than 37 kW (50 hp), emergency engines can 

be required to meet the Tier 4 standards, since none of those standards will necessitate 

unique engine aftertreatment or design features for NOx. For emergency engines greater 

than or equal to 3,000 hp, the Tier 2 standards should be the final standards. Regarding 

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specific emission standards, the commenter states that two need to be changed. For 

engines 19 to 36 kW (25 to 49 hp), the proposal would require that those engines meet 

the interim Tier 4 standard for PM, but the final Tier 4 standard for NOx. This would 

result in a hybrid engine that manufacturers are not slated to produce under the nonroad 

rule. Accordingly, the applicable standards should be the interim (not the final) Tier 4 

standards for PM and NOx (0.30 grams per kilowatt-hour (g/kW-hr) PM (0.22 g/hp-hr); 

7.5 g/kW-hr (5.6 g/hp-hr)) for those engines. For engines 37 to 55 kW (50 to 74 hp), the 

proposal would require that manufacturers meet the optional Tier 4 pull-ahead standard 

of 0.30 g/kW-hr (0.22 g/hp-hr) PM (which standard was adopted to provide nonroad 

manufacturers with the option of deferring compliance with the final nonroad Tier 4 PM 

standard until 2013). Since the final nonroad Tier 4 standards will not apply to 

emergency engines, the optional pull-ahead standard also should not apply. Instead, the 

Tier 3 PM standard of 0.40 g/kW-hr (0.30 g/hp-hr) should be the final standard that 

applies to these engines. 

Response: It is unclear exactly what the commenter means by “interim Tier 4 NOx 

standards.” EPA required Tier 4 standards (interim or final) only for emergency engines 

up to 56 kW (75 hp). No other emergency engines are required to be certified to any Tier 

4 standards. The commenter appears to agree with EPA’s view that Tier 4 standards that 

do not require aftertreatment are appropriate for emergency engines, but appears to want 

to prevent needing to design emergency engines to meet unique standards. For engines 

rated below 19 kW, the commenter appears to have no objection to the proposed 

standards. For engines rated at 19 and below 37 kW, the commenter does not object to 

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EPA’s proposed standard from 2008-2014, which would incorporate the interim Tier 4 

standards, but objects to the incorporation of the final NOx (actually NOx + NMHC) 

standards for these engines because it creates a hybrid set of engine standards that does 

not correspond with any engine standards for nonroad engines. EPA agrees that it is 

inappropriate to require a unique set of standards for these engines and has not 

incorporated the final Tier 4 NOx standard for these engines into the final rule. 

Regarding engines rated at 37 to 55 kW, EPA agrees that as no nonroad engines were 

required to meet the optional interim Tier 4 PM standard, it is appropriate not to require 

emergency engines to be certified to such standards. Regarding engines equal to or 

greater than 3,000 hp, EPA agrees that the final standards should be the Tier 2 standards, 

and EPA proposed this. However, EPA understands that the regulatory language may not 

have been clear regarding these standards, and EPA explicitly refers to Tier 2 standards 

for these engines in the final regulatory language. 

16.1.3 Comment: One commenter (264) agreed with EPA that emergency engines should 

not require the installation of aftertreatment technologies. Tier 3 standards should be the 

final tier of emission standards for emergency applications. 

Response: See Response to 16.1.2. 

16.1.4 Comment: One commenter (243) expressed that EPA’s proposal to exempt 

“emergency” engines from Tier 4-equivalent standards is unjustifiable, given the 

tremendous health benefits associated with reducing diesel exhaust emissions, and is 

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unlawful. The commenter states that even given the poorer cost-effectiveness of controls 

on these engines, the benefits expected from the controls under the cost-benefit analysis 

would still outweigh the costs. The commenter also notes that having different standards 

for emergency and non-emergency engines can create an incentive for consumers to 

choose to buy an emergency engine even if it will be used for non-emergency purposes. 

The commenter claims that failure to require Tier 4 controls on all new stationary engines 

violates tenets of administrative law and reasoned decision making. 

Response: EPA disagrees with this comment and believes it is appropriate and justified 

to regulate stationary CI emergency engines to emission standards that do not require the 

use of aftertreatment controls. This approach is consistent with other rulemaking 

decisions EPA has made in the past for stationary engines, which have not required that 

emergency engines be equipped with add-on controls. Stationary emergency engines are 

infrequently used and their primary purpose is to support equipment during emergency 

situations. Commenter 240 estimates use of emergency engines at approximately 50 

hours per year. As documented in information submitted to the docket for the proposal 

(EPA-HQ-OAR-2005-0029-0011), emergency engines are operated infrequently and 

EPA would agree that 50 hours per year is representative of emergency engine operation. 

A study conducted by the CA ARB in 2002 indicated that emergency CI engines operate 

on average about 30 hours per year. The average includes hours spent in emergency and 

non-emergency service. EPA considered costs, as required by section 111, when 

evaluating BDT for stationary CI emergency engines and determined that the cost of 

CDPF, NOx adsorber, and oxidation catalysts, the main technologies expected to reduce 

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emissions to comply with Tier 4 emission standards, was extremely high compared to the 

amount of pollutant potentially reduced from emergency engines through the application 

of aftertreatment controls. The cost per ton of emission levels that would result from 

requiring aftertreatment are well above normal regulatory cost per ton levels. EPA agrees 

there can be significant health benefits in reducing emissions from emergency engines, 

and EPA has promulgated standards that will reduce such emissions. However, EPA 

believes that the increased upfront costs of engines with aftertreatment are not justified 

for these engines, which are used so rarely and often in situations where greater and more 

immediate harm to human health (e.g., fire or flood) is evident. In addition, EPA does 

not wish to prevent owners from being able to purchase new emergency engines. Given 

that emergency engines with aftertreatment will be appreciably more expensive than 

engines without aftertreatment, EPA believes that substantial increases in cost may 

dissuade owners and operators from purchasing new emergency engines which, given the 

importance of these engines, may be counterproductive to the goal of better human health 

and welfare. In addition, because these engines are used infrequently and in limited 

operations, the exhaust temperatures of these engines when they are in use are not wellsuited for aftertreatment technologies. For these reasons, EPA believes it is justified in 

promulgating standards for stationary CI emergency engines that do not require the use of 

aftertreatment controls. As discussed elsewhere, EPA is finalizing several enforcement 

provisions that will substantially deter consumers from violating the provisions of the 

rule. Further, the CAA provides for substantial penalties for violation of the NSPS. 

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16.1.5 Comment: One commenter (266) said that it appears that the rule did not 

anticipate a common type of operation of a stationary engine generator; the occasional 

use to provide back-up power to critical operations during site or facility interruptions, 

and maintaining and testing of the integrity of the equipment supporting a site’s power. 

While these requirements may be met with a portable generator, it is often safer to use an 

installed permanent generator for this purpose. This generator is also used to provide 

power for emergency purposes as outlined in this proposal. The commenter 

recommended that the rule replace all references to “emergency generator” with “noncontinuously operating generator” to appropriately specify the rule’s application. These 

generators provide standby power and are operated less than 10 percent of the operating 

time for the equipment supported. In addition to the emergency purposes described in the 

proposal, these generators are used for periodic site or facility interruptions, and testing 

and maintenance of electrical power systems. All of which, ensures safe operation of the 

commenter’s operations. These generators should meet Tier 1 standards as shown in 

table 2 of the proposed rule. 

Response: As defined in the proposal, an emergency engine is an engine whose 

operation is limited to emergency situations and required testing. Stationary engines used 

to produce power for critical networks when electric power from the local utility is 

interrupted would be considered emergency engines. EPA believes that the way it has 

defined an emergency engine in the proposal is appropriate, but has made slight 

modifications to the definition. After “local utility,” EPA has added “(or the normal 

power source, if the facility runs on its own power production)” and has also clarified that 

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peak shaving is not considered emergency use. EPA has also added “and maintenance” 

to the first sentence of the definition. Otherwise, the definition remains as proposed, in 

the final rule. The use of emergency engines for other purposes besides emergency 

operation and required maintenance and testing, e.g., such as peak shaving or general 

maintenance of a facility, is not permitted. The commenter did not provide any 

justification for why emergency engines should be regulated to Tier 1 emission standards. 

EPA is already providing flexibility for emergency engines in that these engines do not 

have to meet Tier 4 emission standards that rely on the use of aftertreatment controls. 

EPA does not see why emergency engines should only be regulated to Tier 1 emission 

standards when these engines are fully capable of achieving higher Tier limits. 

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16.2 Engines >750 hp 

16.2.1 Comment: One commenter (240) stated that as was the case with the nonroad 

engines from which stationary CI engines are derived, it remains the case that less 

stringent standards are necessary for non-generator engines greater than 750 hp. 

One commenter (243) said that EPA should set stringent NOx emissions standards for all 

engines greater than 750 hp that are based on the use of add-on control technologies. The 

commenter estimated that stationary diesel engines greater than 750 hp make up about 20 

percent of the total stationary engine population, but account for more than half the total 

emissions of NOx. The commenter has seen enough successful examples of the use of 

SCR to control NOx emissions from stationary engines to conclude that EPA should base 

its NOx emissions standards for these engines on the use of add-on controls. EPA 

describes in docket information that SCR has been successfully installed in several 

applications based on State and vendor information. Several additional add-on NOx 

controls that are under development are described in the docket as well; NOx adsorbers, 

ozone injection and lean NOx catalysts. While these technologies are not commercially 

available yet, they could become viable options within the timeframe of these standards. 

The commenter believed the current use of SCR and the other available options for addon NOx control support the more stringent standards. The commenter is not aware of any 

special issues with add-on controls on non-generator stationary engines. The commenter 

believed the issues would be no different than those associated with stationary generator 

sets and, therefore, saw no reason to set more lenient standards. 

138
One commenter (244) believed that NOx standards for non-generator, stationary engines 

with hp ratings of greater than 750 should be equivalent to NOx standards proposed for 

generators. Selective catalytic reduction systems have already been installed on 

stationary engines in this size range and can provide high efficiency NOx reductions in a 

cost effective manner. The commenter believed that installation issues with SCR on nongenerator engines are no different than those associated with generator engines. 

One commenter (238) strongly urged EPA to set aftertreatment forcing NOx standards 

for all non-emergency engines with a displacement of less than 10 l/cyl and greater than 

750 hp. The rationale for setting less stringent standards for nonroad engines other than 

generator sets were concerns about designing NOx adsorbers for the space constraints 

and physical stresses associated with mobile heavy equipment. These conditions do not 

apply to stationary engines. In the July 2004 nonroad rulemaking, EPA noted the use of 

SCR on stationary engines as a rationale for aftertreatment forcing NOx standards for 

mobile generator set engines. 

Regarding EPA’s request for comments on whether the generator standards for NOx 

should be applied for non-emergency engines greater than 750 hp, one commenter (265) 

believed that the non-emergency generator engines should be limited to the same levels 

of emissions as other available ways to generate electricity from fossil fuel. The 

commenter recommended that limits for engines greater than 750 hp be as stringent as 

limits for non-emergency engines in sizes between 75 hp and 750 hp, because the larger 

139
engines should be able to achieve the same limit as smaller engines, and there is 

sufficient time to transfer technology to engines greater than 750 hp. If a large engine 

cannot achieve comparable emission levels, then cleaner equipment, such as turbines, 

should be used. 

Two commenters (266, 267) made the comment that the requirement for add-on controls 

for engines above 750 hp with a displacement below 10 l/cyl should apply solely to 

continuously operating non-emergency generators. 

Response: EPA proposed emission standards for non-emergency non-generators above 

750 hp that were not based on the use of add-on controls for NOx and were less stringent 

than the proposed standards for generator sets above 750 hp. These standards were 

consistent with nonroad standards for the same size engines. EPA solicited comments on 

this issue in the preamble to the proposed rule and received the comments as summarized 

above. Based on available information and comments received on this issue, EPA still 

believes it is appropriate to distinguish between non-generators and generators when 

finalizing standards for non-emergency stationary CI engines above 750 hp. EPA did not 

receive any specific information or data demonstrating that the standards applicable to 

generator sets are feasible for engines above 750 hp that are not generator sets. Engine 

manufacturers have repeatedly expressed that less stringent standards are necessary for 

non-generator set engines greater than 750 hp. Engine manufacturers have also 

repeatedly expressed the need to have standards for stationary engines that are consistent 

with the standards for nonroad engines. No change has been made to the final rule, 

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which includes, as proposed, emission standards consistent with nonroad standards. The 

standards distinguish between non-generator sets and generator sets, and require less 

stringent levels for non-emergency engines that are not generator sets, based on improved 

combustion systems and engine-based NOx control technologies. (It should be noted that 

the PM standards for engines above 750 hp, both for generators and non-generators, will 

likely require particulate traps.) 

16.3 Engines <75 hp 

16.3.1 Comment: One commenter (244) supported EPA position that the results of the 

planned 2007 nonroad diesel engine technology review focused on smaller diesel engines 

(less than 75 hp) should apply to stationary diesel engines as well. The commenter 

believed some very promising technologies are emerging that could be applied to smaller 

nonroad and stationary diesel engines to provide meaningful PM, NMHC, and NOx 

emission reductions at a reasonable cost with good performance. These technologies 

include such concepts as “open” DPF and lean NOx catalyst. 

Response: No response is needed. 

16.4 Engines with a Displacement of <30 Liters per Cylinder

16.4.1 Comment: One commenter (226) stated that it is unclear why engines with a 

displacement of greater than or equal to 10 l/cyl should have different emission standards 

than those with a displacement of less 10 l/cyl if they are both being used for stationary 

141
service. The commenter suggested that the regulation be strictly based on engine power 

output. 

Response: EPA explained in the preamble to the proposed rule and in supporting 

documentation included in the rulemaking docket why it is appropriate to establish 

different emission standards for stationary CI engines with a displacement of greater than 

or equal to 10 l/cyl. According to engine manufacturers, stationary CI engines with a 

displacement between 10 and 30 l/cyl are not generally used in land-based nonroad 

applications, but are more similar to engines used in marine applications. Additionally, 

stationary CI engines with this displacement are operated differently than nonroad 

engines. Furthermore, EMA members do not produce any stationary CI engines with a 

displacement of greater than or equal to 10 l/cyl that are certified to the nonroad 

standards. For these reasons, it is appropriate to regulate stationary CI engines with a 

displacement between 10 and 30 l/cyl to the emission standards for marine CI engines, as 

proposed, instead of to nonroad standards. To be consistent with the marine standards, 

stationary CI engines cannot be regulated strictly based on engine power, but must be 

regulated according to engine size as well as cylinder displacement. 

For stationary CI engines with a displacement of greater than or equal to 30 l/cyl, EPA 

has been told that these engines are very different from nonroad engines and it would not 

be feasible to control these engines to nonroad certification standards. EPA has 

explained in supporting documentation to the proposed rule that these engines cannot 

apply the same control technologies as nonroad engines due to their large size and fuel 

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used. These engines also have vastly different operating characteristics that support 

requiring different emission standards and different compliance strategies for these 

engines. For these reasons, EPA feels it is justified in requiring different emission 

standards than for other engines, and a displacement cutoff, rather than an engine size 

cutoff, is appropriate to distinguish these unique engines from other engines regulated by 

this rule. 

 

16.4.2 Comment: One commenter (244) supported EPA position that a review of 

proposed standards for stationary diesel engines with a displacement between 10 and 30 

l/cyl should be done once EPA promulgates new emission standards for diesel marine 

engines, including diesel marine engines in this displacement range. The commenter 

believed that exhaust emission control technologies targeted for use to comply with 

EPA’s Tier 4 nonroad diesel engine program have applicability on marine and stationary 

diesel engines in this size range. 

Response: No response is needed. 

16.5 Engines with a Displacement of ≥30 Liters per Cylinder

16.5.1 Comment: One commenter (234) said that the NOx standards for engines with a 

displacement of greater than or equal to 30 l/cyl would incur significant costs for the 

owner and operator, and for emergency engines make it impossible to operate the unit 

reliably when actually needed. If readiness testing is limited to 2.5 hours per month for 

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emergency engines, entire subsystems supporting air pollution control equipment could 

themselves become unreliable. The cost of installing and maintaining an SCR system for 

large CI engines is outrageously high, especially for applications in Alaska. These 

control systems are only marginally cost effective for Alaska units that are meant to be 

operated continuously. The cost of SCR controls for emergency units outweighs the 

benefit of having large reliable emergency power available. A recent prevention of 

significant deterioration project rejected SCR due to high costs. Selective catalytic 

reduction subsystems must be kept instantly ready over a long period of time in standby 

mode. One important aspect is having the urea/water mixture heated to prevent freeze up 

during extremely low temperatures. The system is not simple and operators/mechanics 

have to be well trained. In most areas of Alaska, such skilled labor is not available. 

Unless such large units are simple to maintain/operate, they will quickly fall into 

disrepair or become unusable in an emergency. For emergency engines, the technology 

that is proven to have the highest reliability while in standby mode should be used. Fuel 

Injection Timing Retard (FITR) is the technology. It reduces NOx by 15 to 20 percent, 

and has been demonstrated as the most cost effective for arctic conditions. This 

technology (FITR) should also be allowed for engines with a displacement of greater than 

10 l/cyl unless/until manufacturers establish a proven record of reliable readiness from 

cold start conditions. This may require delay of emission control requirements for an 

additional 3 years beyond current implementation dates. 

This commenter also said that the PM limits in the proposed rule for engines with a 

displacement of greater than or equal to 30 l/cyl are unrealistic, and there are no current 

144
control technologies that are “available11” to meet these standards. There have been no 

applications of ESP to stationary sources in the U.S. to date (based on 

RACT/BACT/LAER Clearinghouse, September 1, 2005). A currently available 

technology, particulate filter traps, is suited to these large units, although PM removal is 

less than 60 percent. The commenter noted that PM emissions will already be reduced 

considerably by the use LSD and ULSD. When the reduction from using low sulfur fuel 

is considered, an additional 50 percent overall reduction from particulate trap technology 

will meet EPA’s goal of reducing PM emissions nationwide. Requiring the use of ESP 

for emergency units undermines unit reliability and would increase unit size. 

Approximately 10 percent of the power generated by an emergency CI ICE would be 

used solely to power an ESP. This would cause all such emergency units to be resized at 

an increased capacity. The commenter recommended a 50 percent PM reduction or an 

emission limit of 0.15 g/kW-hr (0.113 g/hp-hr). 

Response: EPA does not agree with the commenter that SCR control systems are not a 

feasible option for engines located in Alaska. There are at least three facilities in Alaska 

that have stationary engines equipped with SCR, see the memorandum entitled “Emission 

Standards for Engines with a Displacement of ≥30 Liters per Cylinder,” available from 

the rulemaking docket. EPA does not expect that there will be any emergency engines 

with a displacement greater than 30 l/cyl; however, to the extent that such units exist, 

they will be very substantial emitters during use and should be required to use the best 

technology available. In response to the commenter’s statement regarding readiness 

testing, EPA has increased the maintenance and testing allowance for emergency engines 

 

11 “Available” as used here has a meaning consistent with EPA’s “Top-Down” BACT analysis method. 

145
from 30 to 100 hours per year in the final rule, with the option to submit a petition for 

additional hours. EPA agrees in general with the comments regarding the proposed 

emission limitation for PM. The final rule has been written considering the comments 

received and requires 60 percent PM reduction or an emission limit of 0.15 g/KW-hr 

(0.11 g/hp-hr). EPA believes the PM standard will be achievable through the use of 

lower sulfur fuel, on-engine controls, and aftertreatment. EPA believes that the PM 

percent reduction requirement is feasible through application of ESP. Based on 

information EPA has received, the technology is capable of reducing PM by 60 percent. 

Other information indicates that the technology could reduce PM by even more; from 55 

to 85 percent when operating on heavy fuel oil, see information in the docket. For further 

discussion regarding EPA’s final standards for engines with a displacement greater than 

30 l/cyl, see the memorandum entitled “Emission Standards for Engines with a 

Displacement of ≥30 Liters per Cylinder. 

16.5.2 Comment: One commenter (235) provided several comments on the proposed 

standards for engines with a displacement of greater than or equal to 30 l/cyl. The 

proposal states on page 39870 that “The intended effect of the standards is to require all 

new, modified and reconstructed stationary CI ICE to use the best demonstrated system 

of continuous emission reduction, considering costs, non-air quality health, and 

environmental and energy impacts, not just with add-on controls, but also by eliminating 

or reducing the formation of these pollutants.” With respect to the emission limits 

proposed for engines with a displacement of greater than or equal to 30 l/cyl the 

commenter claims that the above principles have not been followed. The commenter 

146
stated that environmental impacts and cost effects have not been evaluated and efficient 

add-on abatement techniques (SCR for NOx, etc.) will always be needed as a result of the 

proposal. Only a small number of large CI ICE are sold per year to the U.S., and 

therefore, one can forecast that the environmental impact of these engines with respect to 

the total emissions in the U.S. is small. Therefore, the proposed strict standards cannot 

be justified based on the air quality need. EPA states on page 39890 of the preamble to 

the proposed rule that it does not expect there to be any engines with a displacement of 

greater than or equal to 30 l/cyl. In U.S. territories there are several of these engines, e.g., 

in Puerto Rico there is a 20 MW electric (MWe) plant and in Guam there is an 80 MWe 

plant, the commenter said. The proposed limits will raise the electricity produced in 

these power plants considerably. This might have impacts on the small governmental 

jurisdiction area flexibility and have significant adverse affect on the supply of energy. 

This would be in contradiction to the Regulatory Flexibility Act and Executive Order 

13211: Actions Concerning Regulations that Significantly Affect Energy Supply, 

Distribution or Use. 

The commenter further stated that costs and environmental quality need to be considered 

in order for the rule to be consistent with the BDT principle, now only the lowest 

achievable emission rate (LAER) principle is being applied. In the U.S., LAER (cost 

aspect is not considered) is applied in non-attainment areas only. No separate limits are 

proposed for large pre-2007 engines as for the smaller displacement categories. Existing 

pre-2007 large engines need to be regulated with their own separate emission limits. 

147
The commenter added that the proposed NOx limit is very strict. The proposed limit of 

0.4 g/kW-hr (0.30 g/hp-hr) equates to about 50 mg/Nm3

 (at 15 percent O2). This limit is 

much stricter than World Bank Guidelines or the United Kingdom (UK) limits as referred 

to in the proposed text. The World Bank NOx limit for non degraded air-sheds is 2,000 

mg/Nm3

 and in degraded air-sheds 400 mg/ Nm3 (at 15 percent O2) (about 3.1 g/kW-hr). 

In the UK, the NOx limits are: 1,300/1,400 mg/Nm3 (at 15 percent O2) (about 10.1/10.9 

g/kW-hr) (light fuel/heavy fuel oils) for plants less than 50 MW and 200-300 mg/Nm3

 (at 

15 percent O2) (about 1.6-2.3 g/kW-hr) for oil fired plants greater than 50 MW. 

Extensive research and development work with NOx emissions from large liquid fired CI 

ICE has reduced emissions remarkably by primary measures (typically 30 to 35 percent) 

during the last decade. Primary methods are low NOx combustion focusing on 

optimizing: closing timing of inlet valve, design of fuel injection equipment on the 

engine, new camshaft, etc. The proposed limit means in practice that SCR is always 

needed. Selective catalytic reduction needs a reagent aqueous urea/ammonia or pure 

ammonia to work, and lack of the reagent delivery infrastructure in certain areas will 

make the proper use of SCR impossible. In order to give industry an incentive to develop 

new cost-effective primary methods and to continue the positive development in the past 

decade, the proposed limit should be more realistic based on the zoning approach 

(attainment/non-attainment area, mainland U.S./other areas). 

This commenter made some recommendations for acceptable emission limits. The 

commenter recommended for pre-2007 units limits according to World Bank. For 2007 

and later for mainland U.S: 

148
Attainment areas: 

<50 MW plants in urban areas: 750 mg/Nm3 (at 15 percent O2) (about 5.8 g/kW-hr) 

<50 MW plants in other areas: 1,600 mg/ Nm3 (at 15 percent O2) (about 12.4 g/kW-hr) 

≥50 MW plants: 750 mg/Nm3 (at 15 percent O2) (about 5.8 g/kW-hr) with emission 

correction for highly efficient engines, see EUROMOT document.12

Non-attainment areas

As in proposal. 

For 2007 and later for U.S. territories: Guam, American Samoa or the Commonwealth of 

the Northern Mariana Islands, the limits according to EUROMOT paper.13 The 

commenter stated that the proposed PM limit of 0.12 g/kW-hr (0.09 g/hp-hr) equals about 

16 mg/Nm3

 (at 15 percent O2). This is a very strict limit, much stricter than the British 

and World Bank limits, which are 50 mg/Nm3 (at 15 percent O2) (about 0.38 g/kW-hr) 

for large CI plants and 100 mg/Nm3 (at 15 percent O2) (about 0.75 g/kW-hr) for smaller 

CI plants. The ESP is bulky and has a high investment cost. In the BREF document14

for large combustion installations, it states that “Due to the different temperature and O2

content of the diesel flue-gas, the electrical properties of the diesel particulates (e.g., 

resistivity, etc.,) are different compared to particulates from a boiler flue-gas, and proper 

testing of the ESP (electrical precipitator) is needed to commercial release.” Only a few 

 

12

www.euromot.org/dowload/news/positions/stationary/EIPPCB_BREF_back_up_document_euromot_com

ments_jun03_table_6_41.pdf. 13 Stationary Engine Emission Legislation – Diesel and Gas, the Euromot Position. November 2004. 

www.euromot.org/dowload/news/positions/stationary/Future_stationary_engine_emission_legislation_Nov

04.pdf. 14 Integrated Pollution Prevention and Control (IPCC), Reference Document on Best Available Techniques 

for Large Combustion Plants. May 2005. European IPCC Bureau. 

ftp://ftp.jrc.es/pub/eippcb/doc/lcp_final_0505.pdf. 

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CI plants are equipped with ESP, and the technical availability of ESP needs to be 

evaluated case-by-case. In the European Integrated Pollution Prevention and Control, the 

best available technique is considered to be the use of low ash and low sulfur fuel. 

Particulate matter limits range from 30 to 50 mg/Nm3

 (at 15 percent O2) (about 0.23 to 

0.38 g/kW-hr) depending on whether heavy or light fuel oil is used. The commenter 

recommended PM limits in line with the EU BREF document for large CI ICE plant 

stations (greater than 50 MW). For smaller CI ICE plants, the commenter recommended 

a PM limit according to the UK approach. 

Response: EPA does not agree with the commenter that EPA did not evaluate costs and 

environmental impacts. EPA has provided detailed analyses of the expected costs of this 

regulation and the expected emission reductions and benefits and evaluated the 

technology for this rule based on best demonstrated technology, not lowest achievable 

emission rate. EPA evaluated the environmental and economic impacts of the best 

demonstrated control technologies, which are documented in a memorandum included in 

the docket entitled “Emission Standards for Engines with a Displacement of ≥30 Liters 

per Cylinder.” While there are few CI ICE with a displacement of greater than or equal 

to 30 l/cyl, they are individually very large emitters of pollutants. Moreover, in 

regulating criteria pollutants such as ozone and PM, it is assumed that the emissions 

come from numerous different sources whose individual contribution may be relatively 

small. Further, as noted in the analyses, there are benefits from these standards in 

attainment areas, and these national regulations are designed to provide protection from 

pollution occurring in all areas of the country, not merely nonattainment areas. EPA does 

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not believe that the final emission standards will have a significant adverse effect on the 

price of electricity and the supply of energy, and the commenters did not provide any data 

to support this assertion. 

While EPA disagrees with much of the commenter’s statements, EPA has evaluated all 

comments received on this matter and agrees with the comments that the proposed NOx 

g/KW-hr emission limitation and the proposed PM emission standards were too stringent. 

The final rule requires engines with a displacement greater than 30 l/cyl to reduce NOx 

emissions by at least 90 percent or meet a NOx emission limitation of 1.6 g/KW-hr (1.2 

g/hp-hr), and to reduce PM emissions by at least 60 percent or meet a PM emission 

limitation of 0.15 g/KW-hr (0.11 g/hp-hr). There are several facilities worldwide that are 

successfully using ESP for PM control. For example, a power plant in Korea is equipped 

with SCR and ESP and is limited to PM emissions of 30 mg/Sm3 at 4 percent O2 (about 

0.06 g/HP-hr) (see rulemaking docket). Also, there is a power plant in Guam operating 

with ESP achieving less than 60 mg/Nm3

 at 15 percent O2 (about 0.3 g/HP-hr) when 

operating on high sulfur fuel. Sources can also use other approaches, including traps, the 

use of lower sulfur fuel, and on-engine controls. The PM emission limit is consistent 

with comments received from commenter 234. See Comment and Response 16.5.1. 

Regarding the NOx standard, SCR has been demonstrated as feasible for stationary CI 

ICE and is in use on several engines in the U.S. As discussed above in the response to 

comment 8.2, SCR has achieved emission reductions of 90 percent or greater in many 

cases. EPA reviewed emission rates of stationary CI engines with a displacement of 

greater than or equal to 30 l/cyl and based on an average uncontrolled NOx emission rate 

from these engines of about 11.8 g/HP-hr, applying SCR with a reduction efficiency of 

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90 percent yields a controlled NOx emission rate of 1.2 g/HP-hr. EPA therefore believes 

the final standards for NOx are appropriate. Also note, that the commenter seems to 

concede that these standards are feasible, because the commenter accepts the proposed 

(more stringent) standards in nonattainment areas. 

EPA notes that this regulation applies only to new engines, not existing engines. The 

only engines manufactured prior to April 1, 2006 covered by this regulation are engines 

that are modified or reconstructed, as is required under the CAA. Further information 

regarding how EPA established the final emission reduction and limitation requirements 

is discussed in a memorandum included in the docket entitled “Emission Standards for 

Engines with a Displacement of ≥30 Liters per Cylinder.” 

16.5.3 Comment: One commenter (243) said that EPA must require stringent PM 

emissions limits for engines with a displacement of greater than or equal to 30 l/cyl. 

Particulate matter emissions from stationary diesel engines are associated with extremely 

serious health impacts, including premature mortality and cancer. It would be clearly 

arbitrary and capricious for EPA to exempt the very largest engines, which it recognizes 

as operating for thousands of hours per year, from protective control requirements for PM 

emissions. EPA is correct in its assessment that the cost of SCR to reduce NOx 

emissions from these engines is justified because they are so large and because the cost of 

SCR would be manageable in comparison to the cost of the engines themselves. 

Similarly, the size of these engines and the hazard posed by their emissions compels EPA 

to require them to achieve PM reductions that are at least as protective, if not greater 

than, those for smaller engines. EPA’s proposal for these very large engines fails to meet 

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the most basic requirement of section 111 of the CAA, that stringent emissions standards 

be applied to all sources within the designated category. There is no evidence that a 

thorough technical analysis of cost or feasibility was performed for these large engines. 

EPA does not explain why particulate filters could not be developed to apply to these 

engines. Nor does it explain why ESP, the technology on which the 60 percent control 

requirement is based, could not be designed to work as effectively in this application as 

they are known to do in many others, and achieve reductions far in excess of 60 percent. 

The commenter urged EPA to remedy this deficiency in the final rule by promulgating 

more stringent control requirements for this class of very large, very highly polluting 

engines. 

Response: EPA disagrees with the commenter and believes that the emission standards 

promulgated for engines with a displacement greater than 30 l/cyl represent the 

application of the best demonstrated control technology for these engines. The emission 

standards being finalized were discussed in response to comment 16.5.2. An analysis of 

the cost and feasibility of emission controls was performed and can be found in the 

rulemaking docket in the memorandum entitled “Emission Standards for Engines with a 

Displacement of ≥30 Liters per Cylinder”. There is nothing in the final rule that would 

preclude the use of particulate filters for these large engines; however, EPA could not 

find any examples of the use of particulate filters on these engines and therefore could 

not base the emission standards on the use of particulate filters. EPA feels that it has 

promulgated the most stringent control requirements based on the best demonstrated 

technology for these large engines that can be achieved considering the technical 

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feasibility and capability of aftertreatment controls and fuels used in these large 

displacement engines. 

16.5.4 Comment: One commenter (266) commenter cited section III.E.3.b of the 

preamble to the proposed rule, which contains the proposed standards for 

owners/operators of engines with a displacement of greater than or equal to 30 l/cyl. The 

commenter stated that this requirement should not include non-continuously operating 

engines for standby power. 

Response: EPA disagrees with the commenter that emission standards for engines with a 

displacement of greater than or equal to 30 l/cyl should not apply to non-continuously 

operating engines. The commenter did not provide any rationale supporting this position. 

In the absence of a technical justification for why emergency engines should be exempted 

from the emission standards, EPA cannot fully evaluate the merits of this comment. Due 

to the magnitude of emissions from engines with a displacement of greater than or equal 

to 30 l/cyl, EPA feels it is appropriate to require the same emission standards for 

emergency and non-emergency stationary engines of this displacement. 

17.0 Peak Shaving 

17.1 Comment: One commenter (242) stated the proposed rule is cost prohibitive with 

little environmental benefit for peak shaving facilities with low operating hours. The 

BDT for non-emergency engines was based on a cost per ton of pollutant removed 

calculated using 1,000 hours per year. The cost per ton of pollutant removed for the 

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commenter’s peak shaving engines with operating hour limitations is closer to the amount 

calculated for emergency engines than for prime engines. The commenter asked that 

EPA add a provision that non-emergency engines that limit their operation to up to 150 

hours per year in a federally enforceable air permit, be allowed to meet the same 

standards as emergency generators. 

Response: EPA does not agree that non-emergency engines that operate 150 hours per 

year or less should meet the same emission standards as emergency engines. The 

commenter did not provide any supporting rationale or data suggesting that nonemergency engines operating up to 150 hours per year are unable to be equipped with 

aftertreatment controls and capable of meeting Tier 4 emission standards that require 

these add-on controls. Costs are not especially high for these engines compared to 

benefits achieved. More importantly, the ability of an engine to run for peak shaving 

purposes will be based on the economic effectiveness of using such power for that 

purpose. If it is cost effective to use such engines for economic gain for such purposes, it 

will be used, but air quality should not be compromised for an essentially profit-based 

decision. Although the cost per ton of pollutant removed, not including economic gain 

from operating the engine, may be similar to that of emergency engines, the decision to 

run an engine for peak shaving purposes is based on economic factors such as generated 

revenue. An emergency engine is entirely different in that the decision to run such 

engine is not revenue based, but is the result of an unplanned, emergency event, 

necessitating the operation of the engine for instances where life safety may be an issue. 

Operating the engine for peak shaving purposes is a relatively planned activity, unlike 

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emergency engines, which are used for unforeseen emergency situations such as fires and 

natural disasters. Peak shaving involves income generation, which is not an emergency 

activity. 

Engines that are used for peak shaving are not emergency engines and should not be 

exempt from meeting the more stringent emission standards applicable for nonemergency engines. This is consistent with previous regulatory decisions EPA has made 

and is also in line with how States treat peak shaving engines, e.g., the State of New York 

(commenter 238) agrees that peak shaving is not emergency use. The CA ARB 

distributed generation rule requires that sources apply the best technology available, a 

requirement that applies to non-emergency and peak shaving engines. Based on other 

comments received, EPA has added to the definition of emergency stationary internal 

combustion engine that peak shaving is not considered emergency use. EPA does not 

agree with the commenter and for the reasons provided in this response, EPA is not 

allowing peak shaving engines to meet the same standards as emergency engines. Peak 

shaving engines are considered non-emergency engines and must meet the applicable 

standards required for those engines. EPA has clarified in the final rule that stationary CI 

ICE used to supply power to an electric grid or that supplies power as part of a financial 

arrangement with another entity are not considered to be emergency engines.

 

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18.0 Need for Regulation 

18.1 Comment: Two commenters (259, 260) stated that stationary CI engine emissions 

are already adequately addressed through fuel quality regulations and 40 CFR part 63, 

subpart ZZZZ for stationary RICE. The rule would add another degree of regulatory 

complexity and more complicated compliance determinations, according to these 

commenters. Commenter 259 said that it is unclear if EPA has reconciled the impacts or 

considered the compliance complexity associated with these layered regulations. EPA 

has not established the regulatory hierarchy or provided a mechanism for eliminating the 

overlapping and redundant regulatory requirements. Commenter 259 requested that the 

hierarchal structure be defined in advance that includes a thorough review of each 

regulation potentially impacting this source group thus eliminating confusion and 

ensuring consistency. 

Response: EPA does not agree with the commenters’ statement that stationary CI engine 

emissions are adequately addressed through fuel quality regulations and 40 CFR part 63, 

subpart ZZZZ. It is not clear to EPA what fuel quality regulations the commenter is 

referring to. No previous federal standards apply to the fuel used in such engines. 

Subpart ZZZZ does not apply to all stationary CI ICE; it only applies to stationary CI ICE 

greater than 500 hp and located at major sources of hazardous air pollutants (HAP) 

emissions. Criteria pollutants were not the focus of subpart ZZZZ, which was a rule 

developed and designed to reduce HAP emissions. This NSPS, on the other hand, must 

address criteria pollutants. In developing this NSPS, EPA reviewed and considered the 

requirements of subpart ZZZZ and the emissions requirements in this proposal are 

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compatible with the emissions requirements of subpart ZZZZ. The control technologies 

that the two rules rely on are compatible with each other; the control technologies that are 

the basis for the NSPS in some cases can reduce HAP in addition to reducing criteria 

pollutants. One example is CDPF, which reduces both PM and HAP. Another example 

is a NOx adsorber combined with an oxidation catalyst. EPA has attempted to reduce 

compliance complexity, particularly for owners and operators, by aligning this regulation 

with pre-existing regulations for nonroad engines and allowing owners and operators to 

rely on engine manufacturer certification to comply with these requirements. 

19.0 Costs 

19.1 Comment: One commenter (244) believed that new strict emission standards for 

stationary engines will be met in a cost-effective manner given adequate lead-time. The 

commenter cited DPF and DOC control costs from the California ARB on stationary 

engines, a CALSTART study on DPF and SCR on passenger ferries, and provided costs 

for large-scale commercial marine SCR applications in Europe. 

Response: No response is needed. 

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20.0 Health/Environmental Impacts 

20.1 Comment: One commenter (243) made the comment that the proposal fails to 

mention, but the Agency has acknowledged in other settings, that diesel air pollution also 

poses substantial cancer risk across the country. Several organizations, including EPA, 

the National Institute for Occupational Safety and Health, the International Agency for 

Research on Cancer, the World Health Organization, California EPA, and the U.S. 

Department of Health and Human Service’s National Toxicology Program have 

designated diesel exhaust as a probable or potential human carcinogen. According to the 

Multiple Air Toxics Exposure Study (MATES-II) conducted for California’s South Coast 

Air Quality Management District, about 70 percent of the total inhalation cancer risk 

from air pollution for the average California resident is due to diesel exhaust. 

California’s Office of Environmental Health Hazard Assessment concluded that “longterm exposure to diesel exhaust particles poses the highest cancer risk of any toxic air 

contaminant evaluated...” A separate assessment suggested that the result for the U.S. as 

a whole is even worse: 80 percent of the total cancer risk from hazardous air pollutants 

nationwide is estimated to be associated with the inhalation of diesel exhaust. The 

commenter indicated that it retained Dr. William Nazaroff 

(http://www.ce.berkeley.edu/~nazaroff/) to conduct a risk assessment of emergency 

backup generators in several California cities. Dr. Nazaroff’s analysis found the cancer 

risk exceeded one in a million for a remarkably expansive zone downwind of an 

emergency back-up generator. Generators operating infrequently nevertheless had risk 

zones spanning 10 to 20 average city blocks. In closer proximity to an emergency use 

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engine, the estimated cancer risk exceeded ten in a million. Relying on dispersion 

modeling, risk analysis, state permit data and GIS analysis, the risk assessment found that 

in four California air quality management districts (i.e., South Coast, San Diego, San 

Joaquin Valley, and Sacramento), some 150,000 children attended schools within the 

cancer risk zones of emergency diesel generators.

Response: EPA acknowledges that there have been links to cancer from diesel exhaust. 

EPA is finalizing standards of performance for emergency engines that are the most 

stringent that can justified and the standards that are being promulgated for stationary 

emergency CI engines will lead to substantial reductions in PM emitted even though addon controls will not be required for emergency engines to meet the standards. EPA is 

also implementing stringent restrictions on the usage of emergency engines for operation 

during any other circumstances besides for emergency purposes, which should reduce 

this problem. Emergency engines do not operate much; some sources estimate only 

about 50 hours per year. EPA has noted that there is a very high cost per ton of putting 

aftertreatment on these engines. We believe that the increased upfront costs of engines 

with aftertreatment are not justified for these engines, which are used so rarely and often 

in situations where greater and more immediate harm to human health (e.g., fire or flood) 

is evident. In addition, EPA does not wish to prevent owners from being able to purchase 

new emergency engines. Given that emergency engines with aftertreatment will be 

appreciably more expensive than engines without aftertreatment, EPA believes that 

substantial increases in cost may dissuade owners and operators from purchasing new 

emergency engines which, given the importance of these engines, may be 

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counterproductive to the goal of better human health and welfare. In particular areas 

where local regulators are concerned about proximity of emergency engines to numerous 

people, the local regulators can regulate these engines. 

21.0 Other 

21.1 Public Comment Period Extension 

21.1.1 Comment: One commenter (217) said that the 60-day public comment period 

provides insufficient time to do a thorough analysis and submit comments on the 

proposed rule. The commenter requested a 30-day extension to the comment period. 

Response: EPA denied the commenter’s request for an extension to the public comment 

period. EPA based its decision on the tight consent decree deadline to issue regulations 

for stationary CI engines and felt that 60 days was an adequate public comment period. 

In addition, EPA pointed out in its denial to extend the public comment period that the 

proposal was posted on EPA’s website about 1 1⁄2 weeks prior to publication in the 

Federal Register. Please refer to the docket for this rulemaking, EPA-HQ-OAR-2005-

0029-0230, for EPA’s official response to the commenter’s request. 

21.2 Corrections Needed 

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21.2.1 Comment: One commenter (240) stated that there appears to be a typo in 

§60.4205(a) of the proposed rule. In the second sentence of that provision, it appears that 

the word “non-emergency” should be “emergency.” 

Response: There was an inadvertent error in 60.4205(a) of the proposed rule. As the 

commenter pointed out, in the second sentence of that provision, the word “nonemergency” should have been “emergency.” This has been corrected in the final rule. 

21.2.2 Comment: One commenter (235) said that on page 39898 of the proposed rule 

formulas are given for the conversion from the concentration unit ppm by volume (ppmv) 

to the mass based unit g/kW-hr. The commenter stated that equation 7 of the proposed 

rule contains an error. When calculating the mass based unit g/kW-hr, the “actual” ppmv 

concentration should be used and not the 15 percent O2 corrected value. The commenter 

added that the factor of 1.912 for converting ppmv NOx to mg/Nm3 indicates Nm3 to be 

given at 25°C. The commenter said that this needs to be mentioned in the text. 

Response: The commenter is correct that the measured concentration and not the 

corrected concentration should be used in equation 7 of the rule. EPA has made this 

correction in the final rule. The conversion constant of 1.912 x 10-03 is at EPA-defined 

standard conditions, which are 20°C (68°F) and 1 atm (14.7 psia). EPA has clarified this 

in the final rule. 

21.3 Format of Standards 

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21.3.1 Comment: One commenter (259) requested that the emission limits include 

concentration-based alternatives (e.g., ppmv for gaseous species, mg/m3for particulate) 

or input-based limits (e.g., pounds per gallon of fuel) to the output based limits (e.g., 

g/hp-hr) so that emissions compliance can be verified for units that cannot readily 

measure output power. Determination of output power may not be accessible for all 

engine sizes and applications. While EPA may consider this a non-issue due to 

manufacturer certification, there is the potential for compliance certification such as 

testing to be added to NSPS affected units due to concerns about “useful life.” In this 

scenario, a concentration-based alternative to the output-based limit would provide the 

ability to certify compliance based on a stack test, and the commenter recommended that 

a concentration-based alternative emission limit be included for instances where 

owner/operator compliance tests are conducted. 

Response: Stationary CI engines affected by this NSPS will for the most part be 

regulated through a certification program and to emission standards generally consistent 

with those that apply to nonroad diesel engines. Also, manufacturers often produce the 

same engine for use in nonroad and stationary applications. For these reasons, it is 

important that the emission standards are in consistent units, i.e., g/kW-hr. In addition, 

EPA has no emissions data to establish alternative concentration-based emission 

standards for stationary CI engines. EPA believes it is appropriate that the format of the 

standards is written in units of g/kW-hr and does not believe it is necessary to include 

concentration-based units in the rule. The units of g/kW-hr will remain in the final rule. 

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21.4 Military Training Engines 

21.4.1 Comment: One commenter (256) recommended that the rule exempt engines used 

in training and testing of military personnel in the operation, maintenance and repair of 

engines. These engines may have to be configured similarly to engines used by the U.S. 

or its allies in combat operations, which may make it difficult or impossible for them to 

comply with the NSPS. 

Response: EPA agrees that it is appropriate to exempt engines used for military 

purposes. A national security exemption exists already (see, e.g., 40 CFR part 89 subpart 

J). Engines meeting the conditions specified in 40 CFR 89.908, and the corresponding 

provisions in parts 94 and 1068, will be considered exempt from the regulations for 

stationary CI ICE. An engine that receives the national security exemption under the 

non-road engine provisions when purchased will continue to be exempt if used as a 

stationary ICE, as long as it continues to be used for national security purposes. In 

addition, for engines that receive a national security exemption will also be exempt from 

the fuel requirements in section 60.4207 of the final regulations. EPA believes that these 

provisions address the commenter’s concerns. 

21.5 Replacement Engines 

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21.5.1 Comment: One commenter (240) stated that a replacement engine exemption 

from the NSPS requirements (such as is found at 40 CFR §§89.1003 and 1068.240) 

should be included only for emergency engines. 

Another commenter (265) noted that EPA has requested comment on the appropriateness 

of including the exemption provisions of 40 CFR 1068.240, which relate to replacement 

engines. This commenter believed that limited exemption provisions for replacement 

engines are appropriate. Those exemptions should only be granted for a limited period 

from the original MY in order to restrict the perpetual use of higher emitting equipment. 

For example, New Jersey specifies a 15 year period for turbine overhaul before state of 

the art emission limits must be reevaluated and incorporated as appropriate. 

Response: EPA believes it is appropriate to include replacement engine provisions from 

the nonroad regulations to this rule; however, the provision is limited to engines going 

into equipment that is less than 15 years old. This change is reflected in the final rule and 

EPA has included nonroad sections §§89.1003(b)(7), 94.1103(b)(3) and (4) and 1068.240 

in the regulation language for the final rule. 

21.6 Temporary Engines 

21.6.1 Comment: One commenter (259) expressed that the rule needs to clearly allow for 

temporary hp replacement using portable engines to ensure that disruptions and outages 

during maintenance are minimized and other short term applications are clearly exempt 

from NSPS requirements. EPA should provide a clear indication that the following 

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applications are not considered stationary engines and are exempt from the NSPS for 

stationary CI engines: 

• A unit that temporarily replaces an engine that is undergoing an overhaul, and is 

then moved to another location to serve as a temporary replacement for another 

unit undergoing overhaul; 

• An existing spare unit that has been in service prior to the subpart IIII proposal 

and is used in an engine rotation program to replace an engine that is overhauled 

and moved into the spare engine rotation; and 

• A temporary engine that is not the identical make, model or hp is acceptable for 

short-term (not to exceed 90 days) replacement. 

Response: EPA agrees that the engines themselves that are used for temporary 

replacement of stationary engines are nonroad engines and are not covered by stationary 

engine regulations, as long they meet the definition of nonroad engine and if they are not 

used beyond the residence limitations in paragraph 2(iii) of the nonroad engine definition 

in 40 CFR 1068.30. However, EPA notes that once the stationary engine is put back in 

operation, it is immediately subject to all the requirements of this subpart. The residence 

time period for the installation continues to run while the temporary engine is in 

operation. Moreover, EPA notes that this subpart, as well as 40 CFR sections 

89.1003(a)(5) and 1068.101(b)(3), forbid any attempt to circumvent the residence time 

requirements of the nonroad engine definition. Use of a nonroad engine that does not 

comply with NSPS standards applicable to the engine it replaces can be seen as 

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circumvention of the residence time requirement if the engine is used for a period beyond 

a period that is reasonably necessary for the temporary purpose it is designed to achieve. 

21.7 Adjustments 

21.7.1 Comment: One commenter (247) was concerned that Caterpillar engines with 

programmable logic controllers (PLC) will be certified using a low emission (low NOx) 

setting, but could possibly be adjusted in the field to a fuel economy setting (higher 

NOx). The rising cost of fuel could increase the potential for this activity. The 

commenter suggested that the NSPS require owners/operators to keep a record of all 

adjustments to the PLC, including the reason for the adjustment and the manufacturer’s 

certification that the engine operating with the adjusted PLC still meets the emission 

standards. 

Response: EPA understands the commenter’s concern that certain stationary CI engines 

may be adjusted while in service for various reasons including for fuel saving purposes. 

The commenter’s suggestion is reasonable, but EPA believes it would be more 

appropriate to incorporate provisions into the rule that limits the owners and operators to 

changing only those settings that are allowed by the engine manufacturer. The engine 

owner or operator must not operate the engine outside the manufacturer’s parameters. 

This provision has been included in the final rule and prevents engines from being 

operated under conditions that would lead to engine out exhaust emissions being out of 

compliance. 

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168
21.8 Biodiesel 

21.8.1 Comment: One commenter (249) provided background information on biodiesel, 

commonly made from vegetable oils such as soybean oil, including benefits of using 

biodiesel fuels in stationary engines. Biodiesel can be used immediately and seamlessly 

as a clean-burning, no-sulfur alternative fuel or lubricity additive, according to the 

commenter. The use of biodiesel contributes to a longer equipment life, lower 

maintenance costs and less equipment downtime. The commenter proposed that EPA 

consider offering incentives and an optional testing program for engine companies to test 

biodiesel, and proposed the following: 

Incentives: Engine companies should receive incentives for conducting biodiesel testing 

on engines, e.g., they could receive double emissions credits. This would encourage 

them to conduct this important testing, provide EPA and other interested stakeholders 

with critical data, and could potentially lead to increased emissions warranties on 

biodiesel. 

Testing must not be duplicative: Biodiesel testing should not be duplicative of already 

required testing on diesel fuel. Rather, the biodiesel testing could be limited to testing 

simply on emissions at a certain blended level. The commenter would be very willing to 

work with EPA to determine which specific tests would need to be conducted on 

biodiesel to make it beneficial and acceptable. 

169
Optional: The testing program must be optional and not mandated. 

Response: EPA would like to encourage the use of renewable fuels such as biodiesel in 

stationary CI engines, but is unable to offer incentives and testing programs, as the 

commenter proposed, in the context of this rulemaking. 

21.9 Dual-Fuel 

21.9.1 Comment: One commenter (261) supported EPA inclusion of liquid pilot units 

(i.e., dual-fuel units with low levels of liquid pilot fuel) in the spark ignition (SI) engine 

equipment category. 

Response: No response is needed. 

21.9.2 Comment: One commenter (256) said that the rule considers dual-fueled CI 

engines that use liquid fuel and gaseous fuel at an annual ratio of less than 2 parts diesel 

fuel per 100 parts total fuel as SI engines, and, therefore, not subject to the regulation. 

The commenter has found that a ratio of 5 parts diesel fuel per 100 parts total fuel is a 

ratio that adequately defines dual-fueled diesel engines using natural gas for regulatory 

purposes. Except as noted below in comment 21.9.3, the commenter recommended that 

dual-fueled engines with a ratio of 5 parts diesel to 100 parts total fuel be considered SI 

engines. 

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Response: Based on information EPA has received and reviewed, EPA believes that 2 

parts diesel fuel to 100 parts of total fuel is an appropriate cutoff for the purposes of this 

regulation. The commenter did not provide any supporting information explaining why it 

believed a ratio of 5 parts diesel to 100 parts of total fuel should be adopted in the final 

rule and why these should be considered SI engines. Therefore, the definition of SI 

engines remains as proposed in the final rule and dual-fuel engines where a liquid fuel is 

used for CI and gaseous fuel is used as the primary fuel, with the exception of landfill or 

digester gas fuels, at an annual average ratio of less than 2 parts diesel fuel to 100 parts 

total fuel on an energy equivalent basis are SI engines. 

21.9.3 Comment: One commenter (256) said that dual-fueled engines using diesel fuel 

and digester or landfill gas may operate at a ratio as high as 30 parts diesel to 100 parts 

total fuel. These engines may have difficulty complying with the proposed emission 

standards because of the composition of the gaseous fuel, especially if the use of 

catalyzed emission control equipment is necessary. Furthermore, there are environmental 

benefits to using digester or landfill gas that would otherwise be flared, to produce useful 

power. The commenter recommended that all dual-fueled engines using a combination 

diesel fuel and digester or landfill gas be exempt from the proposed emission standards of 

this regulation. 

One commenter (271) expressed concern regarding engines in landfill gas service. 

Landfill gas contains siloxanes which will poison any catalytic device. There is no 

known reliable technology for removing siloxanes from landfill gas. The NSPS proposes 

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the use of NOx absorber technology for NOx control and catalyst technology for PM 

control. Both of these technologies would be rendered ineffective for engines used to 

convert the renewable energy from landfill gas methane into useful energy. The 

problems with siloxanes were noted in 40 CFR part 63, subpart ZZZZ for stationary 

RICE. The commenter has several landfill-gas-to-energy projects using diesel engines. 

The commenter believed that diesel engines provide a very effective technology for using 

landfill gas. The commenter also recognized, through experience, that catalytic 

converters will not be effective in this service as a result of landfill gas siloxane content. 

Diesel engines can be used over a range of landfill gas substitutions for liquid fuel. They 

also may be used with no landfill gas. In fact, engine startups are done using only liquid 

fuel. However, once landfill gas is used, the poisoning of the catalyst will quickly 

reduce, and eventually nullify, the effectiveness of the technologies suggested in the 

proposed standard. The commenter’s experience has been a 50 percent reduction in 

catalyst effectiveness in about 200 hours and a greater than 90 percent reduction in less 

than 300 hours. The commenter requested that the NSPS exempt CI engines in landfill 

gas service. 

Response: EPA recognizes that there may be concerns with applying add-on controls to 

stationary CI engines using landfill or digester gas due to the presence of siloxanes in 

these fuels. Siloxanes have been known to poison the catalyst and can reduce the 

effectiveness of the catalyst within brief periods of time. This was acknowledged in 40 

CFR subpart ZZZZ. EPA agrees with the commenters that it would be inappropriate to 

require stationary CI engines burning landfill or digester gas to meet emission standards 

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that rely on the use of aftertreatment controls. EPA, however, does not agree that it is 

appropriate to exempt stationary CI engines burning landfill or digester gas entirely from 

the regulation. The problem with using these fuels is, as mentioned, related to the 

application of aftertreatment controls in combination with these fuels. Therefore, any 

emission standard that does not rely on the use of add-on controls would be suitable. 

Based on the comments received, the issues related to using landfill and digester gas in 

stationary CI engines appears to be limited to applying add-on controls. Therefore, EPA 

believes it is appropriate that stationary CI engines utilizing landfill and digester gas meet 

the most stringent level of control that does not require aftertreatment devices, i.e., either 

Tier 2 or Tier 3, as applicable. The final rule has been written to incorporate this 

provision. EPA believes this provision resolves the commenter’s concerns regarding 

these fuels. 

21.10 SI NSPS 

21.10.1 Comment: One commenter (261) stated that the NSPS proposes to regulate NOx, 

NMHC, PM, and CO. The proposed subpart KKKK for stationary combustion turbines 

proposed to regulate pollutants including NOx, CO, PM, HC, and NMHC. The choice of 

pollutants appears to be based upon the nonroad and marine standards, and it does not 

appear that original analysis was conducted to assess the impacts associated with the 

array of regulated pollutants for stationary CI engines. The commenter did not offer any 

specific recommendations regarding the pollutants included in the proposed standard. 

However, the commenter recommended that EPA carefully consider the pollutants to be 

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regulated when developing the companion SI NSPS, which is scheduled for proposal in 

2006. It is important to understand that emission profiles differ for liquid-fired CI 

engines and gas-fired SI engines. In addition, utilization and operational profiles can 

affect source category emissions. In fact, due to the utilization profile from stationary CI 

engines, it is possible that emissions are different than emissions from nonroad sources 

and regulation of all of the pollutants included in the proposed standard may not be 

warranted. The commenter offered this comment mainly due to concerns regarding the 

upcoming SI NSPS, and recommended that EPA complete a thoughtful review and 

analysis of this topic for the SI NSPS proposal to ensure that only pollutants of concern 

are regulated. 

Response: This comment is outside the scope of the NSPS for stationary CI engines. 

EPA plans to conduct a careful review of which pollutants to be addressed under the 

upcoming SI NSPS. 

21.11 Test Cells 

21.11.1 Comment: One commenter (220) expressed support of the proposed rule. The 

commenter manufactures 5 kW fuel cell systems that run on pure hydrogen, natural gas 

or liquefied petroleum gas, and are an off-the-shelf environmental option to traditional 

diesel back-up generator systems. 

Response: No response is needed. 

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21.11.2 Comment: One commenter (214) requested that the rule state that diesel engine 

test cells/facilities are exempt from the rule. 

Response: The final rule states that the rule does not apply to stationary CI engine test 

cells/stands. 

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