Standards of Performance for Stationary Spark Ignition Internal Combustion Engines and National Emission Standards for Hazardous Air Pollutants for Reciprocating Internal Combustion Engines, 33804-33855 [06-4919]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 71, Number 112 (Monday, June 12, 2006)]
[Proposed Rules]
[Pages 33804-33855]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-4919]



[[Page 33803]]

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Part II





Environmental Protection Agency





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40 CFR Parts 60, 63, et al.



Standards of Performance for Stationary Spark Ignition Internal 
Combustion Engines and National Emission Standards for Hazardous Air 
Pollutants for Reciprocating Internal Combustion Engines; Proposed Rule

Federal Register / Vol. 71, No. 112 / Monday June 12, 2006 / Proposed 
Rules

[[Page 33804]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 60, 63, 85, 90, 1048, 1065, and 1068

[EPA-HQ-OAR-2005-0030, FRL-8176-1]
RIN 2060-AM81 and 2060-AN62


Standards of Performance for Stationary Spark Ignition Internal 
Combustion Engines and National Emission Standards for Hazardous Air 
Pollutants for Reciprocating Internal Combustion Engines

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA is proposing new source standards of performance for 
stationary spark ignition internal combustion engines. EPA is also 
proposing national emission standards for hazardous air pollutants for 
stationary reciprocating internal combustion engines that either are 
located at area sources of hazardous air pollutant emissions or that 
have a site rating of less than or equal to 500 brake horsepower and 
are located at major sources of hazardous air pollutant emissions.

DATES: Comments must be received on or before September 11, 2006, or 60 
days after date of public hearing if later. Under the Paperwork 
Reduction Act, comments on the information collection provisions must 
be received by the Office of Management and Budget (OMB) on or before 
July 12, 2006. Public Hearing. If anyone contacts us requesting to 
speak at a public hearing by July 3, 2006, a public hearing will be 
held on July 12, 2006. If you are interested in attending the public 
hearing, contact Ms. Pamela Garrett at (919) 541-7966 to verify that a 
hearing will be held.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2005-0030, by one of the following methods:
     www.regulations.gov: Follow the on-line instructions for 
submitting comments.
     E-mail: a-and-r-docket@epa.gov.
     Fax: (202) 566-1741.
     Mail: Air and Radiation Docket and Information Center, 
Environmental Protection Agency, Mailcode: 6102T, 1200 Pennsylvania 
Ave., NW., Washington, DC 20460. Please include a total of two copies. 
EPA requests a separate copy also be sent to the contact person 
identified below (see FOR FURTHER INFORMATION CONTACT). In addition, 
please mail a copy of your comments on the information collection 
provisions to the Office of Information and Regulatory Affairs, Office 
of Management and Budget, Attn: Desk Officer for EPA, 735 17th St., 
NW., Washington, DC 20503.
     Hand Delivery: Air and Radiation Docket and Information 
Center, U.S. EPA, Room B102, 1301 Constitution Avenue, NW., Washington, 
DC. Such deliveries are only accepted during the Docket's normal hours 
of operation, and special arrangements should be made for deliveries of 
boxed information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2005-0030. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available on-line 
at https://www.regulations.gov, including any personal information 
provided, unless the comment includes information claimed to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Do not submit information that you 
consider to be CBI or otherwise protected through www.regulations.gov 
or e-mail. The www.regulations.gov Web site is an ``anonymous access'' 
system, which means EPA will not know your identity or contact 
information unless you provide it in the body of your comment. If you 
send an e-mail comment directly to EPA without going through 
www.regulations.gov, your e-mail address will be automatically captured 
and included as part of the comment that is placed in the public docket 
and made available on the Internet. If you submit an electronic 
comment, EPA recommends that you include your name and other contact 
information in the body of your comment and with any disk or CD-ROM you 
submit. If EPA cannot read your comment due to technical difficulties 
and cannot contact you for clarification, EPA may not be able to 
consider your comment. Electronic files should avoid the use of special 
characters, any form of encryption, and be free of any defects or 
viruses.
    Public Hearing: If a public hearing is held, it will be held at 
EPA's campus located at 109 T.W. Alexander Drive in Research Triangle 
Park, NC or an alternate site nearby.
    Docket: All documents in the docket are listed in the 
www.regulations.gov index. We also rely on documents in Docket ID Nos. 
A-96-55 and A-2000-01, and incorporate those dockets into the record 
for this proposed rule. Although listed in the index, some information 
is not publicly available, e.g., CBI or other information whose 
disclosure is restricted by statute. Certain other material, such as 
copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available either electronically 
in www.regulations.gov or in hard copy at the Air and Radiation Docket, 
EPA/DC, EPA West, Room B102, 1301 Constitution Ave., NW., Washington, 
DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday 
through Friday, excluding legal holidays. The telephone number for the 
Public Reading Room is (202) 566-1744, and the telephone number for the 
Air Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Mr. Jaime Pag[aacute]n, Energy 
Strategies Group, Sector Policies and Programs Division (D243-01), 
Environmental Protection Agency, Research Triangle Park, North Carolina 
27711; telephone number (919) 541-5340; facsimile number (919) 541-
5450; email address ``pagan.jaime@epa.gov.''

SUPPLEMENTARY INFORMATION: Organization of This Document. The following 
outline is provided to aid in locating information in the preamble.

I. General Information
    A. Does this action apply to me?
    B. What should I consider as I prepare my comments for EPA?
II. Background
III. Summary of This Proposed Rule
    A. What is the source category regulated by this proposed rule?
    B. What are the pollutants regulated by this proposed rule?
    C. What are the proposed standards?
    D. What are the requirements for sources that are modified or 
reconstructed?
    E. What are the requirements for demonstrating compliance?
    F. What are the reporting and recordkeeping requirements?
IV. Rationale for Proposed Rule
    A. Which control technologies apply to stationary engines?
    B. How did EPA determine the basis and level of the proposed 
standards?
    C. How did EPA determine the compliance requirements?
    D. How did EPA determine the reporting and recordkeeping 
requirements?
    E. Why did EPA determine to exempt area sources from title V 
permit requirements?
V. Summary of Environmental, Energy and Economic Impacts
    A. What are the air quality impacts?
    B. What are the cost impacts?
    C. What are the economic impacts?
    D. What are the non-air health, environmental and energy 
impacts?
VI. Solicitation of Comments and Public Participation
VII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act of 1995

[[Page 33805]]

    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act

I. General Information

A. Does this action apply to me?

    Regulated Entities. Categories and entities potentially regulated 
by this action include:

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                  Category                    NAICS \1\               Examples of regulated entities
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Any manufacturer that produces or any              2211  Electric power generation, transmission, or
 industry using a stationary internal            622110   distribution.
 combustion engine as defined in this            335312  Medical and surgical hospitals.
 proposed rule.                                  333912  Motor and generator manufacturing.
                                                 333992  Pump and compressor manufacturing.
                                                  48621  Welding and soldering equipment manufacturing.
                                                 211111  Natural gas transmission.
                                                 211112  Crude petroleum and natural gas production.
                                                  92811  Natural gas liquids producers.
                                                         National security.
----------------------------------------------------------------------------------------------------------------
\1\ North American Industry Classification System.

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. To determine whether your engine is regulated by this action, 
you should examine the applicability criteria of this proposed rule. If 
you have any questions regarding the applicability of this action to a 
particular entity, consult the person listed in the preceding FOR 
FURTHER INFORMATION CONTACT section.

B. What should I consider as I prepare my comments for EPA?

    1. Submitting CBI. Do not submit this information to EPA through 
regulations.gov or e-mail. Clearly mark the part or all of the 
information that you claim to be CBI. For CBI information in a disk or 
CD ROM that you mail to EPA, mark the outside of the diskor CD ROM as 
CBI and then identify electronically within the disk or CD ROM the 
specific information that is claimed as CBI. In addition to one 
complete version of the comment that includes information claimed as 
CBI, a copy of the comment that does not contain the information 
claimed as CBI must be submitted for inclusion in the public docket. 
Information so marked will not be disclosed except in accordance with 
procedures set forth in 40 CFR part 2. Send or deliver information 
identified as CBI to only the following address: Mr. Jaime 
Pag[aacute]n, c/o OAQPS Document Control Officer (Room C404-02), U.S. 
EPA, Research Triangle Park, NC 27711, Attention Docket ID No. EPA-HQ-
OAR-2005-0030.
    2. Tips for Preparing Your Comments. When submitting comments, 
remember to:
    (a) Identify the rulemaking by docket number and other identifying 
information (subject heading, Federal Register date and page number).
    (b) Follow directions. EPA may ask you to respond to specific 
questions or organize comments by referencing a Code of Federal 
Regulations (CFR) part or section number.
    (c) Explain why you agree or disagree; suggest alternatives and 
substitute language for your requested changes.
    (d) Describe any assumptions and provide any technical information 
and/or data that you used.
    (e) If you estimate potential costs or burdens, explain how you 
arrived at your estimate in sufficient detail to allow for it to be 
reproduced.
    (f) Provide specific examples to illustrate your concerns, and 
suggest alternatives.
    (g) Explain your views as clearly as possible, avoiding the use of 
profanity or personal threats.
    (h) Make sure to submit your comments by the comment period 
deadline identified.
    Docket. The docket number for this proposed rule is Docket ID No. 
EPA-HQ-OAR-2005-0030.
    World Wide Web (WWW). In addition to being available in the docket, 
an electronic copy of this proposed rule will be posted on the WWW 
through the Technology Transfer Network Web site (TTN Web). Following 
signature, EPA will post a copy of this proposed rule on the TTN's 
policy and guidance page for newly proposed or promulgated rules at 
https://www.epa.gov/ttn/oarpg. The TTN provides information and 
technology exchange in various areas of air pollution control.

II. Background

    This action proposes new source performance standards (NSPS) that 
would apply to new stationary spark ignition (SI) internal combustion 
engines (ICE). New source performance standards implement section 
111(b) of the Clean Air Act (CAA), and are issued for categories of 
sources which cause, or contribute significantly to, air pollution 
which may reasonably be anticipated to endanger public health or 
welfare. The standards apply to new stationary sources of emissions, 
i.e., sources whose construction, reconstruction, or modification 
begins after a standard for those sources is proposed. The NSPS for 
stationary SI ICE would be promulgated under 40 CFR part 60, subpart 
JJJJ.
    This action also proposes national emission standards for hazardous 
air pollutants (NESHAP) from existing, new, and reconstructed 
stationary reciprocating internal combustion engines (RICE) with a site 
rating of less than or equal to 500 horsepower (HP) located at major 
sources, and existing, new, and reconstructed stationary RICE located 
at area sources. We are proposing these requirements to meet our 
statutory obligation to address hazardous air pollutants (HAP) 
emissions from these sources under sections 112(d) and 112(k) of the 
CAA. The final NESHAP for stationary RICE would be promulgated under 40 
CFR part 63, subpart ZZZZ, which already contains standards applicable 
to stationary RICE with a site rating above 500 HP located at major 
sources.
    We are proposing these two sets of regulations under one notice of 
proposed rulemaking because the source categories being addressed are 
practically identical. In other words, stationary engines located at 
major and area sources of HAP will also be affected by NSPS 
regulations. Based on the similarities, we decided that it would be 
appropriate to propose the regulations at the same time and attempt to 
bring some consistency between them.

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III. Summary of this Proposed Rule

A. What is the source category regulated by this proposed rule?

    The proposed NSPS apply to new stationary SI ICE. A stationary 
internal combustion engine means any 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. Stationary ICE include 
reciprocating ICE, rotary ICE, and other ICE, except combustion 
turbines. The proposed NESHAP applies only to stationary RICE. To our 
knowledge, no rotary or other types of stationary ICE exist at this 
time.
    The SI NSPS address emissions from new, modified and reconstructed 
stationary SI engines. An SI engine is either a gasoline-fueled engine; 
or any other type of engine, with a spark plug (or other sparking 
device) and with operating characteristics significantly similar to the 
theoretical Otto combustion cycle. Spark ignition engines usually use a 
throttle to regulate intake air flow to control power during normal 
operation. Dual-fuel engines in which a liquid fuel (typically diesel 
fuel) is used for compression ignition and gaseous fuel (typically 
natural gas) is used as the primary fuel at an annual average ratio of 
less than 2 parts diesel fuel to 100 parts total fuel on an energy 
equivalent basis are considered SI engines for purposes of this 
proposed rule.
    The NESHAP address emissions from existing, new, and reconstructed 
stationary engines less than or equal to 500 HP located at major 
sources and all stationary engines located at area sources. A major 
source of HAP emissions is a plant site that emits or has the potential 
to emit any single HAP at a rate of 10 tons (9.07 megagrams) or more 
per year or any combination of HAP at a rate of 25 tons (22.68 
megagrams) or more per year, except that for oil and gas production 
facilities, a major source of HAP emissions is determined for each 
surface site. An area source of HAP emissions is a source that is not a 
major source.
    If you are an owner or operator of an area source subject to this 
proposed rule, you are exempt from the obligation to obtain a permit 
under 40 CFR parts 70 or 71, provided you are not required to obtain a 
permit under 40 CFR 70.3(a) or 40 CFR 71.3(a) for a reason other than 
your status as an area source under this proposed rule.
1. SI NSPS
    New source performance standards for stationary SI engines are 
issued under section 111(b) of the CAA. All new, modified and 
reconstructed stationary SI engines are covered regardless of size. The 
NSPS apply to stationary SI engines combusting any fuel (natural gas, 
gasoline, liquefied petroleum gas (LPG), compressed natural gas, 
landfill gas, digester gas, and any other applicable fuel). New source 
performance standards require these sources to control emissions to the 
level achievable by best demonstrated technology (BDT), considering 
costs and any non-air quality health and environmental impacts and 
energy requirements.
    Under section 111 of the CAA, 42 U.S.C. 7411, the Administrator is 
required to publish, and periodically update, a list of source 
categories that in his or her judgment cause, or contribute 
significantly to, air pollution which may reasonably be anticipated to 
endanger public health or welfare. This list appears in 40 CFR 60.16. 
The list reflects the Administrator's determination that emissions from 
the listed source categories contribute significantly to air pollution 
that may reasonably be anticipated to endanger public health or 
welfare, and it is intended to identify major source categories for 
which standards of performance are to be promulgated.
    EPA has determined that for purposes of NSPS regulations, the 
stationary internal combustion engine source category should be split 
into two source categories--SI engines and compression ignition (CI) 
engines. Proposed NSPS for stationary CI engines were published on July 
11, 2005 (70 FR 39870).
2. NESHAP
    The NESHAP portion of this action is a revision to the regulations 
in 40 CFR part 63, subpart ZZZZ, currently applicable to stationary 
RICE greater than 500 HP located at major sources, which were 
promulgated in 2004. Subpart ZZZZ of 40 CFR part 63 does not currently 
cover stationary engines located at area sources of HAP emissions, nor 
does it apply to stationary engines located at major sources with a 
site rating of 500 HP or less. When the subpart ZZZZ of 40 CFR part 63 
regulations were promulgated in 2004 (69 FR 33474), EPA deferred 
promulgating regulations with respect to stationary engines 500 HP or 
less at major sources until further information on the engines could be 
obtained and analyzed. It was decided to regulate these smaller engines 
at the same time as we regulate engines located at area sources.
    This action proposes to revise 40 CFR part 63, subpart ZZZZ, in 
order to address HAP emissions from stationary RICE less than or equal 
to 500 HP located at major sources and stationary RICE located at area 
sources. For stationary engines less than or equal to 500 HP at major 
sources, EPA must determine what is the appropriate maximum achievable 
control technology (MACT) for those engines under section 112(d)(3) of 
the CAA.
    For stationary engines located at area sources, we have the 
flexibility to promulgate standards based on generally available 
control technology (GACT) under CAA section 112(d)(5). We are required 
to address HAP emissions from stationary RICE located at area sources 
under section 112(k) of the CAA, based on criteria set forth by EPA in 
the Urban Air Toxics Strategy described in the paragraph below.
    On July 19, 1999, EPA announced in the Federal Register its plan 
for addressing exposure to air toxics in urban areas. The Urban Air 
Toxics Strategy (64 FR 38706) listed several source categories that 
emit one or more of the air toxic pollutants of greatest concern in 
urban areas. The stationary engine source category was one of the 
source categories listed and, as such, EPA is required to consider it 
for regulation. The strategy addressed sections 112(c)(3) and 
112(k)(3)(B)(ii) of the CAA that instruct us to identify not less than 
30 HAP which, as the result of emissions from area sources, present the 
greatest threat to public health in the largest number of urban areas, 
and to list sufficient area source categories or subcategories to 
ensure that emissions representing 90 percent of the 30 listed HAP are 
subject to regulation. The strategy included a list of 33 HAP judged to 
pose the greatest potential threat to public health in the largest 
number of urban areas (the urban HAP) and a list of area source 
categories emitting the listed HAP (area source HAP). Once listed, 
these area source categories shall be subject to standards under 
section 112(d) of the CAA.
    We have divided the source category into the following 
subcategories: Stationary RICE less than 50 HP, landfill and digester 
gas stationary RICE, CI stationary RICE greater than or equal to 50 HP, 
and SI stationary RICE greater than or equal to 50 HP. The CI 
stationary RICE greater than or equal to 50 HP subcategory was further 
subcategorized into emergency and non-emergency engines, as was the

[[Page 33807]]

subcategory of SI stationary RICE greater than or equal to 50 HP. Spark 
ignition non-emergency stationary RICE greater than or equal to 50 HP 
were then subcategorized into 2 stroke lean burn (2SLB), 4 stroke lean 
burn (4SLB), and 4 stroke rich burn (4SRB) stationary RICE.
    The regulatory approach being proposed in this action 
differentiates between gasoline, LPG, natural gas, and digester and 
landfill gas. Gasoline and LPG are fuels more commonly used in nonroad 
engines than stationary engines. Nonroad SI engines less than or equal 
to 19 kilowatt (KW) (25 HP) typically use gasoline. It is estimated 
that about 68 percent of SI nonroad engines above 19 KW (25 HP) use 
LPG. A smaller percentage of nonroad SI engines above 19 KW (25 HP) use 
gasoline (about 23 percent) and even less use compressed natural gas 
(about 9 percent). Natural gas fuel is more common in larger, 
stationary applications. Natural gas engines refer to all gaseous-
fueled engines except those fueled by landfill and digester gas. 
Natural gas is primarily composed of methane and typically contains 
very low levels of sulfur. Other fuels used with stationary SI engines 
are landfill and digester gases. These gases are by-products of 
wastewater treatment and land application of municipal reuse. Landfill 
and digester gases, which are formed through anaerobic decomposition of 
organic materials, are principally comprised of methane and carbon 
dioxide, but small quantities of other compounds such as hydrogen 
sulfide, ammonia, volatile organic compounds, and particulate matter 
(PM) may also be present. These gases have a lower methane content than 
natural gas and may range from 50 to 65 percent. Although similar in 
composition to natural gas, there are some differences in the emissions 
from combustion of landfill and digester gases due to e.g., chlorinated 
compounds typically not found in natural gas. Both landfill and 
digester gases contain a family of silicon-based gases collectively 
called siloxanes. Combustion of siloxanes forms compounds that have 
been known to foul fuel systems, combustion chambers, and post-
combustion catalysts.

B. What are the pollutants regulated by this proposed rule?

    New source performance standards are developed under the authority 
of section 111 of the CAA. Emissions of criteria pollutants (those 
pollutants identified under section 110 of the CAA) are generally 
regulated under section 111 of the CAA, while HAP are regulated under 
section 112 of the CAA. Emissions from stationary engines contribute 
significantly to air pollution and cause adverse health and welfare 
effects. The pollutants to be regulated by the proposed NSPS for 
stationary SI engines are nitrogen oxides (NOX), carbon 
monoxide (CO), and non-methane hydrocarbons (NMHC). In addition, a 
sulfur limit on gasoline is being proposed.
    Nitrogen oxides are listed as criteria pollutants and are regulated 
due to their contribution to the formation of ozone. Nitrogen oxides 
are precursors to ozone formation. Exposure to ozone has been linked to 
health and welfare impacts. Health and welfare risks include impaired 
respiratory function, eye irritation, deterioration of materials such 
as rubber, and necrosis of plant tissue. Nitrogen oxides are also a 
major precursor for nitrate PM. Particulate matter, also regulated as a 
criteria pollutant, is associated with premature mortality and a number 
of serious adverse respiratory and cardiovascular effects, especially 
in children, the elderly, and people with existing heart or lung 
disease. Particulate matter also reduces visibility and damages 
building materials. Nitrogen oxides are also associated with various 
other health and welfare effects. Nitrogen dioxide can cause irritation 
of the lungs and can also reduce the resistance to respiratory 
infection. Nitrogen oxides are one of the major pollutants emitted from 
stationary ICE and stationary ICE are considered to cause or contribute 
significantly to nationwide releases of NOX emissions.
    Carbon monoxide is a criteria pollutant and is considered harmful 
to public health and the environment. Carbon monoxide has been linked 
to increased risk for people with heart disease, reduced visual 
perception, cognitive functions and aerobic capacity, and possible 
fetal effects. Stationary engines emit CO and are considered to 
contribute to several areas failing to attain the National Ambient Air 
Quality Standards for CO.
    Emissions of NMHC from stationary engines contribute to the 
formation of ozone. In addition, emissions of NMHC include air toxics 
such as benzene, formaldehyde, acetaldehyde, 1,3-butadiene, and 
acrolein. These substances are known or suspected to be human or animal 
carcinogens, or having noncancer health effects such as irritation or 
corrosion of the eyes, nose, throat, and lungs; pulmonary and 
respiratory problems; and dermatitis and sensitization of the skin and 
respiratory tract. Stationary engines contribute to nationwide releases 
of NMHC emissions.
    Sulfur dioxide (SO2) is a criteria pollutant emitted 
from stationary SI engines due to sulfur in gasoline. It contributes to 
respiratory illness, particularly in children and the elderly, and 
aggravates existing heart and lung diseases. It also contributes to 
acid deposition, damaging forests, aquatic ecosystems, crops, and 
building materials. Sulfur dioxide undergoes chemical reactions in the 
atmosphere to form sulfate PM. The health effects of PM were previously 
described in this section. This proposed rule reduces SO2 
and sulfate PM by requiring the use of gasoline with lower sulfur 
levels, thus improving air quality, public health, and public welfare.
    The NESHAP being proposed in this action would regulate emissions 
of HAP. Available emissions data show that several HAP are emitted from 
stationary engines, which are formed during the combustion process or 
that are contained within the fuel burned. Many HAP have been detected 
from the stationary engine exhaust, but only a handful of HAP represent 
the majority of HAP emissions from stationary engines. These HAP are 
formaldehyde, acrolein, methanol, and acetaldehyde. We described the 
health effects of these HAP and other HAP emitted from the operation of 
stationary ICE in the preamble to 40 CFR part 63, subpart ZZZZ, 
published on June 15, 2004, on page 33474 of the Federal Register. 
These HAP emissions are known to cause, or contribute significantly to 
air pollution, which may reasonably be anticipated to endanger public 
health or welfare.
    Under the RICE NESHAP, we are proposing to limit emissions of HAP 
through emissions standards for NMHC and formaldehyde. We have 
determined that it is appropriate to use NMHC and formaldehyde or CO 
emissions as a surrogate for HAP emissions. For the RICE MHAP 
promulgated in 2004 (69 FR 33474) for engines greater than 500 HP 
located at major sources, EPA chose to select a single pollutant to 
serve as a surrogate for HAP emissions. Formaldehyde is the hazardous 
air pollutant present in the highest concentration from stationary 
engines. In addition, emissions data show that formaldehyde emission 
levels are related to other HAP emission levels. For the NESHAP 
promulgated in 2004, EPA also found that there is a strong relationship 
between CO emissions reductions and HAP emissions reductions from 2SLB, 
4SLB, and CI stationary engines. Therefore, CO emissions reductions 
were chosen as a surrogate for HAP emissions reductions for 2SLB, 4SLB, 
and CI stationary

[[Page 33808]]

engines operating with oxidation catalyst systems for that rule. For 
the standards being proposed in this action, EPA believes that 
previously made decisions regarding the appropriateness of using 
formaldehyde and CO as surrogates for HAP are still valid. For this 
proposal, EPA conducted an analysis using available emissions data to 
look at the relationship between formaldehyde (a surrogate for HAP) and 
NMHC. Based on statistical results of engine exhaust data, these data 
indicate that there is a significant relationship between formaldehyde 
and NMHC emissions from 2SLB, 4SLB, and CI stationary RICE. For this 
reason, EPA believes it is appropriate to use NMHC emissions as a 
surrogate for formaldehyde, and consequently, also as a surrogate for 
HAP emissions. Much of the HAP being regulated are hydrocarbons; e.g., 
formaldehyde, an oxygenated hydrocarbon, is the HAP emitted in largest 
quantities from stationary engines. For more information on EPA's 
analysis of NMHC as a surrogate for HAP, refer to the docket for this 
proposal.

C. What are the proposed standards?

    A description of the proposed standards is provided in the 
following sections.
1. SI NSPS
    a. Stationary SI Engines <=19 KW (25 HP). EPA is proposing emission 
standards that will affect manufacturers, owners, and operators of 
stationary SI engines. Engine manufacturers must certify their 
stationary SI engines with a maximum engine power less than or equal to 
19 KW (25 HP) that are manufactured after January 1, 2008, to the 
certification emission standards for new nonroad SI engines in 40 CFR 
part 90, as applicable. The standards applicable to these engines are 
shown in Table 1 of this preamble.

  Table 1.--NOX, HC, NMHC, and CO Emission Standards in g/KW-hr (g/HP-hr) for Stationary SI Engines <=19 KW (25
                                                       HP)
----------------------------------------------------------------------------------------------------------------
                                       Emission requirement in g/KW-hr (g/HP-hr)
           Engine classc           ------------------------------------------------      Manufacture date\b\
                                        HC+NOX         NMHC+NOXa          CO
----------------------------------------------------------------------------------------------------------------
I.................................            16.1            14.8
                                            (12.0)          (11.0)
I-A...............................              50  ..............             610  January 1, 2008.
                                              (37)  ..............           (455)
I-B...............................              40              37
                                              (30)          (27.6)
II................................            12.1            11.3
                                             (9.0)           (8.4)
----------------------------------------------------------------------------------------------------------------
aNMHC+NOX standards are applicable only to natural gas fueled engines at the option of the manufacturer, in lieu
  of HC+NOX standards.
bModified and reconstructed engines manufactured prior to January 1, 2008, must meet the standards applicable to
  engines manufactured after January 1, 2008.
cClass I-A: Engines with displacement <66 cubic centimeter (cc); Class I-B: Engines with displacement greater
  than or equal to 66 cc and less than 100 cc; Class I: Engines with displacement greater than or equal to 100
  cc and less than 225 cc; Class II: Engines with displacement greater than or equal to 225 cc.

    b. Stationary SI Gasoline Engines >19 KW (25 HP) and Rich Burn LPG 
Engines >19 KW (25 HP). Engine manufacturers must certify their 
stationary SI engines with a maximum engine power greater than 19 KW 
(25 HP) and less than 500 HP that use gasoline or rich burn engines 
greater than 19 KW (25 HP) and less than 500 HP that use LPG that are 
manufactured after January 1, 2008, to the certification emission 
standards for new nonroad SI engines in 40 CFR part 1048, as 
applicable. Engine manufacturers must certify their stationary SI 
engines with a maximum engine power greater than or equal to 500 HP 
that use gasoline or rich burn engines greater than or equal to 500 HP 
that use LPG that are manufactured after July 1, 2007, to the 
certification emission standards for new nonroad SI engines in 40 CFR 
part 1048. The standards applicable to engines greater than 19 KW (25 
HP) that are gasoline or rich burn engines that use LPG are shown in 
Table 2 of this preamble.

 Table 2.--NOX, HC, and CO Emission Standards in g/KW-hr (g/HP-hr) for Stationary SI Gasoline Engines >19 KW (25
                                  HP) and Rich Burn LPG Engines >19 KW (25 HP)
----------------------------------------------------------------------------------------------------------------
                                                                                 Emission requirement in g/KW-hr
                                                                                         (g/HP-hr) a, b
             Maximum engine power                      Manufacture date        ---------------------------------
                                                                                     HC+NOX             CO
----------------------------------------------------------------------------------------------------------------
25=500 d....................................  July 1, 2007...................             2.7              4.4
                                                                                          (2.0)            (3.3)
                                               July 1, 2007...................             2.7            130.0
                                               (severe duty)..................            (2.0)           (97.0) 
----------------------------------------------------------------------------------------------------------------
a You may optionally certify your engines according to the following formula instead of the standards in Table 2
  of this preamble: (HC+NOX)xCO0.784<=8.57. The HC+NOX and CO emission levels you select to satisfy this
  formula, rounded to the nearest 0.1 g/kW-hr, become the emission standards that apply for those engines. You
  may not select an HC+NOX emission standard higher than 2.7 g/kW-hr or a CO emission standard higher than 20.6
  g/kW-hr.
b Provisions in 40 CFR part 1048 allow engines with a maximum engine power at or below 30 KW (40 HP) with a
  total displacement at or below 1,000 cubic centimeters (cc) to comply with the requirements of 40 CFR part 90.

[[Page 33809]]

 
c Modified and reconstructed engines between 25 and 500 HP manufactured prior to January 1, 2008, must meet the
  standards applicable to engines manufactured after January 1, 2008.
d Modified and reconstructed engines greater than or equal to 500 HP manufactured prior to July 1, 2007, must
  meet the standards applicable to engines manufactured after July 1, 2007.

    In addition to the emission standards shown in Table 2 of this 
preamble, there are separate field testing standards required under 40 
CFR part 1048 that are part of the certification requirements for 
engine manufacturers.
    c. Stationary Non-Emergency SI Natural Gas Engines 19X to 2.0 grams 
per HP-hour (g/HP-hr), emissions of CO to 4.0 g/HP-hr, and emissions of 
NMHC to 1.0 g/HP-hr. More stringent emission standards take effect 3 
years later, i.e., for stationary natural gas engines 19 to 37 KW (25 
to 50 HP) and lean burn engines using LPG between 19 and 37 KW (25 and 
50 HP) manufactured after January 1, 2011. These engines must comply 
with a NOX standard of 1.0 g/HP-hr, a CO standard of 2.0 g/
HP-hr, and a NMHC standard of 0.7 g/HP-hr. Engine manufacturers have 
the option to certify their stationary SI engines to these emission 
standards. However, the certification is only voluntary, and it is up 
to the manufacturer to decide if it believes certification is feasible 
and beneficial. Also, engine manufacturers have the option to certify 
stationary SI engines between 19 and 37 KW (25 and 50 HP) that are 
natural gas engines or lean burn engines using LPG to the emission 
standards in 40 CFR part 1048, as shown in Table 2 of this preamble. 
Additionally, engine manufacturers may certify engines between 19 and 
30 KW (25 and 40 HP) with a displacement of 1,000 cc or less to the 
provisions of 40 CFR part 90 (shown in Table 1 of this preamble), which 
is consistent with similar provisions applicable to nonroad engines in 
this displacement and size category. A summary of the proposed 
standards for stationary non-emergency SI natural gas engines between 
19 and 37 KW (25 and 50 HP) and stationary non-emergency lean burn LPG 
engines between 19 and 37 KW (25 and 50 HP) is provided in Table 3 of 
this preamble.
    d. Stationary Non-Emergency SI Natural Gas Engines 50<=HP<500 and 
Lean Burn LPG Engines 50<=HP<500. EPA is proposing emission standards 
in two stages for these engines. Owners and operators who purchase 
stationary SI engines with a maximum engine power between 50 and 500 HP 
that are natural gas engines or lean burn engines using LPG that are 
manufactured after January 1, 2008, must limit their exhaust emissions 
of NOX to 2.0 g/HP-hr, emissions of CO to 4.0 g/HP-hr, and 
emissions of NMHC to 1.0 g/HP-hr. Again, engine manufacturers may 
voluntarily certify these stationary SI engines to these emission 
standards, but the certification is not required by this proposed rule. 
Stationary SI engines with a maximum engine power between 50 and 500 HP 
that are natural gas engines or lean burn engines using LPG that are 
manufactured after January 1, 2011, must limit their exhaust emissions 
of NOX to 1.0 g/HP-hr, emissions of CO to 2.0 g/HP-hr, and 
emissions of NMHC to 0.7 g/HP-hr. A summary of the emission standards 
EPA is proposing for these engines is shown in Table 3 of this 
preamble.

                            Table 3.--NOX, NMHC, and CO Emission Standards in g/HP-hr for Stationary SI Engines >19KW (25 HP)
                                                       [Except Gasoline and Rich Burn LPG Engines]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                   Emission standards in g/HP-hr
          Engine type and fuel               Maximum  engine power             Manufacture date a        -----------------------------------------------
                                                                                                                NOX             CO             NMHC
--------------------------------------------------------------------------------------------------------------------------------------------------------
Non-Emergency SI Natural Gas             25=500.....................  January 1, 2008..................             3.0             5.0             1.0
                                                                       January 1, 2011..................             2.0             5.0             1.0
                                         HP>=500.....................  July 1, 2007.....................             3.0             5.0             1.0
                                                                       July 1, 2010.....................             2.0             5.0             1.0
Emergency..............................  All Sizes...................  January 1, 2009..................             2.0             4.0             1.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Stationary SI natural gas and lean burn LPG engines between 19 and 37 KW (25 and 50 HP) may comply with the requirements of Table 2 of this
  preamble, instead of this table, as applicable.

    e. Stationary Non-Emergency SI Natural Gas Engines >=500 HP and 
Non-Emergency Lean Burn LPG Engines >=500 HP. EPA is proposing emission 
standards in two stages for stationary non-emergency SI natural gas 
engines greater than or equal to 500 HP and non-emergency lean burn LPG 
engines greater than or equal to 500 HP. Owners and operators who 
purchase stationary SI engines with a maximum engine power greater than 
or equal to 500 HP that are natural gas engines or lean burn engines 
using LPG that are manufactured after July 1, 2007, must limit their 
exhaust emissions of NOX to 2.0 g/HP-hr, emissions of CO to 
4.0 g/HP-hr, and emissions of NMHC to 1.0 g/HP-hr. Engine manufacturers 
may voluntarily certify these stationary SI engines to these emission 
standards, but the certification is not required by the rule, as 
proposed. Stationary SI engines with a maximum engine power greater 
than or equal to 500 HP that are natural gas engines or lean burn 
engines using LPG that are manufactured after July 1, 2010, must limit 
their exhaust emissions of NOX to 1.0 g/HP-hr, emissions of 
CO to 2.0 g/HP-hr, and emissions of NMHC to 0.7 g/HP-hr. Again, 
manufacturers may voluntarily certify their engines to these emission 
standards. A summary of the emission standards EPA is proposing for 
these engines is shown in Table 3 of this preamble.

[[Page 33810]]

    f. Stationary SI Landfill/Digester Gas Engines. Similar to other 
stationary SI engines, EPA is proposing emission standards in two 
stages for landfill and digester gas fired engines. Owners and 
operators who purchase stationary landfill or digester SI engines that 
are manufactured after July 1, 2007, that are greater than or equal to 
500 HP must limit their exhaust emissions of NOX to 3.0 g/
HP-hr, emissions of CO to 5.0 g/HP-hr, and emissions of NMHC to 1.0 g/
HP-hr. Stationary landfill and digester gas SI engines greater than or 
equal to 500 HP that are manufactured after July 1, 2010, must limit 
their exhaust emissions of NOX to 2.0 g/HP-hr, emissions of 
CO to 5.0 g/HP-hr, and emissions of NMHC to 1.0 g/HP-hr. Again, engine 
manufacturers may voluntarily certify these stationary SI engines to 
these emission standards, but the certification is not required by the 
rule, as proposed. Stationary SI engines that use landfill or digester 
gas that are less than 500 HP are given an extra 6 months to comply 
with the standards. The first stage of limits of 3.0, 5.0, and 1.0 g/
HP-hr, for NOX, CO, and NMHC, respectively, applies to 
landfill and digester gas engines manufactured after January 1, 2008. 
The second stage of limits of 2.0, 5.0, and 1.0 g/HP-hr, for 
NOX, CO, and NMHC, respectively, applies to landfill and 
digester gas engines manufactured after January 1, 2011. A summary of 
the emission standards EPA is proposing for these engines is shown in 
Table 3 of this preamble.
    g. Stationary Emergency SI Engines. For stationary SI engines that 
are emergency engines, EPA is proposing a single stage of emission 
limits. Owners and operators who purchase stationary emergency engines 
that are manufactured after January 1, 2009, must limit their exhaust 
emissions of NOX to 2.0 g/HP-hr, emissions of CO to 4.0 g/
HP-hr, and emissions of NMHC to 1.0 g/HP-hr.
    h. Fuel Requirements. In addition to emission standards, EPA is 
proposing that owners and operators who use gasoline in their 
stationary SI engine must use gasoline that meets the requirements of 
40 CFR 80.195. The requirements include a gasoline sulfur per gallon 
cap of 80 parts per million (ppm).
2. NESHAP
    a. Engines <=500 HP at Major Sources. We are proposing that owners 
and operators of new and reconstructed stationary SI engines with a 
site rating of equal to or less than 500 HP located at a major source 
of HAP emissions must generally meet the same NMHC emission standards 
for new SI engines as proposed for the NSPS in 40 CFR part 60, subpart 
JJJJ.
    One major difference between the SI NSPS and NESHAP requirements is 
that owners and operators of new or reconstructed 4SLB SI stationary 
engines between 250 and 500 HP located at a major source are required 
to either reduce CO emissions by 93 percent or more, or limit the 
concentration of formaldehyde in the stationary engine exhaust to 14 
ppm by volume, dry basis (ppmvd) or less, at 15 percent oxygen 
(O2). These engines would not be required to meet the NMHC 
standard. The formaldehyde standard is more stringent than the NMHC 
stage 1 and stage 2 emission standards of 1.0 and 0.7 g/HP-hr, 
respectively.
    Under the NESHAP, owners and operators of new and reconstructed 
landfill and digester gas fired engines and new and reconstructed SI 
emergency engines are subject to the NMHC emission standards that are 
being proposed under the SI NSPS. New and reconstructed landfill and 
digester gas engines must, under the NESHAP, meet NMHC emission 
standards consistent with the SI NSPS, i.e., a NMHC standard of 1.0 g/
HP-hr. Owners and operators of stationary landfill and digester gas 
engines must meet the NMHC standard if they are manufactured after 
January 1, 2008.
    For new and reconstructed stationary SI engines with a site rating 
of equal to or less than 500 HP located at a major source of HAP 
emissions that are emergency engines, owners and operators who purchase 
such engines that are manufactured after January 1, 2009, must limit 
their exhaust emissions of NMHC to 1.0 g/HP-hr.
    Finally, owners and operators of new and reconstructed stationary 
CI engines with a site rating of equal to or less than 500 HP located 
at a major source of HAP emissions that purchase 2007 model year and 
later stationary CI engines must meet the NMHC and PM emission 
standards for new CI engines specified in 40 CFR part 60, subpart IIII. 
Those standards are generally based on the certification emission 
standards for new nonroad CI engines. A summary of the standards being 
proposed for stationary engines less than or equal to 500 HP located at 
major sources is presented in Table 4 of this preamble.
    Owners and operators of existing stationary engines with a site 
rating of equal to or less than 500 HP located at a major source of HAP 
emissions have an emissions standard of no emission reduction and are 
not subject to any specific requirements under subpart ZZZZ or subpart 
A of 40 CFR part 63. A stationary RICE is existing if it commences 
construction or reconstruction before June 12, 2006.

     Table 4.--Emission Standards for Stationary RICE <=500 HP Located at Major Sources of HAP Emissions and
                            Stationary RICE Located at Area Sources of HAP Emissions
----------------------------------------------------------------------------------------------------------------
       Engine type and fuel            Maximum engine power          Manufacture date a       Emission standards
----------------------------------------------------------------------------------------------------------------
Existing All Fuels and All Types.  All Sizes..................               No Emission Reduction.
New/Reconstructed SI.............  <=25 HP....................  January 1, 2008............  Meet 40 CFR part 60
                                                                                              subpart JJJJ.
New/Reconstructed SI Gasoline and  25>HP<500..................  January 1, 2008............  Meet 40 CFR part 60
 Rich Burn LPG.                    HP>=500....................  July 1, 2007...............   subpart JJJJ.
New/Reconstructed Non-Emergency    25=500....................  July 1, 2007...............  1.0 g/HP-hr NMHC
 SI Natural Gas.
HP<=500..........................  July 1, 2007...............  1.0 g/HP-hr NMHC...........

[[Page 33811]]

 
               and
 
New/Reconstructed Non-Emergency    ...........................  July 1, 2010...............  0.7 g/HP-hr NMHC.
 SI Lean Burn LPG.
New/Reconstructed Non-Emergency    250=500....................  July 1, 2007...............  1.0 g/HP-hr NMHC.
Emergency SI.....................  All Sizes..................  January 1, 2009............  1.0 g/HP-hr NMHC.
----------------------------------------------------------------------------------------------------------------
a Stationary SI natural gas and lean burn LPG engines between 19 and 37 KW (25 and 50 HP) may comply with the
  requirements of Table 2 of this preamble, instead of this table, as applicable.
b New and reconstructed non-emergency 4SLB engines at major sources with a site rating between 250 and 500 HP
  are not required to meet the 1.0 and 0.7 g/HP-hr NMHC emission standards.

    b. Engines at Area Sources. We are proposing that owners and 
operators of new and reconstructed stationary engines located at area 
sources of HAP emissions generally meet the same requirements that 
apply to new and reconstructed stationary engines with a site rating of 
equal to or less than 500 HP located at a major source of HAP 
emissions. New and reconstructed stationary engines located at area 
sources with a site rating greater than 500 HP are required to meet the 
same NMHC standard as proposed in the SI NSPS for the engine's HP 
classification, or the same NMHC and PM standards as proposed in the CI 
NSPS for the engine's HP classification.
    There is only one difference between the requirements for new and 
reconstructed stationary engines located at area sources and new and 
reconstructed stationary engines with a site rating of equal to or less 
than 500 HP located at major sources. Owners and operators of new or 
reconstructed 4SLB SI stationary engines between 250 and 500 HP located 
at area sources are not required to reduce CO emissions by 93 percent 
or more, or limit the concentration of formaldehyde in the stationary 
engine exhaust to 14 ppmvd or less at 15 percent O2. New and 
reconstructed stationary SI engines located at area sources must, 
however, meet the NMHC emission standards shown in Table 4 of this 
preamble.
    Owners and operators of existing stationary engines located at an 
area source of HAP emissions have an emission standard of no emission 
reduction and are not subject to any specific requirements under 
subpart ZZZZ or of subpart A of 40 CFR part 63.

D. What are the requirements for sources that are modified or 
reconstructed?

1. SI NSPS
    The proposed standards apply to stationary SI engines subject to 
the SI NSPS that are modified or reconstructed after June 12, 2006. The 
guidelines for determining whether a source is modified or 
reconstructed are given in 40 CFR 60.14 and 40 CFR 60.15, respectively.
    Stationary SI ICE less than or equal to 19 KW (25 HP) manufactured 
prior to January 1, 2008 that are modified or reconstructed after June 
12, 2006 are required to meet the standards that apply to engines 
manufactured after January 1, 2008.
    Stationary SI gasoline and rich burn LPG engines between 25 HP and 
500 HP manufactured prior to January 1, 2008 that are modified or 
reconstructed after June 12, 2006 are required to meet the standards 
applicable to engines manufactured after January 1, 2008.
    Stationary SI gasoline and rich burn LPG engines greater than or 
equal to 500 HP manufactured prior to July 1, 2007 that are modified or 
reconstructed after June 12, 2006 are required to meet the standards 
applicable to engines manufactured after July 1, 2007.
    Stationary SI natural gas and lean burn LPG engines less than 500 
HP manufactured prior to January 1, 2008 that are modified or 
reconstructed after June 12, 2006 are required to meet a NOX 
emission standard of 3.0 g/HP-hr, a CO standard of 4.0 g/HP-hr, and a 
NMHC standard of 1.0 g/HP-hr.
    Stationary SI natural gas and lean burn LPG engines greater than or 
equal to 500 HP manufactured prior to July 1, 2007 that are modified 
after June 12, 2006, are required to meet a NOX emission 
standard of 3.0 g/HP-hr, a CO standard of 4.0 g/HP-hr, and a NMHC 
standard of 1.0 g/HP-hr.
    Stationary SI landfill and digester gas engines less than 500 HP 
manufactured prior to January 1, 2008 that are modified or 
reconstructed after June 12, 2006 are required to meet a NOX 
emission standard of 3.0 g/HP-hr, a CO standard of 5.0 g/HP-hr, and a 
NMHC standard of 1.0 g/HP-hr. Stationary SI landfill and digester gas 
engines greater than or equal to 500 HP manufactured prior to July 1, 
2007 that are modified after June 12, 2006 are required to meet a 
NOX emission standard of 3.0 g/HP-hr, a CO standard of 5.0 
g/HP-hr, and a NMHC standard of 1.0 g/HP-hr.
    Stationary SI emergency engines manufactured prior to January 1, 
2009 that are modified or reconstructed after June 12, 2006 are 
required to meet a NOX emission standard of 3.0 g/HP-hr, a 
CO standard of 4.0 g/HP-hr, and a NMHC standard of 1.0 g/HP-hr.
2. NESHAP
    Similar concepts as those discussed above apply to engines subject 
to 40 CFR part 63 regulations; however, the concept of modification is 
not included in 40 CFR part 63. The proposed standards apply to 
stationary engines subject to the NESHAP that commence reconstruction 
on or after June 12, 2006. The reconstruction criteria are provided in 
40 CFR 63.2.

E. What are the requirements for demonstrating compliance?

    The following sections describe the requirements for demonstrating 
compliance under the stationary SI NSPS and NESHAP.
1. SI NSPS
    Owners and operators of stationary engines subject to the 
requirements of the SI NSPS must operate and maintain

[[Page 33812]]

their stationary engine and after treatment control device (if any) 
according to the manufacturer's written instructions. Manufacturers of 
stationary SI engines required to certify their engines must 
demonstrate compliance by certifying that their stationary SI engines 
meet the emission standards, as specified in 40 CFR part 60, subpart 
JJJJ, as applicable, using the certification procedures in subpart B of 
40 CFR part 90 and subpart C of 40 CFR part 1048, as applicable, and 
must test their engines as specified in those parts. Manufacturers who 
conduct voluntary certification must follow the same test procedures 
that apply to large SI nonroad engines under 40 CFR part 1048, but must 
use the D-2 cycle in International Organization for Standardization 
(ISO) 8178-4 for stationary engines. The test cycle requirements that 
manufacturers who conduct voluntary certification should follow are 
provided in Table 3 to 40 CFR 1048.505.
    Manufacturers who opt to voluntary certify their stationary SI 
engines to the emission standards specified in this subpart must 
certify their engines using fuel that meets the definition of pipeline-
quality natural gas, which according to the proposed definition must be 
composed of at least 70 percent methane by volume or have a gross 
calorific value between 950 and 1,100 British thermal units per 
standard cubic foot.
    If the manufacturer chooses to certify its stationary SI engines to 
another fuel, the manufacturer must specify the properties of that fuel 
and what adjustments the owner or operator must make to the engine 
during installation in the field in order to meet the emission 
standards. The manufacturer must also perform certification testing on 
the engine on that fuel, as it would if it was certifying to pipeline-
quality natural gas, in order to assure compliance with the emission 
standards. Manufacturers who conduct voluntary certification of 
stationary SI ICE must also provide instructions to the owner and 
operator for configuring the stationary engine to meet the emission 
standards on fuels that meet the pipeline-quality natural gas 
specifications and fuels that do not meet the pipeline-quality natural 
gas specifications. The manufacturer must provide information to the 
owner and operator of the certified stationary SI engine regarding the 
particular fuels to which the engine is certified, and instructions 
regarding configuring the engine in a manner most appropriate for 
reducing pollutant emissions for engines operating on such fuels. 
Owners and operators may operate their certified engine on other fuels 
that the engine is not certified to, but the engine would no longer be 
considered a certified engine and the owner or operator would be 
required to test the engine to demonstrate compliance with the emission 
standards.
    EPA is proposing to allow owners and operators of natural gas 
engines to use propane as back up fuel for emergency purposes for no 
more than 100 hours per year. If propane is used for more than 100 
hours per year in an engine that is not certified to the emission 
standards when using propane, the owners and operators are required to 
conduct a performance test to demonstrate compliance with the emission 
standards.
    Owners and operators that operate engines that have been certified 
by the engine manufacturer are not required to perform any performance 
testing unless the engine is operated outside of the fuel properties 
specified by the manufacturer. If the owner or operator uses fuels that 
are outside of the fuel specifications or does not follow the 
adjustments specified by the manufacturer, the engine is no longer 
considered a certified engine and the owner or operator must test the 
engine to demonstrate compliance. If the engine is no longer considered 
a certified engine, the owner or operator must test the engine 
according to the test procedures that are specified for uncertified 
engines, as specified in this proposed rule.
    Owners and operators subject to the emission standards specified in 
this proposed rule who use stationary SI engines with a maximum engine 
power of less than or equal to 19 KW (25 HP) or who use stationary SI 
engines with a maximum engine power greater than 19 KW (25 HP) and use 
gasoline or are rich burn engines greater than 19 KW (25 HP) using LPG 
must demonstrate compliance by using an engine certified to the 
emission standards specified in 40 CFR part 90 or 1048, as applicable.
    Owners and operators subject to this proposed rule who use 
stationary SI engines with a maximum engine power greater than 19 KW 
(25 HP) that use fuels other than gasoline and that are not rich burn 
engines greater than 19 KW (25 HP) that use LPG, must demonstrate 
compliance by either using an engine certified to the emission 
standards specified in Table 3 of this preamble or by conducting an 
initial performance test to demonstrate compliance with the emission 
standards specified in Table 3 of this preamble. If the owner or 
operator purchases a certified engine, performance testing would not be 
required (unless the engine is operated differently than specified by 
the manufacturer). Owners and operators of uncertified engines that are 
greater than 500 HP must conduct subsequent performance tests every 3 
years, or 8,760 hours of operation, whichever comes first.
2. NESHAP
    Consistent with the requirements for owners and operators subject 
to the SI NSPS, owners and operators of stationary engines subject to 
the requirements of the NESHAP must also operate and maintain their 
stationary engine and exhaust aftertreatment device (if any) according 
to the manufacturer's written instructions. This requirement applies to 
stationary SI and CI engines regulated under this proposed rule.
    Owners and operators subject to the NESHAP who use stationary SI 
engines must demonstrate compliance by meeting the NMHC emission 
standards specified in 40 CFR part 60, subpart JJJJ (unless they are 
new or reconstructed non-emergency 4SLB SI stationary RICE between 250 
and 500 HP located at major sources). Under 40 CFR part 60, subpart 
JJJJ, as described in the previous section, certain stationary SI 
engin