[Federal Register: January 18, 2008 (Volume 73, Number 13)]
[Rules and Regulations]
[Page 3567-3614]
[DOCID:fr18ja08-10]

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Part III

Environmental Protection Agency

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40 CFR Parts 60, 63, 85 et al.

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

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ENVIRONMENTAL PROTECTION AGENCY

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

[EPA-HQ-OAR-2005-0030, FRL-8512-4]
RIN 2060-AM81

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: Final rule.

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SUMMARY: EPA is promulgating new source standards of performance for
stationary spark ignition internal combustion engines. EPA is also
promulgating national emission standards for hazardous air pollutants
for new and reconstructed 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: This final rule is effective on March 18, 2008. The
incorporation by reference of certain publications listed in the final
rule is approved by the Director of the Federal Register as of March
18, 2008.

ADDRESSES: EPA has established a docket for this action under Docket ID
No. EPA-HQ-OAR-2005-0030. EPA also relies on materials in Docket ID No.
EPA-HQ-OAR-2005-0029 and incorporates that docket into the record for
the final rule. All documents in the docket are listed on the
http://www.regulations.gov Web site. 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, is not placed on the Internet and will be
publicly available only in hard copy form. Publicly available docket
materials are available either electronically through
http://www.regulations.gov or in hard copy at the EPA Headquarters Library,

Room Number 3334, EPA West Building, 1301 Constitution Ave., NW.,
Washington, DC. The EPA/DC Public Reading Room hours of operation will
be 8:30 a.m. to 4:30 p.m. Eastern Standard Time (EST), Monday through
Friday. The telephone number for the Public Reading Room is (202) 566-
1744, and the telephone number for the Air and Radiation Docket and
Information Center is<PHONE_NUMBER>.

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<PHONE_NUMBER>; facsimile number (919) 541-
5450; e-mail address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:
    Background Information Document. EPA proposed new source
performance standards (NSPS) for stationary spark ignition internal
combustion engines, and national emission standards for hazardous air
pollutants (NESHAP) 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, on June 12, 2006 (71 FR 33803), and received 46
comment letters on the proposal. A background information document BID)
(``Response to Public Comments on Proposed Standards of Performance for
Stationary Spark Ignition Internal Combustion Engines and National
Emission Standards for Hazardous Air Pollutants for Stationary
Reciprocating Internal Combustion Engines'') containing EPA's responses
to each public comment and the Economic Impact Analysis Report are
available in Docket ID No. EPA-HQ-OAR-2005-0030.
    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. Where can I get a copy of this document?
    C. Judicial Review
    D. Why is EPA not promulgating a final decision on existing
stationary reciprocating internal combustion engines?
II. Background
III. Summary of the Final Rule
    A. What is the source category regulated by the final rule?
    B. What are the pollutants regulated by the final rule?
    C. What are the final 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. Summary of Significant Changes Since Proposal
    A. Compliance Dates
    B. Distinguishing Sources Based on Size
    C. Hydrocarbon Limit
    D. Alternative Limits in Concentration Units
    E. Emergency Engine Standards
    F. Emergency Engine Definition
    G. Manufacturer O&M Requirements
    H. Streamlined Compliance Requirements
V. Summary of Responses to Major Comments
    A. Compliance Dates
    B. Final Hydrocarbon Emission Limits
    C. Emergency Engine Standards
    D. Emergency Engine Definition
    E. Manufacturer O&M Requirements
    F. Streamlined Compliance Requirements
VI. Summary of Environmental, Energy and Economic Impacts
    A. What are the air quality impacts?
    B. What are the cost impacts?
    C. What are the benefit estimates?
    D. What are the economic impacts?
    E. What are the non-air health, environmental and energy
impacts?
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
    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
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations.
    K. Congressional Review Act

I. General Information

A. Does this action apply to me?

    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                                 distribution.
 combustion engine as defined in the
 final rule.
                                         622110....................  Medical and surgical hospitals.
                                         335312....................  Motor and generator manufacturing.
                                         333912....................  Pump and compressor manufacturing.
                                         333992....................  Welding and soldering equipment
                                                                      manufacturing.
                                         48621.....................  Natural gas transmission.
                                         211111....................  Crude petroleum and natural gas production.
                                         211112....................  Natural gas liquids producers.
                                         92811.....................  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 the final 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. Where can I get a copy of this document?

    In addition to being available in the docket, an electronic copy of
this final action will also be available on the Worldwide Web (WWW)
through the Technology Transfer Network (TTN). Following signature, a
copy of this final action will be posted on the TTN's policy and
guidance page for newly proposed or promulgated rules at the following
address: http://www.epa.gov/ttn/oarpg/. The TTN provides information

and technology exchange in various areas of air pollution control.

C. Judicial Review

    Under section 307(b)(1) of the Clean Air Act (CAA), judicial review
of these final rules is available only by filing a petition for review
in the U.S. Court of Appeals for the District of Columbia Circuit by
September 14, 2007. Under section 307(d)(7)(B) of the CAA, only an
objection to these final rules that was raised with reasonable
specificity during the period for public comment can be raised during
judicial review. Moreover, under section 307(b)(2) of the CAA, the
requirements established by these final rules may not be challenged
separately in any civil or criminal proceedings brought by EPA to
enforce these requirements.

D. Why is EPA not promulgating a final decision for existing stationary
reciprocating internal combustion engines?

    In the notice of proposed rulemaking for this rule, published on
April 12, 2006, EPA proposed maximum achievable control technology
(MACT) and generally available control technology (GACT) standards of
no emission reductions for existing engines. During the comment period
following the proposal, EPA received several comments indicating that
the proposed emission standards for existing engines were not
appropriate. In addition, since the publication of the proposed
rulemaking, the U.S. Court of Appeals for the District of Columbia
Circuit issued a ruling on March 13, 2007 involving litigation on the
Brick MACT, which set emission standards for major sources. (40 CFR
part 63, subpart JJJJJ) that appears to impact EPA's ability to
finalize its proposed ``no reduction'' MACT standards for existing
sources. Sierra Club v. EPA, 479 F.3d 875 (DC Cir 2007). Among other
things, the D.C. Circuit found unlawful EPA's no emission reduction
control floors, which EPA established for categories in which the best
performers used no emission reduction control technology. Because in
the proposed rule EPA used a MACT floor methodology similar to the
methodology used in the Brick MACT, EPA intends to re-evaluate the MACT
floors for existing major sources that have a site rating of less than
or equal to 500 brake horsepower consistent with the Court's decision
in the Brick MACT case. EPA also intends to re-evaluate the standards
for existing area sources in light of the comments received on the
proposed rule.
    For these reasons, this final rule does not promulgate any
standards with regards to existing engines. EPA's plan is to engage in
a separate rulemaking process that will focus on existing sources. EPA
intends to gather further information on existing engines and then
promulgate standards that will take into account the comments it has
received, the intervening court decision, and any new information EPA
receives as a part of the rulemaking process. EPA expects to propose
standards early in 2009.

II. Background

    This action promulgates new source performance standards (NSPS)
that would apply to new, modified and reconstructed stationary spark
ignition (SI) internal combustion engines (ICE). New source performance
standards implement section 111(b) of the 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 is promulgated under 40 CFR part 60, subpart JJJJ.
    This action also promulgates national emission standards for
hazardous air pollutants (NESHAP) from 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
new and reconstructed

stationary RICE located at area sources. The NESHAP are promulgated
under 40 CFR part 63, subpart ZZZZ.

III. Summary of the Final Rule

A. What is the source category regulated by the final rule?

    The final 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 final NESHAP apply 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 the final
rule.
    The final NESHAP address emissions from new and reconstructed
stationary engines less than or equal to 500 HP located at major
sources and all new and reconstructed 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 hazardous air pollutant
(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 the
final rule, you are exempt from the obligation to obtain a permit under
40 CFR part 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 the final 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. Final NSPS for stationary CI engines were published on July
11, 2006 (71 FR 39154).
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. 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 EPA regulates engines located at area sources.
    This action revises 40 CFR part 63, subpart ZZZZ, in order to
address HAP emissions from new and reconstructed stationary RICE less
than or equal to 500 HP located at major sources and new and
reconstructed 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 MACT for those engines under section
112(d)(3) of the CAA.
    For stationary engines located at area sources, EPA has the
flexibility to promulgate standards based on GACT under CAA section
112(d)(5). EPA listed stationary RICE located at area sources under
sections 112(c)(3) and 112(k) of the CAA, and consistent with section
112(c)(3) is establishing standards for the source category in this
final rule. The criteria relevant to EPA's listing of this area source
category is set forth 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 strategy
addressed sections 112(c)(3) and 112(k)(3)(B)(ii) of the CAA that
instruct EPA 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 30 HAP judged to pose the greatest
potential threat to public health in the largest number of urban areas
(the urban HAP). In the strategy, EPA also listed the area source
categories that account for 90 percent of the urban HAP emissions. EPA
listed the stationary internal combustion engine source category under
section 112(c)(3) and (k) for the following urban HAP: 7 PAH,
acetaldehyde, arsenic, benzene, beryllium compounds, cadmium compounds
and formaldehyde. Pursuant to section 112(c), the listed area source
categories shall be subject to standards under section 112(d) of the
CAA.
3. Differentiation by Fuel Type
    The final rule 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. 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 are 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 the final rule?

    The pollutants to be regulated by the final NSPS for stationary SI
engines are nitrogen oxides (NOX), carbon monoxide (CO), and
volatile organic compounds (VOC). In addition, a sulfur limit on
gasoline is being finalized.
    The final NESHAP regulate HAP (for areas sources, the NESHAP
regulates the seven urban HAP listed above) through formaldehyde, CO,
or VOC which EPA has established are appropriate surrogates for HAP
emissions from certain engine types.

C. What are the final standards?

    A description of the final standards is provided in the following
sections.
1. SI NSPS
    a. Stationary SI Engines < =19 KW (25 HP). The final standards
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 July 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 summarized 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)
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                                                                     Emission standards in g/KW-hr (g/HP-hr) b
                         Engine class a                          -----------------------------------------------
                                                                      HC+NOX        NMHC+NOX c          CO
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I...............................................................            16.1            14.8             610
                                                                          (12.0)          (11.0)           (455)
I-A.............................................................              50  ..............
                                                                              37  ..............
I-B.............................................................              40              37
                                                                            (30)          (27.6)
II..............................................................            12.1            11.3
                                                                           (9.0)           (8.4)
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a Class I-A: Engines with displacement less than 66 cubic centimeters (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 Modified and reconstructed engines manufactured prior to July 1, 2008, must meet the standards applicable to
  engines manufactured after July 1, 2008.
c NMHC+NOX standards are applicable only to natural gas fueled engines at the option of the manufacturer, in
  lieu of HC+NOX standards.

    b. Stationary Non-Emergency SI Gasoline Engines >19 KW (25 HP) and
Rich Burn LPG Engines >19 KW (25 HP). Engine manufacturers must certify
their stationary non-emergency 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 July 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 non-
emergency 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 manufacturers of non-emergency
engines greater than 19 KW (25 HP) that are gasoline or rich burn
engines that use LPG are summarized in Table 2 of this preamble.

 Table 2.--NOX, HC, and CO Emission Standards in g/KW-hr (g/HP-hr) for Manufacturers of Stationary Non-Emergency
                   SI Gasoline Engines >19 KW (25 HP) and Rich Burn LPG Engines >19 KW (25 HP)
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                                                                                Emission requirement in g/KW-hr
                                                                                (g/HP-hr) a, b
             Maximum engine power                      Manufacture date        ---------------------------------
                                                                                HC+NOX             CO
----------------------------------------------------------------------------------------------------------------
25< HP< 500 c..................................  July 1, 2008...................             2.7              4.4
                                                                                (2.0)            (3.3)
                                               July 1, 2008...................             2.7            130.0
                                               (severe duty e)................            (2.0)           (97.0)

HP>=500 d....................................  July 1, 2007...................             2.7              4.4
                                                                                (2.0)            (3.3)
                                               July 1, 2007...................             2.7            130.0
                                               (severe duty e)................            (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) CO0.784< =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.
c Modified and reconstructed engines between 25 and 500 HP manufactured prior to July 1, 2008, must meet the
  standards applicable to engines manufactured after July 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.
e Severe-duty engines are engines used in, for example, concrete saws, concrete pumps, and similar severe
  applications where air-cooled engines must be used. There are expected to be very few, if any, severe-duty
  stationary engines.

    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 19< KW< 75
(25< HP< 100) and Lean Burn LPG Engines 19< KW< 75 (25< HP< 100). Engine
manufacturers have the option to certify their stationary non-emergency
SI natural gas engines between 25 HP and 100 HP and lean burn LPG
engines between 25 HP and 100 HP to the certification emission
standards in 40 CFR part 1048, as shown in Table 2 of this preamble.
However, the certification is only voluntary, and it is up to the
manufacturer to decide if it believes certification is feasible and
beneficial. 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. In addition, for engines
manufactured prior to January 1, 2011, manufacturers may alternatively
certify to the standards summarized in Table 4 of this preamble
applicable to engines greater than or equal to 100 HP and less than 500
HP.
    Owners and operators who purchase stationary SI engines with a
maximum engine power between 19 and 75 KW (25 and 100 HP) that are
natural gas engines or lean burn engines using LPG that are
manufactured after July 1, 2008, must meet the NOX, HC, and
CO emission standards in 40 CFR 1048.101(c), as summarized in Table 3
of this preamble.

    Table 3.--NOX, HC, and CO Emission Standards in g/KW-hr (g/HP-hr) for Owners/Operators of Stationary Non-
      Emergency SI Natural Gas Engines 19< KW< 75 (25< HP< 100) and Lean Burn LPG Engines 19< KW< 75 (25< HP< 100)
----------------------------------------------------------------------------------------------------------------
                                                                                Emission requirement in g/KW-hr
                                                                                (g/HP-hr) \a, b\
             Maximum engine power                      Manufacture date        ---------------------------------
                                                                                HC+NOX             CO
----------------------------------------------------------------------------------------------------------------
25< HP< 100 \c\................................  July 1, 2008...................             3.8              6.5
                                                                                (2.8)            (4.8)
                                               July 1, 2008...................             3.8            200.0
                                               (severe duty)..................            (2.8)          (149.2)
----------------------------------------------------------------------------------------------------------------
\a\ You may apply the following formula to determine alternate emission standards that apply to your engines
  instead of the standards in paragraph in Table 3 of this preamble: (HC+NOX)xCO\0.791\< =16.78. HC+NOX emission
  levels may not exceed 3.8 g/kW-hr and CO emission levels may not exceed 31.0 g/kW-hr.
\b\ For natural gas fueled engines, you are not required to measure non-methane hydrocarbon emissions or total
  hydrocarbon emissions for testing to show that the engine meets the emission standards of Table 3 of this
  preamble; that is, you may assume HC emissions are equal to zero.
\c\ Modified and reconstructed engines between 25 and 100 HP manufactured prior to July 1, 2008, must meet the
  standards applicable to engines manufactured after July 1, 2008.

    d. Stationary Non-Emergency SI Natural Gas Engines >=100 HP and
Lean Burn LPG Engines >=100 HP. Owners and operators who purchase
stationary SI engines with a maximum engine power between 100 HP and
500 HP that are natural gas engines or lean burn engines using LPG that
are manufactured between July 1, 2008 and January 1, 2011, 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 VOC to 1.0 g/HP-hr. Owners and
operators may as an alternative limit their exhaust emissions of
NOX to 160 parts per million by volume, dry basis (ppmvd) at
15 percent oxygen (O2), emissions of CO to 540 ppmvd at 15
percent O2, and emissions of VOC to 86 ppmvd at 15 percent
O2 instead of the g/HP-hr limits.

    Stationary SI engines with a maximum engine power between 100 HP
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 VOC to 0.7 g/HP-hr. Again, owners and operators
may as an alternative limit their exhaust emissions of NOX
to 82 ppmvd at 15 percent O2, emissions of CO to 270 ppmvd
at 15 percent O2, and emissions of VOC to 60 ppmvd at 15
percent O2 instead of the g/HP-hr limits.
    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 VOC to
1.0 g/HP-hr, except that these standards apply to lean burn engines
between 500 and 1,350 HP manufactured after January 1, 2008. Instead of
complying with limits in terms of g/HP-hr, owners and operators may
limit their exhaust emissions of NOX to 160 ppmvd at 15
percent O2, emissions of CO to 540 ppmvd at 15 percent
O2, and emissions of VOC to 86 ppmvd at 15 percent
O2.
    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 VOC to 0.7 g/HP-hr. Instead of complying with
limits in terms of g/HP-hr, owners and operators may limit their
exhaust emissions of NOX to 82 ppmvd at 15 percent
O2, emissions of CO to 270 ppmvd at 15 percent
O2, and emissions of VOC to 60 ppmvd at 15 percent
O2.
    Engine manufacturers may voluntarily certify their stationary non-
emergency SI natural gas engines greater than or equal to 100 HP and
lean burn LPG engines greater than or equal to 100 HP, but the
certification is not required by the rule. Additionally, for natural
gas engines below 500 HP manufactured prior to January 1, 2011, and
natural gas engines greater than or equal to 500 HP manufactured prior
to July 1, 2010, engine manufacturers may choose to certify their
engines to the standards for non-severe duty engines in 40 CFR part
1048 (see Table 2 of this preamble).
    A summary of the emission standards that apply to stationary non-
emergency SI natural gas engines greater than or equal to 100 HP and
lean burn LPG engines greater than or equal to 100 HP are shown in
Table 4 of this preamble.
    For lean burn LPG engines greater than or equal to 100 HP,
manufacturers may certify these engines to the certification emission
standards in 40 CFR part 1048 instead of the emission standards shown
in Table 4 of this preamble.

 Table 4.--NOX, CO, and VOC Emission Standards for Stationary SI Engines >=100 HP (Except Gasoline and Rich Burn
           LPG), Stationary SI Landfill/Digester Gas Engines, and Stationary Emergency Engines >25 HP
----------------------------------------------------------------------------------------------------------------
                                                                              Emission standards \a\
                                                                 -----------------------------------------------
      Engine type and fuel         Maximum engine    Manufacture          g/HP-hr             ppmvd at 15% O2
                                        power            date    -----------------------------------------------
                                                                    NOX     CO      VOC     NOX     CO      VOC
----------------------------------------------------------------------------------------------------------------
Non-Emergency SI Natural Gas     100< =HP< 500.......     7/1/2008     2.0     4.0     1.0     160     540      86
 and Non-Emergency SI Lean Burn
 LPG.
                                                        1/1/2011     1.0     2.0     0.7      82     270      60
Non-Emergency SI Lean Burn       500>=HP<1,350.....     1/1/2008     2.0     4.0     1.0     160     540      86
 Natural Gas and LPG.
                                                        7/1/2010     1.0     2.0     0.7      82     270      60
Non-Emergency SI Natural Gas     HP>=500...........     7/1/2007     2.0     4.0     1.0     160     540      86
 and Non-Emergency SI Lean Burn
 LPG (except lean burn
 500>=HP<1,350).
                                 HP>=500...........     7/1/2010     1.0     2.0     0.7      82     270      60
Landfill/Digester Gas (except    HP< 500............     7/1/2008     3.0     5.0     1.0     220     610      80
 lean burn 500>=HP<1,350).
                                                        1/1/2011     2.0     5.0     1.0     150     610      80
                                 HP>=500...........     7/1/2007     3.0     5.0     1.0     220     610      80
                                                        7/1/2010     2.0     5.0     1.0     150     610      80
Landfill/Digester Gas lean burn  500>=HP<1,350.....     1/1/2008     3.0     5.0     1.0     220     610      80
                                                        7/1/2010     2.0     5.0     1.0     150     610      80
Emergency......................  25>HP<130.........     1/1/2009  \b\ 10     387     N/A     N/A     N/A     N/A
                                 HP>=130...........  ...........     2.0     4.0     1.0     160     540     86
----------------------------------------------------------------------------------------------------------------
\a\ Owners and operators of stationary non-certified SI engines may choose to comply with the emission standards
  in units of either g/HP-hr or ppmvd at 15 percent O2.
\b\ The emission standards applicable to emergency engines between 25 HP and 130 HP are in terms of NOX+HC.

    e. Stationary SI Landfill/Digester Gas 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 VOC to 1.0 g/
HP-hr, except that these standards apply to lean burn engines between
500 and 1,350 HP manufactured after January 1, 2008. Instead of
complying with limits in terms of g/HP-hr, owners and operators may
limit their exhaust emissions of NOX to 220 ppmvd at 15
percent O2, emissions of CO to 610 ppmvd at 15 percent
O2, and emissions of VOC to 80 ppmvd at 15 percent
O2.
    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 VOC to 1.0 g/HP-hr. Instead of
complying with limits in terms of g/HP-hr, owners and operators may
limit their exhaust emissions of NOX to 150 ppmvd at 15
percent O2, emissions of CO to 610 ppmvd at 15 percent
O2, and emissions of VOC to 80 ppmvd at 15 percent
O2.

    Stationary SI engines that use landfill or digester gas that are
less than 500 HP are given an extra 12 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 VOC, respectively (or 220, 610, and 80 ppmvd at
15 percent O2), applies to landfill and digester gas engines
manufactured after July 1, 2008. The second stage of limits of 2.0,
5.0, and 1.0 g/HP-hr, for NOX, CO, and VOC, respectively (or
150, 610, and 80 ppmvd at 15 percent O2), applies to
landfill and digester gas engines manufactured after January 1, 2011.
The emission standards applicable to stationary SI landfill and
digester gas engines are shown in Table 4 of this preamble.
    Engine manufacturers may voluntarily certify their stationary SI
landfill and digester gas engines to the emission standards in Table 4
of this preamble, but the certification is not required by the final
rule.
    f. Stationary Emergency SI Engines >19 KW (25 HP). For stationary
SI engines greater than 25 HP that are emergency engines, the final
rule sets a single stage of emission limits; however, EPA has
determined that it is appropriate to have separate standards for
stationary emergency engines above and below 130 HP.
    Owners and operators who purchase stationary emergency engines
greater than 25 HP and less than 130 HP that are manufactured after
January 1, 2009, must limit their exhaust emissions of
HC+NOX to 10.0 g/HP-hr and emissions of CO to 387 g/HP-hr.
These standards are consistent with the Phase I emission standards for
Class II nonroad engines in 40 CFR part 90.
    Owners and operators who purchase stationary emergency engines
greater than or equal to 130 HP 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 VOC to 1.0 g/HP-
hr. Instead of complying with limits in terms of g/HP-hr, owners and
operators may limit the exhaust emissions from their emergency engines
to 160 ppmvd of NOX at 15 percent O2, 540 ppmvd
of CO at 15 percent O2, and 86 ppmvd of VOC at 15 percent
O2.
    Engine manufacturers may voluntarily certify their stationary
emergency SI engines greater than 25 HP, but the certification is not
required by the rule, except for manufacturers of gasoline or LPG rich
burn emergency engines, who must certify their engines to the standards
in 40 CFR part 90 (for engines below 130 HP) or 40 CFR part 1048 (for
engines at or above 130 HP--see Table 2 of this preamble).
    g. Fuel Requirements. In addition to emission standards, the final
rule requires 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. 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 (except
new or reconstructed 4-stroke lean burn (4SLB) stationary RICE with a
site rating of greater than or equal to 250 and less than or equal to
500 brake HP located at major source of HAP emissions), must meet the
requirements of the final SI NSPS (40 CFR part 60, subpart JJJJ). Thus,
if the owners and operators are in compliance with 40 CFR part 60,
subpart JJJJ, they would also be in compliance with 40 CFR part 63,
subpart ZZZZ, for engines equal to or less than 500 HP located at a
major source (except for 4SLB engines greater than or equal to 250 and
less than or equal to 500 brake HP located at a major source). The
requirements that apply under 40 CFR part 60, subpart JJJJ, were
discussed in the previous section of this preamble.
    Similarly, 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 must meet the requirements of the
final CI NSPS (40 CFR part 60, subpart IIII). If the owners and
operators are in compliance with 40 CFR part 60, subpart IIII, they
would also be in compliance with 40 CFR part 63, subpart ZZZZ, for
engines equal to or less than 500 HP located at a major source.
    Owners and operators of new or reconstructed 4SLB SI stationary
engines with a site rating of greater than or equal to 250 and less
than or equal to 500 brake 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
ppmvd or less, at 15 percent O2. These engines would also be
required to meet the requirements in the final SI NSPS, but do not have
to comply with the CO emission standards of the SI NSPS if in
compliance with the NESHAP.
    b. Engines at Area Sources. Owners and operators of new and
reconstructed stationary engines located at area sources of HAP
emissions must meet the requirements of the final CI NSPS (40 CFR part
60, subpart IIII) or SI NSPS (40 CFR part 60, subpart JJJJ), as
appropriate. If the owners and operators are in compliance with either
40 CFR part 60, subpart IIII or JJJJ, as appropriate, they would also
be in compliance with 40 CFR part 63, subpart ZZZZ, for new and
reconstructed engines located at an area source.

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

1. SI NSPS
    The final standards apply to stationary SI engines subject to the
SI NSPS that are modified or reconstructed after June 12, 2006. The
definitions for modification and reconstruction are given in 40 CFR
60.14 and 40 CFR 60.15, respectively. A stationary engine that is
overhauled as part of a maintenance program is not considered a
modification if there is no increase in emissions.
    Stationary SI ICE less than or equal to 19 KW (25 HP) manufactured
prior to July 1, 2008, that are modified or reconstructed after June
12, 2006, are required to meet the standards that apply to engines
manufactured after July 1, 2008 (January 1, 2009 for emergency
engines).
    Stationary SI gasoline and rich burn LPG engines between 25 HP and
500 HP manufactured prior to July 1, 2008, that are modified or
reconstructed after June 12, 2006, are required to meet the standards
applicable to engines manufactured after July 1, 2008 (January 1, 2009
for emergency engines).
    Stationary SI natural gas and lean burn LPG engines greater than 25
HP and less than 100 HP manufactured prior to July 1, 2008, that are
modified or reconstructed after June 12, 2006, are required to meet the
NOX, HC, and CO emission standards in 40 CFR 1048.101(c), as
summarized in Table 3 of this preamble.
    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 greater than or
equal to 100 HP and less than 500 HP manufactured prior to July 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 VOC standard of 1.0 g/HP-hr. Instead
of meeting emission standards in terms of

g/HP-hr, owners and operators may meet NOX, CO, and VOC
emission standards of 250, 540, and 86 ppmvd at 15 percent
O2, respectively.
    Stationary non-emergency SI natural gas and lean burn LPG engines
greater than or equal to 500 HP manufactured prior to July 1, 2007, (or
January 1, 2008, for lean burn natural gas engines greater than or
equal to 500 HP and less than 1,350 HP) 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 VOC standard of 1.0 g/
HP-hr. Again, instead of meeting emission standards in terms of g/HP-
hr, owners and operators may meet NOX, CO, and VOC emission
standards of 250, 540, and 86 ppmvd at 15 percent O2,
respectively.
    Stationary SI landfill and digester gas engines less than 500 HP
manufactured prior to July 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 VOC
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 VOC
standard of 1.0 g/HP-hr. For all modified and reconstructed SI landfill
and digester gas engines, instead of meeting emission standards in
terms of g/HP-hr, owners and operators may meet NOX, CO, and
VOC emission standards of 220, 610, and 80 ppmvd at 15 percent
O2.
    Stationary SI emergency engines greater than or equal to 130 HP
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 VOC standard of 1.0 g/HP-hr. Instead of meeting emission
standards in terms of g/HP-hr, owners and operators may meet
NOX, CO, and VOC emission standards of 250, 540, and 86
ppmvd at 15 percent O2. Stationary SI emergency engines
between 25 HP and 130 HP manufactured prior to January 1, 2009, that
are modified or reconstructed after June 12, 2006, are required to meet
a HC+NOX emission standard of 10.0 g/HP-hr and a CO standard
of 387 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 final standards apply to stationary
engines subject to the NESHAP that commence reconstruction on or after
June 12, 2006, and 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 subject to the emission standards specified in
the final 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 the final 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
Tables 3 or 4 of this preamble, as applicable, or by conducting an
initial performance test (and potentially subsequent performance
testing depending on the engine size) to demonstrate compliance with
the emission standards.
    Owners and operators of all stationary engines subject to the
requirements of the SI NSPS must keep records of maintenance conducted
on the engine. Owners and operators of stationary non-certified
engines, which include certified engines operating in a non-certified
manner, must keep a maintenance plan. Owners and operators of certified
engines may demonstrate compliance by operating and maintaining their
stationary engine and aftertreatment control device (if any) according
to the manufacturer's emission-related written instructions and do not
have to conduct any performance testing.
    Owners and operators of certified engines who do not follow the
manufacturer's emission-related operation and maintenance procedures
will be considered non-certified engines and will be subject to
performance testing. Certified engines operating in a non-certified
manner that are less than 100 HP do not have to conduct performance
testing to demonstrate compliance. Certified engines operating in a
non-certified manner that are greater than or equal to 100 HP and less
than or equal to 500 HP, however, must conduct an initial performance
test within the first year of engine operation to demonstrate
compliance with the emission standards. Finally, certified engines
operating in a non-certified manner that are greater than 500 HP must
conduct a performance test within the first year of operation and every
8,760 hours of operation or 3 years thereafter to demonstrate
compliance. Owners and operators of engines that have never been
certified that are greater than 25 HP and less than or equal to 500 HP
must conduct an initial performance test to demonstrate compliance with
the emission standards. As mentioned, all engines are subject to
recordkeeping of maintenance, which includes these engines. Owners and
operators of engines that have never been certified that are greater
than 500 HP must conduct an initial performance test to demonstrate
compliance and must test every 8,760 hours of operation or 3 years
after that.
    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 or 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-1 cycle in International Organization for
Standardization (ISO) 8178-4: 1996(E) for stationary engines or the
test cycle requirements specified in Table 5 to 40 CFR 1048.505, except
that Table 5 to 40 CFR 1048.505 applies to high load engines only.
    Manufacturers who opt to voluntarily 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 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.
    EPA allows 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 or
emission-related operation and maintenance procedures specified by the
manufacturer. If the owner or operator uses fuels that are outside of
the fuel specifications or does not follow the emission-related
adjustments or maintenance requirements 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.
    Regarding stationary rich burn engines operating with three-way
catalysts or non-selective catalytic reduction, EPA expects that air-
to-fuel ratio controllers will be used in conjunction with the control
device. The AFR controller must be operated in an appropriate manner to
ensure proper operation of the engine and control device in order to
minimize emissions.
2. NESHAP
    For most engines (i.e. except those discussed in the following
paragraph), owners and operators of new and reconstructed stationary SI
RICE equal to or less than 500 HP located at a major source of HAP
emissions and stationary RICE located at an area source, will be able
to demonstrate compliance with the NESHAP if they meet the requirements
of the final SI NSPS (40 CFR part 60, subpart JJJJ). Similarly, 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, will be able to demonstrate compliance with the
NESHAP if they meet the requirements of the final CI NSPS (40 CFR part
60, subpart IIII). If the owners and operators are in compliance with
40 CFR part 60, subpart JJJJ or IIII, as applicable, they will also be
in compliance with 40 CFR part 63, subpart ZZZZ, for engines equal to
or less than 500 HP located at a major source. The compliance
requirements that apply under 40 CFR part 60, subpart JJJJ, were
discussed in the previous section. For the majority of stationary CI
engines, all that is required under 40 CFR part 60, subpart IIII, is
that the owner or operator purchase a certified stationary CI engine
and operate it properly and according to the manufacturer's
specifications.
    Owners and operators of new or reconstructed 4SLB stationary RICE
greater than or equal to 250 HP and less than or equal to 500 brake HP
located at major source are required to follow the compliance
requirements specified in 40 CFR part 63, subpart ZZZZ, consistent with
the compliance requirements for 4SLB stationary RICE greater than 500
HP located at a major source. Those compliance requirements include
demonstrating compliance by conducting an initial performance test.
These engines must also conduct a subsequent performance test
semiannually if they are complying with the requirement to reduce CO
emissions and not using a continuous emissions monitoring system, and
if they are complying with the requirement to limit the concentration
of formaldehyde in the stationary engine exhaust. Under the NESHAP,
these engines must either reduce CO emissions or limit the
concentration of formaldehyde. In addition, these engines would be
required to meet the requirements in the final SI NSPS. However, these
engines do not have to comply with the CO emission standards of the SI
NSPS if in compliance with the NESHAP.

F. What are the reporting and recordkeeping requirements?

    The following sections describe the reporting and recordkeeping
requirements that are required under the SI NSPS and the NESHAP.
1. SI NSPS
    Owners and operators of all engines (certified and non-certified)
are required to maintain records of proper maintenance and non-
certified engines must keep a maintenance plan. An initial notification
is required for owners and operators of engines greater than 500 HP
that are non-certified. Also, owners and operators who conduct
performance testing are required to report the test results within 60
days of each performance test.
    Owners and operators of emergency engines are required to keep
records of their hours of operation. For emergency engines greater than
or equal to 130 HP, this requirement starts for engines manufactured
after the point when more stringent emission standards take effect for
non-emergency engines, either in July 2010 or January 2011, depending
on the power rating of the engine. For emergency engines below 130 HP,
the requirement to keep records of the hours of operation begins for
all engines manufactured after January 1, 2009. Owners and operators of
emergency engines must install a non-resettable hour meter on their
engines to record the necessary information. Emergency stationary
engines may be operated for the purpose of maintenance checks and
readiness testing, provided that the tests are recommended by the
Federal, State or local government, the manufacturer, the vendor, or
the insurance company associated with the engine. Maintenance checks
and readiness testing of such units is limited to 100 hours per year.
Owners and operators can petition the Administrator for additional
hours, beyond the allowed 100 hours per year, if such additional hours
should prove to be necessary for maintenance and testing reasons. A
petition is not required if the hours beyond 100 hours per year for
maintenance and testing purposes are mandated by regulation such as
State or local requirements. There is no time limit on the use of
emergency stationary engines in emergency situations, however, the
owner or operator is required to record the length of operation and the
reason the engine was in operation during that time. Records must be
maintained documenting why the engine was operating to ensure the 100
hours per year limit for maintenance and testing operation is not
exceeded. In addition, owners and operators are allowed to operate
their emergency engines for non-emergency purposes for 50 hours per
year, but those 50 hours are counted towards the total 100 hours
provided for operation other than for true emergencies and owners and
operators

may not engage in income-generating activities during those 50 hours.
The 50 hours per year for non-emergency purposes cannot be used to
generate income for a facility, for example, to supply power to an
electric grid or otherwise supply power as part of a financial
arrangement with another entity.
2. NESHAP
    In general, owners and operators of new and reconstructed
stationary RICE equal to or less than 500 HP located at a major source
of HAP emissions and stationary RICE located at an area source of HAP
emissions, will be able to demonstrate compliance with the NESHAP if
they meet the requirements of the final SI NSPS (40 CFR part 60,
subpart JJJJ) or the final CI NSPS (40 CFR part 60, subpart IIII), as
appropriate, which includes reporting and recordkeeping requirements.
The reporting and recordkeeping requirements that would apply to
stationary RICE were discussed in the previous section of this preamble
and in the preamble to the final CI NSPS (71 FR 39154). No additional
reporting and recordkeeping requirements are required under the 40 CFR
part 63.
    Owners and operators of new or reconstructed 4SLB stationary RICE
greater than or equal to 250 and less than or equal to 500 brake HP
located at major source are required to meet the reporting and
recordkeeping requirements specified in 40 CFR part 63, subpart ZZZZ,
consistent with the compliance requirements for 4SLB stationary RICE
greater than 500 HP located at a major source. The recordkeeping and
reporting requirements that apply to these engines were discussed in
the preamble to the final RICE NESHAP (69 FR 33473).

IV. Summary of Significant Changes Since Proposal

    Most of the rationale used to develop the proposed rule remains the
same for the final rule. Therefore, the rationale previously provided
in the preamble to the proposed rule is not repeated in the final rule,
and the rationale sections of the rule, as proposed, should be referred
to. Major changes that have been made to the rule since proposal are
discussed in this section with rationale following in the Summary of
Responses to Major Comments section.

A. Compliance Dates

    In the final rule, EPA has extended the compliance dates for all
stationary SI ICE that had a compliance date of January 1, 2008, in the
proposal, by 6 months. These engines have a compliance date of July 1,
2008. In addition, stationary SI lean burn engines between 500 and
1,350 HP that had a compliance date of July 1, 2007, in the proposed
rule, have also been provided with an additional 6 months, i.e., these
engines have a compliance date of January 1, 2008.

B. Distinguishing Sources Based on Size

    In the final rule, based on the comments received, EPA is adopting
a size threshold of 100 HP for non-emergency stationary SI engines to
meet nonroad emission standards. That is, non-emergency stationary SI
engines less than 100 HP are subject to the nonroad emission standards
in 40 CFR part 90 (if less than or equal to 25 HP) or 40 CFR part 1048
(if greater than 25 HP). Certification to 40 CFR part 1048 is voluntary
for all stationary SI engines except gasoline and rich burn LPG
engines. Stationary SI engines greater than or equal to 100 HP (except
gasoline and rich burn LPG) are subject to the emission standards
specified in part 60 subpart JJJJ, as shown in Table 4 of this
preamble. Stationary SI lean burn LPG engines have the option of
meeting 40 CFR part 1048 instead of the emission standards specified in
this subpart. EPA has also provided some flexibility on the initial
years of the program for manufacturers to certify to standards in
either 40 CFR part 1048 or as shown in Table 4 of this preamble.

C. Hydrocarbon Limit

    EPA proposed emission limits for NOX, CO, and NMHC. In
the final rule, EPA is adopting a VOC limit in place of the proposed
NMHC limit. The stage 1 and stage 2 emission standards remain as
proposed at 1.0 g/HP-hr and 0.7 g/HP-hr, but the standards are for VOC.
EPA has defined VOC according to 40 CFR part 51, and has noted that
emissions of formaldehyde should not be counted for testing purposes.
That is, the final stage 1 and stage 2 emission limits for VOC
effectively do not include ethane, methane, and formaldehyde.
Formaldehyde was excluded because it cannot be measured by the testing
method used to determine the standard; however, EPA expects
formaldehyde emissions to be reduced using the emission controls
expected for other hydrocarbons and CO. Therefore, we expect
formaldehyde emissions to be reduced comparably to VOCs and CO, which
are used as a surrogate for formaldehyde for the purposes of section
112.

D. Alternative Limits in Concentration Units

    EPA proposed NOX, CO, and NMHC emission limits in terms
of exhaust-based units. Based on various comments and concerns with
finalizing emission standards in terms of these units, EPA finds it
appropriate to include alternative concentration-based emission limits
in the final rule. The concentration-based emission limits, provided in
terms of ppmvd at 15 percent O2, are equivalent to the g/HP-
hr emission limits. The owners and operators may choose if they wish to
comply with the g/HP-hr standards or the ppmvd standards.

E. Emergency Engine Standards

    For stationary emergency engines, EPA proposed that these engines
meet emissions standards of 2.0, 4.0, and 1.0 g/HP-hr for
NOX, CO, and NMHC, respectively, for all emergency engines.
In the final rule, stationary emergency engines between 25 and 130 HP
are subject to emission standards of reduced stringency of 10 g/HP-hr
for NOX+HC and 387 g/HP-hr for CO. Stationary emergency
engines greater than or equal to 130 HP are subject to the emission
standards as proposed. Stationary emergency engines less than or equal
to 25 HP are subject to the emission standards in 40 CFR part 90.

F. Emergency Engine Definition

    In the final rule, EPA has retained the proposed definition of
stationary emergency engine, except that stationary engines greater
than 500 HP located at major sources that were built prior to the
proposal date of this rule (June 12, 2006), are subject to the
emergency engine definition as finalized in 40 CFR part 60, subpart
ZZZZ, on June 15, 2004. All stationary engines built after the date of
proposal of this rule are subject to the new definition of stationary
emergency engine and are limited to 100 hours per year of maintenance
and readiness testing. There is no limit on the time allowed for
emergency operation. Stationary emergency engines may be operated for
non-emergency purposes for up to 50 hours per year, but those 50 hours
are counted towards the 100 hours per year allowed for maintenance and
readiness testing. The 50 hours per year for non-emergency purposes
cannot be used for peak shaving or to generate income for a facility to
supply power to an electric grid or otherwise supply power as part of a
financial arrangement with another entity.

G. Manufacturer O&M Requirements

    The proposed rule required that owners and operators operate and
maintain their stationary SI internal combustion engine and control
device according to the manufacturer's written instructions or
procedures developed by the owner or operator that are approved by the
engine manufacturer. The final rule does not require that owners and
operators follow the manufacturer's instructions. Owners and operators
who operate and maintain their certified stationary ICE and control
device according to the manufacturer's emission-related guidelines are
required to keeping records of conducted maintenance and do not have
any performance testing requirements under the final rule.
    Owners and operators who operate their certified stationary ICE and
control device in a manner that is inconsistent with the manufacturer's
emission-related guidelines are considered non-certified engines and
must keep a maintenance plan, records of conducted maintenance, and
must conduct performance testing under the final rule if the engine is
greater than or equal to 100 HP. Owners and operators of stationary ICE
that have never been certified must keep a maintenance plan, records of
conducted maintenance, and must conduct performance testing for all
size engines.

H. Streamlined Compliance Requirements

    In the final NESHAP, EPA has included a provision that states that
owners and operators of new and reconstructed stationary engines less
than 500 HP located at major sources and new and reconstructed
stationary engines located at area sources (except stationary 4SLB
engines between 250 and 500 HP) will be in compliance with the NESHAP
requirements if they meet the requirements of the SI NSPS (40 CFR part
60, subpart JJJJ) or the CI NSPS (40 CFR part 60, subpart IIII), as
applicable.

V. Summary of Responses to Major Comments

    A more detailed summary of comments and EPA's responses can be
found in the Summary of Public Comments document, which is available
from the rulemaking docket (see ADDRESSES section).

A. Compliance Dates

    Comment: Several commenters stated that more time is needed to
comply with the final rule for owners, operators, and manufacturers.
Two commenters said that because there are no existing Federal
requirements affecting the vast majority of stationary SI engines and
due to the complexity of the regulation, more time is needed to develop
the testing and compliance systems for the proposed requirements. Also,
two commenters added, that the first compliance date of July 1, 2007,
actually occurs prior to the anticipated publication date of the final
rule. One commenter expressed that such a regulatory mandate is
impractical and unworkable considering the uncertainty of the final
regulatory requirements. One commenter believes that an implementation
date of January 1, 2008, is unreasonable. This commenter believes that
the engine control technology requires significant changes to meet the
proposed standards and recommended the implementation date be January
1, 2009, to allow proper development and application time. This
commenter explained that a minimum of 12 months is required for
manufacturer development and testing such as catalyst configuration
changes and component specification for additional engines and fuel
types not certified to 40 CFR part 1048. In addition, any deterioration
factor service accumulation time required will take 6 months to
complete, according to one commenter. Once the development of the
systems are complete, this commenter said that it will take
manufacturers a minimum of 6 months to apply, or ``roll out,'' this
technology to the equipment manufacturer base. The commenter bases this
comment on the experience in implementing the large SI nonroad engine
regulations (40 CFR part 1048), which began implementation in January
of 2004. One commenter requested that the initial compliance dates be
delayed 9 months from the proposed compliance dates. Another commenter
recommended that the initial compliance dates be delayed until at least
6 to 9 months following publication of the final rule in the Federal
Register. Sufficient lead time is required not only for manufacturers,
but also to allow the many thousands of owners/operators affected by
the regulation to be notified and educated regarding the rule's
requirements, according to a commenter. Finally, commenter 154 said
that subsequent compliance dates also should be delayed by the same
amount to assure that the requisite leadtime and stability periods are
preserved for manufacturers.
    Response: Based on comments received on the proposed compliance
dates as summarized in the above comment and on various discussions
post-proposal with engine manufacturers, EPA agrees that it is
appropriate to extend the proposed compliance date of January 1, 2008,
that affected a variety of different engines, many of which are subject
to mandatory certification. In the final rule, EPA has provided an
additional 6 months for engines that had a compliance date of January
1, 2008 in the proposal. The compliance date in the final rule is July
1, 2008, for engines less than 500 HP. EPA believes that July 1, 2008,
will accommodate engine manufacturers and that 6 months will be
sufficient lead-time for both owners/operators and manufacturers. In
particular, EPA believes July 1, 2008, will provide manufacturers
enough time to prepare and complete the certification of new engines.
Although the technology already exists for reducing emissions to the
level required in the rule, an appropriate amount of time should be
provided in order to make the necessary arrangements for engine
manufacturers to obtain certification of their products and otherwise
assist affected parties prepare for the new standards. EPA's approach
is similar to the approach taken in the CI NSPS where sources were
required to comply before the final rule was issued, but some time was
provided prior to the requirement for mandatory certification. Sections
111 and 112 of the CAA define new engines to be all engines for which
construction is commenced following the date of the proposal and it is
routine for sources that commenced construction prior to the final rule
to be subject to standards under these provisions. Also note that the
certification program for large SI engines is voluntary so
manufacturers are not being forced to certify engines by those dates.
Only engines that are 25 HP or smaller or are gasoline or rich burn
LPG-fueled, which are directly related to nonroad engines that are
already subject to certification requirements and are also generally
smaller than 500 HP, must certify. This is one reason why EPA does not
believe that it is necessary to include additional lead-time for large
engines (i.e., those above 500 HP) and the compliance date remains as
proposed for these engines, i.e., July 1, 2007, with the exception that
EPA has granted a delay for certain engines until January 1, 2008,
which EPA discusses below.
    Regarding the comparison with the large SI nonroad engine rule, EPA
notes that the proposal for that rule was published in October 2001,
over 2 years from initiation of a mandatory certification program. EPA
believes that the compliance dates provide adequate time for
manufacturers of engines and

owners/operators to make the necessary preparations and adjustments to
develop engines that comply with the emission standards. Additional
lead-time has been provided for certain engines, as discussed above, as
well as emergency engines. EPA has also provided additional lead-time
in order to meet the Stage 2 emission standards. With that said, EPA
notes that in the final rule that it has provided lean burn engines in
the size range of 500 HP or greater to less than 1,350 HP additional
lead-time. Engine manufacturers have indicated that it would be
problematic to meet the proposed compliance date. EPA believes that
providing engine manufacturers with a later compliance date will make
it possible to complete necessary development and implementation work
necessary in order to prepare these engines for compliance. More
information on this topic can be found in the docket to this
rulemaking.

B. Final Hydrocarbon Emission Limits

    Comment: Several commenters expressed some concerns with the
proposed non-methane hydrocarbons (NMHC) emission standards. One
commenter initially recommended a 1.0 g/HP-hr NMHC emissions limit as
being technically achievable for most engine applications. However,
several engine manufacturers have clarified that the information
submitted to EPA regarding achievable NMHC numbers did not include
aldehydes and other oxygenated hydrocarbon compounds in the totals.
Three commenters recommended that NMHC limitations exclude aldehydes
and other oxygenated HC. One commenter said that if the standard
includes aldehydes, then the emission standard of 1.0 g/HP-hr is not
achievable for most engines, since the initial recommendation the
commenter submitted was based on excluding aldehydes from the NMHC
totals.
    Three commenters requested that ethane be excluded from the
calculation of NMHC. They argue that ethane is not a VOC under 40 CFR
51.100(s)(1) and they say that ethane does not contribute to ozone
formation. The commenters also noted that natural gases with a relative
high content of ethane are primarily present in the western part of the
U.S. and commenter 139 provides information indicating that engines are
not able to meet the NMHC standards when using natural gas that is high
in ethane. Two commenters recommended that EPA examine alternative
standards, indices, and testing methods for hydrocarbon emissions.
Three commenters said that the parameter to be used for natural gas
fueled engines should exclude methane and ethane and have suitable
measurement techniques that are applicable in both factory and field
tests. One commenter said, if EPA decides to retain NMHC as the
appropriate parameter, then at a minimum, the level of the proposed
standards needs to be raised or clarification made that the measured HC
do not include aldehydes.
    Three commenters recommended that if the NSPS includes an emission
limit for HC species, the limit should be for VOC (or non-methane non-
ethane (NMNEHC)) and not NMHC. Three commenters stated that VOC, not
NMHC, are the National Ambient Air Quality Standards (NAAQS) pollutant
regulated as an ozone precursor for stationary sources. The commenters
believe that most available data are reported as VOC rather than NMHC,
and owners/operators are very limited in their ability to assess
whether the data indicate that the proposed NMHC standard is achievable
for field performance tests. The commenters also believe that before
regulating NMHC for stationary engines, EPA should complete an analysis
to identify the potential benefit and cost of regulating ethane or
using NMHC as a surrogate for VOC for gas-fired engines, and ensure
that emissions data from field tests are available to substantiate the
basis for the standard.
    Several commenters also expressed concern over the proposed test
methods for measuring NMHC. Commenters believe that the emissions test
methods should be consistent with the included hydrocarbon species, and
EPA Method 25 of 40 CFR part 60, Appendix A, should not be used for
determination of NMHC or VOC. The commenters support their claim by
saying that NMHC emissions are defined as THC emissions less methane
emissions. However, this definition needs further clarification to
exclude formaldehyde and oxygenates, because the emissions information
provided by manufacturers that serves as the basis of the standard does
NOT include aldehydes or other oxygenated HC. Non-methane hydrocarbon
measurements are typically conducted using a flame ionization detector
(FID) to measure THC and a FID or gas chromatography method to measure
methane. EPA Method 25A of 40 CFR part 60, Appendix A, uses a
continuous FID analyzer to measure exhaust gas THC. Method 18 separates
CH4 (methane) from other exhaust gas species with a gas
chromatograph, and quantifies the methane with an appropriate detector.
Method 18 of 40 CFR part 60, Appendix A, allows exhaust gas to be
collected in a bag or continuously sampled. A flame ionization detector
poorly quantifies oxygenated hydrocarbon species. Formaldehyde, and to
a lesser extent acetaldehyde, methanol, and acrolein, have been
measured in natural gas-fired engine exhaust. The commenters agree with
EPA's conclusion that NMHC test methods are simpler and less costly to
implement than formaldehyde test methods and that NMHC testing will
reduce the testing burden while maintaining emissions compliance
assurance. Recognizing that measuring NMHC with a FID does not directly
measure formaldehyde and that the emission limits are based on
manufacturer data that do not include formaldehyde and other
oxygenates, it is important to understand that NMHC is used as a
formaldehyde surrogate, but NMHC, the regulated pollutant, does NOT
include formaldehyde under this standard. Thus, it is only appropriate
to allow test methods that do NOT measure formaldehyde or other
oxygenated hydrocarbons; therefore, EPA Method 25 should be excluded
from the final rule.
    Response: We agree that the composition of certain western gas
(i.e. the high concentration of ethane) may make compliance with an
NMHC standard more difficult in some cases. As the proposed NMHC
standards were intended to ensure compliance with VOC and HAP reduction
requirements, and pursuant to 51.100(s) ethane is not a VOC, (nor is it
a HAP under CAA section 112(c)) we agree that expressing the standard
in terms of VOC, rather than NMHC is appropriate in this case. EPA's
final hydrocarbon standards for gaseous fueled and lean burn LPG
engines above 100 HP are presented as VOC standards, instead of NMHC
standards. For natural gas engines below 100 HP meeting the NMHC
standards in 40 CFR part 1048, the regulations do not require
measurement of ethane for testing in the field. EPA agrees that EPA
Method 25A does not measure formaldehyde and that all data gathered to
support the emission limit using this method would not have included
formaldehyde. However, EPA Method 25A would measure all other aldehydes
and other oxygenated organic compounds although the measured results
would be less than the actual concentrations in the gas stream. Even
though EPA Method 25A measurements for the other aldehydes and
oxygenated organic compounds would have been less than their true
values, EPA believes that in all cases the measured values would
represent substantially greater than 50 percent of the true value for
these compounds. Because these

compounds are accounted for to a significant extent in the database
supporting the emission limit it would not be appropriate to exclude
them from the definition of VOC. If EPA Method 25A is used to determine
compliance with the emission limit, the reduced response of the
aldehydes and other oxygenated organics will automatically be taken
into account, and the compliance demonstration will be consistent with
the procedures used to establish the emission limit. However, if one of
the alternative methods, such as EPA Method 18 or EPA Method 320 of 40
CFR part 60, Appendix A, is used, these methods will measure 100
percent of the aldehydes and other oxygenated organic compounds. The
results from these methods should be adjusted to account for the bias
in EPA Method 25A by multiplying the measured values of the aldehydes
and other oxygenated organics by the EPA Method 25A response factor for
each measured compound. In addition, when adding the masses of all of
the measured VOC from either of these two methods, the actual mass of
the aldehydes and oxygenated organics should be reported as the
equivalent mass on a propane basis. This will ensure that the results
from these two methods are reported on a basis that is consistent with
the procedures used to establish the emission limit.
    EPA agrees that it is not appropriate to allow EPA Method 25 in the
final rule, and EPA has made this clear in the regulatory text. Since
the final emission standards are based on data that does not include
formaldehyde, it would not be appropriate to include Method 25 since
that method may capture that compound.
    Further, the emission standards for VOC are based on data that does
not include formaldehyde and EPA agrees that it is appropriate to
specify that formaldehyde is not included in the final VOC emission
standard. EPA has made this clarification in the testing requirements
for VOC. In the final rule, EPA has replaced the proposed NMHC limits
in g/HP-hr with VOC limits in the same units. In addition, EPA has
specified VOC limits in terms of concentration (ppmvd at 15 percent
O2). EPA believes, based on evidence, that a final standard
of 1.0 g/HP-hr and 0.7 g/HP-hr for VOC will be achievable for most
engines. (Certain engines, like engines burning landfill gases, are
subject to less stringent final standards.) The proposed NMHC emission
limits are essentially the same as the final VOC emission limits based
on how VOC is defined in the final rule. EPA has defined VOC according
to the definition provided in 40 CFR part 51, and has noted that
formaldehyde is, as discussed, excluded from calculation of VOC
emissions. The magnitude of the final VOC limits is the same as the
proposed NMHC limits and remain unchanged because the test methods used
to capture pollutants are essentially the same.
    EPA recognizes that there may be variability in the ethane content
in natural gas and believes it would be appropriate to exclude ethane
from the final standard. Since EPA has replaced the proposed NMHC
standards with VOC standards in the final rule, and since VOC by
definition excludes ethane, this comment is resolved.
    As discussed, EPA is finalizing emission standards in terms of VOC
not as NMHC, as proposed. Based on review of the emissions information
used to set the proposed standards for NMHC, comments received on the
proposal from industry, and meetings with various stakeholders post-
proposal, EPA believes it is more appropriate finalize a VOC standard
than an NMHC standard as a measure for HC compounds. Many State
regulations affecting stationary sources use VOC and VOC is a more
familiar term than NMHC to the regulated community. Emissions of NMHC
might be difficult to measure in the field and is a pollutant that has
typically been regulated through the manufacturer. Also, because of the
variability of ethane in natural gas fuel, VOC, since it excludes
ethane, it is more appropriate than NMHC.

C. Emergency Engine Standards

    Comment: Several commenters were of the opinion that stationary
emergency engines should be exempt from the rule; at a minimum they
should be exempt from the emission standards. Two commenters were of
the opinion that a size-based exemption threshold or alternative
emission limits should be defined for emergency engines. One commenter
believes that the proposed NSPS notifications and reporting for small
emergency engines will be a cumbersome activity with little
environmental benefit. The commenter noted that in most cases emergency
engines operated less than 500 hours are not permitted or are
considered insignificant due to the limited potential to emit
emissions. The commenter requested that EPA consider exempting all
emergency engines less than 500 HP from the proposed NSPS and NESHAP
regulations. One commenter added that there is little data that show
that by regulating these small emergency engines there will be
significant environmental improvement. This commenter was of the
opinion that as long as hour records are kept to show the engines are
being operated in the manner addressed in the EPA white paper mentioned
above these engines should be considered insignificant emitters. One
commenter requested that EPA exempt stationary emergency engines from
the proposed requirements, other than monitoring and recording annual
operating hours by owners/operators to demonstrate the engines meet the
100-hour annual operating limitation.
    One commenter recommended that emergency engines be exempted from
the NSPS and NESHAP. The commenter said that emergency SI engines
provide essential and needed services to owners/operators when the
normal supply of electricity is disrupted and often serve life-critical
functions in times of emergency. The proper operation and function of
emergency engines is an essential service, according to the commenter.
In addition, because emergency engines operate only during times of
emergencies and are limited in hours of operation for maintenance or
testing operation, emergency SI engines add minimal emissions to the
inventory of criteria or HAP emissions, the commenter added. Commenter
154 believes that there will be negligible emission reductions or
environmental benefits from fully applying the requirements of the
proposed rule to emergency SI engines. In addition, the commenter said
that including emergency engines within the regulations adds a
significantly large number of owners/operators to the affected
regulatory community, and thus significantly increases the reporting,
recordkeeping, and compliance costs of the proposed regulation. Since
emissions from emergency SI engines are small and the cost of
regulatory compliance and reporting are large, the imposition of NSPS
and NESHAP controls on emergency SI engines is not cost-effective,
according to the commenter.
    Two commenters believe that a 400 HP exemption threshold or
alternative emission limits should be defined for emergency engines.
The commenters said that 4SLB engines are not available below 400 HP, a
size range that comprises the majority of emergency units in the oil
and gas industry. The proposed rules would require non-selective
catalytic reduction (NSCR) to be applied to these small engines;
however NSCR application to an emergency engine has inherent
complications, costs, and reliability issues, according to the
commenters.

The proposed rule requires controls for emergency engines, whereas the
existing RICE MACT concluded controls for emergency units were not
necessary and the commenters believe that the proposed rule is
therefore more stringent than the existing RICE MACT.
    Some commenters also requested that EPA provide an exemption for
reconstructed or modified rich burn emergency engines, which would also
require post-combustion control to meet the standards.
    Two commenters said that if a size-based exemption is not included
in the rule, separate subcategories will be needed for emergency
engines based on size with emission limits for smaller units
commensurate with an uncontrolled rich burn engine, as well as an
exemption for existing rich burn emergency engines that are
reconstructed or modified.
    Response: EPA disagrees that stationary emergency engines should be
completely exempted from the rule and also does not agree that
emergency engines should be exempt from emission standards. Emergency
engines are part of the source category and stationary internal
combustion engines and they represent a significant portion of the
engines being regulated under these combined rules, and their aggregate
emissions are not insignificant. EPA believes that their emissions can
be regulated in a manner that is cost-effective and not disruptive.
Moreover, given that EPA has already promulgated standards for
stationary CI emergency engines, failure to regulate SI emergency
engines may create a loophole in regulation. However, as discussed
below, EPA believes that a distinction in emission standards based on
size is appropriate to include for stationary emergency engines to
account for what types of engines and emission controls are available.
In addition, EPA agrees that alternative emission limits should be
finalized for emergency engines, consistent with the proposal that
recognizes a need for different emission standards for emergency
engines. The final standards do not require a second stage of more
stringent standards for emergency engines. For emergency engines equal
to or greater than 130 HP, the standards remain as proposed at 2.0,
4.0, and 1.0 g/HP-hr for NOX, CO and VOC, respectively. As
discussed elsewhere in this document, EPA is also including the option
for owners and operators to meet these emission standards in terms of
concentration. However, for emergency engines below 130 HP, EPA has
found it appropriate to adopt less stringent emission standards in the
final rule. Based on information received post-proposal, EPA has
learned that there are lean burn engines currently in the market down
to 130 HP, and EPA, therefore, disagrees with the commenters who
requested a 400 HP exemption threshold or alternative emission limit
for emergency engines claiming that 4SLB engines are not available
below 400 HP. Information on these engines can be found in the docket.
The final emission standards for emergency engines below 130 HP are
commensurate with the emission standards that are achievable for rich
burn engines without aftertreatment and represent the maximum level of
control that is attainable for small emergency engines without using
aftertreatment. EPA agrees that requiring NSCR for these engines raises
complications and reliability issues that are inappropriate for this
subcategory. The final rule requires emergency engines greater than 25
HP and below 130 HP to meet a NOX+HC standard of 10.0 g/hp-
hr and a CO standard of 387 g/HP-hr. These emission standards are
consistent with the Phase II standards that apply to Class II nonroad
engines.
    EPA does not believe that the recordkeeping requirements for
emergency engines will be significantly burdensome. Emergency engines
have to maintain records hours of operation (of emergency and non-
emergency use) to ensure they are not operated beyond the 100-hour
limit of the rule. Small emergency engines, i.e., those less than 130
HP will be required to begin recordkeeping immediately. However, since
there is no difference between the emission standards for emergency and
non-emergency engines above 130 HP until the stage 2 emission standards
become effective for non-emergency engines, these larger emergency
engines do not have to begin recording hours of operation and keep
records of total hours of operation until July 1, 2010 or January 1,
2011, depending on whether the emergency engine is greater than or
equal to 500 HP or below 500 HP, respectively.
    EPA has made simplifications in the final rule that would affect
emergency engine compliance requirements. In the final NESHAP, EPA has
included a provision that allows emergency engines subject to the
NESHAP that are new or reconstructed and equal to or less than 500
brake HP located at a major source of HAP emissions or located at an
area source of HAP emissions to meet the requirements of the NESHAP by
demonstrating compliance with the SI NSPS. EPA believes that this
provision greatly reduces the compliance burden for owners and
operators of emergency engines and overall simplifies the compliance
process. Further, under the final SI NSPS, engines less than 100 HP
that are certified or that were certified, but are operated in a non-
certified manner will not be subject to any performance testing. This
would include emergency engines.
    EPA recognizes that this final rule is more stringent than the
existing RICE NESHAP covering stationary engines greater than 500 HP at
major sources, but EPA sees nothing improper about adopting more
stringent standards affecting emergency engines under this rule. EPA
often promulgates more stringent requirements in rules subsequent to
initial rules regulating a source category. Emergency engines covered
by the previous NESHAP are not subject to this rule. Only new, modified
or reconstructed engines installed after the publication date of the
notice of proposed rulemaking for this rule are subject to the more
stringent requirements, except that EPA has added explicit limitations
on use of emergency engines for peak shaving and supplying power to an
electric grid or that supply power as part of a financial arrangement
with another entity.
    Regarding the request for an exemption for modified and
reconstructed rich burn emergency engines, EPA disagrees that an
exemption should be provided. The overall goal of the statute for
modified and reconstructed engines is that older engines that are being
modified or reconstructed should be subject to relatively the same
standards as new engines. This reduces the incentive for owners and
operators to continue to use older dirtier engines for very long
periods beyond their normal life. It is not impossible to apply add-on
controls to emergency engines.

D. Emergency Engine Definition

    Comment: One commenter stated that the proposal sets separate
standards for new emergency engines, but fails to impose enforceable
limits so that these engines will be used only in clearly defined
emergencies. The commenter strongly supports EPA's specification of
emissions standards for emergency engines and to require that emergency
engines be equipped with non-resettable meters. In addition to these
requirements, the commenter said that EPA must require that emergency
engines that do not meet otherwise applicable emissions limits be
labeled as such. Additionally the commenter said that EPA must tighten
the definition of a stationary emergency engine. According to the
commenter, by

allowing emergency engines to run for an unlimited number of hours
during emergency situations, but failing to provide a clear definition
of what constitutes an emergency situation or emergency operation, the
proposed rule leaves a highly problematic loophole. The commenter
further noted that since the requirements for emergency engines are not
as stringent as those for non-emergency engines, there could be a
positive economic incentive for consumers to purchase an emergency
engine even if that is not the engine's intended use. To close this
loophole and effectuate the rule's intent, the commenter said that EPA
must provide an unequivocal definition of what constitutes an emergency
situation and emergency operation. The commenter advocated that a clear
and stringent definition is needed to prevent operators of emergency
engines from running these engines for an unlimited number of hours
without triggering the more stringent Phase 2 controls required of non-
emergency engines.
    EPA's proposed definition does preclude one specific activity from
being classified as an emergency situations (i.e., peak shaving), but
it is otherwise far too general. According to the commenter, by
including only examples of what constitutes an emergency engine, EPA is
leaving the definition open to too much interpretation. The commenter
recommended that at the least, the definition of an emergency engine
should replicate the language used for stationary CI engines in stating
that ``Stationary (CI) ICE used to supply power to an electric grid or
that supply power as part of a financial agreement with another entity
are not considered to be emergency engines.''
    The commenter further suggested that the following elements be
incorporated into the definition of an emergency stationary internal
combustion engine:
     The definition should require that the situation be truly
unforeseeable, beyond the control of the owner or operator, and not
part of any contractual obligation. In particular, the definition
should exclude operation for purposes of supplying power for
distribution to the electric grid and operation for training purposes.
     The definition should exclude equipment failure or other
failure to comply with any environmental law caused by improperly
designed equipment, lack of preventive maintenance, careless or
improper operation, or operator error. This will ensure the proper
incentives are in place for care and maintenance of non-backup engines.
    The commenter also said that if EPA finalizes its intent to allow
natural gas-fired stationary SI engines to operate on propane fuel for
up to 100 hours per year for emergency operations, a comprehensive
analysis should be undertaken to evaluate the full emissions
implications of what appears to be a somewhat arbitrary relaxation of
the proposed standards.
    Response: EPA agrees that requiring emission standards for
stationary emergency engines and requiring that emergency engines be
equipped with non-resettable hour meters, but disagrees that the
definition of emergency engine creates a loophole. EPA believes it
proposed an adequate definition and it is not possible to include every
possible situation that might constitute an emergency in the
definition. EPA agrees that it is important to provide language that
minimizes the possibility of affected sources avoiding more stringent
requirements. EPA believes the definition is clear, and furthermore,
believes that the requirement to keep records of the hours of operation
of the engine in emergency and non-emergency situations will prevent
misuse. EPA does agree with the commenter that it is appropriate to
tighten the definition as far as precluding certain activities and has
included in the definition of emergency engine that stationary SI ICE
used to supply power to an electric grid or that supply power as part
of a financial arrangement with another entity are not considered to be
emergency engines. This language is consistent with the final CI NSPS.
As for the comment related to labeling of emergency engines, EPA
proposed in Sec.  60.4242(d) that manufacturers label their emergency
engines that only meet the emergency engine emission standards as such
and that the engine is for emergency use only. This requirement has
been retained in the final rule, and EPA believes this satisfies the
commenter's concern on this topic.
    Regarding the comment on EPA's provision allowing natural gas-fired
stationary SI engines to operate on propane fuel for up to 100 hours
per year for emergency operations, EPA included that provision to
provide flexibility in emergency situations when the main fuel may not
be available. EPA believes such an allowance is appropriate and does
not expect that emissions will be significantly affected by including a
provision to operate on propane for 100 hours per year for emergency
purposes. Numbers EPA has available, which are presented in information
included in the docket to the proposed rule, show that regulated
pollutant emissions (NOX, CO, and VOC/NMHC/THC) from engines
running on propane are the same or lower than emissions from engines
running on natural gas (rich burn and lean burn), with a few
exceptions. Therefore, for the reasons provided, it is not expected
that the propane allowance will significantly affect emissions and EPA
has retained the propane use allowance in the final rule.
    Comment: Two commenters believe that the emergency engine
requirements in the proposed NSPS/NESHAP are more restrictive than the
requirements in the RICE NESHAP. The commenters believe the proposed
rules should be amended to be consistent with the emergency engine
definition and exemption provided in the RICE NESHAP. Two commenters
said that the emergency engine definition in the existing RICE MACT
that was developed based on input and review from a broad stakeholder
group should be retained. The commenters believe that the proposed rule
substantially and materially alters the definition as follows:
     Maintenance and readiness testing limited to 100 hours per
year versus no time limit on the use of emergency stationary RICE for
routine testing and maintenance.
     Elimination of an additional 50 hours per year in non-
emergency situations.
     Requirement to maintain documentation for maintenance and
testing operation to ensure the 100 hour per year limit is not
exceeded.
     Maintenance and readiness testing operation provisions as
recommended by third party Federal, State or local government, the
manufacturer, the vendor, or the insurance company associated with the
engine has been introduced.
    The commenters believe that the current NESHAP places no
restriction on the use of emergency stationary RICE in emergency
situations and for routine testing and maintenance. In addition, it
offers an additional 50 hours per year in non-emergency situations.
This clause was included as an outcome of the industrial combustion
coordinated rulemaking (ICCR) process to provide adequate time to tests
systems related to the emergency unit. For example, firewater systems
where engine checks are necessary, and a systems check is also required
and may be completed as part of a safety exercise. Commenter 150
believes that EPA has confused the additional non-emergency allocation
with a perceived hour restriction for

annual maintenance and readiness checks.
    Also, the commenter stated that in consideration relative to the
RICE MACT, the proposed NESHAP amendments broaden the category of
affected equipment to include units that are less than or equal to 500
HP and area sources. With more stringent criteria in the proposed rule,
the commenter believes that EPA is requiring more stringency for small
engines and area sources than what was deemed necessary for larger
engines under the existing RICE MACT. Further, the added burden and
cost associated with documenting and maintaining records describing why
the engine was operating must be assessed and the benefit for this
requirement rationalized. As an alternative to continuing with the
revised definition in the proposed rule, the commenters recommend that
the current definition be retained.
    Response: It is true that EPA proposed a more stringent emergency
engine definition and requirements as compared to the existing RICE
MACT emergency engine definition. Regarding the commenters' request to
retain the existing RICE MACT definition, EPA believes that keeping the
proposed definition is appropriate for the most part. EPA recognizes
that the existing definition was based on input and review from
industry, and EPA is not ignoring the products of the ICCR process nor
the extensive participation and commitment of industry members.
However, EPA has learned a lot since the ICCR process from 10 years ago
and knows now that there are health consequences for failing to
regulate emergency engines and for having a broad definition that
allows engines that are used for more than emergencies to emit at
higher levels. EPA feels the existing RICE MACT definition of emergency
engines was not given appropriate restrictions and would
unintentionally allow significant operation of an engine in non-
emergency situations such as the unlimited maintenance allowance.
    Based on vast information received since the time of the ICCR
process and the RICE MACT rulemaking, EPA has concluded that it is
appropriate to limit the hours of operation during maintenance and
testing to 100 hours per year. The issue of allowable hours for
maintenance and testing was discussed extensively under the CI NSPS
rulemaking and more information can be found in the final CI NSPS rule
(71 FR 39153) and Responses to Comments (RTC) document (see EPA-HQ-OAR-
2005-0029-0324). EPA recognizes that the existing RICE MACT places no
restriction on the use of emergency engines in emergency situations and
for routine maintenance and testing. EPA agrees that is appropriate to
retain a no time limit on the use of emergency stationary engines in
emergency situations; however, does not agree that routine maintenance
and testing should be unlimited. Again, EPA has gained much information
regarding emergency engine operation since the ICCR process a decade
ago and must consider environmental and health consequences for failing
to regulate the operation of emergency engines appropriately and
prevent loop-holes. Numerous comments received during the public
comment period for NSPS for stationary CI engines argued that EPA
should allow 100 hours per year for emergency engines to conduct
necessary maintenance and testing. Based on those comments, EPA
continues to believe that it is appropriate to finalize a 100 hours per
year limit for maintenance and testing operation for emergency engines
under the NSPS. EPA disagrees that maintenance and testing should be
unrestricted. However, EPA believes it is crucial to allow sufficient
hours for maintenance and readiness testing to ensure that the
emergency engine will respond as expected in the event of an emergency,
and EPA believes that 100 hours per year is adequate.
    The commenters expressed particular concern over the elimination of
the additional 50 hours per year for non-emergency situations included
in the original RICE MACT emergency engine definition, but excluded
from the proposed requirements affecting emergency engines in this rule
and EPA understands the commenters' concerns. It is true that in the
preamble to the proposed rule, EPA confused the existing 50 hours per
year currently allowed for non-emergency operation in the RICE MACT
with the 100 hours per year for maintenance and readiness checks, and
may be, as the commenters indicated, a result of comparing the SI NSPS
too closely to the CI NSPS that was recently promulgated. Industry has
expressed that it might be forced to use portable emergency engines
instead of stationary emergency engines to avoid certain requirements
of the rule and indicated that the portable engines will be dirtier
than the stationary engines. EPA certainly does not wish to create such
outcome of the rulemaking and therefore believes it is appropriate to
allow owners/operators to operate their engines for 50 hours per year
for non-emergency purposes and has made that clarification in Sec.
60.4243(d) of the final rule. However, EPA is concerned that if
stationary emergency engines are allowed to operate in non-emergency
situations they may be inappropriately used for peaking power. In
response to EPA's concern, industry has noted that its intent is not to
use stationary emergency engines for peaking purposes. Even so, EPA has
specified that the 50 hours allowed for non-emergency situations cannot
be used to generate income for a facility to supply power to an
electric grid or otherwise supply power as part of a financial
arrangement with another entity. If this happens, the engine is no
longer considered to be an emergency engine and the engine would be
required to meet the non-emergency engine emission standards, which are
more stringent. In addition, the allowed 50 hours of operation for non-
emergency situations must be within the currently allowable 100-hour
total for purposes of maintenance and testing. In other words, the
total hours of operation per year cannot exceed 100 hours for purposes
of maintenance and testing and for running the engine for non-emergency
purposes.
    Regarding the requirement to maintain records to ensure the 100-
hour limit is not exceeded for emergency engines as specified in Sec.
60.4245(b) of the proposed rule, EPA feels this requirement is
necessary and appropriate. This requirement is consistent with the
final CI NSPS (see 40 CFR 60.4214(b)). To ensure compliance with the
100-hour limit, EPA must require recordkeeping for all operation of
emergency engines, emergency situations as well as required testing.
This is a reasonable way to enforce this limit to ensure that the non-
emergency hours of operation are not exceeded beyond allowable limits.
Clearly, this requirement yields environmental benefits since it will
limit the likelihood that sources subject to the rule that operate
emergency engines would exceed the 100-hour annual non-emergency limit.
As noted in the RTC document for the final CI NSPS, 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.
Also, certain facilities already maintain such documentation, e.g.,
operating hours and operating conditions are currently maintained at
hospitals. EPA wishes to prevent owners/operators from operating
emergency engines illegally and circumventing the regulation and
believes the additional recordkeeping requirements will greatly enhance
EPA's ability to enforce this requirement. The

requirement 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. As noted, owners/operators of emergency engines
already keep documentation of when and why such engines were operated
so EPA feels the recordkeeping requirement is no significant additional
burden.
    However, EPA does believe it is necessary to clarify that emergency
engines above 500 HP at major sources that were installed prior to the
proposal date for this rule (June 12, 2006), but after the proposal
date (December 19, 2002) for the previous RICE MACT (and thus, new
emergency engines under 40 CFR part 63, subpart ZZZZ, and subject to
the old rule) should be governed by the old definition of emergency
engines, except that the definition includes the clarification that
emergency engines do not include engines used for peaking power or to
supply power to an electric grid or otherwise supply power as part of a
financial arrangement with another entity. This clarification has been
made to the definition of emergency stationary RICE in section 63.6675
of the final rule. EPA believes this clarification addresses some of
the commenters' concerns on this issue.
    Comment: One commenter stated that by reducing the scope of engines
that qualify as ``emergency engines,'' the proposed revision could
expand the universe of engines that are subject to more stringent
NESHAP requirements. Commenter 145 believes that its member utilities
would be directly affected, since they deploy emergency engines to
support their obligation to deliver energy to customers safely and
reliably. In addition, this revision would impact utility customers who
deploy emergency engines, such as hospitals and nursing homes, since
there is no minimal size threshold on the engines affected by the
proposal.
    Response: EPA disagrees that the rule necessarily expands the
universe of engines that are subject to the standards applicable to
non-emergency engines. Operation of engines during emergencies is not
restricted by the rule and if an engine is truly an emergency engine,
it would not be subject to more stringent requirements. Available
information indicates that emergency engines operate on average about
50 hours per year, which includes the hours spent for maintenance and
testing purposes. EPA recognizes that there may be stationary emergency
engine applications that operate beyond 50 hours per year for
maintenance and testing purposes, which is why EPA proposed a 100-hour
allowance for such purposes. EPA received numerous comments on the
testing and maintenance allowance on the proposed CI NSPS. Based on the
number of commenters who indicated that the proposed maintenance and
testing allowance of 30 hours per year was not enough, EPA chose to
increase the number to 100 hours per year, which was consistent with
what commenters recommended. Even though the original RICE NESHAP
covering stationary engines greater than 500 HP located at major
sources did not have a time limit on the use of emergency stationary
engines for routine testing and maintenance, EPA believes that
providing 100 hours per year is more than sufficient. In those few
cases where 100 hours is not sufficient, EPA has included the provision
allowing owners/operators to petition for additional hours (unless the
owner/operator maintains records indicating that Federal, State, or
local standards require maintenance and testing of emergency ICE beyond
100 hours per year, in which case, a petition is not necessary.) Note,
however, that in the final rule, EPA has made it clear that ``new''
engines affected by the NESHAP that are installed prior to the proposal
of the NSPS would be covered by the old definition included in the
original NESHAP at 40 CFR part 63, subpart ZZZZ. In addition, EPA has
specified that 50 of the 100 hours allowed for maintenance and testing
can be use for non-emergency purposes.

E. Manufacturer O&M Requirements

    Comment: Several commenters expressed concern over the proposed
requirements requiring owners/operators to operate and maintain SI ICE
according to the manufacturer's written instructions or procedures
developed by the owners/operators that are approved by the engine
manufacturer. One commenter believes that compliance requirements
should reflect best practices developed by the owners/operators with
experience with using the engines in the field. Another commenter felt
that the manufacturers do not have the long-term experience in
operating and maintaining these engines in the field and recommended
that the proposed NESHAP allow owners/operators to use the existing
maintenance requirements of the General Provisions of both the NSPS (40
CFR part 60, subpart A) and the NESHAP (40 CFR part 63, subpart A)
rules to meet the requirements of this rule.
    One commenter recommended for voluntarily certified engines, the
owners/operators be given a choice of either accepting the
manufacturers certification or opting for a ``verification program''
modeled after the performance testing of Sec.  60.4243(d)(2) of the
proposal.
    One commenter expressed that it is in general agreement that
owners/operators should maintain their SI ICE in accordance to the
original manufacturer's specifications for larger engines. However, the
commenter had concerns about imposing these requirements on limited use
and small engines. The commenter believes that this requirement does
not appear to be commensurate with the environmental impact.
    One commenter expressed that the operation and maintenance (O&M)
requirements in manufacturer's manuals is too stringent and inflexible
and needs to be changed and stated that engine manufacturers do not
want to become involved in approving or reviewing procedures developed
by owners/operators. The commenter added that in many cases, owners/
operators of stationary engines have developed and follow their own O&M
procedures and have extensive experience in operating their engines to
optimize performance and life in their specific applications within
regulatory emissions limits. Further, the commenter said, owners/
operators of non-certified engines are required to conduct performance
testing to assure compliance. Therefore, since these owners/operators
will use other means to assure compliance, there should not be a
regulatory requirement to follow manufacturer's procedures, the
commenter expressed. However, if EPA includes the requirement to follow
engine manufacturer's procedures in the final rule, the referenced
procedures should be limited to those required to maintain emissions
control, the commenter said, and recommended that EPA develop a suite
of options and requirements to assure compliance as follows:
     For certified engines, owners/operators should be required
to set up the engine and follow manufacturers' recommended maintenance,
but only for systems or components that affect emissions.
     For non-certified engines, appropriate emissions testing
and monitoring should be all that is required.
     In addition, owners/operators should be able to purchase a
certified

engine but operate it according to their own procedures. In that case,
appropriate emissions testing and monitoring should be all that is
required.
    One commenter's objection to the proposed requirement to follow the
manufacturer's procedures was based on the assertion that most
operators of these engines have developed proprietary procedures for
their engines, varying from region to region and across the broad
spectrum of applications of these engines; that reviewing procedures
would subject engine manufacturers to an administrative burden. This
requirement is unnecessary, the commenter noted, because owners/
operators bear responsibility for compliance, and are already required
to demonstrate such compliance through extensive testing.
    Two commenters requested that EPA allow owners/operators to define
O&M requirements for gas-fired engines, rather than the manufacturer
O&M. These two commenters stated that owners/operators have developed
and refined O&M practices to address the specific challenges, rigor,
and accessibility of their application. However, if EPA chooses to
mandate manufacturer O&M, then the commenters requested that the
manufacturers be required to reasonably review and approve
alternatives, and the cost of the program be borne by the manufacturer.
One commenter stated that allowing owners/operators to follow their own
O&M procedures is consistent with the requirements of the subpart A
General Provisions. The commenter stated that the EPA should clearly
indicate that owners/operators of gas-fired engines can choose
compliance monitoring based on owners/operators defined O&M and
periodic tests even if a certified engine is available.
    Response: EPA agrees with some of the comments received on the
issue of operating the engine according to manufacturer O&M procedures.
EPA agrees that any requirement to operate and maintain engines
according to manufacturer instructions should be limited to emission-
related operation and maintenance. In addition, in the final rule, EPA
has not included the requirement for owners/operators of non-certified
engines to operate and maintain their engines according to the
manufacturer's written instructions or procedures developed by the
owners/operators that are approved by the engine manufacturer. Instead,
owners/operators will be required to operate and maintain their engines
in a proper manner, consistent with their own maintenance plan. Owners
and operators of non-certified engines will be required to keep records
of the maintenance performed on the engine. In addition, EPA is
requiring performance testing of non-certified engines to demonstrate
compliance with the emission standards, consistent with the proposal.
    Based on information received during the final rulemaking and in
public comments, EPA does not believe it is appropriate to require
manufacturer O&M procedures for all owners/operators of certified
engines without allowing alternative procedures and is therefore
providing an alternative option to owners/operators. However, if an
owner/operator has a certified engine that it wishes to operate
according to its own well-established procedures based on its own
experience with operating that engine (or engines), that particular
engine that was originally certified will no longer be considered
certified and the engine must be tested. EPA will consider that engine
to be operating in a non-certified manner, and will require testing if
the engine is greater than or equal to 100 HP. Engines below 100 HP
operating in a non-certified manner will be exempt from performance
testing, but are required to keep a maintenance plan and records. EPA
wishes to encourage the certified route for smaller engines and expects
that the majority of engines in this size group will be certified.
Engines greater than or equal to 100 HP and less than or equal to 500