[Federal Register: January 18, 2008 (Volume 73, Number 13)]
[Rules and Regulations]               
[Page 3567-3614]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr18ja08-10]                         


[[Page 3567]]

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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


[[Page 3568]]


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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 (202) 566-1742.

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

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:

[[Page 3569]]



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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

[[Page 3570]]

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

[[Page 3571]]

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)

[[Page 3572]]


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.

[[Page 3573]]

    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.

[[Page 3574]]

    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

[[Page 3575]]

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

[[Page 3576]]

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

[[Page 3577]]

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.

[[Page 3578]]

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

[[Page 3579]]

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

[[Page 3580]]

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.

[[Page 3581]]

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

[[Page 3582]]

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

[[Page 3583]]

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

[[Page 3584]]

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

[[Page 3585]]

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 the