AUTHORIZATION REQUEST SUPPORT DOCUMENT 

CALIFORNIA’S REQUEST FOR A CLEAN AIR ACT SECTION 209(e) 

AUTHORIZATION FOR THE AIRBORNE TOXIC CONTROL MEASURE FOR 

PORTABLE DIESEL ENGINES 50 HORSEPOWER AND GREATER 

December 2006 

I. INTRODUCTION 

In this proceeding, the California Air Resources Board (CARB or the Board) is 

requesting pursuant to Clean Air Act (CAA) section 209(e)(2) that the Administrator of 

the U.S. Environmental Protection Agency (U.S. EPA) authorize California to adopt and 

enforce the CARB airborne toxic control measure (ATCM) for in-use portable dieselfueled engines 50 brake horsepower (hp) and greater (portable engines). This request 

covers the following four primary substantive requirements of the regulation: 

1. Starting January 1, 2010, all portable engines in the State must be 

certified to meet a federal or California standard for newly manufactured 

nonroad1 engines, subject to specified exceptions; 

2. Starting January 1, 2020, all portable engines in the State must be either 

(a) certified to meet Tier 4 emission standards, (b) equipped with a 

properly functioning Level-3 verified technology, or (c) equipped with a 

combination of control strategies that have been verified together to 

achieve at least an 85 percent reduction in diesel particulate matter (PM) 

emissions, subject to specified exceptions; 

3. All portable engines that, prior to January 1, 2006, have not been either 

registered in CARB’s Portable Equipment Registration Program 

(Statewide Program or PERP) or permitted under the permit program of 

an air quality management district or air pollution control district (local air 

district) must meet the most stringent of the federal or California emission 

standards for nonroad engines, subject to specified exceptions; 

4. Each fleet of portable engines must comply with increasingly more 

stringent weighted PM emission fleet averages that apply starting 

January 1, 2013, January 1, 2017, and January 1, 2020, subject to 

specified exceptions. 

Clean Air Act preemption of state regulations concerning nonroad engines is governed 

by CAA section 209(e). In Engine Manufacturers Association, et al. v. Environmental 

Protection Agency (EMA v. EPA), 88 F.3d 1075, 1093-94. (D.C. Cir. 1996), the Court 

 

1

 CARB has, at times, used the term “off-road” to describe nonroad mobile sources. For purposes of this 

request, nonroad refers to both nonroad and off-road engines. 

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held that the implied preemption resulting from CAA section 209(e)(2) covers state 

standards and other requirements pertaining to in-use as well as new nonroad engines, 

but does not extend to restrictions on the operational use of nonroad engines. The four 

requirements of CARB’s portable engine ATCM listed above constitute standards for 

in-use nonroad engines and accordingly are covered by the implied preemption of 

section 209(e)(2). A fifth substantive requirement of the regulation pertains to the fuels 

that may be used in in-use portable diesel-fueled engines in California. (§ 93116.3(a), 

title 17, California Code of Regulations (CCR).) This requirement is not preempted by 

CAA section 209(e) (Appendix A to Subpart A of 40 CFR Part 89; see also 69 F.R. 

38958, 39072-3 (June 29, 2004) (CAA § 211(c)(4)(A) does not preempt state regulation 

of fuels used in locomotives, and implicitly such regulation is not covered by § 209(e)). 

CARB accordingly is seeking an authorization for all elements of the regulation except 

for the fuels requirement. By its terms, the portable engine regulation does not apply to 

any preempted engine categories covered by CAA section 209(e)(1). (§ 93316.1(b)(6), 

title 17, CCR.) 

II. PROCEDURAL HISTORY 

The eleven-member Board considered the proposed Portable Diesel-Fueled Engine 

regulation at a February 26, 2004, public hearing. At the conclusion of the hearing, the 

Board adopted Resolution 04-7 (Tab 1), in which it directed the Executive Officer to 

adopt new sections 93116-93116.5, title 17, CCR, with specified modifications approved 

by the Board and such other conforming modifications as may be appropriate, after 

making the modified regulatory language available for public comment for a period of 

15 days.2 The Board directed the Executive Officer to consider such written comments 

as may be submitted during the supplemental comment period, make further 

modifications as may be appropriate in light of the comments received or as necessary 

to ensure consistency with the modifications approved by the Board, and bring any 

proposed changes to the Board for further consideration if the Executive Officer 

believes that it is warranted. The Executive Officer subsequently made the modified 

regulatory text available for a supplemental comment period ending June 1, 2004. After 

considering the supplemental comments, the Executive Officer issued Executive Order 

G-04-080 on December 23, 2004 (Tab 2), adopting the ATCM, which was then 

submitted to California’s Office of Administrative Law (OAL) on January 4, 2005. OAL 

approved the ATCM on February 9, 2005 (Tab 3), and it became operative March 11, 

2005. 

III. THE PORTABLE ENGINE ATCM 

A. Background 

California Health and Safety Code (HSC) sections 39600 (General Powers) and 39601 

(Standards, Definitions, Rules, and Measures) confer on CARB the general authority to 

 

2

 Under California law, an agency may not adopt a regulation that reflects other than nonsubstantial 

modifications to the originally proposed text unless the modified text is made available for a supplemental 

comment period of 15 days or more. (Cal. Government Code § 11346.8(c).) 

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adopt rules and measures necessary to execute the Board's powers and duties 

imposed by State law. More specifically, California's Air Toxics Program, established 

under California law by Assembly Bill (AB) 1807 (Stats. 1983, Ch. 1047), and set forth in 

HSC sections 39650 through 39675, mandates the identification and control of air toxics 

in California. The identification phase of the Air Toxics Program requires the ARB, with 

participation of other state agencies, such as the Office of Environmental Health Hazard 

Assessment (OEHHA), to evaluate the health impacts of and exposure to substances 

and to identify those substances that pose the greatest health threat as toxic air 

contaminants (TACs). CARB's evaluation is made available to the public and is formally 

reviewed by the Scientific Review Panel (SRP), established under HSC section 39670. 

Following CARB's evaluation and the SRP's review, the Board may formally identify a 

TAC at a public hearing. Following the identification of a substance as a TAC, 

HSC sections 39658 and 39665 require CARB, with the participation of the local air 

districts, and in consultation with affected sources and interested parties, to prepare a 

report on the need and appropriate degree of regulation for that substance (risk 

management phase). 

In August 1998, the Board identified diesel PM as a TAC, and in September 2000, 

CARB adopted the "Risk Reduction Plan to Reduce Particulate Matter Emissions from 

Diesel-fueled Engines and Vehicles" (Diesel Risk Reduction Plan). The Diesel Risk 

Reduction Plan was the first formal product of the risk management phase and serves 

as the needs assessment under the AB 1807 process. In the Diesel Risk Reduction 

Plan, CARB identified the available options to reduce diesel PM and the recommended 

control measures to achieve reductions, including a measure to reduce diesel PM from 

diesel-fueled portable engines. The ultimate goal of the Diesel Risk Reduction Plan is 

to reduce California’s diesel PM emissions and associated cancer risks by 85 percent 

by 2020. 

In 1999, the Legislature amended California’s Air Toxics Program (Senate Bill 25 (Stats. 

1999, Ch. 731)) to require further consideration of health impacts to infants and 

children. As amended, OEHHA was required to identify up to five TACs that make 

children especially susceptible to illness. OEHHA published the "Prioritization of Toxic 

Air Contaminants under the Children's Environmental Health Protection Act" in 

October 2001, identifying diesel PM as one of the five TACs. Additional requirements 

established by Senate Bill 25 in HSC section 39669.5 direct CARB to adopt ATCMs, as 

appropriate, to protect public health, particularly infants and children, from these 

specially identified TACs. 

Diesel exhaust is a complex mixture of thousands of gases and fine particles that 

contains more than 40 identified toxic air contaminants. These include many known or 

suspected cancer-causing substances, such as benzene, arsenic, and formaldehyde. 

Diesel exhaust can irritate the eyes, nose, throat, and lungs and can cause coughing, 

headaches, light-headedness and nausea. Diesel exhaust is a major source of ambient 

particulate matter pollution as well, and numerous studies have linked elevated particle 

levels in the air to increased hospital admission, emergency room visits, asthma 

attacks, and premature deaths among those suffering from respiratory problems. 

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The ATCM for portable diesel fueled engines that is the subject of this authorization 

request fulfills the goals of the Diesel Risk Reduction Plan to reduce diesel PM 

emissions and associated risk from the use of diesel-fueled portable engines in 

California. CARB estimates that the ATCM, when fully implemented in 2020, will reduce 

diesel PM emissions from portable engines by 95 percent from year 2000 emission 

levels. Diesel PM emissions are estimated to be responsible for about 70 percent of the 

total cancer risk from inhalation in California 

B. Summary of Requirements 

The ATCM affects all diesel-fueled portable3 engines that are 50 hp and greater. This 

includes all engines that are subject to local air district permits as well as, with several 

exceptions, those engines that have been exempt to date from district permitting 

requirements. The ATCM will reduce emissions of diesel PM by first requiring all 

portable engines to be certified to Tier 1, 2, or 3 U.S. EPA /CARB off-road engine 

standards by January 1, 2010.4

 All portable engines that have not been registered or 

permitted in state or local air district programs prior to January 1, 2006 must meet the 

new engine certification standards at the time of application for registration or a permit. 

All portable engines that have been registered or permitted before January 1, 2006 

have until January 1, 2010 to come into compliance. After 2010, the ATCM further 

requires all fleets (as defined by the regulation and discussed below in section II.C.5.) of 

portable engines to meet diesel PM emission fleet average standards that become 

increasingly more stringent in 2013, 2017, and 2020. Owners/operators of these fleets 

will have flexibility in determining how the fleet emission standards are to be satisfied. 

Options that are available to satisfy these standards include: purchasing new equipment 

with cleaner engines, repowering existing equipment with cleaner engines , using 

verified add-on control devices on existing equipment and engines, switching to 

alternative diesel fuels or alternative fuels, or electrifying some or all of the fleet and 

receiving emission credits. 

To meet the diesel PM standard for 2020, all engines in a fleet must either: a) be 

certified to U.S. EPA Tier 4 newly manufactured off-road engine emission standards; or 

b) be equipped with a Level-3 PM control technology; or c) be a certified engine 

equipped with a combination of verified control technologies that achieve an emission of 

0.04 g/bhp-hr for engines that are less than 175 horsepower or 0.02 g/bhp-hr for 

engines that are 175 horsepower and larger. Level-3 PM control technology refers to a 

control technology that has been verified to achieve PM reductions of at least 

85 percent under ARB’s Verification Procedure, Warranty and In-Use Compliance 

 

3 Portable engines are engines that may be moved easily from location to location. The engines are used 

to power a variety of equipment, including pumps, ground support equipment at airports, cranes, oil-well 

drilling and workover rigs, power generators, dredging equipment, rock crushing and screening 

equipment, welding equipment, woodchippers, and compressors. (§ 93116.2(bb), title 17, CCR.)

4

 Control of Emissions of Air Pollution from Nonroad Diesel Engines and Fuel; Final Rule, Vol. 69, No. 

124 Fed.Reg. 38957-39273 (June 29, 2004); Amendments to the California Exhaust Emission Standards 

and Test Procedures for New 2008 and Later Tier 4 Off-Road Compression-Ignition Engines and 

Equipment, title 13, CCR, sections 2420 et seq. 

4
Requirements for In-Use Strategies to Control Emission from Diesel Engines 5

(Verification Program). 

C. Detailed Description of the Portable Engine ATCM 

1. Applicability 

As stated, the ATCM applies to all diesel-fueled portable engines 50 hp and greater. As 

defined by the ATCM, to be portable, the engine must not reside at any one location for 

more than 12 consecutive months. A location is any place of operation or single site at 

a building, structure, facility, installation, or well site. An engine that remains at one 

location for more than 12 consecutive months would be considered a stationary engine. 

2. Exemptions

There are certain types of diesel-fueled engines that are exempt from the ATCM. The 

exemptions are as follows: 

Engines Used In Mobile Applications 

Engines used to propel mobile equipment and motor vehicles are not regulated by the 

ATCM. These engines include dual-use engines that both propel the equipment and 

operate the attached equipment. Examples of a dual-use engine include cranes and 

cherry pickers. Power Take-Off (PTO) applications are also not subject to the ATCM. 

PTO refers to a piece of equipment attached to a motor vehicle that is powered by the 

same engine that is used to propel the vehicle. An example would be a welder on a 

utility truck that is powered by the truck’s engine. 

Dual-Fuel Diesel Pilot Engines 

Dual-fuel diesel pilot engines that use alternative fuel or alternative diesel fuel are not 

subject to the ATCM. These engines use a small amount of diesel fuel, typically less 

than 5% of the total fuel used by the engine, and therefore the emissions of diesel PM 

are only a small portion of the engine's total emissions. 

Military Tactical Support Equipment (TSE) 

TSE is also not covered by the ATCM. TSE refers to portable equipment that is owned 

by the United States Department of Defense and its allies and used in combat, combat 

support, tactical or relief operations, or training for such operations. HSC section 41754 

specifically exempts TSE from control technology requirements and in-use operational 

controls. Portable diesel-fueled engines that are not considered TSE at military 

installations in California are subject to the ATCM. 

 

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 Approved by the Board in May 2002. Sections 2700-2710, title 13, CCR. 

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Ground Support Equipment (GSE) 

GSE refers to mobile and portable equipment used to support the operation of an 

airport. Portable equipment typically represents just a small fraction (10 - 15 percent) 

of the total ground support equipment at an airport. This equipment includes ground 

power units, air conditioners, and start-carts. 

To address emissions from GSE in the South Coast Air Quality Management District 

(SCAQMD), CARB, SCAQMD, and the major air carriers at the five major airports within 

the District recently signed a Memorandum of Understanding (MOU) which requires the 

air carriers to reduce the emissions of diesel PM and ozone precursors from their GSE 

fleets over a specific timetable. In recognizing the commitments made by the air 

carriers under the MOU, CARB has provided in the ATCM that if the airports are able to 

achieve equivalent or greater overall PM reductions under the MOU, portable 

equipment subject to the MOU would be exempted from the ATCM. It is CARB’s 

position that should similar MOUs be executed at other major airports across the State, 

the portable equipment portion of the affected GSE would also qualify for exemption 

from the ATCM. 

Other Categories 

Portable engines that use an alternative fuel -- such as natural gas, propane, butane, 

and gasoline – are not subject to the ATCM, as it only applies to portable engines that 

are fueled with diesel. Portable engines used at San Clemente or San Nicolas Island 

are also not subject to the requirements of the ATCM. This exemption is consistent with 

the SCAQMD and Ventura County Air Pollution Control District internal combustion 

engine regulations, which exempt engines on these islands from their permitting 

requirements. 

3. Fuel Requirements for Diesel-Fueled Portable Engines

The ATCM requires portable engines to use CARB diesel fuel. The regulations for 

CARB diesel fuel were recently revised to limit the sulfur content of diesel fuel to 

15 parts per million (ppm).6

 The revised CARB diesel fuel regulations, which require 

the widespread availability of low-sulfur diesel fuel by mid-summer 2006, will help 

promote the use of diesel particulate filters, the most efficient diesel PM control devices. 

The revised fuel regulation allows mixtures of up to 50 percent biodiesel or 100 percent 

Fischer-Tropsch fuels to qualify as CARB diesel fuel as long as specific requirements 

are satisfied. While the use of biodiesel or Fischer-Tropsch fuels have been shown to 

reduce diesel PM, they have, to date, not been verified by CARB for use as a PM 

control technology. 

 

6

 Approved by the Board in July 2003. Revisions to section 2281, Title 13, California Code of 

Regulations. 

6
The requirements for verification differ depending on whether the fuel is treated as an 

alternative diesel fuel or as a specific additive, which would be considered a control 

technology. If the additive is supplied to the engine fuel by an on-board dosing 

mechanism, is directly mixed into the fuel, or is added to the fuel at the time of refueling, 

then the additive is considered a control technology, not an alternative diesel fuel. 

As noted above, these fuel provisions are not preempted by CAA section 209(e) and 

CARB accordingly is not seeking a section 209(e)(2) authorization for them. 

4. Requirements for Individual Portable Engines

The ATCM requires all portable diesel-fueled engines in California to be certified to 

CARB or U.S. EPA emission standards for newly manufactured off-road engines by 

January 1, 2010. Starting January 1, 2006, the ATCM requires all portable diesel-fueled 

engines initially registering or applying for permits from CARB or local air districts, 

respectively, to be certified to the most stringent of the federal or California emission 

standards for nonroad engines. On or after January 1, 2010, all portable diesel-fueled 

engines operating in the state – whether or not registered or permitted – must be 

certified to the California or federal Tier 1, 2 or 3 off-road emission standard. About 

20,000 preexisting engines will need to be replaced. 

Recognizing that some portable engines operate only on a limited annual basis, the 

ATCM includes n exception to the 2010 requirement for portable engines that are used 

strictly for emergency purposes or are low-use engines that operate 80 hours or less in 

a calendar year, including time for maintenance and testing. These engines are exempt 

from the 2010 requirements if the fleet owner commits to replacing the engines with 

engines certified to Tier 4 standards within two years of Tier 4 engines becoming 

available. If the fleet owner does not agree to early replacement of these engines, the 

portable engines would not be exempt from the ATCM and must be replaced with 

engines certified to existing emission standards by January 1, 2010. 

By requiring engine replacement by January 1, 2010, the ATCM uses present 

technology or technology that will be available in the next few years to reduce diesel PM 

in the near term. Verified add-on technologies are not yet available for most off-road 

diesel engines, and Tier 4 engines will, in general, not be available until 2011. Setting 

an engine replacement schedule that would take effect significantly before 2010 would 

be less effective in the long run, as many of the cleaner Tier 3 engines only become 

commercially available in the 2006-2008 timeframe. Staff believes that requiring the 

engines to be replaced by 2010 will allow engine manufacturers sufficient time to satisfy 

the demand caused by the ATCM’s 2010 requirement. 

5. Fleet Average Requirements

After 2010, owners of fleets of portable engines must satisfy progressively more 

stringent diesel PM emission fleet emission standards by January 1, 2013, 2017, and 

2020. The purpose of the diesel PM fleet emission standards is to create additional 

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diesel PM emission reductions beyond those that would be achieved from normal 

engine turnover after 2010. 

Definition of Fleet

A fleet includes portable engines registered with ARB’s Statewide Program, permitted 

with local air districts, and those that have been previously exempt from district permit 

requirements. The fleet definition excludes portable engines that operate exclusively 

outside of California, engines operated only within the Outer Continental Shelf (OCS), 

engines used exclusively in emergency applications, and engines qualifying as low-use. 

Portable engines can also be exempt from the fleet requirements if equipped, as of 

January 1, 2004, with a properly operating selective catalytic reduction (SCR) system. 

A fleet is defined in the ATCM as an engine or group of engines either under the same 

ownership or owned by entities under the control of a “Responsible Official” – an 

individual who has the authority to certify that portable engines under his/her control 

comply with the applicable requirements of the ATCM, has authority to manage the use 

of the portable equipment, and may be involved in the purchase of the equipment. 

A company or public agency can have more than one fleet if each fleet is under the 

control of a different Responsible Official. For example, companies owned by the same 

holding company could be considered to have separate fleets if each fleet's operation 

and composition are controlled by separate Responsible Officials. In the case of 

military installations, each installation is considered a separate fleet instead of one fleet 

under the control of the Department of Defense. Conversely, if several companies were 

under the common control of one Responsible Official, then all the portable engines of 

the companies would be considered one fleet. 

Fleet Diesel PM Standards 

The ATCM addresses diesel PM standards for three ranges of engine sizes: engines 

less than 175 hp, engines between 175 hp and 749 hp, and engines greater than or 

equal to 750 hp. The fleet diesel PM standards (grams per brake horsepower-hour 

(g/bhp-hr)) are illustrated below: 

Fleet Standard 

Compliance 

Date 

 Engines 

<175 hp 

(g/bhp-hr) 

Engines 

 >175 to 749 hp 

(g/bhp-hr) 

Engines 

 > 750 hp 

(g/bhp-hr) 

/1/2013 0.3 0.15 0.25 

/1/2017 0.18 0.08 0.08 

/1/2020 0.04 0.02 0.02 

The three sets of fleet diesel PM standards for each implementation period reflect the 

differences in engine classification size. Emission standards for certified portable 

engines less than 175 hp are less stringent than the standards for the larger classes of 

engines. A separate fleet standard for engines greater than or equal to 750 hp was 

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created because these large engines are expensive to replace and have a much longer 

useful life than engines that fall between 175 hp and 749 hp. These larger engines 

must meet a higher fleet standard in 2013, providing owners more time to replace or 

retrofit these more expensive engines. Starting January 1, 2017, these engines will be 

required to meet the same fleet standard as engines between 175 hp and 749 hp. 

The fleet emission standards take into account the potential commercial availability of 

Tier 4 engines, which should become available in the 2011-2014 timeframe. They also 

take into account the future availability of verified Level-3 PM control technologies. The 

2013 fleet average emission standards are intended to force replacement of Tier 1 

engines <750 hp with either Tier 3 or Tier 4 engines. The PM standard for Tier 3 and 

Tier 4 off-road engines are significantly lower than the Tier 1 engine PM standard. At 

this time, most Tier 1 engines being replaced would have been operated 10 to 17 years. 

The CARB staff believes that the 2013 fleet average standards will likely not affect 

owners who had replaced uncertified engines with Tier 2 or Tier 3 engines prior to 2010. 

The 2017 standards are likely to result in half of the engines in a fleet being replaced 

with engines certified to Tier 4 standards or equipped with Level-3 control technology or 

a combination of verified control technologies to achieve an 85 percent reduction in 

diesel PM emissions. By this time, the affected engines would have operated between 

6 to 17 years. The 2020 standards are likely to result in all engines in the fleet being 

certified to Tier 4 standards or equipped with Level-3 verified technology or a 

combination of verified control technologies to achieve 85 percent diesel PM emission 

reduction. 

Weighted Fleet Average 

Owners of portable engine fleets will determine compliance with the fleet standard by 

comparing the fleet's actual weighted diesel PM emission rate with the fleet average 

emission standard. The fleet's actual weighted emission rate shall be determined by 

using the following formula: 

∑ Summation for each engine in the fleet (bhp x emission factor)

∑Summation for each engine in the fleet (bhp) 

 Where: bhp = horsepower at maximum rated capacity 

 Emission factor = diesel PM emission rate 

For example: A fleet owner has five certified engines with the following horsepower and 

PM emission factors: 

 75 hp emission rate of 0.30 g/bhp-hr 

 75 hp emission rate of 0.30 g/bhp-hr 

100 hp emission rate of 0.22 g/bhp-hr 

150 hp emission rate of 0.22 g/bhp-hr 

150 hp emission rate of 0.22 g/bhp-hr 

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 (75 X 0.30) + (75 X 0.30) +(100 X 0.22) + (150 X 0.22) + (150 X 0.22) 

75 + 75 + 100 + 150 + 150 

 Fleet’s weighted diesel PM emission rate = 0.24 g/bhp-hr 

These emission factors can be modified using the emissions reductions for the control 

technologies that have been verified through the CARB Verification Program. For 

example, if an engine owner installs a diesel particulate filter that has been verified to an 

85 percent control effectiveness, the engine’s emission factor would be the certified 

value multiplied by 0.15. 

Emergency and Low-Use Engines 

Portable engines that are used exclusively in emergency applications or are deemed 

low-use engines are not subject to the fleet emission standards of the ATCM. These 

engines would be required, by January 1, 2020, to: 1) be replaced with portable engines 

certified to the Tier 4 newly manufactured nonroad engine emission standards, 2) be 

equipped with a Level-3 PM control technology, or 3) be equipped with a combination of 

verified control technologies to achieve diesel PM emissions of 0.04 g/bhp-hr for 

engines <175 hp or 0.02 g/bhp-hr for engines that are >175 hp. The ATCM delayed 

compliance for these engines until January 1, 2020, because these engines emit less 

than one percent of the total diesel PM emissions from portable engines and requiring 

these engines to meet the interim fleet averages would not be cost-effective. 

Engines Equipped with Selective Catalytic Reduction (SCR) 

Portable engines may be exempt from the fleet requirements if equipped, as of 

January 1, 2004, with a properly operating SCR system. Source test results have 

shown that an SCR system, typically used to reduce oxides of nitrogen (NOx), also 

significantly reduces diesel PM emissions. In addition, the pressure drop requirements 

for engines make it technically challenging today to add additional control technologies, 

such as a diesel particulate filter, to an engine already equipped with SCR. To qualify 

for the exemption, engine owners must submit specific information to the Executive 

Officer indicating that the SCR system is operating properly. 

Owners of portable engines equipped with SCR may alternatively elect to include these 

engines as part of their fleet weighted diesel PM average. Engine-specific source tests 

from these engines must be used to determine diesel PM emission rates. PM 

measurements can be performed using CARB Test Method 5 front-half (filter and probe 

wash) or equivalent district methods. Requiring only the front-half of CARB Test 

Method 5 is consistent with the recommendations of the Test Method Working Group 

that was created during the development of the Stationary Compression Ignition Engine 

ATCM and consistent with test methods used to certify engines to nonroad engine 

standards. The Test Method Working Group was formed to evaluate different test 

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methods for measuring PM from diesel-fueled engines and to recommend the most 

appropriate measuring technique for diesel PM. 

6. Incentives

To encourage the use of cleaner technologies and to encourage repowering or 

replacement of older engines with new, lower-emitting engines, the ATCM provides for 

several incentives to promote these options as part of the fleet reduction approach. 

One incentive allows credit toward satisfying a fleet standard by allowing, under certain 

circumstances, alternative-fueled engines into the fleet. To obtain the credit, the engine 

must operate at least 100 hours annually. 

The ATCM also allows credit for applications where grid power is used in lieu of using a 

portable diesel-fueled engine. The credit is granted where more than 200 hours of grid 

power is used for a given project and the necessary recordkeeping and reporting 

requirements are satisfied. 

Finally, a credit is included to encourage the purchase of engines certified to the Tier 4 

standards. 

The credit can be used when fleet owners purchase Tier 4 engines prior to 

January 1, 2015. In these cases, the owner can count the Tier 4 engine twice in the 

calculations for the fleet weighted diesel PM emission rates. To use the credit for the 

2013 standard, the engine must be in the fleet prior to January 1, 2013. Double 

counting the Tier 4 engines will result in lower fleet weighted diesel PM rates for 

compliance with the 2013 and 2017 diesel PM standards. The double counting of 

Tier 4 engines is not allowed for compliance with the diesel PM standards for 2020 

because all engines must be certified to the Tier 4 standards or retrofitted with verified 

control devices to achieve 85 percent reduction by that date. 

7. Recordkeeping and Reporting Requirements

As discussed below, the ATCM specifies recordkeeping and reporting requirements to 

enhance enforceability. These recordkeeping and reporting requirements may be in 

addition to requirements that are specified in applicable state registration or district 

permitting programs for portable engines. 

The ATCM requires that owners maintain records and report their findings to CARB will 

to ensure the ATCM's enforceability. Recordkeeping and reporting requirements are 

not specified in the ATCM for determining a company’s or agency’s compliance with the 

2010 requirement. CARB believes that compliance with the 2010 requirement can be 

enforced through the existing PERP and district permit programs. 

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Recordkeeping

For many fleets, the required recordkeeping would only consist of keeping track of all 

the engines in the fleet and their associated emission factors. If the fleet's diesel PM 

emission rate average satisfies the 2020 fleet standards, the fleet’s owner would not be 

required to meet the recordkeeping or reporting requirements of the ATCM for individual 

portable engines in the fleet. 

The recordkeeping requirements extend only to those engines in a fleet that have 

minimum or maximum hourly limitations, engines equipped with SCR, and fleets taking 

advantage of the electrification incentive. Engines with hourly limitations include 

alternative-fueled portable engines that are run for at least 100 hours per year, engines 

operating 80 hours or less per year (low-use engines), and engines used exclusively in 

emergency applications in which yearly use is limited. These engines must be 

equipped with non-resettable hour meters, and the operator must maintain records on 

the engines’ annual hours of operation. The ATCM requires the owner/operator to 

maintain the records at a central location for five years. In addition, the owner/operator 

is required to forward copies of records within three business days, if requested by 

either the CARB or local air district staff. 

Recordkeeping requirements are also required if electrification is used to satisfy a fleet 

requirement and for all engines equipped with SCR. If electrification is used to 

determine the fleet average, CARB must be notified in advance of projects that will rely 

on electrification instead of diesel engines. The notification must identify each engine 

that will be affected by the electrification project and shall include information on the 

electrification activity. For engines equipped with SCR, records must be maintained to 

demonstrate that the SCR system is operating properly. The records must be retained 

for five years. In addition, a company is required to forward copies of these records 

within three business days, if requested by either the CARB or local air district staff. 

Status Reports 

The ATCM requires the Responsible Official of the fleet to submit a status report by 

March 1, 2011, and subsequent compliance statements by March 1 of each applicable 

year when a new fleet emission standard becomes effective. 

The purpose of the status report is to provide CARB and local air districts specific 

information on the composition of the fleet. The 2011 status report must include the 

fleet's average diesel PM emission rate for the 2010 calendar year, as well as a 

summary of each engine’s emission rate, in g/bhp-hr. The status report should indicate 

the number of fleet(s) in each company or agency and the Responsible Official in 

charge of each fleet. The status report must also identify whether each engine in each 

fleet within a company or agency is registered with CARB’s PERP program or permitted 

with local air districts. Alternative fueled engines must be identified by fuel type. 

Sufficient information should be provided for each engine to be able to identify the 

engine, including the make, model, serial number, year of manufacture, and local air 

12
district permit or state registration number. Additionally, the status report must identify 

each engine that the owner commits to replacing with an engine certified to the Tier 4 

standards, engines used exclusively in emergency applications, engines satisfying the 

low-use engine requirements, and all necessary documentation to demonstrate that 

engine equipped with SCR are operating properly. 

Compliance Statements 

The Responsible Official must provide a signed statement of compliance indicating the 

applicable fleet emission standard is being achieved and identifying each engine in the 

fleet and the associated emission rate. The statement of compliance is due March 1 of 

the year a new fleet emission standard becomes effective (i.e. 2013, 2017, 2020). 

Compliance is based upon the composition of the fleet as of January 1 of that year. The 

Responsible Official must provide sufficient information for each engine in the fleet to 

allow CARB to properly identify the engine, including the make, model, serial number 

and year of manufacture. The compliance report will have to identify engines used 

exclusively in emergency applications, low-use engines, and engines excluded from the 

fleet because they are operated exclusively outside of California or operated only within 

the OCS. If electrification is used for calculating the fleet average, the Responsible 

Official must provide documentation supporting the credit claimed for electrification. As 

part of the compliance report, the responsible official must also certify the following: 

• All alternative-fueled engines included in the fleet average operated at least 

100 hours in the previous calendar year; 

• engines designated as emergency were only used for emergency applications; 

• engines designated as low-use were operated no more than 80 hours in the 

previous calendar year; and 

• engines equipped with SCR comply with applicable district or statewide registration 

requirements. 

The ATCM allows CARB and local air district staff to require additional information from 

a fleet owner, beyond the submittal of compliance reports, that demonstrates the fleets 

are in compliance with the applicable fleet standards. The fleet owner must provide the 

requested information within 30 days. 

8. Enforcement Requirements

HSC section 39666(d) requires the local air districts to implement and enforce an ATCM 

that has been approved by the Board. Therefore, both CARB and the districts have the 

authority to review or seek enforcement action for violation of the fleet emission 

standards. Despite this overlapping jurisdiction, it is not the intent of the ATCM to place 

engine owners in “double jeopardy.” Appropriate enforcement action will be taken by 

either CARB or the local air districts, as necessary. 

13
D. Air Quality Impacts of the Portable Engine ATCM 

The ATCM will reduce diesel PM emissions and associated exposures from portable 

engines throughout California. The table below provides estimates of diesel PM 

emissions reductions from portable engines resulting from implementation of the ATCM 

in addition to benefits from the PERP. The estimates are based upon reductions from 

the year 2000 base year. California’s air quality will also experience benefits from 

reduced criteria pollutant emissions (e.g. NOx and reactive organic gas (ROG)). The 

table also provides estimates for NOx and ROG reductions. By 2010, diesel PM 

emissions will be reduced by 2.2 TPD, or about 803 TPY, and NOx emissions will be 

reduced by 34 TPD, or about 12,400 TPY. 

Year Diesel PM 

Emissions 

(TPD) 

Percent 

Reduction 

NOx 

Emissions

(TPD) 

Percent 

Reduction

ROG 

Emissions 

(TPD) 

Percent 

Reduction

2000 4.2 -- 67 -- 6.7 -- 

2010 2.0 52% 33 51% 4.6 30% 

2015 1.3 69% 26 61% 2.9 57% 

2020 0.2 95% 23 66% 1.2 78% 

CARB anticipates significant health cost savings due to reduced mortality, incidences of 

cancer, PM-related cardiovascular effects, chronic bronchitis, asthma, and hospital 

admissions from pneumonia and asthma-related conditions. The diesel PM reductions 

are expected to reduce the number of premature deaths in California. Although the 

implementation date for the final diesel PM emission standards in the regulation is 2020, 

CARB believes that the full benefits of the diesel PM standard requirements will extend 

to 2037. (CARB assumed that through a normal engine turnover rate, all portable 

diesel-fueled engines would have been replaced by engines that are certified to Tier 4 

standards by approximately 2037. Therefore, the costs and benefits of the ATCM 

extend to 2037, despite full implementation by 2020.). CARB estimates that by 2037, 

768 premature deaths will be avoided. Prior to 2037, cumulatively, it is estimated that 

50 premature deaths would be avoided by 2010 and 339 by 2020. Additional health 

benefits are expected from the reduction of NOx emissions, which give rise to 

secondary PM from the conversion of NOx to PM2.5 nitrate. CARB has concluded that 

no significant adverse environmental impacts should occur from adoption of, and 

compliance with, the ATCM. 

14
IV. AUTHORIZATION ANALYSIS 

A. Introduction 

Section 209(e)(2) of the CAA sets forth the protocol for granting California authorization 

to adopt and enforce standards and other requirements relating to controlling emissions 

from nonroad engines that are not otherwise specifically preempted from all state 

regulations under section 209(e)(1). Under section 209(e)(2), the Administrator is 

directed to grant the authorization to California if the State has determined that the its 

standards will be, in the aggregate, at least as protective of public health and welfare as 

applicable federal standards, unless he finds that: (1) the protectiveness finding of the 

state is arbitrary and capricious; (2) California does not need separate state standards 

to meet compelling and extraordinary conditions; or (3) the state standards and 

accompanying enforcement procedures are not consistent with section 209 of the CAA. 

In adopting the authorization process of section 209(e)(2), Congress provided California 

with authority to adopt and enforce its own emission standards and regulations for nonpreempted nonroad engines. This authority is similar to that which Congress granted to 

the State in section 209(b) – the right to adopt and enforce independent emission 

standards for motor vehicles. Section 209(e)(2), like section 209(b), requires California 

to obtain the Administrator’s approval (i.e., waiver or authorization). In acting on a 

California request for a waiver under section 209(e)(2), the Administrator must consider 

criteria nearly identical to those considered under section 209(b). In light of these 

almost identical protocols, the U.S. EPA has confirmed that it would similarly interpret 

sections 209(b) and (e) where the language is similar.7 In Resolution 01-23, the Board 

made the determinations that section 209 requires (Tab 1, p. 6), and the Executive 

Officer later affirmed these acts (Tab 2, p. 2). Therefore, authorization must be granted 

unless the Administrator makes one or more of the three findings enumerated in section 

209(e)(2) of the CAA. 

B. The Principles Regarding Consideration of CAA Section 209(b) Waiver 

Requests Should Apply to Section 209(e) Authorization Requests 

In adopting the CAA Amendments of 1990, Congress adopted provisions in section 

209(e)(2) that allow California, upon receiving authorization from the U.S. EPA, to adopt 

and enforce its own standards and other requirements relating to the control of 

emissions for all nonroad vehicles or engines not specifically preempted under section 

209(e)(1). This allowance to California closely parallels the right provided to California 

to adopt separate standards for motor vehicles under section 209(b). Section 209(b), 

like section 209(e), requires California to receive U.S. EPA’s approval for adoption and 

enforcement of separate standards.8

 

7

 Air Pollution Control; Preemption of State Regulation for Nonroad Engine and Vehicle Standards (Final 

209(e) Rule), 59 Fed. Reg. 36969, 36981 (July 20, 1994); see also Utility Authorization, Decision 

Document, at p. 11. 

8

 CARB agrees with U.S. EPA's interpretation of section 209(e) to require California to first adopt its 

regulations before seeking authorization to enforce. This enables U.S. EPA to review final regulations 

15
In light of the similar language of sections 209(b) and (e)(2), CARB believes that the 

U.S. EPA should analyze requests for California authorization under 209(e)(2) using the 

same principles that it has applied in analyzing motor vehicle waiver requests under 

section 209(b). These principles include: (1) U.S. EPA should limit its inquiry to the 

specific criteria identified in section 209(e)(2); (2) U.S. EPA should give substantial 

deference to the policy judgments California has made in adopting its regulations; and 

(3) those parties opposed to the granting of authorization have the burden of persuading 

the Administrator that no basis exists for granting the authorization request. 

1. The Scope of the Authorization Hearing Should Be Limited

The scope of the Administrator’s inquiry in determining whether to deny an authorization 

request is limited by the express terms of section 209(e)(2). In the Final 209(e) Rule, 

U.S. EPA acknowledged that its inquiry would be so limited.9 Thus, once California 

determines that its standards are, in the aggregate, at least as protective of public 

health and welfare as applicable federal standards, the Administrator must grant the 

authorization request unless one of the three specified findings can be made. This 

reading of the statute is consistent with the decision in Motor and Equipment 

Manufacturers Association v. EPA, 627 F.2d 1095 (D.C. Circuit 1979) (MEMA I) and 

with prior U.S. EPA waiver decisions interpreting section 209(b), which hold that the 

review of California’s decision to adopt separate standards is a narrow one.10 As 

Administrator William D. Ruckelshaus stated in a 1971 decision: 

The law makes it clear that the waiver request cannot be denied unless 

the specific findings designated in the statute can properly be made. The 

issue of whether a proposed California requirement is likely to result in 

only marginal improvement in air quality not commensurate with its cost or 

is otherwise an arguably unwise exercise of regulatory power is not legally 

pertinent to my decision under section 209.... 11

2. Deference Should be Given to California’s Policy Judgments

As indicated in the waiver decision quoted above, in granting waivers to California’s 

motor vehicle program, U.S. EPA has routinely deferred to the policy judgments of 

California’s decision makers. U.S. EPA has recognized that the intent of Congress in 

creating a limited review of California’s determinations that California needs its own 

separate standards was to ensure that the federal government not second-guess the 

wisdom of state policy.12 Administrators have recognized that the deference is wideranging: 

 

rather than moving targets. See 40 Code of Federal Regulations (CFR) section 85.1604, and citation to it 

in the Utility Authorization, Decision Document, at p. 46. 9

 Final 209(e) Rule, 59 Fed. Reg. at 36983. 10 See 40 Fed.Reg. 23102, 23103 (May 28, 1975). 11 36 Fed.Reg. 17158 (August 31, 1971). See also 40 Fed.Reg. 23102, 23104; 58 Fed.Reg. 4166 

(January 7, 1993), Decision Document, at p. 20. 

12 40 Fed.Reg. 23102, 23103. 

16
The structure and history of the California waiver provision clearly indicate 

both a Congressional intent and an EPA practice of leaving the decision 

on ambiguous and controversial matters of public policy to California’s 

judgment. 

* * * * * * 

It is worth noting . . . I would feel constrained to approve a California 

approach to the problem which I might also feel unable to adopt at the 

federal level in my own capacity as a regulator. The whole approach of 

the CAA is to force the development of new types of emission control 

technology where that is needed by compelling the industry to “catch up” 

to some degree with newly promulgated standards. Such an approach . . . 

may be attended with costs, in the shape of a reduced product offering, or 

price or fuel economy penalties, and by risks that a wider number of 

vehicle classes may not be able to complete their development work in 

time. Since a balancing of these risks and costs against the potential 

benefits from reduced emissions is a central policy decision for any 

regulatory agency under the statutory scheme outlined above, I believe I 

am required to give very substantial deference to California’s judgments 

on this score.13

In allowing California to adopt its own emission standards for nonroad vehicles and 

engines and by establishing almost identical requirements for U.S. EPA review of 

authorizing requests under section 209(e)(2) as it requires for waiver decisions under 

section 209(b), Congress unmistakably intended that the U.S. EPA accord similar 

deference to California’s decisions under section 209(e)(2).14

3. Burden of Proof Should Be on Those Opposed to the Authorization Request

As stated above, under both sections 209(b) and (e)(2), the Administrator must deny a 

waiver or an authorization if he makes one of the three findings set forth in those 

sections. In interpreting the language of section 209(b), it has been held that the 

burden of proof to show that there is a basis for making one of the three findings is 

squarely on the opponents of a waiver. As the appellate court stated in MEMA I at 

pages 1120-21: 

It is not necessary for the Administrator affirmatively to find that these 

conditions do not exist before granting a waiver. The statute does not say, 

“the Administrator shall grant a waiver only if” he makes the negative of 

these findings. That he must deny a waiver if certain facts exist does not 

 

13 40 Fed.Reg. 23102, 23104 (emphasis added). See also 58 Fed.Reg. 4166, Decision Document, at p. 4. 14 See discussion in Engine Manufacturers Association v. U.S. EPA, 88 F.3d 1075, 1090 (D.C. Cir. 1996) 

(EMA), wherein the court recognized California's leadership in emission control regulation in both new 

motor vehicles and new and in-use nonroad engines. 

17
mean that he must independently proceed to make the opposite of those 

findings before he grants the waiver regardless of the state of the 

record.... The language of the statute and its legislative history indicate 

that California’s regulations, and California’s determination that they 

comply with the statute, when presented to the Administrator are 

presumed to satisfy the waiver requirements and that the burden of 

proving otherwise is on whoever attacks them. California must present its 

regulations and findings at the hearing, and thereafter the parties 

opposing the waiver request bear the burden of persuading the 

Administrator that the waiver request should be denied. 

Given the identical structure and near identical language of sections 209(b) and (e)(2), 

the opponents of an authorization request bear a similar burden of proof when arguing 

that authorization should be denied under section 209(e)(2). The U.S. EPA has so 

stated in all nonroad road authorization decisions to date.15

B. No Basis Exists for the Administrator to Deny This Authorization Request 

1. The Adopted Regulations Are Not Subject to the 50-State Preemption of CAA 

Section 209(e)(1)

Section 209(e)(1) of the CAA preempts all states, including California, from establishing 

emission standards and other emission-related requirements for new engines under 

175 hp used in farm and construction equipment and new locomotives and engines 

used in locomotives. The ATCM does not apply to new locomotive and locomotive 

engines. Moreover, the portable engines subject to the ATCM are engines that are 

used in in-use equipment. To the extent that an owner or operator may elect to replace 

existing equipment with new equipment with new engines or repower existing 

equipment with new engines, the ATCM requires the use of engines meeting federal 

and California certification requirements for new engines.16 Therefore, the ATCM does 

not establish emission standards that are otherwise preempted under CAA section 

2099(e)(1). CARB received no information calling this determination into question. 

Accordingly, no party opposing this authorization can reasonably argue that the ATCM 

establishes new emission standards or other requirement relating to the control of 

emissions for sources preempted under CAA section 209(e)(1). 

2. Protectiveness Determination

U.S. EPA has interpreted the first two criteria for determining nonroad authorization 

requests similarly to how it has interpreted the same criteria in determining waivers 

 

15 OHRV Authorization, Decision Document, at pp. 16-17; Utility Authorization, Decision Document, at 

p. 14; 60 Fed. Reg. 48981 (September 21, 1995) (HDOR Authorization), Decision Document, at p. 13. 

See also Waiver of Federal Preemption California Low-Emission Vehicle Standards, 58 Fed. Reg. 4166 

(January 7, 1993) (LEV Waiver), Decision Document, at p. 21. 16 CARB has adopted emission certification standards that are aligned with federal nonroad standards 

and has requested that the Administrator grant California to adopt and enforce such standards pursuant 

to CAA section 209(e)(2). 

18
under section 209(b). In finding that California has met the protectiveness criterion in 

the previously granted authorizations, U.S. EPA accepted CARB’s determinations that 

the standards, in the aggregate, are at least as protective of public health and welfare 

as the applicable federal standards in that the regulations were expected to result in 

further reductions in pollutant emissions.17

In Resolution 04-7, CARB, acting on behalf of the State of California, determined that 

the standards set in the ATCM will be, in the aggregate, at least as protective of public 

health and welfare as any applicable federal standards. The protectiveness 

determination was a simple matter, because there are no federal standards for in-use 

portable engines. ARB received no information calling this determination into question. 

Accordingly, the ATCM is undisputedly at least as stringent as applicable federal 

regulations, a conclusion that for the above reasons clearly is not arbitrary or capricious. 

3. The Adopted Regulations are Necessary to Meet Compelling and Extraordinary 

Circumstances

California needs its own nonroad engine and vehicle program to meet serious air 

pollution problems unique to the State. The Administrator has previously and 

consistently recognized California’s unique needs when granting waivers for motor

vehicles under section 209(b) and authorizations for California’s nonroad regulations 

under section 209(e) of the CAA. 

The relevant inquiry under section 209(e)(2)(A)(ii) is whether California needs its own 

emission control program to meet compelling and extraordinary conditions, not whether 

any given standard is necessary to meet such conditions.18 In approving waivers under 

section 209(b), the Administrator has determined that: 

“compelling and extraordinary conditions” does not refer to levels of 

pollution directly, but primarily to the factors that tend to produce them: 

geographical and climatic conditions that, when combined with large 

numbers and high concentrations of automobiles, create serious air 

pollution problems.19

California -- in particular, the South Coast and San Joaquin Valley Air Basins −

continues to experience some of the worst air quality in the nation.20 The unique 

geographical and climatic conditions, and the tremendous growth in vehicle population 

and use that moved Congress to authorize California to establish separate vehicle 

standards in 1967, still exist today. As of March 2, 2006, U.S. EPA’s “Green Book” 

listing of non-attainment areas of the 8-hour ozone standard identified both air basins as 

 

17 OHRV Authorization, Decision Document, at pp. 21-22; Utility Authorization, Decision Document, at 

p. 23; HDOR Authorization, Decision Document, at p. 16. See also LEV Waiver, Decision Document, at 

pp. 45-46; Final 209(e) Rule, 59 Fed. Reg. 36969 at 36982. 18 49 Fed. Reg. 18887, 18892 (May 3, 1984).) 19 Id.. 20 See e.g. Approval and Promulgation of State Implementation Plans; California -- South Coast, 64 FR 

1770, 1771 (January 12, 1999). 

19
severe.21 Both air basins also continue to be identified as non-attainment for PM2.5.

22 

U.S. EPA recently affirmed ARB’s judgment, on behalf of the State of California, on this 

matter.23

In the California Clean Air Act of 1988, the California Legislature found that: 

despite the significant reductions in vehicle emissions which have been 

achieved in recent years, continued growth in population and vehicle miles 

traveled throughout California have the potential not only to prevent 

attainment of the state standards, but in some cases, to result in 

worsening of air quality.24

In response to the undisputed severe air quality problems in California, the California 

Legislature authorized CARB to consider adopting, inter alia, standards and regulations 

for nonroad engines.25 Given the serious air pollution problems California faces and the 

resultant need to achieve the maximum reductions in emissions, the California 

Legislature and CARB believe it is necessary to develop emission controls for nonroad 

sources as well as for motor vehicles.26 CARB continues to find such previously 

uncontrolled nonroad engines to be significant emission sources for which controls are 

necessary to meet federal and state air quality standards.27 The ATCM adds to 

California’s program for nonroad sources by regulating a nonroad engine category not 

covered by previously granted nonroad authorizations. 

By adding federal and state authority to regulate nonroad engines, Congress and 

California’s Legislature, respectively, acknowledged the increasing importance of 

reducing emissions from all mobile sources, including nonroad engines. The 

Administrator has repeatedly agreed with CARB that California’s continuing 

extraordinary conditions justify separate California nonroad programs.28 Nothing in 

these conditions has changed to warrant a change in this determination. Accordingly, 

for all the aforementioned reasons, there can be no doubt of the continuing existence of 

compelling and extraordinary conditions justifying California’s need for its own program 

within its nonroad vehicle and engine emissions control program. 

 

21 http://www.epa.gov/oar/oaqps/greenbk/gncs.html#CALIFORNIA 22 Id. 

23 California State Motor Vehicle Pollution Control Standards; Waiver of Federal Preemption -- Notice of 

Decision, 68 Fed.Reg.19811,19812 (April 22, 2003). 24 California Health and Safety Code section 43000.5. 25 California Health and Safety Code sections 43013 and 43018. 26 See California Health and Safety Code sections 41750, 41754, 43000.5, 43013 and 43018. 

27 Resolution 01-23 (Tab 2), at p. 2. See also Staff Report (Tab 5) at pp. 14-15 and 44-47. 28 Utility Authorization, Decision Document, at p. 33; OHRV Authorization, Decision Document, at 

pp. 27-29; and HDOR Authorization, Decision Document, at pp. 16-18. 

20
4. Consistency

The ATCM is fully consistent with section 209 of the CAA. Section 209(e)(2)(A)(iii) 

provides that the Administrator shall not authorize California to regulate nonroad 

sources if “California’s standards and accompanying enforcement procedures are not 

consistent with this section.” In the Final 209(e) Rule, U.S. EPA interpreted “consistent 

with this section” to mean all of section 209, including section 209(b)(1)(C). It 

accordingly concluded that the “consistency” criterion review of nonroad requests 

should parallel that of onroad motor vehicle waiver requests.29 

Under section 209(b)(1)(C), California’s motor vehicle standards and enforcement 

procedures must be consistent with section 202(a). The Administrator has established 

a two-part test for determining whether California’s standards and test procedures are 

consistent with section 202(a). First, California’s standards and test procedures must 

be technologically feasible in the lead time provided considering the cost of compliance. 

Second, the State’s test procedures must be compatible with federal test procedures. 

Applying the test to the ATCM, CARB believes that the Administrator should find them 

consistent with section 209. As previously stated, the ATCM neither applies to motor 

vehicles that are preempted under section 209(a) or to new engines less than 175 hp 

used in farm and construction equipment and vehicles or to new locomotives or 

locomotive engines. 

a. Technological Feasibility and Lead Time

Section 202(a)(2) provides that a regulation shall take effect after such period as the 

Administrator finds necessary to permit the development and application of the requisite 

technology, giving appropriate consideration to the cost of compliance. In making 

determinations under section 209(b)(1)(C), the Administrator has relied upon federal 

court decisions applying the requirements of section 202(a)(2) to federal standards. 

The leading federal cases construing section 202(a)(2) are Natural Resources Defense 

Council v. U.S. EPA, 655 F.2d 318 (D.C. Cir. 1981) (NRDC) and International Harvester 

Co. v. Ruckelshaus, 478 F.2d 615 (D.C. Cir. 1973) (International Harvester). 

NRDC makes clear that Congress intended U.S. EPA to project future advances in 

pollution control technology rather than be limited to the technology existing when the 

standards were set.30 The NRDC court noted that a longer lead time “gives the EPA 

greater scope for confidence that theoretical solutions will be translated successfully 

into mechanical realizations.”31 In addition, “[t]he presence of substantial lead time for 

development before manufacturers will have to commit themselves to mass production 

of a chosen prototype gives the agency greater leeway to modify its standards if the 

actual future course of technology diverges from expectation.” (Id.) The court 

concluded: 

 

29 59 Fed.Reg. 36969, 36983. 30 655 F.2d at 328. 

31 Id. at 329. 

21
We think that the EPA will have demonstrated the reasonableness of its 

basis for prediction if it answers any theoretical objections to the [projected 

control technology], identifies the major steps necessary in refinement of 

the [technology], and offers plausible reasons for believing that each of 

those steps can be completed in the time available.32

The emission standards and related requirements adopted in the ATCM satisfy the 

criteria set forth in the International Harvester and NRDC cases. In both its Staff Report: 

Initial Statement of Reasons for Rulemaking (Staff Report, Tab 4) and Final Statement 

of Reasons (Tab 5), CARB either has demonstrated that the necessary technology 

presently exists to meet the established standards or has specifically identified the 

projected control technology, answered objections raised by industry regarding that 

technology, and has explained its reasons for believing that each of the steps can be 

completed in the time available.33

As discussed above, the emission reduction goals of the ATCM are expected to be 

achieved with a combination of engine replacement and verified diesel PM retrofit 

strategies. Engine replacement or repower will be the likely method for satisfying the 

individual portable engine requirements of the ATCM and the initial fleet average 

requirement that become effective in 2013. The emission standards for certified 

portable engines are all technologically feasible in the time provided in this ATCM, in 

that they parallel emission standards for off-road compression ignition engines set forth 

in title 13, CCR, section 2423 and 40 CFR Part 89. In promulgating the federal 

regulations, U.S. EPA made express findings pursuant to CAA section 202(a) that the 

Tier I through 4 emission standards are technologically feasible. Moreover, Tier 1, 2, 

and 3 portable engines are presently being manufactured and sold for most kilowatt 

ratings. 

Portable engine owners and operators will likely use a combination of new engine 

replacement and verified diesel PM retrofit strategies to satisfy the fleet average 

requirements that become effective in 2017 and 2020. Verified diesel PM retrofit 

strategies refer to emission control strategies that have been verified pursuant to 

CARB’s Verification Program.34 Because U.S. EPA does not administer a comparable 

program, the Verification Program mechanism and available control strategies are 

discussed below. 

The Verification Program establishes a process through which manufacturers of 

emission control equipment can demonstrate and verify the emission reduction 

capabilities of control technologies. Examples of emission control technologies that can 

be considered for verification include: diesel particulate filters, diesel oxidation catalysts, 

 

32 Id. at 331-32. Accord, Husqvarna AB v. Environmental Protection Agency, 254 F.3d 195, 201 (D.C. 

Cir. 2001) and National Petrochemical & Refiners Association v. Environmental Protection Agency, 287 

F.3d 1130, 1136 (D.C. Cir. 2002). 

33 Id. 34 See footnote 5. 

22
exhaust gas recirculation, selective catalytic reduction systems, fuel additives and 

alternative diesel fuel systems. The Verification Program is voluntary and applies to 

emission control technologies for onroad, off-road and stationary applications. 

The Verification Program requires emission control strategy applicants to establish the 

emissions reduction capabilities for an emission control device, conduct a durability 

demonstration, conduct a field demonstration and submit results with additional 

information in a prescribed-format application to CARB. The applicant verifies the 

product for a specific engine manufacturer, years produced, engine family and series. If 

after reviewing the application CARB verifies the diesel emission control strategy, it will 

issue an Executive Order to the applicant stating the verified emission reduction and 

any conditions that must be met for the diesel emission control strategy to function 

properly. The Verification Program also requires that the applicants provide a warranty 

to the end-user and conduct in-use compliance testing. 

The results of the Verification Program testing determine the control technology 

classification. The multi-level verification system consists of three PM reduction levels. 

The Verification Program also has provisions for verifying strategies that reduce NOx 

emissions. Control device verifications for both PM and NOx are classified by level as 

listed below. 

Verification Classifications for Diesel Emission Control Strategies 

Pollutant Reduction Classification 

< 25% Not Verified 

> 25% Level 1 

> 50 % Level 2 

PM 

> 85% or <0.01 g/bhp-hr Level 3 

NOx < 15% Not Verified 

> 15% Verified in 5% increments

Once a device has been verified, the executive order and accompanying information is 

posted on CARB's web site at http://www.arb.ca.gov/diesel/verifieddevices/verdev.htm. 

Emission Control Strategies 

A brief description of the available control strategies is given below. 

Diesel Oxidation Catalyst 

A diesel oxidation catalyst (DOC) reduces the emissions of PM, carbon monoxide (CO) 

and gaseous reactive organic gas (ROG) from diesel engines by catalytic oxidation. 

The technology is only effective on the soluble organic faction of diesel PM, and 

therefore the overall reduction that can be achieved by a DOC is limited – the range of 

reduction is typically between 10 to 30 percent. 

23
Diesel Particulate and Flow Through Filters 

A diesel particulate filter (DPF) reduces diesel PM emissions through filtration. This 

technology is very efficient in controlling diesel PM emissions, and has been 

demonstrated to reduce diesel PM by over 90 percent. DPFs can be categorized into 

several classifications: passive, active, or flow-through. 

A passive DPF uses a catalytic material that allows the trapped PM to be burned-off or 

oxidized at a lower temperature. For the system to be successful, the engine must be 

operated such that the exhaust maintains a minimum temperature for a certain period of 

time. Otherwise, diesel PM will accumulate in the filter, eventually causing operating 

problems. 

An active DPF performs the same function as a passive DPF. The difference is that the 

active DPF does not use heat from the engine exhaust to oxidize the trapped PM. An 

active DPF is better suited for low exhaust temperatures or engines with high PM 

emissions. Most common methods use electrical regeneration by passing an electrical 

current through the filter medium, injecting fuel to provide additional heat to oxidize the 

trapped PM, or adding fuel-borne catalyst or other reagents to initiate periodic 

regeneration. 

Flow through filter (FTF) technology is a relatively new technology for reducing diesel 

PM emissions. Unlike a DPF, in which only gasses can pass through the substrate, the 

FTF does not physically "trap" and accumulate PM. Instead, exhaust flows through a 

medium (such as wire mesh) that has a high density of interrupted flow channels. The 

FTF medium is typically treated with an oxidizing catalyst that is able to reduce 

emissions of PM, ROG, and CO, or used in conjunction with a fuel-borne catalyst. 

Consequently, the FTF is not as efficient as a particulate filter in reducing diesel PM 

emissions. 

 Fuel Additives

Fuel additives are essentially any substances added to the fuel. These additives can 

reduce the total mass of PM, with variable effects on CO, NOx and ROG production. 

Fuel borne catalysts (FBC) are additives to diesel fuel to aid in soot removal in DPFs by 

lowering the ignition temperatures of the carbonaceous particles in the exhaust stream. 

If the ignition temperature is lower, then more of the carbonaceous portion of the 

exhaust stream is incinerated and not trapped in the DPF. These FBCs are to be used 

in conjunction with passive and active DPFs. FBCs use various metals such as cerium, 

platinum, copper, and iron. Most fuel additives will work with a range of sulfur 

concentrations as well with other fuels and other fuel additives. 

24
Alternative Diesel Fuels 

An alternative diesel fuel is a fuel that can be used in a diesel engine without 

modification to the engine. Alternative diesel fuels include emulsified fuels, biodiesels, 

Fischer-Tropsch (F-T) fuels and any combination of these fuels with regular diesel fuels. 

Water emulsion diesel fuel mixes water with diesel and adds an agent to keep the fuel 

and water from separating. The water is suspended in the droplets within the fuel, 

creating a cooling effect in the combustion chamber that decreases NOx emissions. A 

fuel-water emulsion creates a leaner fuel to air ratio in the combustion chamber, 

generating less soot at combustion, thus lowering PM emissions. 

Biodiesel is a mono-alkyl ester-based oxygenated fuel made from vegetable oils, such 

as oilseed plants or used vegetable oils, or animal fats. Biodiesel has similar properties 

to petroleum-based diesel fuel, and can be blended into petroleum-based diesel fuel at 

20 percent, and is called B20. Pure biodiesel is called B100. U.S. EPA recently 

evaluated biodiesel using publicly available data and concluded that while biodiesel and 

biodiesel blends reduce PM, ROG, and CO emission, NOx emissions increase, 

depending on the biodiesel to diesel fuel blend ratio 

Fischer-Tropsch fuels have been used to some degree since the 1920s. Today, these 

fuels are being used in South Africa to power buses, trucks and taxicabs. FischerTropsch technology converts coal, natural gas and low-value refinery products into a 

high-value, clean burning fuel. This fuel is interchangeable with conventional diesel fuel 

and can be blended with diesel fuel in any ratio with little or no modification. FischerTropsch fuels do have emissions reduction benefits. A study showed that PM 

emissions were reduced by 30 percent and NOx emissions by five percent. 

Demonstration of Technological Feasibility 

Historically, control techniques developed for diesel engines are first developed for 

onroad applications, and the experience gained is subsequently applied to nonroad 

applications. The additional time for developing and implementing control techniques 

for nonroad applications is necessary because of the wider range in engine sizes duty 

cycles for nonroad applications. For example, the most stringent emission standards for 

onroad applications apply to models manufactured in 2007 and later (40 CFR Part 86 

and title 13 CCR). In contrast, the most stringent emission standards for off-road 

applications are applicable to engines manufactured beginning in 2011 (the standards 

are phased in by engine size and are fully implemented by 2015) − four to eight years 

after similar standards are implemented in onroad applications (40 CFR Part 1039 and 

title 13 CCR). 

In general, developing retrofit techniques for diesel engines presents a greater 

challenge than manufacturing new diesel engines in order to meet emission standards. 

A number of these retrofit techniques have been developed for onroad and stationary 

applications. Control techniques such as DOC, DPF (both passive, active, and flow25
through), and water emulsion diesel fuel have been verified for onroad applications. 

Overall, 26 different products have been verified for onroad applications, including 14 

verified at level 3, or 85 percent PM reduction. In addition, five different products have 

been verified for stationary applications. 

Based on the activity of the Verification Program, there is a solid base of control 

technology development for both onroad and stationary applications. Given that owners 

and operators of portable equipment will not be required by the ATCM to use retrofit 

technologies until 2017 -- more than 10 years from now − manufacturers of control 

techniques will have about ten years to develop the necessary products − ample lead 

time to allow the development of the necessary control techniques. Two techniques 

have already been verified for nonroad applications: an active DPF and emulsion diesel 

fuel. These verifications limit the usage to specified types of nonroad equipment; 

however, both manufacturers are exploring the possibility of expanding these 

verifications to other types of nonroad equipment. CARB staff believes these two 

technologies are the technologies most likely to be used to achieve the goals of the 

ATCM. 

Manufacturers will also have the opportunity to observe the implementation of the Tier 4 

nonroad emission standards. The control techniques applied to these newly 

manufactured engines will also be applicable to the in-use fleet. Again, the Tier 4 

standards are phased in beginning in 2011 and fully implemented by 2015, two years 

before retrofit technology is expected to be applied to the in-use portable equipment 

fleet. 

Finally, CARB has committed to perform a technology review regarding the 

development of retrofit technologies and will make the necessary modifications to the 

ATCM based on the findings of the technology review. This technology review is 

expected to be completed by 2008-2009. 

Of course, California is not bound by U.S. EPA’s feasibility and lead time analyses for 

its own rulemakings, let alone by preambles stating advisory opinions without proposing 

exhaust emission standards.35 The U.S. EPA has consistently and correctly reasoned 

that placing such a requirement on California's determination would effectively limit 

technology-forcing for the California market to that of the national market, effectively 

closing California as the nation's emissions control laboratory.36 Such a result would 

render CAA section 209(e) a nullity without independent force or effect, contrary to the 

long history of section 209(b) waiver implementation and Congress's endorsement of 

that implementation scheme for nonroad engines. 

 

35 Supra note 1. 

36 See e.g., Utility Authorization, Decision Document at pp. 54-55. 

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b. Test Procedure Consistency

The portable engine ATCM does not establish any test procedures for which there are 

comparable federal test procedures. Therefore, there is no issue of test procedure 

inconsistency.

CONCLUSION

Based on the foregoing, CARB respectfully requests authorization for California to 

enforce the portable engine ATCM, as presented in Tab 3. The following tabbed 

documents pertaining to the ATCM covered by this request are enclosed: 

1. Resolution 04-7. 

2. Executive Order G-04-080. 

3. Face sheet (Form 400) as approved by OAL February 9, 2005 and filed with the 

Secretary of State, along with the Final Regulation Order containing the newly 

adopted sections 93116 through 93116.5 of title 17, California Code of 

Regulations, effective March 11, 2005. 

4. Staff Report: Initial Statement of Reasons for Proposed Rulemaking and 

Proposed Regulations and Incorporated Documents, January 2004 

5. Final Statement of Reasons for Rulemaking, Including Summary of Comments 

and Agency Responses and Addendum to the Final Statement of Reasons, filed 

January 4, 2005. 

6. February 26, 2004 Air Resources Board Hearing Transcript. 

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