Control of Emissions from Marine SI
   and Small SI Engines, Vessels, and
   Equipment


   Final Regulatory Impact Analysis
United States
Environmental Protection
Agency

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               Control of Emissions from Marine SI
                and Small SI Engines, Vessels, and
                              Equipment

                  Final Regulatory Impact Analysis
                           Assessment and Standards Division
                          Office of Transportation and Air Quality
                          U.S. Environmental Protection Agency
v>EPA
United States                                  EPA420-R-08-014
Environmental Protection                            _ ^ ,  
Agency                                     September 2008

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                                 Table of Contents

Executive Summary  	ES-1

CHAPTER 1: Industry Characterization
    1.1 Manufacturers of Small SI Engines  	1-1
    1.2 Manufacturers of Marine Spark-Ignition Engines  	1-2
    1.3 Fuel System Components	1-6

CHAPTER 2: Air Quality, Health, and Welfare Concerns
    2.1 Ozone 	2-3
    2.2 Paniculate Matter	2-14
    2.3 Air Quality Modeling Methodology	2-33
    2.4 Air Toxics	2-39
    2.5 Carbon Monoxide	2-44
    2.6 Acute Exposure to Air Pollutants	2-47

CHAPTER 3: Emission Inventory
    3.1 Overview of Small Nonroad and Marine SI Engine Emissions Inventory
       Development 	3-2
    3.2 Baseline Emission Inventory Estimates 	3-4
    3.3 Contribution of Small Nonroad and Marine SI Engines to National Emissions
       Inventories	3-19
    3.4 Controlled Nonroad Small Spark-Ignition and Marine Engine Emission Inventory
       Development 	3-26
    3.5 Projected Emissions Reductions from the New Standards	3-34
    3.6 Emission Inventories Used for Air Quality Modeling 	3-43

CHAPTER 4: Feasibility of Exhaust Emission Control
    4.1 General Description of Spark-Ignition Engine Technology	4-1
    4.2 General Description of Exhaust Emission  Control Technologies  	4-8
    4.3 Feasibility of Small SI Engine  Standards	4-23
    4.4 Feasibility of Outboard/Personal Watercraft Marine Engine Standards  	4-38
    4.5 Feasibility of Sterndrive/Inboard Marine Engine Standards 	4-43
    4.6 Feasibility of Standard for Marine Generator  Sets	4-55
    4.7 Test Procedures	4-56
    4.8 Impacts on  Safety, Noise, and Energy  	4-72
    APPENDIX 4A: Normalized Modal Emissions for a 7.4 L MPI SD/I	4-81

CHAPTER 5: Feasibility of Evaporative Emission Control
    5.1 Diurnal Breathing Loss Evaporative Emissions	5-2
    5.2 Running Loss Emissions	5-26
    5.3 Fuel Tank Permeation	5-29
    5.4 Fuel/Vapor Hose Permeation 	5-70
    5.5 Other Evaporative Emissions	5-89
    5.6 Evaporative Emission Test Procedures	5-91
    5.7 Impacts on Noise, Energy, and Safety  	5-109

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   APPENDIX 5A:  Diurnal Temperature Traces	5-112
   APPENDIX 5B:  Emission Results for Small SI Equipment Fuel Tanks Showing Effect of
   Venting on Diffusion	5-115
   APPENDIX 5C:  Diurnal Emission Results: Canister and Passive-Purge 	5-120
   APPENDIX 5D:  Material Properties of Common Fuel System Materials	5-121
   APPENDIX 5E:  Diurnal Test Temperature Traces  	5-125

CHAPTER 6: Costs of Control
   6.1 Methodology	6-1
   6.2 Exhaust Emission Control Costs for Small SI Engines  	6-2
   6.3 Exhaust Emission Control Costs for Outboard and Personal Watercraft Engines ... 6-44
   6.4 Exhaust Emission Control Costs for Sterndrive/Inboard Marine Engines	6-56
   6.5 Evaporative Emission Control Costs for Small SI Equipment	6-64
   6.6 Costs of Evaporative Emission Controls for Marine Vessels	6-78
   6.7 Cost Sensitivity  Analysis 	6-92

CHAPTER 7: Cost Per Ton
   7.1 30-Year Net  Present Value Cost effectiveness	7-1
   7.2 Results	7-2

CHAPTER 8: Cost-Benefit Analysis
   8.1 Overview	8-2
   8.2 Air Quality Impacts for Benefits Analysis	8-5
   8.3 PM-Related Health Benefits Estimation - Methods and Inputs	8-7
   8.4 Health Impact Functions  	8-9
   8.5 Economic Values for Health Outcomes	8-27
   8.6 Benefits Analysis Results for the Final Standards 	8-35
   8.7 Comparison of Costs and Benefits	8-45
   Appendix 8 A: Sensitivity Analyses of Key Parameters in the Benefits Analysis	8-52
   Appendix 8B: Health-Based Cost-Effectiveness of Reductions in Ambient O3 and PM25
      Associated with the Final Small SI and Recreational Marine Engine Rule  	8-61

CHAPTER 9: Economic Impact Analysis
   9.1 Overview and Results  	9-1
   9.2 Economic Methodology 	9-16
   9.3 EIM Data Inputs and Model Solution	9-36
   9.4 Methods for Describing Uncertainty  	9-66
   Appendix 9A: Impacts on Small SI Markets	9-74
   Appendix 9B: Impacts on Marine SI Markets	9-92
   Appendix 9C: Time  Series of Social Cost	9-104
   Appendix 9D: Overview of Model Equations and Calculation	9-108
   Appendix 9E: Elasticity Parameters for Economic Impact Modeling	9-113
   Appendix 9F: Derivation of Supply Elasticity  	9-127
   Appendix 9G: Initial Market Equilibrium - Price Forecasts	9-129
   Appendix 9H: Sensitivity Analysis	9-131

CHAPTER 10: Small-Business Flexibility Analysis
   10.1  Overview of the Regulatory Flexibility Act  	10-1

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   10.2 Need for and Objective of the Rulemaking  	10-2
   10.3 Summary of Significant Public Comments	10-3
   10.4 Definition and Description of Small Entities	10-4
   10.5 Type and Numbers of Small Entities Affected 	10-5
   10.6 Reporting, Recordkeeping, and Compliance Requirements	10-7
   10.7 Steps Taken to Minimize the Impact on Small Entities	10-8
   10.8 Projected Economic Effects of the Rulemaking  	10-17

CHAPTER 11: Regulatory Alternatives
   11.1 Identification of Alternative Program Options	11-1
   11.2 Cost per Engine	11-7
   11.3 Emission Reduction 	11-18
   11.4 Cost Effectiveness	11-20
   11.5 Summary and Analysis of Alternative Program Options	11-21
   APPENDIX 11 A: Emission Factors for the Less Stringent Alternative	11-26
   APPENDIX 1 IB: Emission Factors for the More Stringent Alternative  	11-27

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                                                                   Executive Summary
                            Executive Summary

   The Environmental Protection Agency (EPA) is establishing new requirements to reduce
emissions of hydrocarbon (HC) and oxides of nitrogen (NOx) from nonroad small spark ignited
engines below 19kW ("Small SI engines") and marine spark ignited engines ("Marine SI
engines"). This rule includes exhaust and evaporative emission standards for these engines as
well as related gasoline fuel tanks and fuel lines.

   This executive summary describes the relevant air-quality issues, highlights the new exhaust
and evaporative emission standards, and gives an overview of the analyses in the rest of this
document.

Air Quality Background and Environmental Impact of the Rule

   Emissions from Small SI engines and equipment and Marine SI engines and vessels
contribute to a number of serious air pollution problems and will continue to do so in the future
absent further reduction measures. Such emissions lead to adverse health and welfare effects
associated with ozone, particulate matter (PM),  nitrogen oxides (NOx), volatile organic
compounds (VOC) including toxic compounds, and carbon monoxide (CO). These emissions
also cause significant public welfare harm, such as damage to crops and regional haze.

   Millions of Americans continue to live in areas with unhealthy air quality that may endanger
public health and welfare. As of March 2008 approximately 139 million people live in the 72
areas that are designated as nonattainment for the 8-hour ozone National Ambient Air Quality
Standards (NAAQS). In addition, approximately 88 million people live in areas that are
designated as nonattainment for the PM2 5 NAAQS. Federal, state, and local governments are
working to bring ozone and PM levels into attainment with the NAAQS. The reductions
included in this rule will be useful to states in attaining and maintaining the ozone, CO, and PM
NAAQS.

   In 2002, emissions from land-based nonroad Small SI engines and Marine SI
engines were estimated to be about 26 percent of the total mobile-source inventory of VOC
emissions and  1 percent of the NOx inventory.  As presented in Figures 1 and 2, this rule will
significantly reduce future Small SI and Marine SI emission inventories.
                                         ES-1

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Final Regulatory Impact Analysis
    Figure 1: Small Spark Ignition VOC+NOx Baseline and Phase 3 Control Emission
                                    Inventory
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1 000 000
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1
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   Figure 2: Marine Spark Ignition VOC+NOx Baseline and Phase 3 Control Emission
                                    Inventory
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                                       ES-2

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                                                                       Executive Summary
Exhaust and Evaporative Emission Standards

    Tables 1 through 4 show the exhaust and evaporative emission standards and when they will
apply. For Small SI nonhandheld engines, the standards are expected to result in the use of
engine modificiations, aftertreatment systems, and some use of electronic fuel injection in Class
II engines. As shown in Tables 1 through 4, we are phasing in many of the standards over time
to address considerations of lead time, workload, and overall feasibility.  In addition, the rule
includes other provisions designed to address the transition to meeting the standards.

Table 1:  Small SI Nonhandheld Engine Exhaust Emission Standards and Schedule
Engine Class
Class I (>80cc to <225cc)b
Class II (>225cc)
Model Year
2012
2011
HC+NOx
[g/kW-hr]
10.0
8.0
coa
[g/kW-hr]
610
610
a 5 g/kW-hr CO for Small SI engines powering marine generators.
b Nonhandheld engines at or below 80cc will be subject to the emission standards for handheld engines.
       Table 2: Small SI Equipment Evaporative Emission Standards and Schedule

Standard Level
Handheld
Class I
Class II
Fuel Line Permeation
15 g/nf/day
2012a'b
2009
2009
Tank Permeation
1.5 g/m2/day
2009-2013
2012
2011
Running Loss
Design Standard
NA
2012
2011
a 2013 for small-volume families.
b A separate set of declining fuel line permeation standards applies for cold-weather equipment from 2012 through
2016. A standard of 225 g/nf/day for cold-weather equipment fuel lines applies for 2016 and later.
0 2009 for families certified in California, 2013 for small-volume families, 2011 for structurally integrated nylon fuel
tanks, and 2010 for remaining families.
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Final Regulatory Impact Analysis
       Table 3a: Outboard/PWC Marine SI Engine Exhaust Standards and Schedule3
Pollutant
HC+NOx
CO
Powe^
P < 4.3 kW
P> 4.3 kW
P < 40 kW
P> 40 kW
Emission Standard15
30.0
2.1+0.09 x (151 + 557/P09)
500 - 5.0 x p
300
Model Year
2010
2010
2010
2010
a These engines are also subject to not-to-exceed standards
b P = maximum engine power in kilowatts (kW).
     Table 3b: Sterndrive/Inboard Marine SI Engine Exhaust Standards and Schedule
Power3
P < 373 kWb
High-performance engines < 485 kW d
High-performance engines < 485 kW d
Model Year
2010C
2010
2011
2010
2011
HC+NOx fs/kW-hrl
5.0
20.0
25.0
16.0
22.0
CO Ts/kW-hrl
75
350
350
350
350
a P = maximum engine power in kilowatts (kW).
b These engines are also subject to not-to-exceed standards. This category also includes engines >373 kW that do
not otherwise meet the definition of "high-performance."
0 2011 for small-businesses and for engines built using the 4.3L or 8.1L GM engine blocks.
d For small businesses, the 2010 standards do not apply and the 2011 standards are delayed until 2013.
        Table 4: Marine SI Engine Evaporative Emissions Standards and Schedule

Standard Level
Portable Tanks
PWC
Other Installed Tanks
Fuel Line Permeation
15 g/nf/day
2009a
2009
2009a
Tank Permeation
1.5 g/mVday
2011
2011
2012
Diurnal
0.40 g/gal/day
2010b
2010
2011c'd
a 2011 for primer bulbs. Phase-in for under cowl fuel lines, by length, on OB engines: 30% 2010, 60% 2011, 90%
2012,  100% 2015.
b Design standard.
0 Fuel  tanks installed in nontrailerable boats (> 26 ft. in length or >8.5 ft. in width) may meet a standard of 0.16
g/gal/day over an alternative test cycle.
d The standard is effective July 31, 2011. For boats with installed fuel tanks, this standard is phased-in 50%/100%
over the first two years. As an alternative, small manufacturers may participate in a diurnal allowance program.
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                                                                    Executive Summary
   EPA has also taken steps to ensure that engines built to these standards achieve more
accurate emissions reductions and is upgrading the test requirements to those listed in
40CFR1065 as outlined in Preamble Section IX General Test Procedures.

Feasibility of Meeting the Small SI Engine Exhaust Emission Standards

   Since 1997, exhaust emission control development for Small SI engines has concentrated on
engine redesign including carburetor design, improved engine combustion and engine cooling.
The primary technical focus of the new emission standards will be engine upgrades as needed,
catalyst application to the majority of Small SI engines and electronic fuel injection on some
Class II engines. Related information is in Chapter 4.

   We are finalizing, more stringent exhaust HC+NOx standards for Class I and II Small SI
engines. We are also establishing a new CO standard for Small SI engines used in marine
generator applications. The standards differ by engine size. Class I engines have a total engine
displacement of < 225cc.  Class II engines have a total engine displacement of >225cc.

   In the 2008 model year, manufacturers certified nearly 235 Class I and II engine families to
the Phase 2 standards using a variety of engine designs and emission control technology. All
Class I engines were produced using carbureted air-fuel induction systems and are air cooled.
An extremely small number of engines used catalyst-based emission control technology.
Similarly,  Class II engines were predominantly carbureted and air cooled. A limited number of
these engines used catalyst technology, electronic engine controls and fuel injection, and/or
water
cooling.

   The market focus has a large part to play in the engine design and quality.  The large number
of residential and commercial applications have led to a wide variety of engine qualities and
designs in the marketplace today. Some of the more durable engine designs already incorporate
the base design requirements needed to incorporate a catalyst to meet the Phase 3 emission
standards.  In addition, a number of engine families in both classes are currently certified at
levels that would comply with the Phase 3 standards.

   Based  on our own testing of advanced technology for these  engines, our engineering
assessments, and statements from the affected industry,  we believe the requirements will lead
many engine manufacturers to adopt exhaust aftertreatment technology using catalyst-based
systems. Other likely engine changes include improvements in engine designs, cooling system
designs and fuel delivery systems. The addition of electronic controls and/or fuel injection
systems to some Class II engine families may obviate the need for catalytic  aftertreatment, with
the most likely candidates being multi-cylinder engine designs.

   Information herein on the feasibility assessment of exhaust emissions on Small SI engines
includes the emission evaluation of current product and advanced technology engines.  Areas
covered include laboratory and field evaluations, review of patents of existing catalyst/muffler

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Final Regulatory Impact Analysis
designs for Class I engines, discussions with engine manufacturers and suppliers of emission
control-related engine components regarding recent and expected advances in emissions
performance, and an analysis of catalyst/muffler units that were already in mass production by an
original equipment manufacturer for use on European walk-behind lawn mowers.

   EPA used this information to design, build and emission test prototype catalyst-based
emission control systems that were capable of effectively and safely achieving the Phase 3
emission standards on both Class I and Class II engines. Chapter 4 projects that in some cases
manufacturers of Class I and Class II engines may need to improve the durability of their basic
engine designs,  cooling system designs, ignition systems, or fuel metering systems for some
engines in order to comply with the Phase 3 emission regulations over the useful life. EPA also
built and tested  electronic fuel injection systems on two twin cylinder Class II engines and
emission tested  them with and without catalysts. EFI improves the management of air-fuel
mixtures  and ignition spark timing and each of the  engines achieved the requisite emission limit
for HC+NOx (e.g., 8.0 g/kW-hr). Based on this work and information from one manufacturer of
emission controls, we believe that either a catalyst-based system or electronic engine controls
appear sufficient to meet the standard.  Manufacturers adopting the EFI approach will likely
realize other advantages such as easier starting, more stable and reliable engine operation, and
reduced fuel consumption.

   We also used the information and the results of our engine testing to assess the potential need
for improvements to engine, cooling and fuel system designs. A great deal of this effort was
conducted in association with our more in-depth study regarding the efficacy and safety of
implementing advanced  exhaust emission controls  on Small SI and recreational Marine SI
engines, as well as new evaporative requirements for these engines, equipment,  and vessels.  The
results of that study are also discussed in Chapter 4.

   There are a  number of Class II engines that use gaseous fuels  (i.e., liquid propane gas or
compressed natural gas). Based on  our engineering evaluation of current and likely emission
control technology for these engines, we conclude that these  engines will use catalysts, or larger
catalysts than current,  in order to achieve the Phase 3 HC+NOx standard.  Some engines
currently meet the Phase 3 emission standards.

   Regarding the marine generator CO standard, two manufacturers that produce the majority of
marine generators have announced that as a result of boat builder demand, they are converting
their marine generator product lines to new designs which can achieve more than a 99 percent
reduction in CO emissions in order to reduce the risk of CO poisoning. These low CO emission
designs used closed-loop electronic fuel injection and catalytic control on engines which are
water cooled using the lake or sea water.  Both of these manufacturers have certified some low
CO engines and have expressed their intent to convert their full product lines in the near future.
These manufacturers also make use of electronic controls to monitor catalyst function.

Feasibility of Meeting the Marine SI Exhaust Emission Standards

   The technology is available for marine engine manufacturers to use to meet the new

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                                                                     Executive Summary
standards. This technology is the same that manufacturers are anticipated to use to meet the
California ARB standards in 2008.  For outboards and personal watercraft (OB/PWC) this
largely means extended use of lower-emitting engine technology widely used today. For
sterndrive and inboard (SD/I) marine engines, this means the use of catalytic converters in the
exhaust system. Chapter 4 includes detailed descriptions of low emission technologies for
marine engines, including emissions test data on these technologies.

   OB/PWC

   Over the past several years, manufacturers have demonstrated their ability to achieve
significant HC+NOx emission reductions from OB/PWC engines.  This has largely been
accomplished through the introduction of two-stroke direct injection engines in some
applications and conversion to four-stroke engines. Current certification data for these types of
engines show that these technologies may be used to achieve emission levels significantly below
the existing exhaust emission standards. In fact, California has adopted standards requiring a 65
percent reduction beyond the current federal standards beginning in 2008.

   Our own analysis of recent certification data shows that most four-stroke outboard engines
and many two-stroke direct injection outboard engines currently meet the new HC+NOx
standard.  Similarly, although PWC engines tend to have higher HC+NOx emissions,
presumably due to their higher power densities, many of these engines also meet the new
HC+NOx standard.  Although there is currently not a CO emission standard for OB/PWC
engines, OB/PWC manufacturers are required to report CO emissions from their engines.  These
emissions are based on test data from new engines and do not consider deterioration or
compliance margins. Based on this data, all  of the two-stroke direct injection engines show
emissions well below the new standards.  In  addition, the majority of four-stroke engines meet
the CO standards as well.

   We therefore believe the HC+NOx and CO emission standards can be achieved by phasing
out conventional carbureted two-stroke engines and replacing them with four-stroke engines or
two-stroke direct injection engines. This has been the market-driven trend over the last five
years. Chapter 4 compares recent certification data to the new standards.

   SD/I

   Engine manufacturers can adapt readily available technologies to control emissions from
SD/I engines. Electronically controlled fuel injection gives manufacturers more precise control
of the air/fuel ratio in each cylinder, thereby giving them greater flexibility in how they  calibrate
their engines. With the addition of an oxygen sensor, electronic controls give manufacturers the
ability to use closed-loop control, which is especially valuable when using a catalyst. In
addition, manufacturers can achieve HC+NOx reductions through the use of exhaust gas
recirculation. However, the most effective technology for controlling emissions is a three-way
catalyst in the exhaust stream.

   In SD/I engines, the exhaust manifolds are water-jacketed and the water mixes with the

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Final Regulatory Impact Analysis
exhaust stream before exiting the vessel.  Manufacturers add a water jacket to the exhaust
manifold to meet temperature-safety protocol.  They route this cooling water into the exhaust to
protect the exhaust couplings and to reduce engine noise. Catalysts must therefore be placed
upstream of the point where the exhaust and water mix-this ensures the effectiveness and
durability of the catalyst.  Because the catalyst must be small enough to fit in the exhaust
manifold, potential emission reductions are not likely to exceed 90 percent, as is common in
land-based applications. However, as discussed in Chapter 4 of the Final RIA, data on
catalyst-equipped SD/I engines show that emissions may be reduced by 70 to 80 percent for
HC+NOx and 30 to 50 percent for CO over the test cycle.  Larger reductions, especially for CO,
have been achieved at lower-speed operation.

   Chapter 4 discusses issues that have been addressed in  catalyst designs for SD/I engines such
as sustained operation at high load, potential saltwater effects on catalyst efficiency, and thermal
shock from cold water contacting a hot catalyst. Test programs have been performed to evaluate
catalysts in the laboratory and on the water. Three SD/I engine manufacturers have certified SD/I
engines to the California ARB standards, and some catalyst-equipped engines are available for
purchase nationwide. Manufacturers have indicated that they have successfully completed
durability testing, including extended in-use testing on saltwater.

Feasibility of Meeting the Evaporative Emission Standards

   There are many feasible control technologies that manufacturers can use to meet the
evaporative emission standards. We have collected emission test data on a wide range of
technologies for controlling evaporative emissions. Chapter 5 presents a description of the
evaporative emission sources which include permeation, diurnal, running loss, hot soak, and
refueling emissions. In addition,  Chapter 5 presents evaporative emission test data for current
Small SI and marine fuel systems and on a wide range of evaporative emission control
technologies. Below is an overview of technologies that are available for meeting the
evaporative emission standards.

   Low-permeation fuel lines are in production today. One fuel line design, already used in
some marine applications, uses a thermoplastic layer between two rubber layers to control
permeation.  This thermoplastic barrier may either be nylon or ethyl vinyl acetate (EVOH).
Barrier approaches in automotive applications  include fuel lines with fluoroelastomers such as
FKM and fluoroplastics such as Teflon and THV.  In  addition to presenting data on
low-permeation fuel lines, Chapter 5 lists several fuel-system materials and their permeation
rates. Molded rubber fuel line components, such as primer bulbs and some handheld fuel lines,
could meet the standard by using  a fluoroelastomer such as FKM.

   Plastic fuel tanks used in Small SI and Marine SI applications can be molded using several
processes. While no fuel tank permeation control  strategy  will work for all production processes
and materials, there are multiple control strategies available for fuel tanks manufactured with
each of the molding processes.  These molding processes include blow-molding, injection-
molding, thermoforming, rotational-molding, and hand built constructions (fiberglass).
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                                                                     Executive Summary
   Multi-layer fuel tanks can be formed using most of these molding processes.  These fuel tank
constructions include a barrier layer of a low permeation material such as ethylene vinyl alcohol
(EVOH) or nylon.  This technology has been used in blow-molded fuel tanks for automotive
applications for many years and can achieve emission levels well below the new standard.  For
thermoformed fuel tanks, a similar barrier formed into the plastic sheet that is later molded into a
fuel tank.  Rotationally-molded fuel tanks can be produced with an inner barrier layer such as
nylon.  As an alternative, in the blow-molding process, a low-permeable resin can be blended
with polyethylene and extruded it with a single screw.  Although the barrier is not continuous,
this strategy can still be used to meet the permeation standard.  A similar strategy may be used
for fiberglass fuel tank where the barrier material is clay nanocomposites.  Finally, fuel tanks
may be formed entirely out of a low permeation material such as nylon or an acetal copolymer.
Many fuel tanks used with handheld equipment use nylon fuel tanks.

   Another approach to producing fuel tanks that meet the permeation standards would be to
create permeation barrier through a post-processing step. Regardless of the molding process,
another type of low-permeation technology for high-density polyethylene fuel tanks would be to
treat the surfaces with a barrier layer.  Two ways of achieving this are known as fluorination and
sulfonation.  In these processes, the tanks are exposed to a gas which forms a permeation barrier
on the  surfaces of the fuel tank. Either of these processes can be used to reduce gasoline
permeation by more than 95 percent. Additionally, a barrier layer can be put onto a fuel tank
with the use of an epoxy barrier coating.

   There are several technologies that can be used to reduce diurnal emissions from marine fuel
tanks.  The simplest approach is to seal the fuel tank. Portable fuel tanks currently use manual
valves  that can be closed to  seal the fuel tank.  PWC typically use sealed fuel systems with
pressure relief valves that open at pressures ranging from 0.5 to 4.0 psi. For other vessels with
installed fuel tanks, manufacturers have commented that even 1.0 psi of pressure would be too
high for their applications. Through the use of a carbon canister in the vent line, diurnal
emissions can be controlled from these fuel tanks without creating significant pressure in the fuel
tank. With this technology, vapor generated in the  tank is vented to a canister containing
activated carbon.  The fuel tank must be sealed such that the only venting that occurs is through
the carbon canister. The activated carbon collects and stores the hydrocarbons.  The activated
carbon bed in the canister is refreshed by purging the vapors with air flow.  The standard is
based on the air flow being generated by the natural breathing of the fuel tank as it heats and
cools.

   Running loss emissions can be controlled from  Small SI equipment by sealing the fuel cap
and routing vapors from  the fuel tank to the engine intake.  In doing so, vapors generated by heat
from the engine will be burned in the engine's combustion chamber.  It may be necessary to use
a valve or limited-flow orifice in the purge line to prevent too much fuel vapor from reaching the
engine and to prevent liquid fuel from entering the  line if the equipment flips over. Depending
on the  configuration of the fuel system and purge line, a one-way valve in the fuel cap may be
desired to prevent a vacuum in the fuel tank during engine operation. We anticipate that a
system like this would eliminate running loss emissions. However, higher temperatures during
operation and the additional length of vapor line would slightly increase permeation.

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Final Regulatory Impact Analysis
Considering these effects, we still believe that the system described here would reduce running
losses from Small SI equipment by more than 90 percent.

   Many manufacturers today use fuel caps that by their design effectively limit the diffusion of
gasoline from fuel tanks. In any case, we expect that the new running loss design standard will
limit any diffusion emissions from this equipment. As discussed in Chapter 5, venting a fuel
tank through a tube (rather than through an open orifice) greatly reduces diffusion.

Estimated Costs and Cost-Effectiveness for Small  SI Engines and Equipment

   There are approximately 410 nonroad equipment  manufacturers using Small SI engines in
over a thousand different equipment models.  There are more than 50 engine manufacturers
certifying Small SI engine families for these applications. Fixed costs consider engine research
and development, engine tooling, engine certification, and equipment redesign.  Variable costs
include estimates for new emission-control hardware. Near-term and long-term costs for some
example pieces of equipment are shown in Table 5. Also shown in Table 5 are typical prices for
each piece of equipment for reference. See Chapter 6 for detailed information related to our
engine and equipment cost analysis.

        Table 5:  Estimated Costs for Several Example Pieces of Equipment ($2005)a
              Over the Range of Useful Life Categories for Small SI Enginesb

Exhaust Near Term
Long Term
Evaporative Near Term
Long Term
Total (without fuel savings)
Near Term
Long Term
Total (with fuel savings)0
Near Term
Long Term
Estimated Equipment Price Range
Class I
$10 to $26
$10 to $12
$3.05
$2.20
$14 to $26
$11 to $17
$13 to $25
$10 to $16
$100-$2,800
Class II
$17 to $60
$12 to $30
$6.73
$5.16
$46 to $92
$27 to $52
$l-$48/$40-$86
-$18-$6/$21-$46
Engines w/ and w/o EFI
$300-$6800
Handheld
(Class III-V)
$0.28
$0.00
$0.82
$0.69
$1.12
$0.69
$0.72
$0.29
$210 avg
a Near-term costs include both variable costs and fixed costs; long-term costs include only variable costs
and represent those costs that remain following recovery of all fixed costs.
b Class I (125,250, or 500 hours), Class II (250, 500, or 1000 hours)
0 Class I, Class II and handheld have fuel savings from evaporative measures.  Class II engines with EFI have fuel
savings of $39 based on the lifetime savings in the use of a residential ride on mower. There are no fuel savings
related to compliance with the exhaust emission standard for Class I, handheld, or Class II engines without EFI.
    Chapter 6 presents aggregate costs of compliance for the new exhaust and evaporative
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                                                                   Executive Summary
emission standards for Small SI engines. Table 6 presents the annualized aggregate costs and
fuel savings for the period from 2008-2037.  The annualized fuel savings for Small SI engines
are due to reduced fuel costs form the sue of electronic fuel injection on Class II engines as well
as fuel savings from evaporative measures on all Small SI engines.

  Table 6: Estimated Annualized Cost to manufacturers and Annualized Fuel Savings for
             Small SI Engines and Equipment at a 7% Discount Rate (2005$)

Exhaust
Evaporative
Aggregate
Annualized Cost to Manufacturers
(millions/yr)
$182
$65
$247
Annualized fuel savings
(millions/yr)
$24
$53
$77
   Chapter 7 describes the cost effectiveness analysis.  In this analysis, the aggregate costs of
compliance are determined for the period 2008-2037.  The discounted aggregate costs for the
period are divided by the discounted aggregate HC_NOx emission reductions.

          Table 7:  Aggregate Cost per Ton for Small SI Engines and Equipment
               2008-2037 Net Present Values at 7% Discount Rate ($2005)
Pollutant
NOx+HC
7%
Aggregate Discounted
Lifetime Cost per ton
Without Fuel Savings
$978
Aggregate Discounted
Lifetime Cost per ton
With Fuel Savings
$650
Estimated Costs and Cost-Effectiveness for Marine SI Engines

    According to the US Coast Guard there are well over a thousand different boat builders
using Marine SI engines. There are about 10 engine manufacturers certifying to the current
OB/PWC exhaust emission standards. We have identified more than 30 companies
manufacturing SD/I marine engines.  Fixed costs consider engine research and development,
engine tooling, engine certification, and equipment redesign. Variable costs include estimates
for new emission-control hardware. Near-term and long-term costs for three different Marine SI
applications are shown in Table 8.  Also shown in Table 8 are typical prices for these types of
marine vessels.  See Chapter 6 for detailed information related to our engine and equipment cost
analysis.
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Final Regulatory Impact Analysis
Table 8: Estimated Average Incremental Costs for SI Marine Engines and Vessels ($2005)a
Engine Category
(Fuel Storage System)
Exhaust
Near Term
Long Term
Evaporative
Near Term
Long Term
Total (without fuel savings)*
Near Term
Long Term
Total (with fuel savings)"
Near Term
Long Term
Estimated Vessel Price Range
Outboard
(Portable)
$291
$224
$12
$8
$433
$336
$245
$148
$10,000-50,000
PWC
$359
$272
$17
$11
$376
$283
$165
$72
$6,000-12,000
SD/I
(Installed)
$355
$266
$74
$62
$487
$376
$348
$237
$20,000-200,000
a Near-term costs include both variable costs and fixed costs; long-term costs include only variable costs and
represent those costs that remain following recovery of all fixed costs.
b Total costs are presented as an average per boat and consider that many boats have multiple engines.
    Chapter 6 presents aggregate costs of compliance for the new exhaust and evaporative
emission standards for Marine SI engines.  Table 9 presents the annualized aggregate costs and
fuel savings for the period from 2008-2037. The annualized fuel savings for Marine SI engines
are due to reduced fuel costs from the use of more fuel efficient engines as well as fuel savings
from evaporative measures.

  Table 9: Estimated Annualized Cost to Manufacturers and Annualized Fuel Savings for
              Marine SI Engines and Vessels at a 7% Discount Rate (2005$)

Exhaust
Evaporative
Aggregate
Annualized Cost to Manufacturers
(millions/yr)
$123
$22
$144
Annualized Fuel Savings
(millions/year)
$56
$22
$78
    Chapter 7 describes the cost effectiveness analysis. In this analysis, the aggregate costs of
compliance are determined for the period 2008-2037. The discounted aggregate costs for the
period are divided by the discounted aggregate HC+NOx emission reductions over that same
period.  Table 10 presents the cost per ton estimates with and without fuel savings.
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                                                                    Executive Summary
          Table 10: Aggregate Cost per Ton for SI Marine Engines and Vessels
                2008-2037 Net Present Values at 7% Discount Rate ($2005)
Pollutant
NOx+HC
7%
Aggregate Discounted
Lifetime Cost per ton
Without Fuel Savings
$780
Aggregate Discounted
Lifetime Cost per ton
With Fuel Savings
$360
Economic Impact Analysis

   We prepared a final Economic Impact Analysis estimate the market and social welfare
impacts of the new standards.  This analysis can be found in Chapter 9.  According to this
analysis, the average price of a Marine SI engine in 2030 is projected to increase by less than 2
percent ($213) as a result of the new standards, and the average price of a Marine  SI vessel is
projected to increase by between 0.7 percent and 2.4 percent ($218 to $702), depending on the
type of vessel. The average price of a Small SI engine in 2030 is projected to increase by about
7.4 percent ($12), and the average price of Small SI nonhandheld equipment is projected to
increase by between 2.2 percent and 5.6 percent ($15 to $20), depending on equipment class.
Changes in quantity produced  are expected to be small, at less than 2 percent. The exceptions
are PWC (4.8 percent) and Class II equipment (2.4 percent).

   The net social costs of the program in 2030 are estimated to be $186 million. This includes
$459 million of direct social costs and $273 million on fuel savings for the end users of these
products. Overall, the consumers of Marine SI vessels and Small SI equipment are expected to
bear the majority of the costs of complying with the program: 76 percent of the Marine SI
program social costs in 2030, and 91 percent of the Small SI program social costs. However,
when the fuel savings are considered, the social costs burden for consumers of Marine SI
equipment becomes a net benefit (the fuel savings are greater than the compliance costs of the
program), while the end-user share of the Small SI program drops to 86 percent.

Benefits

   We estimate that the requirements in this rulemaking will result in substantial benefits to
public health and welfare and the environment, as described in Chapter 8. The benefits analysis
performed for this rulemaking  uses sophisticated air quality and benefit modeling tools and is
based on peer-reviewed studies of air quality and health and welfare effects associated with
improvements in air quality and peer-reviewed studies of the dollar values of those public health
and welfare effects.

   The range of benefits associated with this program are  estimated based on the risk of several
sources of PM- and ozone-related mortality effect estimates, along with all other PM and ozone
non-mortality related benefits information. These benefits are presented in Table  11. The
benefits reflect two different sources of information about the impact of reductions in PM on
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Final Regulatory Impact Analysis
reduction in the risk of premature death, including an estimate of mortality derived from the
epidemiological literature (the American Cancer Society (ACS) cohort study - Pope et al., 2002)
and an expert elicitation study conducted by EPA in 2006. In order to provide an indication of
the sensitivity of the benefits estimates to alternative assumptions, in Chapter 8 of the RIA we
present a variety of benefits estimates based on two epidemiological studies (including the ACS
Study and the Six Cities Study) and the expert elicitation. EPA intends to ask the Science
Advisory Board to provide additional advice as to which scientific studies should be used in
future RIAs to estimate the benefits of reductions in PM.

   The range of ozone benefits associated with the final standards is also estimated based on
risk reductions estimated using several sources of ozone-related mortality effect estimates.
There is considerable uncertainty in the magnitude of the association between ozone and
premature mortality.  This analysis presents four alternative estimates for the association based
upon different functions reported in the scientific literature. We use the National Morbidity,
Mortality and Air Pollution Study (NMMAPS), which was used as the primary basis for the risk
analysis in the ozone Staff Paper and reviewed by the Clean Air Science Advisory Committee
(CASAC).  We also use  three studies that synthesize ozone mortality data across a large number
of individual studies. Note that there are uncertainties within each study that are not fully
captured by this range of estimates. Chapter 8 of the RIA presents the results of each of the
ozone mortality studies separately.

   In a recent report on the estimation of ozone-related premature mortality published by the
National Research Council (NRC), a panel of experts and reviewers concluded that
ozone-related mortality should be included in estimates of the health benefits of reducing ozone
exposure. The report also recommended that the estimation of ozone-related premature mortality
be accompanied by broad uncertainty analyses while giving little or no weight to the assumption
that there is no causal association between ozone  exposure and premature mortality.  Because
EPA has yet to develop a coordinated response to the NRC report's findings and
recommendations, however, we have retained  the approach to estimating ozone-related
premature mortality used in RIA for the final Ozone NAAQS.  EPA will specifically address the
report's findings and recommendations in future rulemakings.

   The range of total ozone- and PM-related benefits associated with the final  standards is
presented in Table 11. We present total benefits based on the PM- and ozone-related premature
mortality function used.  The benefits ranges therefore reflect the addition of each estimate  of
ozone-related premature mortality (each with its own row in Table 11) to estimates of
PM-related premature mortality, derived from  either the epidemiological literature or the expert
elicitation.
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                                                                                Executive Summary
  Table 11:  Estimated Monetized PM- and Ozone-Related Health Benefits of the Small SI
                                 and Marine SI Engine Standards
2030 Total Ozone and PM Benefits - PM Mortality Derived from Epidemiology Studies3
Premature Ozone Mortality
Function or Assumption
NMMAPS
Meta-analysis
Reference
Bell etal, 2004
Bell etal, 2005
Ito etal., 2005
Levy etal., 2005
Assumption that association is not causal6
Mean Total Benefits
(Billions, 2005$, 3% discount
rate)c'd
$2.4
$3.7
$4.4
$4.4
$1.8
2030 Total Ozone and PM Benefits - PM Mortality Derived from Expert Elicitationb
Premature Ozone Mortality
Function or Assumption
NMMAPS
Meta-analysis
Reference
Bell etal., 2004
Bell etal., 2005
Ito etal., 2005
Levy etal., 2005
Assumption that association is not causal6
Mean Total Benefits
(Billions, 2005$, 3% discount
rate)c'd
$1.7 to $9.7
$3.0 to $11
$3. 7 to $12
$3. 7 to $12
$1.1 to $9.1
a Total includes ozone and PM2.5 benefits.  Range was developed by adding the estimate from the ozone premature
mortality function to an estimate of PM2.5-related premature mortality derived from the ACS (Pope et al., 2002)
study.
b Total includes ozone and PM2.5 benefits.  Range was developed by adding the estimate from the ozone premature
mortality function to both the lower and upper ends of the range of the PM2.5 premature mortality functions
characterized in the expert elicitation. The effect estimates of five of the twelve experts included in the elicitation
panel fall within the empirically-derived range provided by the ACS and Six-Cities studies. One of the experts fall
below this range and six of the experts are above this range.  Although the overall range across experts is
summarized in this table, the full uncertainty in the estimates is reflected by the results for the full set of 12 experts.
The twelve experts'judgments as to the likely mean effect estimate are not evenly distributed across the range
illustrated by arraying the highest and lowest expert means.
0 Note that total benefits presented here do not include a number of unqualified benefits categories. A detailed
listing of unqualified health and welfare effects is provided in Table 8.4-1.
d Results reflect the use of a 3 percent discount rate.  Monetary results presented in Table 8.6-2 use both a 3 and 7
percent discount rate, as recommended by EPA's Guidelines for Preparing Economic Analyses and OMB Circular
A-4. Results are rounded to two significant digits for ease of presentation and computation.
eA recent report published by the National Research Council (NRC, 2008) recommended that EPA "give little or no
weight to the assumption that there is no causal association between estimated reductions in premature mortality and
reduced ozone exposure."
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Final Regulatory Impact Analysis
   We estimate that by 2030, the annual emission reductions associated with these more
stringent standards will annually prevent 230 PM-related premature deaths (based on the ACS
cohort study), between 77 and 350 ozone-related premature deaths (assuming a causal
relationship between ozone and mortality), 1,700 hospital admissions and emergency room
visits, 23,000 work days lost, and approximately 590,000 minor restricted-activity days.
Impact on Small Businesses

   Chapter 10 discusses our Small Business Flexibility Analysis, which evaluates the impacts of
the emission standards on small entities. As a part of this analysis, we interacted with several
small entities representing the various affected sectors and convened a Small Business Advocacy
Review (SBAR) Panel to gain feedback and advice from these representatives.  The small
entities that participated in the process included engine manufacturers, equipment manufacturers,
vessel manufacturers, fuel tank manufacturers, and fuel hose manufacturers. The feedback from
these companies was used to develop regulatory options which could address the impacts of the
rule on small businesses.  Small entities raised general concerns related to potential difficulties
and costs of meeting the  new standards.

   The SBAR Panel consisted of representatives from EPA, the Office of Management and
Budget, and the Small Business Administration.  The Panel developed a wide range of regulatory
flexibilities to mitigate the impacts of the standards on small entities,  and recommended that we
propose and seek comment on the flexibilities. Chapter 10 discusses the flexibilities
recommended by the Panel, and the flexibilities we are finalizing with today's rule. We are
establishing several  provisions that give affected small entities several compliance options aimed
specifically at reducing their compliance burdens.  In general the options are similar to small
entity provisions adopted in prior rulemakings where EPA set standards for other types of
nonroad engines. The provisions include extra lead time for complying with the new standards,
reduced testing requirements for demonstrating compliance with the new standards, and hardship
provisions to address significant economic impacts and unusual circumstances related to the new
standards. These provisions are intended to reduce the burden on small entities that will be
required to meet the new emission standards when they are implemented.  Given all of the
flexibilities being adopted for small entities, we believe that this action will not have a
significant economic impact on a substantial number of small entities.

Alternative Program Options

   In developing the emission standards, we considered several alternatives including less
and/or more stringent options. The paragraphs below summarize the information considered in
Chapter 11 of the Draft RIA.

Small SI Engines

   For Small SI engines, we considered what was achievable with catalyst technology. Our
technology assessment work indicated that the emission standards are feasible in the context of

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                                                                    Executive Summary
provisions for establishing emission standards prescribed in section 213 of the Clean Air Act.
We also considered what could be achieved with larger, more efficient catalysts and improved
fuel induction systems. In particular, Chapter 4 of the Draft RIA presents data on Class I
engines with more active catalysts and on Class II engines with closed-loop control fuel injection
systems in addition to a catalyst.  In both cases larger emission reductions were achieved.

   Based on this work we considered HC+NOx standards which would have involved a 50
percent reduction  for Class I engines and a 65-70 percent reduction for Class II engines.  Chapter
11 of the Draft RIA evaluates these alternatives, including an assessment of the overall
technology and costs of meeting more stringent standards.  For Class I engines a 50 percent
reduction standard would require base engine changes not necessarily involved with the new
standards and the use of a more active catalyst. For Class II engines this would require the
widespread use of closed loop control fuel injection systems rather than carburetors, some
additional engine upgrades, and the use three-way catalysts. We believe it is not appropriate at
this time to establish more stringent exhaust emission standards for Small SI engines.  Our key
concern is lead time. More stringent standards would require several years (3-5) more lead time
beyond the 2011 model year start date. We believe it would be more effective to implement the
Phase 3 standards we are finalizing today to achieve near-term emission reductions needed to
reduce ozone precursor emissions and to minimize growth in the Small SI exhaust emissions
inventory in the post 2010 time frame. More  efficient catalysts, engine improvements, and
closed loop electronic fuel injection could be  the basis for more stringent emission standards at
some point in the future.

Marine SI Engines

   In developing  the final emission standards for SD/I engines, we considered both what was
achievable without catalysts and what could be achieved with larger, more efficient catalysts
than those used in our test programs. Without catalysts, we believe exhaust gas recirculation is a
technologically feasible and cost-effective approach to reducing emissions from SD/I marine
engines.  However, we believe greater reductions could be achieved through the use of catalysts.
We considered basing an interim standard on  EGR, but were concerned that this will divert
manufacturers' resources away from catalyst development and could have the effect of delaying
emission reductions from this sector.

   Several of the  marine engines with catalysts that were tested as part of the development of
the standards had HC+NOx emission rates appreciably lower than 5 g/kW-hr, even with
consideration of expected in-use emissions deterioration associated with catalyst aging. We
considered a 2.5 g/kW-hr HC+NOx standard in our analysis of alternatives. However, we
believe a standard of 5 g/kW-hr is still appropriate given the potential variability of in-use
performance and in test data.

   For OB/PWC  engines, we considered a level of 10 g/kW-hr HC+NOx for OB/PWC engines
greater than 40 kW with an equivalent percent reduction below the new standards for engines
less than 40 kW. This second tier of standards could apply in the 2012 or later time frame.  Such
a standard would be consistent with currently certified emission levels from a significant number

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Final Regulatory Impact Analysis
of four-stroke outboard engines. We have three concerns with adopting this second tier of
OB/PWC standards.  First, while some four-stroke engines may be able to meet a 10 g/kW-hr
standard with improved calibrations, it is not clear that all engines could meet this standard
without applying catalyst technology. As described in Section IV.H.3 of the preamble, we
believe it is not appropriate to base standards in this rule on the use of catalysts for OB/PWC
engines.  The technology is yet to be adequately demonstrated. Second, certification data for
personal watercraft engines show somewhat higher exhaust emission levels, so setting the
standard at 10 g/kW-hr would likely require catalysts for many models. Third, two-stroke direct
injection engines operate with lean air-fuel ratios, so reducing NOx emissions with any kind of
aftertreatment is challenging.

   Therefore, unlike the standards for SD/I engines, we are not pursuing OB/PWC  standards
that will require the use of catalysts. Catalyst technology would be necessary for significant
additional control of HC+NOx and CO emissions. While there is good potential for eventual
application of catalyst technology to OB/PWC engines, we believe the technology is not
adequately demonstrated at this point.

Evaporative Emission Controls

   We considered both less and more stringent evaporative emission control alternatives for fuel
systems used in Small SI equipment and Marine SI vessels.  Chapter 11 of the Draft RIA
presents details on this analysis of regulatory alternatives. The results of this analysis are
summarized below.  We believe that the permeation standards are reflective of available
technology and represent a step change in emissions performance. Therefore, we consider the
same permeation control  scenario in the less stringent and more stringent regulatory alternatives.

   For Small SI equipment, we considered a less stringent alternative without running loss
emission standards for Small SI engines. However, we believe that controlling running loss
emissions from non-handheld equipment is feasible at a relatively low cost.  Running loss
emissions can be controlled by changing the fuel tank and cap venting scheme and  routing
vapors from the fuel tank to the engine intake.  Not requiring these controls would be
inconsistent with section 213 of the Clean Air Act. For a more stringent alternative, we
considered applying a diurnal emission standard for all Small SI equipment. We believe that
passively purging carbon canisters could reduce diurnal emissions by 50 to 60 percent from
Small SI equipment.  However, we believe there would be significant costs to add carbon
canisters to all Small SI equipment nationwide, especially when taking packaging and vibration
into account.  The cost sensitivity is especially noteworthy given the relatively low emissions
levels (on a per-equipment basis) from such small fuel tanks.

   For Marine  SI vessels, we considered a less stringent alternative, where there would be no
diurnal emission standard for vessels with installed fuel tanks. However, installed fuel tanks on
marine vessels are much larger in capacity than those used in Small SI  applications. Our
analysis indicates that traditional carbon canisters are feasible for boats at relatively low cost.
While packaging and vibration are also issues with marine applications, we believe  these issues
have been addressed. Carbon canisters were installed on fourteen boats by industry  in a pilot

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                                                                     Executive Summary
program. The results demonstrated the feasibility of this technology.  The standards would be
achievable through engineering design-based certification with canisters that are very much
smaller than the fuel tanks.  In addition, sealed systems, with pressure control strategies would
be accepted under the engineering design-based certification.  For a more stringent scenario, we
consider a standard that would require boat builders to use an actively purged carbon canister.
This means that, when the engine is operating, it would draw air through the canister to purge the
canister of stored hydrocarbons. However, we rejected this option because active purge occurs
infrequently due to the low hours of operation per year seen by many boats. The gain in overall
efficiency would be quite small relative to the complexity active purge adds into the system in
that the engine must be integrated into a vessel-based control strategy. The additional benefit of
an actively purged diurnal control system is small in comparison to the cost and complexity of
such a system.

Conclusion

   We believe the new emission standards reflect what manufacturers can achieve through the
application of available technology.  We believe the lead time is necessary and adequate for
manufacturers to select, design, and produce emission control strategies that will work best for
their product lines.  We expect that meeting these requirements will pose a challenge, but one
that is feasible when taking into consideration the availability and cost of technology, lead time,
noise, energy, and safety.
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                                                             Industry Characterization
              CHAPTER 1:  Industry Characterization

       The information contained in this chapter on the Small SI engine and Marine SI engine
industries was assembled by RTI International, a Health, Social and Economics Research firm in
cooperation with EPA. RTI prepared one report each on the Small SI and Marine SI industries,
"Industry Profile for Small Nonroad Spark Ignition Engines and Equipment"1 and "Industry
Profile for Marine SI Industry"2 report.  The following sections provide a brief report overview.
The reader is encouraged to refer to the reports for greater detail. In addition, this chapter
includes an overview of production practices for fuel system component manufacturers. Chapter
10 provides more information on businesses that would be affected by new standards.

1.1  Manufacturers of Small SI Engines

       The nonroad spark-ignition (SI) industry includes a wide variety of handheld and
nonhandheld equipment. Nonhandheld equipment is powered mainly by four-stroke gasoline
engines; handheld equipment is powered mainly by two-stroke gasoline engines.  Comprising
much of what the general public considers "lawn and garden (L&G) equipment," this industry
also produces significant numbers of generators, compressors, and construction and maintenance
equipment. The industry often refers to itself as the "outdoor power equipment" industry.

       The industry profile report prepared by RTI for Small SI provides background
information on the engines and equipment that make up the small nonroad SI industry, defined
as those products rated less than or equal to 19 kilowatt (kW) (roughly equivalent to 25
horsepower [hp]).  The profile describes markets for engines and equipment, and discusses their
use in both consumer and commercial applications. In each market, producers and consumers
are described, along with product attributes and the effect of those attributes  on production cost
and demand. The market analysis emphasizes assessing suppliers' cost of production and
industry structure, along with demanders' price responsiveness and consumption alternatives.

       The variety of products in this industry is usefully partitioned by both application
categories and engine type. Figure 1-1 illustrates the links between the market segments of the
Small SI engine supply chain included  in the profile, from engine manufacturing and sale to
equipment production,  and on to purchase by consumers and commercial customers. Although
more than 98 percent of total unit sales in the L&G equipment sector go to households, other
sectors' sales are dominated by commercial equipment. Because of the significantly higher
prices of commercial units, commercial sales represent a considerable share of the total value of
production.

       It should be noted that there is a fair amount of vertical integration in the handheld
industry, with the same parent firm making both engines and the equipment in which those
engines are used. Handheld equipment includes string trimmers, leaf blowers, and chainsaws.
This situation is known as "captive" engine production; data on internal consumption of engines
and transfer prices are typically not available outside the firm.  The makers of non-handheld

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Final Regulatory Impact Analysis
engines typically sell their engines to independent equipment manufacturers in a merchant
engine market, where prices and quantities exchanged can be directly observed.

       The industry profile report prepared by RTI for Small SI presents information on product
characteristics, supply-side considerations, consumer demand, and market structure for small
nonroad SI engines. The report also  includes similar types of information on equipment
markets, broken down by  application category. Considerations related to consumer and
commercial markets are included in the report.

               Figure 1-1:  The Nonroad Small SI Industry
              Consumers
                                            C o m m e re ia I U s e rs
                          EquipmentMarkets
                                 Lawnmowers
                         Handheld Lawn and  Garden
                           Other Lawn and  Garden
                          Generators  and Welders
                          Compressors  and Pumps
                            Recreational Products
                               Snow  Blowers
                               Other S m a II SI
 I m p o rts
   Engines
   Equipment
N onintegrated
  E q u ip m e n t
M a n u fa c t u re rs
                    S m a I
                             I Engine
                             Class
                            Size
                                      M a rk e ts
                            M e re h a n t
                             E n g in e
                          M a n u fa c tu re rs
  In te g ra te d
  E q u ip m e n t
M a n u fa c tu re rs
                              C a ptiv e
                              E n g in e
                           M a n u fa c t u re rs
1.2  Manufacturers of Marine Spark-Ignition Engines

       The Marine SI industry is dominated by recreational applications with some commercial
use and includes markets for several types of boats, personal watercraft (PWC), and SI engines
that power them. The industry profile presented in the "Industry Profile for Marine SI Industry"
report by RTI describes producers and consumers for each market segment; product attributes
and the effects of these attributes on production costs and demand are described as well.  As part
of the market characterization, particular emphasis is placed on assessing suppliers' industrial
organization and cost of production and demanders' price responsiveness and substitution
possibilities. The Marine SI industry is divided into three applications areas: outboard (OB)
boats, sterndrive and inboard (SD/I) boats, and PWC.
                                           1-2

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                                                              Industry Characterization
1.2.1 OB Boats

       An OB boat is a vessel powered by one or more gasoline engines, which are located
outside the hull at the back of the boat. The engine and drive unit are combined in a single
package. An engine can easily be removed from the boat for inspection or repair, and it is quite
common for the boat owner to change engines during the life of the vessel.  The OB boat
segment is the largest of the three application areas; in 2002, 213,000 units were sold, which is
more than the combined sales of SD/I and PWC.

       The OB application area can be further divided into "recreational" and "luxury"
categories.  The luxury category includes more-expensive vessels, for which the engine
constitutes only a small portion of the cost of the entire vessel.  The NMMA distinguishes
between 14 types of OB vessels, 10 of which are considered recreational and 4 luxury.

1.2.2 SD/I Boats

       SD/I vessels have an engine installed inside the hull of the vessel. An inboard vessel is a
boat in which the engine is located inside the hull at the center of the boat with a propeller shaft
going through the rear of the boat.  A sterndrive (or inboard/outboard) vessel is a boat in which
the engine is located inside the hull at the back of the boat with a drive assembly couple directly
to the propeller, propeller shaft going through the rear of the boat.  In contrast to OB vessels,
SD/I vessels' engine is an integral part. Removal or replacement is significantly more difficult,
so most repair work is done with the  engine in place.  Just like OBs, the SD/I application area is
divided into recreational and luxury categories.

1.2.3 PWC

       According to the Personal Watercraft Industry Association (PWIA), a PWC is defined as
a "vessel with an inboard motor powering a water jet pump as its primary source of motive
power, and which is designed to be operated by a person  sitting, standing, or kneeling on the
vessel."

       The PWC application area is  divided into the entry level, high end, and performance
categories based on the horsepower ratings of the vessel.  These categories correspond to 50 to
100 hp, 100  to 175 hp, and over  175  hp accordingly.  Our study considers two categories that
were available in 2002:  entry level and high end. The performance category was introduced in
2003.

1.2.4 Marine SI Engines

       Some OB engine manufacturers specifically build their engines to be incorporated into
boats produced by another division within the same parent company. Other manufacturers
produce and sell their engines to independent OB boat builders  or consumers who need a
replacement engine.  SD/I engine manufacturers typically build custom engines for SD/I boats
by marinizing automotive engines. All PWC vessel manufacturers build their own engines for

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Final Regulatory Impact Analysis
their vessels

       Marine SI engines sold today are a mix of three primary technologies: crankcase
scavenged two-stroke engines, direct-injection two-stroke engines, and four-stroke engines.
Table 6.2.2-11 in Chapter 6 presents our best estimate of the technology mix for OB and PWC
engines by power class. This technology mix is based on data submitted by manufacturers when
the certify to our existing HC+NOx exhaust emission standards. Prior to the implementation of
the existing standards, the vast majority of outboard and PWC engines were crankcase
scavenged two-stroke engines.

The following Figures show the flow of engines from the engine manufacturer to the consumer
for the different engine types.
              Figure 1-2. OB Marine Economic Model Conceptual Flow Chart
         Consumers
          Loose Engines
                   Imports
                    Engines
                    Equipment
Consumers
New Boats
i
k
                                      Equipment Market
Noninteg rated
  Equipment
Manufacturers
                                        Marine SI Engine
                                            Markets
                                            Merchant
                                             Engine
                                          Manufacturers
  Integrated
  Equipment
Manufacturers
                              Captive
                               Engine
                            Manufacturers
                                          1-4

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                                                  Industry Characterization
     Figure 1-3: PWC Economic Model Conceptual Flow Chart
Consumer
>
k
                          Equipment Market
t
Integrated
Manufa
i
Captive
Manufa
k
Equipment
cturers
k
Engine
cturers
Figure 1-4: Inboard Marine Economic Model Conceptual Flow Chart
          Integrated
          Equipment
         Manufacturer
i
k.
Merchant
Engine
Manufacturer
                               1-5

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Final Regulatory Impact Analysis
1.3  Fuel System Components

       The primary fuel system components that would be affected by the rule are the fuel tanks
and fuel lines on affected equipment and vessels. This section gives an overview of the
production practices for these products.

1.3.1 Fuel Tank Production Practices

       Plastic fuel tanks are either blow-molded, injection-molded, or rotational-molded.
Generally, portable, PWC, and mid-sized Small SI fuel tanks are blow-molded. Blow-molding
involves forming polyethylene in large molds using air pressure to shape the tank. Because this
has high fixed costs, blow molding is only used where production volumes are high.  This works
for portable fuel tanks where the volumes are high and a single shape can be used for most
applications.  For portable tanks, the fuel tank manufacturer will generally design the tank, then
send it out to  a blow molder for production.

       Smaller fuel tanks used in Small SI equipment are often injection-molded. In the
injection molding process, fuel tanks are formed by forcing heated plastic into molds at high
pressure. Generally, two fuel tank halves are formed, which are later fused together. This
process requires high tooling costs, but lower total fixed costs than blow-molding. Injection-
molding is typically used for smaller fuel tanks and has the advantage of giving manufacturers
the ability to work with complex tank designs.

       Larger fuel tanks used on Class II equipment and in boats with installed fuel tanks are
typically rotational-molded out of cross-link polyethylene. Rotational-molding is a lower cost
alternative for smaller production volumes.  In this method, a mold is filled with a powder form
of polyethylene with a catalyst material.  The mold is rotated in  an oven; the heat melts the
plastic and activates the catalyst which causes a strong cross-link material structure to form.
This method is used for Class II fuel tanks where the tanks are unshielded on the equipment.
These fuel tanks  also used meet specific size and shape requirements for boats and are preferred
because they  do not rust like metal tanks, but at the same time are more fire resistant than high-
density polyethylene fuel tanks.

       Metal fuel tanks are also used on both Small SI equipment and boats.  Typically, metal
tanks on Small SI equipment are made of steel.  These tanks  are typically stamped out in two
pieces  and either welded or formed together with a seal. Aluminum  fuel tanks are also used
primarily for  installed marine fuel tanks because aluminum is more resistant to oxidation than
steel. In the marine industry, tank manufacturers generally custom make each tank to meet the
boat manufacturers needs. Generally, sheet aluminum is used and is cut, bent, and welded into
the required configuration.

1.3.2 Fuel Hose Production Practices

       Marine hose is designed to meet the Coast Guard performance requirements as defined
by the  Society of Automotive Engineer's recommended practice SAE J 1527.  For fuel supply

                                           1-6

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                                                               Industry Characterization
lines, this includes a permeation rate of 100 g/m2/day at 23C (Class 1).  For other fuel hose not
normally continuously in contact with fuel (vent and fuel fill neck), the permeation standard is
300 g/m2/day (Class 2).  In general, boat builders will use Class 1 hose for both fuel supply and
vent lines for simplicity. Some boat builders use low permeation barrier hose, for which,
specifications are now included in SAE J 1527. For fuel fill necks, boat builders generally use
Class 2 hose. Small SI hose is typically produced to manufacturer specifications. However,
manufacturers may specify hose based on industry standards such as those listed in SAE J30.

       Most fuel supply and vent hose is extruded nitrile rubber with a coating for better wear
and flame resistance. Hose may also be reinforced with fabric or wire. (In contrast, plastic
automotive fuel lines are extruded without reinforcement and are generally referred to as
"tubing.")  Hose manufacturers offer a wide variety of fuel hoses including those with a barrier
layer of low permeability material, such as nylon, THV, FKM or ethyl vinyl alcohol, either on
the inside surface or sandwiched between layers of nitrile rubber. These technologies are
discussed in more detail  in Chapter 5.

       Fuel fill hose used on boats is generally manufactured by hand wrapping layers of rubber
and reinforcement materials around a steel mandril.  This hose is then heated to cure the rubber.
Fuel fill hose generally has a much larger diameter than fuel supply and vent hose and this
process offers an effective method of producing this larger diameter hose.

       Pre-formed fuel lines are made  in two ways.  The first, and more common method, is to
cut lengths  of extruded hose, before it is vulcanized, and slip them over a contoured mandril.
The hose is then vulcanized in the oven on the  mandril to give it a preformed shape. The second
way, primarily used on handheld equipment, but also for some outboard engine fuel system
components, is to injection-mold small parts. To make the parts hollow, they are molded with a
mandril inside.  To remove the mandril, the part is typically inflated with air for just long enough
to pull it off the mandril. Primer bulbs are also made in this manner.
                                           1-7

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Final Regulatory Impact Analysis
Chapter 1 References




1.  "Industry Profile for Small Nonroad Spark-Ignition Engines and Equipment," RTI International, October 2006.



2. "Industry Profile for Marine SI Industry," RTI International, October 2006.
                                              1-8

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Final Regulatory Impact Analysis
CHAPTER 2: Air Quality, Health, and Welfare Concerns

       The standards finalized in this action will reduce emissions of hydrocarbons (HC),
oxides of nitrogen (NOx), carbon monoxide (CO) and air toxics from the engines, vessels and
equipment subject to this rule. Emissions of these pollutants contribute to ozone, PM and CO
nonattainment and to  adverse health effects associated with air toxics.  The emissions from
these engines, vessels and equipment also contribute to adverse environmental effects.

       The health and environmental effects associated with emissions from Small SI engines
and equipment and Marine SI engines and vessels are a classic example of a negative
externality (an activity that imposes uncompensated costs on others). With a negative
externality, an activity's social cost (the cost on society imposed as a result of the activity
taking place) exceeds its private cost (the cost to those directly engaged in the activity). In
this case, as described in this chapter, emissions from Small SI engines and equipment and
Marine SI engines and vessels impose public health and environmental costs on society.  The
market system itself cannot correct this externality.  The end users of the  equipment and
vessels are often unaware of the environmental impacts of their use for lawn care or
recreation.  Because of this, consumers fail to  send the  market a signal  to provide cleaner
equipment and vessels. In addition, producers  of these engines, equipment, and vessels are
rewarded for emphasizing other aspects of these products (e.g., total power). To correct this
market failure and reduce the negative externality, it is  necessary to give producers social cost
signals. The standards EPA is finalizing will accomplish this by mandating that  Small SI
engines and equipment and Marine SI engines and vessels reduce their emissions to a
technologically feasible limit. In other words, with this rule the costs of the services provided
by these engines and equipment will account for social costs more fully.

       In this Chapter we will discuss the impacts of the pollutants emitted by Small  SI
engines and equipment and Marine SI engines and vessels on health and welfare, National
Ambient Air Quality  Standard (NAAQS) attainment, and personal exposure. Air quality
modeling and monitoring data presented in this chapter indicate that a large number of people
live in counties that are designated as nonattainment for either or both of the 8-hour ozone or
PM2.5 NAAQS. Figure 2-1 illustrates the widespread nature of the ozone and PM2.5
nonattainment areas and also depicts mandatory class I areas. The emission standards in this
rule will help reduce HC, NOx, PM, air toxic and CO emissions and their associated health
and environmental effects.
                                            2-2

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                                             Air Quality, Health and Welfare Concerns
  Legend

    | Class I Areas
  m PM2 5 and Ozone NonAttainment
      Ozone NonAttainment
      PM2.5 NonAttainment
                                                                   Map current through March 12. 2008
  Figure 2-1: 8-Hour Ozone and PMi.s Nonattainment Areas and Mandatory Class I
  Federal Areas
2.1    Ozone

       In this section we review the health and welfare effects of ozone exposure.  We also
describe the air quality monitoring and modeling data that indicates people in many areas
across the country are exposed to levels of ambient ozone above the 1997 and 2008 ozone
NAAQS.  The data also indicates that in the future people will continue to live in counties
with ozone levels above the NAAQS without additional federal, state or local measures.
Emissions of volatile organic compounds (VOCs), of which HC are a subset, and NOx from
the engines, vessels and equipment subject to this rule contribute to these ozone
concentrations. Information on air quality was gathered from a variety of sources, including
monitored ozone concentrations, air quality modeling forecasts conducted for this rulemaking,
and other state and local air quality information.
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Final Regulatory Impact Analysis
2.1.1  Science of Ozone Formation

       Ground-level ozone pollution is formed by the reaction of VOCs and NOx in the
atmosphere in the presence of heat and sunlight.  These pollutants, often referred to as ozone
precursors, are emitted by many types of pollution sources such as highway vehicles and
nonroad engines (including those subject to this rule), power plants, chemical plants,
refineries, makers of consumer and commercial products, industrial facilities, and smaller area
sources.

       The science of ozone formation, transport, and accumulation is complex.1  Ground-
level ozone is produced and destroyed in a cyclical set of chemical reactions, many of which
are sensitive to temperature and sunlight. When ambient temperatures and sunlight levels
remain high for several days  and the air is relatively stagnant, ozone and its precursors can
build up and result in more ozone than typically would occur on a single high-temperature
day.  Ozone can be transported hundreds of miles downwind of precursor emissions, resulting
in elevated ozone levels even in areas with low VOC or NOx emissions.

       The highest levels of ozone are produced when both VOC and NOx emissions are
present in significant quantities on clear summer days. Relatively small amounts of NOx
enable ozone to form rapidly when VOC levels are relatively high, but ozone production is
quickly limited by removal of the NOx.  Under these conditions NOx reductions are highly
effective in reducing ozone while VOC reductions have little effect.  Such conditions are
called "NOx-limited". Because the contribution of VOC emissions from biogenic (natural)
sources to local ambient ozone concentrations can be significant, even some areas where man-
made VOC emissions are relatively low can be NOx-limited.

       Ozone concentrations in an area also can be lowered by the reaction of nitric oxide
(NO) with ozone, forming nitrogen dioxide (NO2); as the air moves downwind and the cycle
continues, the NO2 forms additional ozone. The importance of this reaction depends, in part,
on the relative concentrations of NOx, VOC, and ozone, all of which change with time and
location.  When NOx levels are relatively high and VOC levels relatively low, NOx forms
inorganic nitrates (i.e., particles) but relatively little ozone.  Such conditions are called "VOC-
limited". Under these conditions, VOC reductions are effective in reducing ozone, but NOx
reductions can actually increase local ozone under certain circumstances. Even in VOC-
limited urban areas, NOx reductions are not expected to increase ozone levels if the NOx
reductions are sufficiently large.

      Rural  areas are usually NOx-limited, due to the relatively large amounts of biogenic
VOC emissions in such areas. Urban areas can be either VOC- or NOx-limited, or a mixture
of both, in which ozone levels exhibit moderate sensitivity to changes in either pollutant.

2.1.2 Health Effects of Ozone Pollution

      Exposure to ambient ozone contributes to a wide range of adverse health effectsA.
A Human exposure to ozone varies over time due to changes in ambient ozone concentration and because people
move between locations which have notable different ozone concentrations. Also, the amount of ozone

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                                             Air Quality, Health and Welfare Concerns
These health effects are well documented and are critically assessed in the EPA ozone air
                                                         91
quality criteria document (ozone AQCD) and EPA staff paper. '  We are relying on the data
and conclusions in the ozone AQCD and staff paper, regarding the health effects  associated
with ozone exposure.

       Ozone-related health effects include lung function decrements, respiratory symptoms,
aggravation of asthma,  increased hospital and emergency room visits, increased asthma
medication usage, and a variety of other respiratory effects.  Cell-level effects such as,
inflammation of lungs,  have been documented as well. In addition, there is suggestive
evidence of a contribution of ozone to cardiovascular-related morbidity and highly suggestive
evidence that short-term ozone exposure directly or indirectly contributes to non-accidental
and cardiopulmonary-related mortality, but additional research is needed to clarify the
underlying mechanisms causing these effects. In a recent report on the estimation of ozone-
related premature mortality published by the National Research Council  (NRC), a panel of
experts and reviewers concluded that short-term exposure to ambient ozone is likely to
contribute to premature deaths and that ozone-related mortality should be included in
estimates of the health benefits of reducing ozone exposure.4 People who appear to be more
susceptible to effects associated with exposure to ozone include children, asthmatics and the
elderly. Those with greater exposures to ozone, for instance due to time spent outdoors (e.g.,
children and outdoor workers), are also of concern.

       Based on a large number of scientific studies, EPA has identified several key health
effects associated with  exposure to levels of ozone found today in many  areas of the country.
Short-term (1 to 3 hours)  and prolonged exposures (6 to 8 hours) to higher ambient ozone
concentrations have been linked to lung function decrements, respiratory symptoms, increased
hospital admissions and emergency room visits for respiratory problems.5'6'7'8'9'10 Repeated
exposure to ozone can increase susceptibility to respiratory infection and lung inflammation
and can aggravate preexisting respiratory diseases, such as asthma.11'12'13'14'15 Repeated
exposure to sufficient concentrations of ozone can also cause inflammation of the lung,
impairment of lung defense mechanisms, and possibly irreversible changes in lung structure,
which over time could affect premature aging of the lungs and/or the development of chronic
respiratory illnesses, such as emphysema and chronic bronchitis.16'17'18'19

       Children and adults who are outdoors and active during the summer months, such as
construction workers, are among those most at risk of elevated ozone exposures.20 Children
and outdoor workers tend to have higher ozone exposure because they typically are active
outside, working, playing and exercising, during times of day and seasons (e.g., the summer)
when ozone levels are highest.21 For example,  summer camp studies in the Eastern United
States and Southeastern Canada have reported statistically significant reductions in lung
function in children who are active outdoors.22'23'24'25'26'27'28'29  Further, children are more at
risk of experiencing health effects from ozone exposure than adults because their respiratory
systems are still developing. These individuals (as well as people with respiratory illnesses
such as asthma, especially asthmatic children) can experience reduced lung function and
increased respiratory symptoms, such as chest pain and cough, when exposed to relatively low

delivered to the lung is not only influenced by the ambient concentration but also by the individuals breathing
route and rate.

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Final Regulatory Impact Analysis
ozone levels during prolonged periods of moderate exertion.30'31; 32'33

2.1.3  Current Ozone Levels

       The small SI and marine SI engine emission reductions will assist ozone
nonattainment areas in reaching the standard by each area's respective attainment date and/or
assist in maintaining the ozone standard in the future. In this and the following section we
present information on current and model-projected future ozone levels.

       A nonattainment area is defined in the CAA as an area that is violating a NAAQS or is
contributing to a nearby area that is violating the NAAQS. EPA designated nonattainment
areas for the 1997 ozone NAAQS in June 2004. The final rule on Air Quality Designations
and Classifications for the 1997 Ozone NAAQS (69 FR 23858, April 30, 2004) identifies the
criteria that EPA considered in making the 1997 8-hour ozone nonattainment designations,
including 2001-2003 measured data, air quality in adjacent areas, and other factors.8

       As  of March 12, 2008 there are approximately 140 million people living in 72 areas
designated as nonattainment with the 1997 8-hour ozone NAAQS.  There are 337 full or
partial counties that make up the 8-hour ozone  nonattainment areas.  These numbers do not
include the people living in  areas where there is a future risk of failing to maintain or attain
the 8-hour  ozone NAAQS.  The 1997 8-hour ozone nonattainment areas, nonattainment
counties, and populations are listed in Appendix 2A to this RIA.

       EPA has recently amended the ozone NAAQS (73 FR 16436, March 27, 2008). The
final ozone NAAQS rule addresses revisions to the primary  and  secondary NAAQS for ozone
to provide  increased protection of public health and welfare, respectively.  With regard to the
primary standard for ozone, EPA has revised the level of the 8-hour standard to 0.075 parts
per million (ppm), expressed to three decimal places. With regard to the secondary standard
for ozone, EPA has revised  the current 8-hour standard by making it identical to the revised
primary standard.

       States with ozone nonattainment areas are required to take action to bring those areas
into compliance in the future.  The attainment date assigned to an ozone nonattainment area is
based on the area's classification.  Most ozone  nonattainment areas will be required to attain
the 1997 8-hour ozone NAAQS in the 2007 to 2013 time frame and then be required to
maintain it thereafter.0  The attainment dates associated with the potential nonattainment areas
B An ozone design value is the concentration that determines whether a monitoring site meets the NAAQS for
ozone. Because of the way they are defined, design values are determined based on three consecutive-year
monitoring periods. For example, an 8-hour ozone design value is the fourth highest daily maximum 8-hour
average ozone concentration measured over a three-year period at a given monitor. The full details of these
determinations (including accounting for missing values and other complexities) are given in Appendices H and
I of 40 CFR Part 50. For a county, the design value is the highest design value from among all the monitors with
valid design values within that county. If a county does not contain an ozone monitor, it does not have a design
value.  However, readers should note that ozone design values generally represent air quality across abroad area
and that absence of a design value does not imply  that the county is in compliance with the ozone NAAQS.
c The Los Angeles South Coast Air Basin 8-hour ozone nonattainment area is designated as severe and will have
to attain before June 15, 2021.  The South Coast Air Basin has recently applied to be redesignated as an extreme

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                                             Air Quality, Health and Welfare Concerns
based on the 2008 8-hour ozone NAAQS will likely be in the 2013 to 2021 timeframe,
depending on the severity of the problem. Table 2-1  provides an estimate, based on 2004-06
air quality data, of the counties with design values greater than the 2008 ozone NAAQS.  We
expect many of the ozone nonattainment areas will need to adopt additional emissions
reduction programs to attain and maintain the ozone NAAQS.  The expected VOC and NOX
reductions from these standards, which take effect between 2009 and 2013, will be useful to
states as they seek to either attain or maintain the ozone NAAQS.

Table 2-1 Counties with Design Values Greater Than the 2008 Ozone NAAQS Based on
2004-2006 Air Quality Data

1997 Ozone Standard: counties within the 72
areas currently designated as nonattainment
2008 Ozone Standard: additional counties that
would not meet the 2008 NAAQS6
Total
Number of Counties
337
74
411
Population"
139,633,458
15,984,135
155,617,593
Notes:
" Population numbers are from 2000 census data.
* Attainment designations for the 2008 ozone NAAQS have not yet been made. Nonattainment for the 2008
Ozone NAAQS will be based on three years of air quality data from later years. Also, the county numbers in the
table include only the counties with monitors violating the 2008 Ozone NAAQS. The numbers in this table may
be an underestimate of the number of counties and populations that will eventually be included in areas with
multiple counties designated nonattainment.
2.1.4  Projected Ozone Levels

       In conjunction with this rulemaking, we performed a series of air quality modeling
simulations for the continental U.S.  The model simulations were performed for several
emissions scenarios including the following: 2002 baseline projection, 2020 baseline
projection, 2020 baseline projection with small Si/marine SI engine controls, 2030 baseline
projection, and 2030 baseline projection with small Si/marine SI engine controls. Information
on the air quality modeling methodology is contained in Section 2.3 as well as the air quality
modeling technical support document (AQ TSD). In the following sections we describe our
modeling of 8-hour ozone levels in the future with and without the controls being finalized in
this action.

2.1.4.1 Projected 8-Hour Ozone Levels without this Rulemaking

       EPA has already adopted many emission control programs that are expected to reduce
ambient ozone levels.  These control programs include the Locomotive and Marine Rule (73
FR 25098, May 6, 2008), Clean Air Interstate Rule (70 FR 25162, May 12, 2005), the Clean
Air Nonroad Diesel rule (69 FR 38957, June 29, 2004), and the Heavy Duty Engine and
Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements (66 FR 5002, Jan.
18, 2001). As a result of these programs, the number of areas that continue to violate the 8-
hour ozone NAAQS in the future is expected to decrease.

nonattainment area which will make their attainment date June  15, 2024.

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Final Regulatory Impact Analysis
       The baseline air quality modeling completed for this rule predicts that without
additional local, regional or national controls there will continue to be a need for reductions in
8-hour ozone concentrations in some areas in the future.  The determination that an area is at
risk of exceeding the 8-hour ozone standard in the future was made for all areas with current
design values greater than or equal to 85 ppb (or within a 10 percent margin) and with
modeling evidence that concentrations at and above these levels will persist into the future.0
Those interested in greater detail should review the air quality modeling TSD which is
included in the docket for this rule.34

       The baseline inventories that underlie the modeling conducted for this rulemaking
include emission reductions  from existing federal, state and local controls. There was no
attempt to examine the prospects of areas attaining or maintaining the standard with future
possible controls. We expect many of the areas to adopt additional emission reduction
programs, but we are unable to quantify or rely upon future reductions from additional
programs since they have not yet been promulgated. With  reductions from programs already
in place (but excluding the emission reductions from this rule), the number of counties in
2020 with projected 8-hour ozone design values at or above 85 ppb is expected to be 8 with a
population of 22 million people.  In addition, in 2020, 37 counties where 27 million people
are projected to live, will be  within 10 percent of violating the 1997 8-hour ozone NAAQS.
The results should therefore  be interpreted as indicating counties at risk for violating the
ozone NAAQS in the future  without additional federal, state or local measures in addition to
this rulemaking.

2.1.4.2 Projected 8-Hour Ozone Levels with this Rulemaking

       This section summarizes the results of our modeling of ozone air quality impacts in
the future due to the reductions in small SI and marine SI emissions finalized in this action.
Specifically, we compare baseline scenarios to scenarios with controls. Our modeling
indicates that the reductions  from this rule  will provide nationwide improvements in ambient
ozone concentrations and minimize the  risk of exposures in future years.  Since some of the
VOC  and NOX emission reductions from this rule go into effect during the period when some
areas  are still working to attain the 8-hour ozone NAAQS, the projected emission reductions
will assist state and local agencies in their effort to attain the 8-hour ozone standard and help
others maintain the standard. Emissions reductions from this rule will also help to counter
potential ozone increases due to climate change, which are  expected in many urban areas in
the United States, but are not reflected in the modeling shown here.35

       On a population-weighted basis, the average modeled future-year 8-hour ozone  design
values will decrease by 0.57 ppb in 2020 and 0.76 ppb in 2030. Table 2-2 shows the average
change in future year eight-hour ozone  design values for: (1) all counties with 2002 baseline
design values, (2) counties with baseline design values that exceeded the standard in 2000-
2004 ("violating" counties),  (3) counties that did not exceed the standard, but were within  10
percent of it in 2000-2004, (4) counties  with future year design values that exceeded the
D Ozone design values are reported in parts per million (ppm) as specified in 40 CFR Part 50. Due to the scale of
the design value changes in this action results have been presented in parts per billion (ppb) format.

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                                              Air Quality, Health and Welfare Concerns
standard, and (5) counties with future year design values that did not exceed the standard, but
were within 10 percent of it in 2020 and 2030.  Counties within ten percent of the standard are
intended to reflect counties that meet the standard, but will likely benefit from help in
maintaining that status in the face of growth. All of these metrics show a decrease in 2020
and 2030, indicating in five different ways the overall improvement in ozone air quality.

 Table 2-2 Average Change in Projected Future Year 8-hour Ozone Design Value as a Result
                          of the Small SI and Marine SI controls
Average"
All
All, population-weighted
Counties whose base year is violating the 1997
8 -hour ozone standard
Counties whose base year is violating the 1997
8-hour ozone standard, population-weighted
Counties whose base year is within 10 percent of
the 1997 8-hour ozone standard
Counties whose base year is within 10 percent of
the 1997 8-hour ozone standard, population-
weighted
Counties whose future year is violating the 1997
8 -hour ozone standard
Counties whose future year is violating the 1997
8-hour ozone standard, population-weighted
Counties whose future year is within 10 percent
of the 1997 8-hour ozone standard
Counties whose future year is within 10 percent
of the 1997 8-hour ozone standard, population-
weighted
Number
of US
Counties
660
660
261
261
223
223
8 (2020)
6 (2030)
8 (2020)
6 (2030)
37 (2020)
23 (2030)
37 (2020)
23 (2030)
Change in
2020 design
value6 (ppb)
-0.47
-0.57
-0.62
-0.61
-0.42
-0.55
-0.13
-0.17
-0.71
-0.54
Change in
2030 design
value6 (ppb)
-0.66
-0.76
-0.88
-0.80
-0.61
-0.78
-0.10
-0.13
-1.05
-0.79
Notes:
" averages are over counties with 2002 modeled design values
* Ozone design values are reported in parts per million (ppm) as specified in 40 CFR Part 50. Due to the scale of
the design value changes in this action results have been presented in parts per billion (ppb) format.

       Table 2-3 lists the counties with projected 8-hour ozone design values that violate or
are within 10 percent of the 1997 8-hour ozone standard in 2020after application of the small
SI and marine SI controls.  Counties are marked with a "V" in the table if their projected
design values are greater than or equal to 85 ppb. Counties are marked with an "X" in the
table if their projected annual design values are greater than or equal to 76.5 ppb,  but less than
85 ppb. The counties marked "X" are not projected to violate the standard, but to be close to
it, so the rule will help assure that these counties continue to meet the  standard. The current
design values are also presented in Table 2-3. Recall that we project future design values only
for counties that have current design values, so this list is limited to those counties with
ambient monitoring data sufficient to calculate current 3-year design values.
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Final Regulatory Impact Analysis
       Figure 2-2 illustrates the geographic impact of the small SI and marine SI engine
controls on 8-hour ozone design values in 2020. Some of the most significant decreases will
occur in the great lakes region, the gulf coast region, the northeast corridor and in the Seattle
region. The maximum decreases in a 2020 design values is 2.0 ppb in Cape Cod,
Massachusetts.
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                                               Air Quality, Health and Welfare Concerns
 Table 2-3 Counties with 2020 8-hour Ozone Design Values in Violation or Within 10 percent
       of the 1997 Ozone Standard as a Result of the Small SI and Marine SI Controls
State
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CT
CT
IN
LA
MD
NJ
NJ
NJ
NJ
NY
OH
OH
PA
PA
TX
TX
TX
WI
WI
WI
County
El Dorado
Fresno
Kern
Kings
Los Angeles
Madera
Merced
Nevada
Orange
Placer
Riverside
Sacramento
San Bernardino
San Diego
Stanislaus
Tulare
Tuolumne
Fairfield
New Haven
Lake
East Baton Rouge
Harford
Camden
Gloucester
Mercer
Ocean
Suffolk
Ashtabula
Geauga
Bucks
Philadelphia
Brazoria
Harris
Jefferson
Kenosha
Racine
Sheboygan
2000-2004
Average 8-Hour
Ozone DV (ppb)"
105.0
110.0
114.3
95.7
121.3
91.0
101.7
97.7
85.3
98.3
115.0
99.0
128.7
92.3
95.0
105.7
91.0
98.3
98.3
88.3
87.0
100.3
99.7
98.0
97.7
105.7
97.0
95.7
99.0
99.0
96.7
94.0
102.0
91.0
98.3
91.7
97.0
2020 modeling
projections of
8-Hour Ozone
DV
X
X
X
V
X
V
V
V
V
V
X
V
X
V
V
X
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
X
V
V
V
V
2020
Population
236,310
1,066,878
876,131
173,390
10,376,013
173,940
277,863
131,831
3,900,599
451,620
2,252,510
1,640,590
2,424,764
3,863,460
607,766
477,296
70,570
962,824
898,415
509,293
522,399
317,847
547,817
304,105
392,236
644,323
1,598,742
108,355
114,438
711,275
1,394,176
322,385
4,588,812
272,075
184,825
212,351
128,777
Notes:
a Ozone design values are reported in parts per million (ppm) as specified in 40 CFR Part 50. Due to the scale of
the design value changes in this action results have been presented in parts per billion (ppb) format.
                                         2-11

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     Final Regulatory Impact Analysis
Legend       Number of Counties
|     | <= -2.0          1
   J >-2.0 to -1.0    69
     | >-1.0 to -0.5   186
     | >-0.5 to -0.1   360
^^ = 0.0          44
I     |>0.0           0
                                                                                                     2020cc_bond impact
     Figure 2-2 Impact of Small SI and Marine SI controls on 8-hour Ozone Design Values in 2020 (units are ppb)
                                                                   2-12

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2.1.5 Environmental Effects of Ozone Pollution

       There are a number of public welfare effects associated with the presence of ozone in
the ambient air.36  In this section we discuss the impact of ozone on plants, including trees,
agronomic crops and urban ornamentals.

2.1.5.1 Impacts on Vegetation

       The Air Quality Criteria Document for Ozone and related Photochemical Oxidants
notes that "ozone affects vegetation throughout the United States, impairing crops, native
vegetation, and ecosystems more than any other air pollutant. Like carbon dioxide (CO2) and
other gaseous substances, ozone enters plant tissues primarily through apertures (stomata) in
leaves in a process called "uptake".37 Once sufficient levels of ozone, a highly reactive
substance, (or its reaction products) reaches the interior of plant cells, it can inhibit or damage
essential cellular components and functions, including enzyme activities, lipids, and cellular
membranes, disrupting the plant's osmotic (i.e., water) balance and energy utilization
patterns.38'39 This damage is commonly manifested as visible foliar injury such as chlorotic or
necrotic spots, increased leaf senescence (accelerated leaf aging) and/or reduced
photosynthesis. All these effects reduce a plant's capacity to form carbohydrates, which are
the primary form of energy used by plants.40 With fewer resources available, the plant
reallocates existing resources away from root growth and storage, above ground growth or
yield, and reproductive processes, toward leaf repair and maintenance. Studies have shown
that plants stressed in these ways may exhibit a general loss of vigor, which can lead to
secondary impacts that modify plants' responses to other environmental factors. Specifically,
plants may become more sensitive to  other air pollutants, more susceptible to disease, insect
attack, harsh weather (e.g., drought, frost) and other environmental stresses. Furthermore,
there is evidence that ozone can interfere with the formation of mycorrhiza, essential
symbiotic fungi associated with the roots of most terrestrial plants, by reducing the amount of
carbon available for transfer from the host to the symbiont.41'42

       Ozone can produce both acute and chronic injury in sensitive species depending on the
concentration level and the duration of the exposure. Ozone effects also tend to  accumulate
over the growing season of the plant,  so that even lower concentrations experienced for a
longer duration have the potential to create chronic stress on sensitive vegetation. Not all
plants, however, are equally  sensitive to ozone. Much of the variation in sensitivity between
individual plants or whole species is related to the plant's ability to regulate the extent of gas
exchange via leaf stomata (e.g., avoidance of Os uptake through closure of stomata).43'44'45
Other resistance mechanisms may involve the intercellular production of detoxifying
substances. Several biochemical substances capable of detoxifying ozone have been reported
to occur in plants including the antioxidants ascorbate and glutathione. After injuries have
occurred, plants may be  capable of repairing the damage to a limited extent.46

       Because of the differing sensitivities among plants to ozone, ozone pollution can also
exert a selective pressure that leads to changes in plant community composition. Given the
range of plant sensitivities and the fact that numerous other environmental factors modify
plant uptake and response to ozone, it is not possible to identify threshold values above which

                                       2-13

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Regulatory Impact Analysis
ozone is consistently toxic for all plants.  The next few paragraphs present additional
information on ozone damage to trees, ecosystems, agronomic crops and urban ornamentals.

       Ozone also has been conclusively shown to cause discernible injury to forest trees.47'48
In terms of forest productivity and ecosystem diversity, ozone may be the pollutant with the
greatest potential for regional-scale forest impacts. Studies have demonstrated repeatedly that
ozone concentrations commonly observed in polluted areas can have substantial impacts on
plant function.49'50

       Because plants are at the center of the food web in many ecosystems, changes to the
plant community can affect associated organisms and ecosystems (including the suitability of
habitats that support threatened or endangered species and below ground organisms living in
the root zone). Ozone impacts at the community and ecosystem level vary widely depending
upon numerous factors, including concentration and temporal variation of tropospheric ozone,
species composition, soil properties and climatic factors.51  In most instances, responses to
chronic or recurrent exposure in forested ecosystems are subtle and not observable for many
years.  These injuries can cause stand-level forest decline in sensitive ecosystems.52'53'54 It is
not yet possible to predict ecosystem responses to ozone with much certainty; however,
considerable knowledge of potential ecosystem  responses has been acquired through long-
term observations in highly damaged forests in the United States.

       Laboratory and field experiments have also shown reductions in yields for agronomic
crops exposed to ozone, including vegetables (e.g., lettuce) and field crops (e.g., cotton and
wheat). The most extensive field experiments, conducted under the National Crop Loss
Assessment Network (NCLAN) examined 15 species and numerous cultivars.  The NCLAN
results show that "several economically important crop species are sensitive to ozone levels
typical of those found in the Unites States."55 In addition, economic studies have shown
reduced economic benefits as a result of predicted reductions in crop yields associated with
observed ozone levels.56'57'58

       Urban ornamentals represent an additional vegetation category likely to experience
some degree of negative effects associated with exposure to ambient ozone levels.  It is
estimated that more than $20 billion (1990 dollars) are spent annually on landscaping using
ornamentals, both by private property owners/tenants and by governmental units responsible
for public areas.59 This is therefore a potentially costly environmental effect. However, in the
absence of adequate exposure-response functions and economic damage functions for the
potential range of effects relevant to these types of vegetation, no direct quantitative analysis
has been conducted.

2.2    Participate Matter

       In this section we review the health and welfare effects of PM. We  also describe air
quality monitoring and modeling data that indicate many areas across the country continue to
be exposed to levels of ambient PM above the NAAQS. Emissions of PM, HCs and NOx
from the  engines, vessels and equipment subject to this rule contribute to these PM
concentrations.  Information on air quality was gathered from a variety of sources, including
                                         2-14

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monitored PM concentrations, air quality modeling forecasts conducted for this rulemaking,
and other state and local air quality information.

2.2.1  Science of PM Formation

       Particulate matter (PM) represents a broad class of chemically and physically diverse
substances. It can be principally characterized as discrete particles that exist in the condensed
(liquid or solid) phase spanning several orders of magnitude in size.  PMio refers to particles
generally less than or equal to 10 micrometers (//m) in aerodynamic diameter.  PM2.5 refers to
fine particles, generally less than or equal to 2.5 //m in aerodynamic diameter.  Inhalable (or
"thoracic") coarse particles refer to those particles generally greater than 2.5 //m but less than
or equal to 10 //m in aerodynamic diameter. Ultrafine PM refers to particles generally less
than 100 nanometers (0.1 //m) in aerodynamic diameter. Larger particles (>10 //m) tend to be
removed by the respiratory clearance mechanisms, whereas smaller particles are deposited
deeper in the lungs.

       Fine particles are produced primarily by combustion processes and by transformations
of gaseous emissions (e.g., SOx, NOx and VOCs) in the atmosphere. The chemical and
physical  properties of PM2.5 may vary greatly with time, region, meteorology and source
category. Thus, PM2.s, may include a complex mixture of different pollutants including
sulfates,  nitrates, organic compounds, elemental carbon and metal compounds.  These
particles  can remain in the atmosphere for days to weeks and travel through the atmosphere
hundreds to thousands of kilometers.

       Particles span many sizes and shapes and consist of hundreds of different chemicals.
Particles are emitted directly from sources and are also formed through atmospheric chemical
reactions; the former are often referred to as "primary" particles, and the latter as "secondary"
particles. In addition, there are also physical, non-chemical reaction  mechanisms that
contribute to secondary particles.  Particle pollution also varies by time of year and location
and is affected by several weather-related factors,  such as temperature, clouds, humidity, and
wind. A further layer of complexity comes  from a particle's ability to shift between
solid/liquid and gaseous phases, which is influenced by concentration, meteorology, and
temperature.

2.2.2  Health Effects of PM

       As stated in EPA's Paniculate Matter Air Quality Criteria Document (PM AQCD),
available scientific findings "demonstrate well that human health  outcomes are associated
with ambient PM."E We are relying on the data and conclusions in the PM AQCD and PM
Staff Paper, which reflects EPA's analysis of policy-relevant science from the PM AQCD,
regarding the health effects associated with  particulate matter.60'61 We also present additional
E Personal exposure includes contributions from many different types of particles, from many sources, and in
many different environments. Total personal exposure to PM includes both ambient and nonambient
components; and both components may contribute to adverse health effects.


                                       2-15

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Regulatory Impact Analysis
recent studies published after the cut-off date for the PM AQCD.F62 Taken together this
information supports the conclusion that PM-related emissions such as those controlled in this
action are associated with adverse health effects. Information on PM-related mortality and
morbidity is presented first, followed by information on near-roadway exposure studies,
marine ports and rail yard exposure studies.

2.2.2.1 Short-term Exposure Mortality and Morbidity Studies

       As discussed in the PM AQCD, short-term exposure to PM2.5 is associated with
mortality from cardiopulmonary diseases (PM AQCD, p. 8-305), hospitalization and
emergency department visits for cardiopulmonary diseases (PM  AQCD, p. 9-93), increased
respiratory symptoms (PM AQCD,  p. 9-46), decreased lung function (PM AQCD Table 8-34)
and physiological changes or biomarkers for cardiac changes (PM AQCD, Section 8.3.1.3.4).
In addition, the PM AQCD describes a limited body of new evidence  from epidemiologic
studies for potential relationships between short term exposure to PM and health endpoints
such as low birth weight, preterm birth, and neonatal and infant mortality. (PM AQCD,
Section 8.3.4).

       Among the studies of effects from short-term exposure to PM2.5, several specifically
address the contribution of mobile sources to short-term PM2 5 effects on daily mortality.
These studies indicate that there are statistically significant associations between mortality
and PM related to mobile source emissions (PM AQCD, p.8-85). The analyses incorporate
source apportionment tools into daily mortality studies and are briefly mentioned here.
Analyses incorporating source apportionment by factor analysis  with  daily time-series studies
of daily death indicated a relationship between mobile source PM2.5 and mortality.63'64
Another recent study in 14 U.S. cities examined the effect of PMi0 exposures on daily hospital
admissions for cardiovascular disease.  This study found that the effect of PMio was
significantly  greater in areas with a larger proportion of PMio coming from motor vehicles,
indicating that PMio from these sources may have a greater effect on the toxicity of ambient
PMio when compared with other sources.65  These studies provide evidence that PM-related
emissions, specifically from mobile sources, are associated with adverse health effects

Long-term Exposure Mortality and Morbidity Studies

       Long-term exposure to elevated ambient PM2.5 is associated with mortality from
cardiopulmonary diseases and lung cancer (PM AQCD, p. 8-307), and effects on the
respiratory system such as decreased lung function or the development of chronic respiratory
disease (PM AQCD, pp.  8-313, 8-314). Of specific importance to this rulemaking, the PM
AQCD also notes that the PM components  of gasoline and diesel engine exhaust represent
F These additional studies are included in the 2006 Provisional Assessment of Recent Studies on Health Effects
of Paniculate Matter Exposure. The provisional assessment did not and could not (given a very short timeframe)
undergo the extensive critical review by EPA, CASAC, and the public, as did the PM AQCD. The provisional
assessment found that the "new" studies expand the scientific information and provide important insights on the
relationship between PM exposure and health effects of PM. The provisional assessment also found that "new"
studies generally strengthen the evidence that acute and chronic exposure to fine particles and acute exposure to
thoracic coarse particles are associated with health effects.
                                          2-16

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one class of hypothesized likely important contributors to the observed ambient PM-related
increases in lung cancer incidence and mortality (PM AQCD, p. 8-318).

       The PM AQCD and PM Staff Paper emphasize the results of two long-term studies,
the Six Cities and American Cancer Society (ACS) prospective cohort studies, based on
several factors - the inclusion of measured PM data, the fact that the study populations were
similar to the general population, and the fact that these studies have undergone extensive
reanalysis (PM AQCD, p. 8-306, Staff Paper, p.3-18).66'67'68 These studies indicate that there
are significant associations for all-cause, cardiopulmonary, and lung cancer mortality with
long-term exposure to PM2 5. One analysis of a subset of the ACS cohort data, which was
published after the PM AQCD was finalized but in time for the 2006 Provisional Assessment,
found a larger association than had previously been reported between long-term PM2.s
exposure and mortality in the Los Angeles area using a new exposure estimation method that
accounted for variations in concentration within the city.69

       As discussed in the PM AQCD, the morbidity studies that combine the features of
cross-sectional and cohort studies provide the best evidence for chronic exposure effects.
Long-term studies evaluating the effect of ambient PM on children's development have
shown some evidence indicating effects of PM2.5 and/or PMio on reduced lung function
growth (PM AQCD, Section 8.3.3.2.3).  In another recent publication included in the 2006
Provisional Assessment, investigators in southern California reported the results of a cross-
sectional study of outdoor PM2 5 and measures of atherosclerosis in the Los Angeles basin.70
The study found significant associations between ambient residential PM2.5 and carotid
intima-media thickness (CIMT), an indicator of subclinical atherosclerosis, an underlying
factor in cardiovascular disease.

2.2.2.3 Roadway-Related PM Exposure and Health Studies

       A recent body  of studies examines traffic-related PM exposures and adverse health
effects.  These studies are relevant to this rule because highway SI vehicles and nonroad SI
engines, vessels and equipment have similar chemical and physical exhaust properties.
However, this comparison is qualitative in nature since the near-road environment is
influenced by both gasoline (SI) and diesel vehicles, as well as re-entrained road dust and
brake and tire wear. One  study was done in North Carolina looking at concentrations of PM2.5
inside police cars  and  corresponding physiological changes in the police personnel driving the
cars. The authors report significant elevations in markers of cardiac risk associated with
concentrations of PM2.5 inside police cars on North Carolina state highways.71 Other studies
have found associations between traffic-generated particle concentrations at residences and
adverse effects, including all-cause mortality, infant respiratory symptoms, and reduced
cognitive functional development.72'73'74'75  There are other pollutants  present in the near
roadway environment, including air toxics which are discussed in Section 2.4. Additional
information on near-roadway health effects can be found in the recent Mobile Source Air
Toxics rule (72 FR 8428, February 26, 2007).
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Regulatory Impact Analysis
2.2.3  Current and Projected PM Levels

       The emission reductions from this rule will assist PM nonattainment areas in reaching
the standard by each area's respective attainment date and assist PM maintenance areas in
maintaining the PM standards in the future.  In this and the following section we present
information on current and model-projected future PM levels.

2.2.3.1 Current PM2.5 Levels

       The small  SI and marine SI engine emission reductions will assist PM nonattainment
areas in reaching the standard by each area's respective attainment date and/or assist in
maintaining the PM standard in the future. In this and the following section we present
information on current and model-projected future PM levels.

       A nonattainment area is defined in the Clean Air Act (CAA) as an area that is
violating an ambient standard or is contributing to a nearby area that is violating the standard.
In 2005, EPA designated 39 nonattainment areas for the 1997 PM2.5 NAAQS based on air
quality design values and a number of other factors (70 FR 943, January 5, 2005; 70 FR
19844, April 14, 2005). These areas are comprised of 208 full or partial counties with a total
population exceeding 88 million. The 1997 PM2.5 nonattainment counties,  areas and
populations, as of March 2008, are listed in Appendix 2B to this RIA.

       EPA has recently amended the NAAQS for PM25 (71 FR 61144, October 17, 2006).
The final PM NAAQS rule addressed revisions to the primary and secondary NAAQS for
PM25 to provide increased protection of public health and welfare, respectively. The primary
PM25NAAQS includes a short-term (24-hour) and a long-term (annual) standard. The level
of the 24-hour PM25 NAAQS has been revised from 65 ug/m3to 35 ug/m3 to provide increased
protection against health effects associated with  short-term exposures to fine particles. The
current form of the 24-hour PM25 standard was retained (e.g., based on the  98th percentile
concentration averaged over three years). The level of the annual PM25NAAQS was retained
at 15 ug/m3,  continuing protection against health effects associated with long-term exposures.
The current form of the annual PM25 standard was retained as an annual arithmetic mean
averaged over three years, however, the following two aspects of the spatial averaging criteria
were narrowed: (1) the annual mean concentration at each site will now be within 10 percent
of the spatially averaged annual mean, and (2) the daily values for each monitoring site pair
will now yield a correlation coefficient of at least 0.9 for each calendar quarter.

       With regard to the secondary standards for PM25, EPA has revised these standards to
be identical in all respects to the revised primary standards.  Specifically, EPA has revised the
current 24-hour PM25 secondary standard by making it identical to the revised 24-hour PM25
primary standard and retained the annual PM25 secondary standard. This suite of secondary
PM25 standards is intended to provide protection against PM-related public welfare effects,
including visibility impairment, effects on vegetation and ecosystems, and  material damage
and soiling.
 ' The full details involved in calculating a PM2 5 design value are given in Appendix N of 40 CFR Part 50.


                                         2-18

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       States with PM2.5 nonattainment areas will be required to take action to bring those
areas into compliance in the future. Most PM2 5 nonattainment areas will be required to attain
the 1997 PM2.5 NAAQS in the 2010 to 2015 time frame and then be required to maintain the
1997 PM2.s NAAQS thereafter.11 Nonattainment areas will be designated with respect to the
2006 PM2.5 NAAQS in early 2010. The attainment dates associated with the potential
nonattainment areas based on the 2006 PM2.5 NAAQS will likely be in the 2014 to 2019
timeframe. Table 2-4 provides an estimate, based on 2003-05 air quality data, of the counties
with design values greater than the 2006 PM25 NAAQS. The emission standards being
finalized in this action will become effective between 2009  and 2013.  The expected PM2 5
inventory reductions will be useful to states in attaining or maintaining the PM2 5 NAAQS.

Table 2-4 Counties with Design Values Greater Than the 2006 PM25NAAQS Based on 2003-
2005 Air Quality Data

1997 PM25 Standards: counties within the 39
areas currently designated as nonattainment
2006 PM25 Standards: additional counties that
would not meet the 2006 NAAQS6
Total
Number of Counties
208
49
257
Population"
88,394,000
18,198,676
106,592,676
Notes:
a Population numbers are from 2000 census data.
* Attainment designations for the 2006 PM2 5 NAAQS  have not yet been made. Nonattainment for the 2006
PM2 5 NAAQS will be based on three years of air quality data from later years. Also, the county numbers in the
table include only the counties with monitors violating the 2006 PM2 5 NAAQS. The numbers in this table may
be an underestimate of the number of counties and populations that will eventually be included in areas with
multiple counties designated nonattainment.
H The EPA finalized PM25 attainment and nonattainment areas in April 2005. The EPA finalized the PM
Implementation rule in March 2007.
                                        2-19

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Regulatory Impact Analysis
2.2.3.2 Current PMio Levels

       EPA designated PMio nonattainment areas in 1990.1  As of March 2008,
approximately 28 million people live in the 47 areas that are designated as PMio
nonattainment, for either failing to meet the PMio NAAQS or for contributing to poor air
quality in a nearby area. There are 46 full or partial counties that make up the PMio
nonattainment areas/

2.2.3.3 Projected PM2.5 Levels

       In conjunction with this rulemaking, we performed a series of air quality modeling
simulations for the continental U.S.  The model simulations were performed for several
emissions scenarios including the following: 2002 baseline projection, 2020 baseline
projection, 2020 baseline projection with small Si/marine SI engine controls, 2030 baseline
projection, and 2030 baseline projection with small Si/marine SI engine controls.  Information
on the air quality modeling methodology is contained in Section 2.3 as well as the air quality
modeling technical support document (AQ TSD).  In the following sections we describe
projected PM2 5 levels in the future with and without the controls being finalized in this action.

  2.2.3.2.1    ProjectedPM2.s Levels without this Rulemaking

       Even with the implementation of all current state and federal regulations, including the
Locomotive and Marine Rule, CAIR Rule, the NOX SIP call, nonroad and on-road diesel rules
and the Tier 2 rule, there are projected to be U.S. counties violating the PM2 5 NAAQS well
into the future. The model outputs from the 2002, 2020 and 2030 baselines, combined with
current air quality data, were used to identify areas expected to exceed the PM2 5 NAAQS in
the future.

       The baseline air quality modeling conducted for this final rule projects that in 2020,
with all current controls in effect, up to  11  counties, with a population of 25 million people,
may not attain the annual standard of 15 |ig/m3  This does not account for additional areas
that have air quality measurements within 10 percent of the PM25 standard. These areas,
although not violating the  standard, will also benefit from the emissions reductions, ensuring
long term maintenance of the PM NAAQS. For example, in 2020, an additional 16 million
people are projected to live in 13 counties that have air quality measurements within 10
percent of the 2006 PM NAAQS. This modeling supports the conclusion that there are a
substantial number of counties across the US projected to experience PM2.5 concentrations at
or above the PM2 5 NAAQS into the future.  Emission reductions from small SI and marine SI
engines will be helpful for these counties in attaining and maintaining the PM2 5 NAAQS.
1 A PM10 design value is the concentration that determines whether a monitoring site meets the NAAQS for
PM10. The full details involved in calculating a PM10 design value are given in Appendices H and I of 40 CFR
Part 50.

1 The PM10 nonattainment areas are listed in Appendix 2C to this RIA.
                                         2-20

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  2.2.3.2.2    ProjectedPM25Levels With this Rulemaking

       The impacts of the small SI and marine SI engine controls were determined by
comparing the model results in the future year control runs against the baseline simulations of
the same year. On a population-weighted basis, the average modeled future-year annual
PM2 5 design value (DV) for all counties is expected to decrease by 0.02 |ig/m3 in 2020 and
2030. There are areas with larger decreases in their future-year annual PM2.5 DV, for instance
the Chicago region will experience a 0.08 |ig/m3 reduction by 2030. Figure 2-3 illustrates the
geographic impact of the small SI and marine SI engine controls on annual PM25 design
values in 2020.
                                      2-21

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    Regulatory Impact Analysis
   Legend
                       Number of Counties



           <= -0.50           0




           >= -0.49 to -0.25     0




           >=-0.24 to-0.10     0




           >= -0.09 to -0.05     3




           >= -0.04 to 0.0     553



           >0.0              0
                                                                                                         2020cc_bond impact
Figure 2-3 Impact of Small SI and Marine SI controls on annual PM2 s Design Values (DV) in 2020 (units are ug/m3)
                                                                 2-22

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       Table 2-5 lists the counties with projected annual PM2.5 design values that violate
or are within 10 percent of the annual PM2 5 standard in 2020.  Counties are marked with
a "V" in the table if their projected design values are greater than or equal to 15.05
|ig/m3.  Counties are marked with an "X" in the table if their projected annual design
values are greater than or equal to 13.55 |ig/m3, but less than 15.05 |ig/m3. The counties
marked "X" are not projected to violate the standard, but to be close to it, so the rule will
help assure that these counties continue to meet the standard. The current design values
are also presented in  Table 2-5.  Recall that we project future design values only for
counties that have current  design values, so this list is limited to those counties with
ambient monitoring data sufficient to calculate current 3-year design values.

Table 2-5 Counties with 2020 Projected Annual PM2 5 Design Values in Violation or
Within 10 percent of the Annual PM2.5 Standard as a Result of the Small SI and Marine
SI Controls
State
Alabama
California
California
California
California
California
California
California
California
California
California
California
California
California
Georgia
Illinois
Illinois
Kentucky
Michigan
Montana
New York
Ohio
Pennsylvania
West Virginia
County
Jefferson Co
Fresno Co
Imperial Co
Kern Co
Kings Co
Los Angeles Co
Merced Co
Orange Co
Riverside Co
San Bernardino Co
San Diego Co
San Joaquin Co
Stanislaus Co
Tulare Co
Fulton Co
Cook Co
Madison Co
Jefferson Co
Wayne Co
Lincoln Co
New York Co
Cuyahoga Co
Allegheny Co
Hancock Co
2000-
2004
Average
annual
PM25
DV
(ug/m3)
18.36
20.02
14.44
21.77
18.77
23.16
16.47
18.27
27.15
24.63
15.65
14.84
16.49
21.33
18.29
17.06
17.27
16.58
19.32
15.85
17.16
18.36
20.99
17.30
2020
modeling
projections
of
annual
PM2 5 DV
V
X
V
X
X
X
X
X
X
X
V
V
V
X
V
V
V
V
X
V
V
V
X
V
2020
Population
681,549
1,066,878
161,555
876,131
173,390
10,376,013
277,863
3,900,599
2,252,510
2,424,764
3,863,460
743,469
607,766
477,296
929,278
5,669,479
278,167
726,257
1,908,196
20,147
1,700,384
1,326,680
1,242,587
30,539
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Regulatory Impact Analysis
2.2.4  Environmental Effects of PM Pollution

       In this section we discuss some of the public welfare effects of PM and its
precursors, including NOx, such as visibility impairment, atmospheric deposition, and
materials damage and soiling.

2.2.4.1 Visibility Impairment

       Visibility can be defined as the degree to which the atmosphere is transparent to
visible light.76 Visibility impairment manifests in two principal ways: as local visibility
impairment and as regional haze77 Local visibility impairment may take the form of a
localized plume, a band or layer of discoloration appearing well above the terrain as a
result of complex local meteorological conditions.  Alternatively, local visibility
impairment may manifest as an urban haze, sometimes referred to as a "brown cloud."
This urban haze is largely caused by emissions from multiple sources in the urban area
and is not typically attributable to only one nearby source or to long-range transport. The
second type of visibility impairment, regional  haze, usually results from multiple
pollution sources spread over a large geographic region. Regional  haze can impair
visibility over large regions and across states.

       Visibility is important because it has direct significance to people's enjoyment of
daily activities in all  parts of the country.  Individuals value good visibility for the well-
being it provides them directly,  where they live and work and in places where they enjoy
recreational opportunities. Visibility is also highly valued in significant natural areas
such as national parks and wilderness areas, and special emphasis is given to protecting
visibility in these areas.

       Fine particles are the major cause of reduced visibility in parts of the United
States.  To address the welfare effects of PM on visibility, EPA sets secondary PM2.5
standards which work in conjunction with the  regional haze program. The secondary
(welfare-based) PM2.5 NAAQS  is equal to the suite of primary (health-based) PM2.5
NAAQS.  The regional haze rule (64 FR 35714, July 1999) was put in place to protect the
visibility in mandatory class I federal areas. These areas are defined in Section 162 of the
Act as those national parks exceeding 6,000 acres, wilderness areas and memorial parks
exceeding 5,000 acres, and all international parks which were in existence on August 7,
1977. A list of the mandatory class I federal areas is included in Appendix 2D.  Visibility
is impaired in both PM2.5 nonattainment areas and mandatory class I federal areas.

       Control of small SI and marine SI emissions will improve visibility. The small SI
and marine SI engines subject to this rule  emit PM and PM precursors and thus contribute
to visibility impairment.  In the  next sections we present current information and
projected estimates about visibility impairment related to ambient PM2.5 levels across the
country and visibility impairment in mandatory class I federal areas. We conclude that
visibility will continue to be impaired in the future and the  emission reductions from this
rule will help improve visibility conditions across the country and in mandatory class I
                                       2-24

-------
federal areas. For more information on visibility see the PM AQCD as well as the 2005
PM Staff Paper.78'79

  2.2.4.1.1   Current Visibility Impairment in PM2.sNonattainment Areas
       As mentioned above, the secondary PM2.5 standards were set as equal to the suite
of primary PM2 5 standards. Almost 90 million people live in the 208 counties that are in
nonattainment for the 1997 PM2.5 NAAQS, (see Appendix 2A for the complete list of
current nonattainment areas).  These populations, as well as large numbers of individuals
who travel to these areas can experience visibility impairment.

  2.2.4.1.2   Current Visibility Impairment at Mandatory Class I Federal Areas
       Detailed information about current and historical visibility conditions in
mandatory class I federal areas is summarized in the EPA Report to Congress and the
2002 EPA Trends Report.80'81 The conclusions draw upon the Interagency Monitoring of
Protected Visual Environments (IMPROVE) network data. One of the objectives of the
IMPROVE monitoring network program is to provide regional haze monitoring
representing all mandatory class I federal areas where practical.  The National Park
Service report also  describes the state of national park visibility conditions and discusses
the need for improvement.82

       The regional haze rule requires states to establish goals for each affected
mandatory class I federal area that 1) improves visibility on the haziest days (20% most
impaired days), 2) ensures no degradation occurs on the cleanest days (20% least
impaired days), and 3) achieves natural background visibility levels by 2064.  Although
there have been general trends toward improved visibility, progress is still needed on the
haziest days.  Specifically, as discussed in the 2002 EPA Trends Report, without the
effects of pollution a natural visual range in the United States is approximately 75 to 150
km in the East and  200 to 300 km in the West. In 2001, the mean visual range for the
                                                   QO
worst days was 29 km in the East and 98 km in the West.

  2.2.4.1.3 Future  Visibility Impairment

       Additional emission reductions will be needed from a broad set of sources,
including those in this action, as part of the overall strategy to achieve the visibility goals
of the Act and the regional haze program.

       Modeling was used to project visibility conditions in 133 mandatory class I
federal areas across the US in 2020 and 2030 as a result of the small SI and marine  SI
engine standards. The AQ modeling TSD and Section 2.3 of this RIA provide
information on the  modeling methodology. Table 2-6 below indicates the current
monitored deciview values,  the natural background levels each area is attempting to
reach, and also the  projected deciview values in 2020 and 2030 with and without the
standards. In 2030, the greatest visibility improvement due to this rule (0.14 deciview)
will occur at Brigantine,  New Jersey.

                                       2-25

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Regulatory Impact Analysis
Table 2-6 Current (2002) and Future (2020 and 2030) Projected Visibility Conditions With and
Without Small SI and Marine SI Rule in Mandatory Class I Federal Areas (20% Worst Days)
Class 1 Area
Sipsey Wilderness
Caney Creek Wilderness
Upper Buffalo Wilderness
Chiricahua NM
Chiricahua Wilderness
Galiuro Wilderness
Grand Canyon NP
Mazatzal Wilderness
Petrified Forest NP
c Baseline
btate Visibility
AL
AR
AR
AZ
AZ
AZ
AZ
AZ
AZ
Pine Mountain Wilderness AZ
Saguaro NM
Sierra Ancha Wilderness
Sycamore Canyon
Wilderness
Agua Tibia Wilderness
Caribou Wilderness
Cucamonga Wilderness
Desolation Wilderness
Dome Land Wilderness
Emigrant Wilderness
Hoover Wilderness
Joshua Tree NM
Lassen Volcanic NP
Lava Beds NM
Mokelumne Wilderness
Pinnacles NM
Point Reyes NS
Redwood NP
San Gabriel Wilderness
San Gorgonio Wilderness
San Jacinto Wilderness
South Warner Wilderness
Thousand Lakes
Wilderness
Ventana Wilderness
Yosemite NP
Black Canyon of the
Gunnison NM
Eagles Nest Wilderness
Flat Tops Wilderness
Great Sand Dunes NM
AZ
AZ
AZ
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA

CA
CA
CA
CO
CO
CO
CO
29.03
26.36
26.27
13.43
13.43
13.43
11.66
13.35
13.21
13.35
14.83
13.67
15.25
23.50
14.15
19.94
12.63
19.43
17.63
12.87
19.62
14.15
15.05
12.63
18.46
22.81
18.45
19.94
22.17
22.17
15.05

14.15
18.46
17.63
10.33
9.61
9.61
12.78
2020 2020 Bond
Base Rule
23
22
22
13
13
13
11
12
12
12
14
13
14
21
13
17
12
18
17
12
17
13
14
12
17
21
17
17
20
19
14

13
17
17
9
9
9
12
.73
.05
.35
.09
.09
.07
.09
.72
.83
.58
.47
.20
.94
.14
.60
.36
.13
.34
.21
.72
.93
.54
.42
.30
.36
.99
.86
.25
.22
.87
.59

.52
.64
.14
.79
.03
.25
.35
23
22
22
13
13
13
11
12
12
12
14
13
14
21
13
17
12
18
17
12
17
13
14
12
.72
.03
.33
.09
.09
.06
.09
.71
.82
.56
.48
.20
.93
.13
.60
.38
.13
.34
.20
.72
.97
.54
.42
.30
17.34
21
17
17
20
19
14

13
17
17
9
.98
.86
.25
.24
.90
.59

.52
.63
.14
.79
9.03
9.25
12
.35
2030 2030 Bond Natural
Base Rule Background
23.66
21.92
22.19
13.09
13.09
13.09
11.08
12.73
12.75
12.54
14.44
13.15
14.93
20.94
13.51
17.10
12.12
18.11
17.19
12.74
17.71
13.43
14.32
12.31
17.09
21.79
17.79
16.93
19.70
19.55
14.52

13.41
17.62
17.11
9.77
8.96
9.24
12.34
23
21
22
13
13
13
11
12
12
12
14
13
14
20
13
17
12
18
17
12
17
13
14
12
17
21
17
16
19
19
14

13
17
17
9
8
9
12
.64
.89
.17
.09
.09
.09
.08
.71
.75
.53
.45
.14
.93
.94
.51
.10
.12
.11
.19
.74
.72
.43
.32
.30
.09
.79
.78
.93
.71
.52
.52

.40
.62
.11
.77
.95
.24
.34
10.99
11.58
11.57
7.21
7.21
7.21
7.14
6.68
6.49
6.68
6.46
6.59
6.69
7.64
7.31
7.06
6.12
7.46
7.64
7.91
7.19
7.31
7.86
6.12
7.99
15.77
13.91
7.06
7.30
7.30
7.86

7.31
7.99
7.64
6.24
6.54
6.54
6.66
                                         2-26

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Class 1 Area
La Garita Wilderness
Maroon Bells-Snowmass
Wilderness
Mesa Verde NP
Mount Zirkel Wilderness
Rawah Wilderness
Rocky Mountain NP
Weminuche Wilderness
West Elk Wilderness
Chassahowitzka
Everglades NP
St. Marks
Cohutta Wilderness
Okefenokee
Wolf Island
Craters of the Moon NM
Sawtooth Wilderness
Mammoth Cave NP
Acadia NP
Moosehorn
Roosevelt Campobello
International Park
Isle Royale NP
Seney
Voyageurs NP
Hercules-Glades
Wilderness
Anaconda-Pintler
Wilderness
Bob Marshall Wilderness
Cabinet Mountains
Wilderness
Gates of the Mountains
Wilderness
Medicine Lake
Mission Mountains
Wilderness
Scapegoat Wilderness
Selway-Bitterroot
Wilderness
UL Bend
Linville Gorge Wilderness
Swanquarter
Lostwood
Theodore Roosevelt NP
0. . Baseline
State ... ......
Visibility
CO
CO
CO
CO
CO
CO
CO
CO
FL
FL
FL
GA
GA
GA
ID
ID
KY
ME
ME

ME
Ml
Ml
MN

MO

MT
MT

MT

MT
MT

MT
MT

MT
MT
NC
NC
ND
ND
10.33
9.61
13.03
10.52
10.52
13.83
10.33
9.61
26.09
22.30
26.03
30.30
27.13
27.13
14.00
13.78
31.37
22.89
21.72

21.72
20.74
24.16
19.27

26.75

13.41
14.48

14.09

11.29
17.72

14.48
14.48

13.41
15.14
28.77
25.49
19.57
17.74
2020 2020 Bond
Base Rule
9.89
9.21
12.39
10.05
10.04
13.08
9.85
9.15
21.94
19.77
21.82
23.33
23.42
23.37
12.97
13.63
25.48
19.77
18.63

18.45
19.10
21.72
17.58

22.93

13.14
14.13

13.54

10.91
16.19

14.04
14.16

13.04
14.64
22.45
21.15
17.70
16.49
9.89
9.21
12.39
10.05
10.03
13.06
9.85
9.15
21.92
19.76
21.81
23.32
23.41
23.35
12.96
13.63
25.47
19.75
18.62

18.44
19.08
21.70
17.56

22.92

13.13
14.12

13.53

10.91
16.19

14.04
14.15

13.04
14.63
22.44
21.11
17.70
16.48
2030 2030 Bond Natural
Base Rule Background
9.88
9.20
12.37
10.04
10.04
13.01
9.85
9.14
21.91
19.94
21.83
23.28
23.40
23.32
12.82
13.63
25.44
19.81
18.64

18.47
19.04
21.66
17.43

22.81

13.11
14.08

13.46

10.87
16.09

13.99
14.12

12.99
14.58
22.41
21.15
17.60
16.34
9.87
9.20
12.37
10.03
10.02
12.99
9.84
9.14
21.88
19.91
21.81
23.26
23.39
23.29
12.80
13.63
25.42
19.78
18.62

18.45
19.01
21.63
17.41

22.78

13.11
14.07

13.44

10.86
16.09

13.99
14.11

12.99
14.57
22.39
21.10
17.60
16.34
6.24
6.54
6.83
6.44
6.44
7.24
6.24
6.54
11.21
12.15
11.53
11.14
11.44
11.44
7.53
6.43
11.08
12.43
12.01

12.01
12.37
12.65
12.06

11.30

7.43
7.74

7.53

6.45
7.90

7.74
7.74

7.43
8.16
11.22
11.94
8.00
7.79
2-27

-------
Regulatory Impact Analysis

Class 1 Area
Great Gulf Wilderness
Presidential Range-Dry
River Wilderness
Brigantine
Bandelier NM
Bosque del Apache
Gila Wilderness
Pecos Wilderness
Salt Creek
San Pedro Parks
Wilderness
Wheeler Peak Wilderness
White Mountain
Wilderness
Jarbidge Wilderness
Wichita Mountains
Crater Lake NP
Diamond Peak
Wilderness
Eagle Cap Wilderness
Gearhart Mountain
Wilderness
Hells Canyon Wilderness
Kalmiopsis Wilderness
Mount Hood Wilderness
Mount Jefferson
Wilderness
Mount Washington
Wilderness
Mountain Lakes
Wilderness
Strawberry Mountain
Wilderness
Three Sisters Wilderness
Cape Remain
Badlands NP
Wind Cave NP
Great Smoky Mountains
NP
Joyce-Kilmer-Slickrock
Wilderness
Big Bend NP
Carlsbad Caverns NP
Guadalupe Mountains NP
Arches NP
Bryce Canyon NP
0. . Baseline
State ... ......
Visibility
NH
NH
NJ
NM
NM
NM
NM
NM

NM
NM

NM
NV
OK
OR

OR
OR
OR
OR
OR
OR

OR
OR

OR
OR
OR
SC
SD
SD
TN
TN
TX
TX
TX
UT
UT
22.82
22.82
29.01
12.22
13.80
13.11
10.41
18.03

10.17
10.41

13.70
12.07
23.81
13.74

13.74
18.57
13.74
18.55
15.51
14.86

15.33
15.33

13.74
18.57
15.33
26.48
17.14
15.84
30.28
30.28
17.30
17.19
17.19
11.24
11.65
2020 2020 Bond
Base Rule
19
19
24
11
12
12
9
16

9
9

12
11
20
13

13
17
13
17
14
14

14
14

13
17
14
22
15
14
23
23
16
15
15
11
11
.45
.45
.85
.35
.85
.54
.97
.59

.43
.88

.88
.86
.62
.27

.20
.83
.37
.20
.98
.13

.77
.75

.24
.73
.82
.74
.84
.91
.93
.43
.13
.89
.87
.11
.34
19
19
24
11
12
12
9
16

9
9

12
11
20
13

13
17
13
17
14
14

14
14

13
17
14
22
15
14
23
23
16
15
15
11
11
.43
.43
.75
.35
.85
.54
.97
.58

.43
.88

.89
.85
.60
.25

.19
.82
.37
.19
.97
.12

.76
.74

.23
.72
.81
.72
.83
.91
.92
.42
.13
.89
.86
.11
.34
2030 2030 Bond Natural
Base Rule Background
19.46
19.46
24.91
11.29
12.73
12.54
9.97
16.52

9.40
9.87

12.87
11.85
20.55
13.20

13.12
17.71
13.33
17.04
14.93
14.14

14.76
14.72

13.17
17.60
14.79
22.71
15.74
14.87
23.86
23.37
16.15
15.87
15.84
11.03
11.31
19
19
24
11
12
.43
.43
.77
.28
.73
12.53
9
16

9
9

12
11
20
13

13
17
13
17
14
14

14
14

13
17
14
22
15
14
23
23
16
15
15
11
11
.97
.52

.40
.87

.86
.85
.53
.18

.11
.70
.33
.01
.92
.12

.75
.71

.16
.59
.78
.68
.74
.86
.85
.35
.14
.87
.84
.01
.31
11.99
11.99
12.24
6.26
6.73
6.69
6.44
6.81

6.08
6.44

6.86
7.87
7.53
7.84

7.84
8.92
7.84
8.32
9.44
8.44

8.79
8.79

7.84
8.92
8.79
12.12
8.06
7.71
11.24
11.24
7.16
6.68
6.68
6.43
6.86
                                         2-28

-------
Class 1 Area
Canyonlands NP
Zion NP
James River Face
Wilderness
Shenandoah NP
Lye Brook Wilderness
Alpine Lake Wilderness
Glacier Peak Wilderness
Goat Rocks Wilderness
Mount Adams Wilderness
Mount Rainier NP
North Cascades NP
Olympic NP
Pasayten Wilderness
Dolly Sods Wilderness
Otter Creek Wilderness
Bridger Wilderness
Fitzpatrick Wilderness
Grand Teton NP
North Absaroka
Wilderness
Red Rock Lakes
Teton Wilderness
Washakie Wilderness
Yellowstone NP
0. . Baseline
State ... ......
Visibility
UT
UT

VA
VA
VT
WA
WA
WA
WA
WA
WA
WA
WA
WV
WV
WY
WY
WY

WY
WY
WY
WY
WY
11.24
13.24

29.12
29.31
24.45
17.84
13.96
12.76
12.76
18.24
13.96
16.74
15.23
29.04
29.04
11.12
11.12
11.76

11.45
11.76
11.76
11.45
11.76
2020 2020 Bond
Base Rule
10.81
12.92

23.34
22.80
21.08
16.71
13.60
12.05
12.01
17.24
13.57
15.82
14.84
22.35
22.29
10.80
10.85
11.35

11.16
11.43
11.40
11.17
11.38
10.81
12.95

23.31
22.78
21.06
16.69
13.60
12.03
12.00
17.23
13.57
15.82
14.84
22.34
22.28
10.80
10.85
11.35

11.16
11.42
11.39
11.16
11.37
2030 2030 Bond Natural
Base Rule Background
10.82
12.81

23.26
22.76
21.11
16.60
13.67
12.03
11.97
17.21
13.67
15.89
14.81
22.33
22.27
10.79
10.84
11.31

11.13
11.39
11.36
11.14
11.34
10.85
12.83

23.23
22.73
21.08
16.57
13.66
12.02
11.96
17.18
13.66
15.86
14.81
22.31
22.25
10.78
10.84
11.31

11.12
11.39
11.36
11.14
11.33
6.43
6.99

11.13
11.35
11.73
8.43
8.01
8.36
8.36
8.55
8.01
8.44
8.26
10.39
10.39
6.58
6.58
6.51

6.86
6.51
6.51
6.86
6.51
 The level of visibility impairment in an area is based on the light-extinction coefficient and a unitless
visibility index, called a "deciview", which is used in the valuation of visibility. The deciview metric
provides a scale for perceived visual changes over the entire range of conditions, from clear to hazy. Under
many scenic conditions, the average person can generally perceive a change of one deciview. The higher
the deciview value, the worse the visibility.  Thus, an improvement invisibility is a decrease in deciview
value.

2.2.4.2 Particulate Matter Deposition

        Paniculate matter contributes to adverse effects on vegetation and ecosystems,
and to soiling and materials damage.  These welfare effects result predominately from
exposure to excess amounts of specific chemical species, regardless of their source or
predominant form (particle, gas or liquid).  Reflecting this fact, the PM AQCD concludes
that regardless of size fractions, particles containing nitrates and sulfates have the greatest
potential for widespread environmental significance, while effects are also related to
other chemical constituents found in  ambient PM,  such as trace metals and organics. The
following characterizations of the nature of these welfare effects are based on the
information contained in the PM  AQCD and PM Staff Paper.
                                          2-29

-------
Regulatory Impact Analysis
  2.2.4.2.1    Deposition of Nitrates and Sulfates

       At current ambient levels, risks to vegetation from short-term exposures to dry
deposited particulate nitrate or sulfate are low.  However, when found in acid or
acidifying deposition, such particles do have the potential to cause direct leaf injury.
Specifically, the responses of forest trees to acid precipitation (rain, snow) include
accelerated weathering of leaf cuticular surfaces, increased permeability of leaf surfaces
to toxic materials, water, and disease agents; increased leaching of nutrients from foliage;
and altered reproductive processesall which serve to weaken trees so that they are more
susceptible to other stresses (e.g., extreme weather, pests, pathogens). Acid deposition
with levels of acidity associated with the leaf effects described above are currently found
in some locations in the eastern U.S.84 Even higher concentrations of acidity  can be
present in occult depositions (e.g., fog, mist or clouds) which more frequently impacts
higher elevations. Thus, the risk of leaf injury occurring from acid deposition in some
areas of the eastern U.S. is high.  Nitrogen deposition has also been shown to impact
ecosystems in the western U.S.  A study conducted in the Columbia River Gorge
National Scenic Area (CRGNSA), located along a portion of the Oregon/Washington
border, indicates that lichen communities in the CRGNSA have shifted to a higher
                                                                               oc
proportion of nitrophilous species and the nitrogen content of lichen tissue is elevated.
Lichens are sensitive indicators of nitrogen deposition effects to terrestrial ecosystems
and the lichen  studies in the Columbia River Gorge clearly show that ecological effects
from air pollution are occurring.

       Some of the most significant detrimental effects associated with excess reactive
nitrogen deposition are those associated with a syndrome known as nitrogen saturation.
These effects include: (1) decreased productivity, increased mortality, and/or shifts in
plant community composition, often leading to decreased biodiversity in many natural
habitats wherever atmospheric reactive  nitrogen deposition increases significantly and
critical thresholds are exceeded; (2) leaching of excess nitrate and associated base cations
from soils into streams, lakes, and rivers, and mobilization  of soil aluminum;  and (3)
fluctuation of ecosystem processes such as nutrient and energy cycles through changes in
the functioning and species composition of beneficial soil organisms.86

       In the U.S. numerous forests now show severe symptoms of nitrogen saturation.
These forests include: the northern hardwoods and mixed conifer forests in the
Adirondack and Catskill Mountains of  New York; the red spruce forests at Whitetop
Mountain, Virginia, and Great Smoky Mountains National  Park, North Carolina; mixed
hardwood watersheds at Fernow Experimental Forest in West Virginia; American beech
forests in Great Smoky Mountains National Park, Tennessee; mixed conifer forests and
chaparral watersheds in southern California and the southwestern Sierra Nevada in
Central California; the alpine tundra/subalpine conifer forests of the Colorado Front
Range; and red alder forests in the Cascade Mountains in Washington.

       Excess nutrient inputs into aquatic ecosystems (i.e.  streams, rivers, lakes,
estuaries or oceans) either from direct atmospheric deposition, surface runoff, or leaching
from nitrogen saturated soils into ground or surface waters  can contribute to conditions of
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severe water oxygen depletion; eutrophication and algae blooms; altered fish
distributions, catches, and physiological states; loss of biodiversity; habitat degradation;
and increases in the incidence of disease.

       Severe and persistent eutrophication often directly impacts human activities. For
example, losses in the nation's fishery resources may be directly caused by fish kills
associated with low dissolved oxygen and toxic blooms. Declines in tourism occur when
low dissolved oxygen causes noxious smells and floating mats of algal blooms create
unfavorable aesthetic conditions. Risks to human health increase when the toxins from
algal blooms  accumulate in edible fish and shellfish, and when toxins become airborne,
causing respiratory problems due to inhalation. According to a NOAA report, more than
half of the nation's estuaries have moderate to high expressions of at least one of these
symptoms - an indication that eutrophication is well developed in more than half of U.S.
estuaries.87

  2.2.4.2.2  Deposition of Heavy Metals

       Heavy metals, including cadmium, copper, lead, chromium, mercury, nickel and
zinc, have the greatest potential for influencing forest growth (PM AQCD, p. 4-87).88
Investigation of trace metals near roadways and industrial facilities indicate that a
substantial load of heavy metals can accumulate on vegetative surfaces. Copper, zinc,
and nickel have been documented to cause direct toxicity to vegetation under field
conditions (PM AQCD, p. 4-75). Little research has been conducted on the effects
associated with mixtures of contaminants found in ambient PM. While metals typically
exhibit low solubility, limiting their bioavailability and direct toxicity, chemical
transformations of metal compounds occur in the environment, particularly in the
presence of acidic or other oxidizing species. These chemical changes influence the
mobility and toxicity of metals in the environment. Once taken up into plant tissue, a
metal compound can undergo chemical changes, accumulate and be passed along to
herbivores or can re-enter the soil and further cycle in the environment. Although there
has been no direct evidence of a physiological association between tree injury and heavy
metal exposures, heavy metals have been implicated because of similarities between
metal deposition patterns and forest decline (PM AQCD, p.  4-76). This hypothesized
relationship/correlation was further explored in high elevation forests in the northeastern
U.S. These studies measured levels of a group of intracellular compounds found in plants
that bind with metals and are produced by plants as a response to sublethal concentrations
of heavy metals.  These studies indicated a systematic and significant increase in
concentrations of these compounds associated with the extent of tree injury. These data
strongly imply that metal stress causes tree injury and contributes to forest decline in the
northeastern United States (PM AQCD 4-76,77).89 Contamination of plant leaves by
heavy metals can lead to elevated soil levels.  Trace metals absorbed into the plant
frequently bind to the leaf tissue, and then are lost when the leaf drops (PM AQCD, p. 4-
75).  As the fallen leaves decompose,  the heavy metals are transferred into the soil.90'91

       The environmental sources and cycling of mercury are currently of particular
concern due to the bioaccumulation and biomagnification of this metal in aquatic
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Regulatory Impact Analysis
ecosystems and the potent toxic nature of mercury in the forms in which is it ingested by
people and other animals. Mercury is unusual compared with other metals in that it
largely partitions into the gas phase (in elemental form), and therefore has a longer
residence time in the atmosphere than a metal found predominantly in the particle phase.
This property enables mercury to travel far from the primary source before being
deposited and accumulating in the aquatic ecosystem. The major source of mercury in the
Great Lakes is from atmospheric deposition, accounting for approximately eighty percent
of the mercury in Lake Michigan.92'93 Over fifty percent of the mercury in the
Chesapeake Bay has been attributed to atmospheric deposition.94 Overall, the National
Science and Technology Council identifies atmospheric deposition as the primary source
of mercury to aquatic systems.95 Forty-four states have issued health advisories for the
consumption offish contaminated by mercury; however, most of these advisories are
issued in areas without a mercury point source.

       Elevated levels of zinc and lead have been identified in streambed sediments, and
these elevated levels have been correlated with population density and motor vehicle
use.96'97 Zinc and nickel have also been identified in urban water and soils. In addition,
platinum, palladium, and rhodium,  metals found in the catalysts of modern motor
vehicles, have been measured at elevated levels along roadsides.98 Plant uptake of
platinum has been observed at these locations.

  2.2.4.2.3  Deposition of Poly cyclic Organic Matter

       Poly cyclic organic matter (POM) is a byproduct of incomplete combustion and
consists of organic compounds with more than one benzene ring and a boiling point
greater than or equal to  100 degrees centigrade.99 Poly cyclic aromatic hydrocarbons
(PAHs) are a class of POM that contains compounds which are known or suspected
carcinogens.

       Major sources of PAHs include  mobile sources.  PAHs in the environment may be
present as a gas or adsorbed onto airborne parti culate matter.  Since the majority of PAHs
are adsorbed onto particles less than 1.0 jim in diameter, long range transport is possible.
However, studies have shown that PAH compounds adsorbed onto diesel exhaust
particulate and exposed to ozone have half lives of 0.5 to 1.0 hours.100

       Since PAHs are  insoluble, the compounds generally are particle reactive and
accumulate in sediments. Atmospheric deposition of particles is believed to be the major
source of PAHs to the sediments of Lake Michigan.101'102  Analyses of PAH deposition in
Chesapeake and Galveston Bay indicate that dry deposition and gas exchange from the
atmosphere to the surface water predominate.103'104 Sediment concentrations of PAHs are
high enough in some segments of Tampa Bay to pose an environmental health threat.
EPA funded a study to better characterize the sources and loading rates for PAHs into
Tampa Bay.105 PAHs that enter a water body through gas  exchange likely partition into
organic rich particles and can be biologically recycled, while dry deposition of aerosols
containing PAHs tend to be more resistant to biological recycling.106  Thus, dry
deposition is likely the main pathway for PAH concentrations in sediments while
gas/water exchange at the surface may lead to PAH distribution into the food web,
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leading to increased health risk concerns.

       Trends in PAH deposition levels are difficult to discern because of highly variable
ambient air concentrations, lack of consistency in monitoring methods, and the
significant influence of local sources on deposition levels.107 Van Metre et al. noted PAH
concentrations in urban reservoir sediments have increased by 200-300% over the last
forty years and correlate with increases in automobile use.108

       Cousins et al. estimate that more than ninety percent of semi-volatile organic
compound (SVOC) emissions in the United Kingdom deposit on soil.109 An analysis of
PAH concentrations near a Czechoslovakian roadway indicated that concentrations were
thirty times greater than background.110

  2.2.4.2.4  Materials Damage and Soiling

       The effects of the deposition of atmospheric pollution, including ambient PM, on
materials are related to both physical damage and impaired aesthetic qualities.  The
deposition of PM (especially sulfates and nitrates) can physically affect materials, adding
to the effects of natural weathering processes, by potentially promoting or accelerating
the corrosion of metals, by degrading paints, and by deteriorating building materials such
as concrete and limestone.  Only chemically active fine particles or hygroscopic coarse
particles contribute to these physical effects. In addition, the deposition of ambient PM
can reduce the aesthetic appeal of buildings and culturally important articles through
soiling. Particles consisting primarily of carbonaceous compounds cause soiling of
commonly used building materials and culturally important items such as statues and
works of art.

2.3    Air  Quality Modeling Methodology

       In  this section we present information on the air quality modeling, including the
model domain and modeling inputs.  Further discussion of the modeling methodology,
including  evaluations of model performance, is included in the Air Quality Modeling
Technical  Support Document (AQM TSD).111

2.3.1 Air Quality Modeling Overview

       A national scale air quality modeling analysis was performed to estimate future
year 8-hour ozone concentrations, annual PM2.5 concentrations, and visibility levels.
These projections were used as inputs to the calculation of expected benefits from the
small SI and marine SI emissions controls considered in this assessment.  The 2002-based
CMAQ modeling platform was used as the  tool for the air quality modeling of future
baseline emissions and control scenarios. It should be noted that the 2002-based
modeling  platform has recently been finalized and the 2001-based modeling platform was
used as the tool for the air quality modeling performed for the proposal.  In the next
paragraph we discuss some of the differences between the 2001-based platform used for
the proposal and the 2002-based platform used for this final rule.
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       The 2002-based modeling platform includes a number of updates and
improvements to data and tools compared to the 2001-based platform that was used for
the proposal modeling.  For the final rule modeling we used the new 2002 National
Emissions Inventory along with updated versions of the models used to project future
emissions from electric generating units (EGUs) and onroad and nonroad vehicles.  The
proposal modeling was based on the 2001 National Emissions Inventory. The new
platform also includes 2002 meteorology and more recent ambient design values which
were used as the  starting point for projecting future air quality. For proposal,  we used
meteorology for 2001 for modeling the East and 2002 for modeling the West. The
updates to CMAQ between proposal and final include (1) an in-cloud sulfate chemistry
module that accounts for the nonlinear sensitivity of sulfate formation to varying pH; (2)
improved vertical convective mixing; (3) heterogeneous reaction involving nitrate
formation; (4) an updated gas-phase chemistry mechanism, Carbon Bond 2005 (CB05);
and (5) an aqueous chemistry mechanism that provides a comprehensive simulation of
aerosol precursor oxidants.

       The CMAQ model is a three-dimensional grid-based Eulerian air quality model
designed to estimate the formation and fate of oxidant precursors, primary and secondary
particulate matter concentrations and deposition over regional and urban spatial scales
(e.g., over the contiguous U.S.).112'113'114 Consideration of the different processes that
affect primary (directly emitted) and secondary (formed by atmospheric processes) PM at
the regional scale in different locations  is fundamental to understanding and assessing the
effects of pollution control measures that affect PM, ozone and deposition of pollutants to
the surface.  In addition to the CMAQ model, the modeling platform includes the
emissions, meteorology, and initial/boundary condition data which are inputs  to this
model.
       The CMAQ model was peer-reviewed in 2003 for EPA as reported in  "Peer
Review of CMAQ Model".115  The latest version of CMAQ (Version 4.6.1) was
employed for this modeling analysis. This version reflects updates, as mentioned above,
in a number of areas to improve the underlying science which include (1) use  of a state-
of-the science inorganic and organic aerosol module, (2) an in-cloud sulfate chemistry
module that accounts for the nonlinear sensitivity of sulfate formation to varying pH, (3)
improved vertical convective mixing, (4) heterogeneous reaction involving nitrate
formation and (5) an updated Carbon Bond 05 (CB05) gas-phase chemistry mechanism
and aqueous chemistry mechanism that provides a comprehensive simulation  of aerosol
precursor oxidants.

2.3.2 Model Domain and Configuration

       The CMAQ modeling domain encompasses all of the lower 48 States and portions
of Canada and Mexico. The modeling domain is made up  of a large continental U.S. 36
km grid and two  12 km grids (an Eastern US and a Western US domain), as shown in
Figure 2-4. The modeling domain contains 14 vertical layers with the top of the
modeling domain at about 16,200 meters, or 100 millibars  (mb).
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        12km Western Domain {WRAP}
        Ofigin: -2412000. -972000
        col: 213 row: 192
                                                        12km Eastern Domain
       Figure 2-4. Map of the CMAQ modeling domain
2.3.3 Model Inputs

       The key inputs to the CMAQ model include emissions from anthropogenic and
biogenic sources, meteorological data, and initial and boundary conditions. The CMAQ
meteorological input files were derived from a simulation of the Pennsylvania State
University / National Center for Atmospheric Research Mesoscale Model116 for the entire
year of 2002. This model, commonly referred to as MM5, is a limited-area,
nonhydrostatic, terrain-following system that solves for the full set of physical and
thermodynamic equations which govern atmospheric motions.  The meteorology for the
national 36 km grid and the 12 km Eastern U.S. grid were developed by EPA and are
described in more detail within the AQM TSD. The meteorology for the 12 km Western
U.S. grid was developed by the Western Regional Air Partnership (WRAP) Regional
Planning Organization. The meteorological outputs from MM5 were processed to create
model-ready inputs for CMAQ using the Meteorology-Chemistry Interface Processor
(MCIP) version 3.1 to derive the specific inputs to CMAQ, for example: horizontal wind
components (i.e., speed and direction), temperature, moisture, vertical diffusion rates, and
rainfall rates for each grid cell in each vertical layer.117

       The lateral boundary and initial species concentrations are provided by a three-
dimensional global atmospheric chemistry model, the GEOS-CHEM model.118 The
global  GEOS-CHEM model simulates atmospheric chemical and physical processes
driven  by assimilated meteorological observations from the NASA's Goddard Earth
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Regulatory Impact Analysis
Observing System (GEOS). This model was run for 2002 with a grid resolution of 2
degree x 2.5 degree (latitude-longitude) and 20 vertical layers. The predictions were used
to provide one-way dynamic boundary conditions at three-hour intervals and an initial
concentration field for the 36 km CMAQ simulations. The future base conditions from
the 36 km coarse grid modeling were used as the initial/boundary state for all subsequent
12 km finer grid modeling.

       The emissions inputs used for the 2002 base year and each of the future year base
cases and control scenarios are summarized in Chapter 3 of this RIA.

2.3.4 CMAQ Evaluation

       An operational model performance evaluation for PM2.5 and its related speciated
components (e.g., sulfate, nitrate,  elemental carbon, organic carbon, etc.) was conducted
using the 2002 data in  order to estimate the ability of the CMAQ modeling system to
replicate base year concentrations. In summary, model performance statistics were
calculated for observed/predicted  pairs of daily/monthly/seasonal/annual concentrations.
Statistics were generated for the following geographic groupings: domain wide, Eastern
vs. Western (divided along the 100th meridian), and each Regional Planning
Organization (RPO) region.K  The "acceptability" of model performance was judged by
comparing our results to those found in recent regional PM2.5 model applications for
other, non-EPA studies.L Overall, the performance for the 2002 modeling platform is
within the range of these other applications. A detailed  summary of the 2002 CMAQ
model performance evaluation is available within the AQM TSD.

 2.3.5 Model Simulation Scenarios

       As part of our analysis for this rulemaking the CMAQ modeling system was used
to calculate 8-hour ozone concentrations, annual PM2 5 concentrations, and visibility
estimates for each of the following emissions  scenarios:

2002 base year
2020 base line projection
2020 base line projection with small SI and marine SI controls
2030 base line projection
2030 base line projection with small SI and marine SI controls
K Regional Planning Organization regions include: Mid-Atlantic/Northeast Visibility
Union (MANE-VU), Midwest Regional Planning Organization - Lake Michigan Air
Directors Consortium (MWRPO-LADCO), Visibility Improvement State and Tribal
Association of the Southeast (VISTAS), Central States Regional Air Partnership
(CENRAP), and Western Regional Air Partnership (WRAP).

L These other modeling studies represent a wide range of modeling analyses which cover
various models, model configurations, domains, years and/or episodes, chemical
mechanisms, and aerosol modules.
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       It should be noted that the emission control scenarios used in the air quality and
benefits modeling are slightly different than the emission control program being
finalized.  The differences reflect further refinements of the regulatory program since we
performed the air quality modeling for this rule. Chapter 3 of this RIA describes the
changes in the inputs and resulting emission inventories between the preliminary
assumptions used for the air quality modeling and the final regulatory scenario.  These
refinements to the program would not significantly change the results summarized here or
our conclusions drawn from this analysis.

       We use the predictions from the model in a relative sense by combining the 2002
base-year predictions with predictions from each future-year scenario and applying these
modeled ratios to ambient air quality observations to estimate annual PM2.5
concentrations, 8-hour ozone concentrations, and visibility levels for each of the 2020
and 2030 scenarios.  The ambient air quality observations are average conditions, on a
site by site basis, for a period centered around the model base year (i.e., 2000-2004).
After completing this process, we then calculated the effect of changes in PM, ozone and
visibility air quality  metrics resulting from this rulemaking on the health and welfare
impact functions of the benefits analysis.

       The projected annual PM2.5 design  values were calculated using the Speciated
Modeled Attainment Test (SMAT) approach.  The SMAT uses an Federal Reference
Method FRM mass construction methodology that results in reduced nitrates (relative to
the amount measured by routine speciation networks), higher mass associated with
sulfates (reflecting water included in FRM measurements), and a measure of organic
carbonaceous mass that is derived from the difference between measured PM2 5 and its
non-carbon components.  This characterization of PM2 5 mass also reflects crustal
material and other minor constituents.  The resulting characterization provides a complete
mass balance. It does not have any unknown mass that is sometimes presented as the
difference between measured PM2 5 mass and the characterized chemical components
derived from routine speciation measurements.  However, the assumption that all mass
difference is organic carbon has not been validated in many areas of the US. The SMAT
methodology uses the following PM2.5 species components: sulfates, nitrates, ammonium,
organic carbon mass, elemental carbon, crustal, water, and blank mass (a fixed value of
0.5 |ig/m3). More complete details of the SMAT procedures can be found in the report
"Procedures for Estimating Future PM2.5 Values for  the CAIR Final Rule by Application
of the (Revised) Speciated Modeled Attainment Test (SMAT)".119 For this latest
analysis, several datasets and techniques were updated. These changes are fully
described within the AQM TSD. The projected 8-hour ozone design values were
calculated using the  approach identified in EPA's guidance on air quality modeling
attainment demonstrations.

 2.3.6  Visibility Modeling Methodology

       The modeling platform described in this section was also used to project changes
in visibility.  The estimate of visibility benefits was based on the projected improvement
in annual average visibility at mandatory class I federal areas. There are 156 Federally

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Regulatory Impact Analysis
mandated Class I areas which, under the Regional Haze Rule, are required to achieve
natural background visibility levels by 2064. These mandatory class I federal areas are
mostly national parks, national monuments, and wilderness areas.  There are currently
116 Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring
sites (representing all 156 mandatory class I federal areas) collecting ambient PM25 data
at mandatory class I federal areas, but not all of these sites have complete data for 2002.
For this analysis,  we quantified visibility improvement at the 133 mandatory class I
federal areas which have complete IMPROVE ambient data for 2002 or are represented
by IMPROVE monitors with complete data.M

       Visibility  impairment is quantified in extinction units. Visibility degradation is
directly proportional to decreases in light transmittal in the atmosphere.  Scattering and
absorption by both gases and particles decrease light transmittance. To quantify changes
in visibility, our analysis computes  a light-extinction coefficient (bext) and visual range.
The light extinction coefficient is based on the work of Sisler, which shows the total
fraction of light that is decreased per unit distance. This coefficient accounts for the
scattering and absorption of light by both particles and gases and accounts for the higher
extinction efficiency of fine particles compared to coarse particles. Fine particles with
significant light-extinction efficiencies include sulfates, nitrates, organic carbon,
elemental carbon, and soil.120

       Visual range is a measure of visibility that is inversely related to the extinction
coefficient.  Visual range can be defined as the maximum distance at which one can
identify a black object against the horizon sky.  Visual range (in units of kilometers) can
be calculated from bext using the formula:  Visual Range (km) = 3912/bext (bext units are
inverse megameters [Mm"1])
The future year visibility impairment was calculated using a methodology which applies
modeling results in a relative sense similar to the  Speciated Modeled Attainment Test
(SMAT).

       In calculating visibility impairment, the extinction coefficient is made up of
individual component species (sulfate, nitrate, organics, etc). The predicted change in
visibility is calculated as the percent change in the extinction coefficient for each of the
PM species (on a daily average basis).  The individual daily species extinction
coefficients are summed to get a daily total extinction value. The daily extinction
coefficients are converted to visual  range and then averaged across all days.  In this way,
we can calculate annual average extinction and visual range at each IMPROVE site.
Subtracting the annual average control case visual range from the base case visual range
gives a projected  improvement in visual range (in km) at each mandatory class I federal
area.  This serves as the visibility input for the benefits analysis (See Chapter X).
M There are 100 IMPROVE sites with complete data for 2002. Many of these sites collect data that is
"representative" of other nearby unmonitored mandatory class I federal areas. There are a total of 133
mandatory class I federal areas that are represented by the 100 sites. The matching of sites to monitors is
taken from "Guidance for Tracking Progress Under the Regional Haze Rule".
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       For visibility calculations, we are continuing to use the IMPROVE program
species definitions and visibility formulas which are recommended in the modeling
guidance.121  Each IMPROVE site has measurements of PM25 species and therefore we
do not need to estimate the species fractions in the same way that we did for FRM sites
(using interpolation techniques and other assumptions concerning volatilization of
species).
2.4    Air Toxics

       Small SI and Marine SI emissions contribute to ambient levels of air toxics
known or suspected as human or animal carcinogens, or that have noncancer health
effects.  The population experiences an elevated risk of cancer and other noncancer health
effects from exposure to air toxics.122 These compounds include, but are not limited to,
benzene, 1,3-butadiene, formaldehyde, acetaldehyde, acrolein, poly cyclic organic matter
(POM), and naphthalene. These compounds, except acetaldehyde, were identified as
national or regional risk drivers in the 1999 National-Scale Air Toxics Assessment
(NATA) and have significant inventory contributions from mobile sources.

     Table2-7 Mobile Source Inventory Contribution to 1999 Emissions of NATA Risk Drivers"
1999 NATA Risk Driver
Benzene
1,3 -Butadiene
Formaldehyde
Acrolein
Polycyclic organic matter (POM)*
Naphthalene
Diesel PM and Diesel exhaust organic
gases
Percent of Emissions
Attributable to All Mobile
Sources
68%
58%
47%
25%
5%
27%
100%
Percent of Emissions
Attributable to Non-road
Sources
19%
17%
20%
11%
2%
6%
62%
" This table is generated from data contained in the pollutant specific Microsoft Access database files found
in the County-Level Emission Summaries section of the 1999 NATA webpage
(http://www.epa.gov/ttn/atw/natal999/tables.html).
*This POM inventory includes the 15 POM compounds: benzo[b]fluoranthene, benz[a]anthracene,
indeno(l,2,3-c,d)pyrene, benzo[k]fluoranthene, chrysene, benzo[a]pyrene, dibenz(a,h)anthracene, anthracene,
pyrene, benzo(g,h,i)perylene, fluoranthene, acenaphthylene, phenanthrene, fluorine, and acenaphthene.
       According to NATA for 1999, mobile sources were responsible for 44 percent of
outdoor toxic emissions and almost 50 percent of the cancer risk. Benzene is the largest
contributor to cancer risk of all 133 pollutants quantitatively assessed in the 1999 NATA
and mobile sources were responsible for 68 percent of benzene emissions in 1999. In
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Regulatory Impact Analysis
response, EPA has recently finalized vehicle and fuel controls that address this public
health risk.N

       People are exposed to toxics from spark-ignition engines as a result of operating
these engines and from intrusion into the home of emissions that occur in residential
attached garages. A study of aldehyde exposures among lawn and garden equipment
operators found formaldehyde and acetaldehyde exposure concentrations, during
approximately 30 to 120 minutes of engine use, that were one to two orders of magnitude
greater than those measured at an upwind monitor.123 The study also reported measurable
concentrations of transition metals emitted from most test engines, in addition to high
organic carbon concentrations in PM2.5 samples. Analyses of organic material emitted
from hand-held engines have detected PAHs and other compounds, suggesting that
exposures to hand-held engine emissions are similar in composition to those found in
motor vehicle-affected environments, such as near major roadways.124 Numerous studies
have reported elevated benzene concentrations in residential attached garages. 125>126>127
These studies indicate the potential for elevated exposures as a result of the use and
storage  of small spark-ignition engines.

       Noncancer health effects can result from chronic,0 subchronic,P or acuteQ
inhalation exposures to air toxics, and include neurological, cardiovascular, liver, kidney,
and respiratory effects as well as effects on the immune and reproductive systems.
According to the 1999 NAT A, nearly the entire U.S. population was exposed to an
average concentration of air toxics that has the potential for adverse noncancer
respiratory health effects. This will continue to be the case in 2030, even though toxics
concentrations will be lower. Mobile sources were responsible for 74 percent of the
noncancer (respiratory) risk from outdoor air toxics in 1999.  The majority of this risk
was  from exposure to acrolein. The confidence in the RfC for acrolein is medium and
confidence in NATA estimates of population noncancer hazard from ambient exposure to
this pollutant is low.128'129

       The NATA modeling framework has a number of limitations which prevent its
use as the sole basis for setting regulatory standards. These limitations and uncertainties
are discussed on the 1999 NATA website.130 Even so, this modeling framework is very
N U.S. EPA (2007) Control of Hazardous Air Pollutants from Mobile Sources. 72 FR 8428; February 26,
2007.

0 Chronic exposure is defined in the glossary of the Integrated Risk Information (IRIS) database
(http://www.epa.gov/iris) as repeated exposure by the oral, dermal, or inhalation route for more than
approximately 10% of the life span in humans (more than approximately 90 days to 2 years in typically
used laboratory animal species).

p Defined in the IRIS database as repeated exposure by the oral, dermal, or inhalation route for more than
30 days, up to approximately 10% of the life span in humans (more than 30 days up to approximately 90
days in typically used laboratory animal species)..

Q Defined in the IRIS database as exposure by the oral, dermal, or inhalation route for 24 hours or less.
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useful in identifying air toxic pollutants and sources of greatest concern, setting
regulatory priorities, and informing the decision making process.
       Benzene: The EPA's IRIS database lists benzene as a known human carcinogen
(causing leukemia) by all routes of exposure, and concludes that exposure is associated
with additional health effects, including genetic changes in both humans and animals and
increased proliferation of bone marrow cells in mice.131'132'133 EPA states in its IRIS
database that data indicate a causal relationship between benzene exposure and acute
lymphocytic leukemia and suggest a relationship between benzene exposure and chronic
non-lymphocytic leukemia and chronic lymphocytic leukemia. The International Agency
for Research on Carcinogens (IARC) has determined that benzene is a human carcinogen
and the U.S. Department of Health and Human Services (DHHS) has characterized
benzene as a known human carcinogen.134'135

       A number of adverse noncancer health effects including blood disorders,  such as
preleukemia and aplastic anemia,  have also been associated with long-term exposure to
benzene.136'137 The most sensitive noncancer effect observed in humans, based on current
data, is the depression of the absolute lymphocyte count in blood.138'139  In addition,
recent work, including studies sponsored by the Health Effects Institute (HEI), provides
evidence that biochemical responses are occurring at lower levels of benzene exposure
than previously known.140'141'142'143 EPA's IRIS program has not yet evaluated these new
data.

       1,3-Butadiene: EPA has characterized 1,3-butadiene as carcinogenic to humans
by inhalation.144'145  The IARC has determined that 1,3-butadiene is a human carcinogen
and the U.S. DHHS has characterized  1,3-butadiene as a known human carcinogen.146'147
There are numerous studies consistently demonstrating that 1,3-butadiene is metabolized
into genotoxic metabolites by experimental animals and humans. The specific
mechanisms of 1,3-butadiene-induced carcinogenesis are unknown; however, the
scientific evidence strongly suggests that the carcinogenic effects are mediated by
genotoxic metabolites. Animal data suggest that females may be more sensitive than
males for cancer effects associated with 1,3-butadiene exposure; there are insufficient
data in humans from which to draw conclusions about sensitive subpopulations.  1,3-
butadiene  also causes a variety of reproductive and developmental effects in mice; no
human data on these effects are available.  The most sensitive effect was ovarian atrophy
observed in a lifetime bioassay of female mice.148

       Formaldehyde: Since 1987, EPA has classified formaldehyde as a probable
human carcinogen based on evidence in humans and in rats, mice, hamsters, and
monkeys.149 EPA is currently reviewing recently published epidemiological data. For
instance, research conducted by the National Cancer Institute (NCI) found an increased
risk of nasopharyngeal cancer and lymphohematopoietic malignancies such as leukemia
among workers exposed to formaldehyde.150'151  NCI is currently performing an update of
these studies. A recent National Institute of Occupational Safety and Health (NIOSH)
study of garment workers also found increased risk of death due to leukemia among
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Regulatory Impact Analysis
workers exposed to formaldehyde.152 Extended follow-up of a cohort of British chemical
workers did not find evidence of an increase in nasopharyngeal or lymphohematopoietic
cancers, but a continuing statistically significant excess in lung cancers was reported.153

       In the past 15 years there has been substantial research on the inhalation
dosimetry for formaldehyde in rodents and primates by the CUT Centers for Health
Research (formerly the Chemical Industry Institute of Toxicology), with a focus on use of
rodent data for refinement of the quantitative cancer dose-response assessment.154'155'156
CIIT's risk assessment of formaldehyde incorporated mechanistic and dosimetric
information on formaldehyde.

       Based on the developments of the last decade, in 2004, the working group of the
International Agency for Research on Cancer (IARC) concluded that formaldehyde is
carcinogenic to humans (Group 1), on the basis of sufficient evidence in humans and
sufficient evidence in experimental  animals - a higher classification than previous IARC
evaluations. After reviewing the currently available epidemiological evidence, the IARC
(2006) characterized the human evidence for formaldehyde carcinogenicity  as
"sufficient," based upon the data on nasopharyngeal cancers; the epidemiologic evidence
on leukemia was characterized as "strong."157 EPA is reviewing the recent work cited
above from the NCI and NIOSH, as well as the analysis by the CUT Centers for Health
Research and other studies, as part of a reassessment of the human hazard and dose-
response associated with formaldehyde.

       Formaldehyde  exposure also causes a range of noncancer health effects, including
irritation of the eyes (burning and watering of the eyes), nose and throat. Effects from
repeated exposure in humans include respiratory tract irritation, chronic bronchitis and
nasal epithelial lesions such as metaplasia and loss of cilia. Animal studies  suggest that
formaldehyde may also cause airway inflammation - including eosinophil infiltration into
the airways. There are several studies that suggest that formaldehyde may increase the
risk of asthma - particularly in the young.158'159

       Acetaldehyde:  Acetaldehyde is classified in EPA's IRIS database as a probable
human carcinogen, based on nasal tumors in rats, and is considered toxic by the
inhalation, oral, and intravenous routes.160 Acetaldehyde is reasonably anticipated to be a
human carcinogen by the U.S. DHHS in the  11th Report on Carcinogens and is classified
as possibly carcinogenic to humans (Group 2B) by the IARC.161'162 EPA is  currently
conducting a reassessment of cancer risk from inhalation exposure to acetaldehyde.

       The primary noncancer effects of exposure to acetaldehyde vapors include
irritation of the eyes, skin, and respiratory tract.163 In short-term (4 week) rat studies,
degeneration of olfactory epithelium was observed at various concentration  levels of
acetaldehyde exposure.164'165 Data from these studies were used by EPA to  develop an
inhalation reference concentration.  Some asthmatics have been shown to be a sensitive
subpopulation to decrements in functional expiratory volume (FEV1 test) and
bronchoconstriction upon acetaldehyde inhalation.166 The agency is currently conducting
a reassessment of the health hazards from inhalation exposure to acetaldehyde.
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       Acrolein: EPA determined in 2003 that the human carcinogenic potential of
acrolein could not be determined because the available data were inadequate.  No
information was available on the carcinogenic effects of acrolein in humans and the
animal data provided inadequate evidence of carcinogen!city.167 The IARC determined
in 1995 that acrolein was not classifiable as to its carcinogenicity in humans.168

       Acrolein is extremely acrid and irritating to humans when inhaled, with acute
exposure resulting in upper respiratory tract irritation, mucus hypersecretion and
congestion. Levels considerably lower than  1 ppm (2.3 mg/m3) elicit subjective
complaints of eye and nasal irritation and a decrease in the respiratory rate.169'170 Lesions
to the lungs and upper respiratory tract of rats, rabbits, and hamsters have been observed
after subchronic exposure to acrolein. Based on animal data, individuals with
compromised respiratory function (e.g., emphysema, asthma) are expected to be at
increased risk of developing adverse responses to strong respiratory irritants such as
acrolein.  This was demonstrated in mice with allergic airway-disease by comparison to
non-diseased  mice in a study of the acute respiratory irritant effects of acrolein.171

       EPA is currently in the process of conducting an assessment of acute exposure
effects for acrolein.  The intense irritancy of this carbonyl has been demonstrated during
controlled tests in human subjects, who suffer intolerable eye and nasal mucosal sensory
reactions within minutes of exposure.172

       Polycyclic Organic Matter (POM): POM is generally defined as a large class of
organic compounds which have multiple benzene rings  and a boiling point greater than
100 degrees Celsius.  Many of the compounds included in the class of compounds known
as POM are classified by EPA as probable human carcinogens based on animal data.
One of these compounds, naphthalene, is discussed separately below.  Polycyclic
aromatic hydrocarbons (PAHs) are a subset of POM that contain only hydrogen and
carbon atoms. A number of PAHs are known or suspected carcinogens. Recent studies
have found that maternal exposures to PAHs (a subclass of POM) in a population of
pregnant women were associated with several adverse birth outcomes, including low
birth weight and reduced length at birth, as well as impaired cognitive development at
age three.173'174  EPA has not yet evaluated these recent studies.

       Naphthalene: Naphthalene is found in small quantities in gasoline and diesel
fuels. Naphthalene emissions have been measured in larger quantities in both gasoline
and diesel exhaust compared with evaporative emissions from mobile sources, indicating
it is primarily a product of combustion.  EPA recently released an external review draft of
a reassessment of the inhalation carcinogenicity of naphthalene based on a number of
recent animal carcinogenicity studies.175 The draft reassessment recently  completed
external peer review.176  Based  on external peer review  comments received to date,
additional analyses are being undertaken. This external review draft does not represent
official agency opinion and was released solely for the purposes of external peer review
and public comment. Once EPA evaluates public and peer reviewer comments, the
document will be revised.  The  National Toxicology Program listed naphthalene as
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Regulatory Impact Analysis
"reasonably anticipated to be a human carcinogen" in 2004 on the basis of bioassays
reporting clear evidence of carcinogenicity in rats and some evidence of carcinogenicity
in mice.177  California EPA has released a new risk assessment for naphthalene, and the
IARC has reevaluated naphthalene and re-classified it as Group 2B: possibly
carcinogenic to humans.178 Naphthalene also causes a number of chronic non-cancer
effects in animals, including abnormal cell changes and growth in respiratory and nasal
       179
tissues.

       The small SI and marine SI standards will reduce air toxics emitted from these
engines, vessels and equipment, thereby helping to mitigate some of the adverse health
effects associated with their operation.  The assumption that toxic reductions track
reductions in HC are supported by results from numerous test programs, including recent
testing on small nonroad gasoline engines with and without controls.180

2.5    Carbon Monoxide

       Unlike many gases, CO is odorless, colorless, tasteless, and nonirritating.  Carbon
monoxide results from incomplete combustion of fuel and is emitted directly from
vehicle tailpipes. Incomplete combustion is most likely to occur at low air-to-fuel ratios
in the engine.  These conditions are common during vehicle starting when air supply is
restricted ("choked"), when vehicles are not tuned properly, and at high altitude, where
"thin" air effectively reduces the amount of oxygen available for combustion (except in
engines that are designed or adjusted to compensate for altitude).  High concentrations  of
CO generally occur in areas with elevated mobile-source emissions. Carbon monoxide
emissions increase dramatically in cold weather.  This is because engines  need more fuel
to start at cold temperatures and because some emission control devices (such  as oxygen
sensors and catalytic converters) operate less efficiently when they are cold. Also,
nighttime inversion conditions are more frequent in the colder months of the year. This is
due to the enhanced stability in the atmospheric boundary layer, which inhibits vertical
mixing of emissions from the surface.

 2.5.1  Health Effects of CO Pollution

       We  are relying on the data and conclusions in the EPA Air Quality Criteria
Document for CO (CO Criteria Document), which was published in 2000, regarding the
health effects associated with CO exposure.R181  Carbon monoxide enters  the bloodstream
through the lungs and forms carboxyhemoglobin (COHb), a compound that inhibits the
blood's capacity to carry oxygen to organs and tissues.182'183 Carbon monoxide has long
been known to have substantial adverse effects on human health, including toxic effects
on blood and tissues, and effects on organ functions.  Although there are effective
compensatory increases in blood flow to the brain, at some concentrations of COHb,
somewhere above 20 percent, these compensations fail to maintain sufficient oxygen
delivery, and metabolism declines.184 The subsequent hypoxia in brain tissue then
R The NAAQS review process is underway for CO and the CO Integrated Science
Assessment is scheduled to be completed in 2010.
                                      2-44

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produces behavioral effects, including decrements in continuous performance and
             IOC
reaction time.

       Carbon monoxide has been linked to increased risk for people with heart disease,
reduced visual perception, cognitive functions and aerobic capacity, and possible fetal
effects.186 Persons with heart disease are especially  sensitive to carbon monoxide
poisoning and may experience chest pain if they breathe the gas while exercising.187
Infants, elderly persons, and individuals with respiratory diseases are also particularly
sensitive.  Carbon monoxide can affect healthy individuals, impairing exercise capacity,
visual perception, manual dexterity, learning functions, and ability to perform complex
tasks.188

       Several epidemiological studies have shown  a link between CO and premature
morbidity (including angina, congestive heart failure, and other cardiovascular diseases).
Several studies in the United States and Canada have also reported an association
between ambient CO exposures and frequency of cardiovascular hospital admissions,
especially for congestive heart failure (CHF). An association between ambient CO
exposure and mortality has also been reported in epidemiological studies, though not as
consistently or specifically as with CHF admissions. EPA reviewed these studies as part
of the CO Criteria Document review process and noted the possibility that the average
ambient CO levels used as exposure indices in the epidemiology studies may be
surrogates for ambient air mixes impacted by combustion sources and/or other
constituent toxic components of such mixes.  More research will be needed to better
clarify CO's role.189

       As noted above, CO has been linked to numerous health effects.  In  addition to
health effects from chronic exposure to ambient CO  levels, acute exposures to higher
levels are also a problem. Acute exposures to CO are discussed further in Section 2.6.

 2.5.2  Attainment and Maintenance of the CO NAAQS

       On July 3, 1995 EPA made a finding that small land-based spark-ignition engines
cause or contribute to CO nonattainment (60 FR 34581, July 3, 1995). Marine spark-
ignition engines, which have relatively high per engine CO emissions, can also be a
source of CO emissions in CO nonattainment areas.  In the preamble for this proposed
rule EPA makes a finding that recreational marine engines and vessels cause or
contribute to CO nonattainment and we provide information showing CO emissions from
spark-ignition marine engines and vessels in the CO nonattainment areas in 2005. Spark-
ignition marine engines and vessels contribute to CO nonattainment in more than one of
the CO nonattainment areas.

       A nonattainment area is defined in the Clean Air Act (CAA) as an area that is
violating an ambient standard or is contributing to a  nearby area that is violating the
standard. EPA has designated nonattainment areas for the CO NAAQS by calculating air
quality design values and considering other factors.8
s The full details involved in calculating a CO design value are given in 40 CFR Part 50.8.

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Regulatory Impact Analysis
       There are two CO NAAQS.  The 8-hour average CO NAAQS is 9 ppm, not to be
exceeded more than once per year, and the 1-hour average CO NAAQS is 35 ppm, not to
be exceeded more than once per year. As of March 12, 2008, there are approximately
850 thousand people living in 4 areas (which include 5 counties) that are designated as
nonattainment for CO, see Table 2-8.  The emission reductions in this rule will help areas
to attain and maintain the CO NAAQS.

  Table 2-8: Classified Carbon Monoxide Nonattainment Areas as of March 2008a
Area
Las Vegas, NV
El Paso, TX
Reno, NV
Total
Classification
serious
moderate <= 12.7 ppm
moderate <= 12.7 ppm

Population (1000s)
479
62
179
719.5
       a This table does not include Salem, OR which is an unclassified CO nonattainment area.

       In addition to the CO nonattainment areas, there are areas that have not been
designated as nonattainment where air quality monitoring may indicate a need for CO
control. For example, areas like Birmingham, AL and Calexico, CA have not been
designated as nonattainment although monitors in these areas have recorded multiple
exceedances since 1995.190

       There are also almost 69 million people living in CO maintenance areas, see
Table 2-9.T Carbon monoxide maintenance areas may remain at risk for high CO
episodes especially in geographic areas with unusually challenging meteorological and
topographical conditions and in areas with high population growth and increasing vehicle
miles traveled.

Table 2-9: Carbon Monoxide Maintenance Areas as  of March 2008
[Number of Areas [Number of Counties [Population (1000s)
Serious
Moderate > 12.7ppm
Moderate <= 12.7ppm
Unclassified
Total
6
4
30
33
73
15
19
62
38
127
20,496,077
17,575,606
23,371,653
7,480,907
68,924,243
       A 2003 NAS report found that in geographical areas that have achieved
attainment of the NAAQS, it might still be possible for ambient concentrations of CO to
sporadically exceed the standard under unfavorable conditions such as strong winter
 The CO nonattainment and maintenance areas are listed in Appendix 2E to this RIA.
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inversions. Areas like Alaska are prone to winter inversions due to their topographic and
meteorological conditions. The report further suggests that additional reductions in CO
are prudent to further reduce the risk of violations in regions with problematic
topography and temporal variability in meteorology.191 The reductions in CO emissions
from this rule will assist areas in maintaining the CO standard.

       As discussed in the preamble, Small SI engines and equipment and Marine SI
engines and vessels do contribute to CO nonattainment. The CO emission benefits from
this rule will help states in their strategy to attain the CO NAAQS.  Maintenance of the
CO NAAQS is also challenging and many areas will be able to use the emissions
reductions from this rule to assist  in maintaining the CO NAAQS into the future.

2.6    Acute Exposure to Air Pollutants

       Emissions from Small SI engines and equipment and Marine SI engines and
vessels contribute to ambient concentrations of ozone, CO, air toxics and PM and acute
exposures to air toxics, CO and PM. The standards being finalized in this action can help
reduce acute exposures to emissions from Marine SI engines and vessels and Small SI
engines and equipment.

 2.6.1 Exposure to CO from Marine SI Engines and Vessels

       In recent years, a substantial number of CO poisonings and deaths have occurred
on and around recreational boats across the nation.  The actual number of deaths
attributable to CO poisoning while boating is difficult to estimate because CO-related
deaths in the water may be labeled as drowning. An interagency team consisting of the
National Park Service, the U.S. Department of Interior, and the National Institute for
Occupational Safety and Health maintains a record of published CO-related fatal and
nonfatal poisonings.192  Between 1984 and 2004, 113 CO-related deaths and 458 non-
fatal CO poisonings have  been identified based on hospital records, press accounts, and
other information. Deaths have been attributed to exhaust from both onboard generators
and propulsion engines. Houseboats, cabin cruisers, and ski boats are the most common
types of boats associated with CO poisoning cases.  These incidents have prompted other
federal agencies, including the United States Coast Guard and National Park Service, to
issue advisory statements  and other interventions to boaters to avoid activities that could
lead to excessive CO exposure.193

       CO concentrations can be  extremely elevated within several meters of the exhaust
port. Engineers and industrial hygienists from CDC/NIOSH and other state and federal
agencies have conducted field studies of CO concentrations on and around houseboats.
In one study of houseboat concentrations, CO concentrations immediately at the point of
generator exhaust discharge on one houseboat averaged 0.5% (5,000 ppm), and ranged
from 0.0% to 1.28% (12,800 ppm).194  With both propulsion and generators running,
time-averaged concentrations on the swim deck were 0.2 - 169 ppm at different locations
on one boat's swim platform, 17-570 ppm on another's, and 0-108  on another. Other
studies also show the potential for high concentrations with extreme peaks in CO
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Regulatory Impact Analysis
concentrations in locations where boaters and swimmers can be exposed during typical
boating activities, such as standing on a swim deck or swimming near a boat.

 2.6.2 Exposure to CO and PM from Small SI Engines and Equipment

       A large segment of the population uses small, gasoline-powered SI lawn and
garden equipment on a regular basis. Emissions from many of the Small SI engines
powering this equipment may lead to elevated air pollution exposures for a number of
gaseous and paniculate compounds, especially for individuals such as landscapers, whose
occupations require the daily use of these engines and equipment.

       Emission studies with lawn and garden equipment suggest a potential for high
exposures during the Small SI engine operation.195'196 Studies investigating air pollutant
exposures during small engine use did report elevated personal exposure measurements
related to lawn and garden equipment use.197'198  Bunger et al. reported elevated CO
personal measurements related to chainsaw use, with short-term concentrations exceeding
400 ppm for certain cutting activities.  This study evaluated personal exposures during
the use of uncontrolled chainsaws. Baldauf at al. evaluated the use of lawnmowers,
chainsaws and string trimmers meeting US EPA Phase 2 standards.  In this study, short-
term exposures during lawnmower and chainsaw use exceeded 120 ppm of CO, while
string trimmer use resulted in some short-term exposures approaching 100 ppm of CO.
This study also indicated that short-term PM2.5 exposures could exceed  100 //g/m3.
Pollutant exposures were highly dependent on the operator's orientation to the engine and
wind direction, as well as the activities being conducted.

       These studies indicate that emissions from some lawn and garden equipment
meeting EPA's current Phase 2 standards may contribute to elevated exposures to certain
pollutants.  The potential for elevated exposure to CO and PM2.5 for operators of Small SI
engines and equipment will be reduced by this rule.
1 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. Error! Main Document Only.This document is
contained in Docket Identification EPA-HQ-OAR-2004-0008-0455 to 0457.

2 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. Error! Main Document Only.This document is
contained in Docket Identification EPA-HQ-OAR-2004-0008-0455 to 0457.

3 U.S. EPA, Review of the National Ambient Air Quality Standards for Ozone: Policy Assessment of
Scientific and Technical Information, OAQPS Staff Paper, Washington, DC, EPA-452/R-07-003, January
                                       2-48

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2007. Error! Main Document Only.This document is available in Docket EPA-HQ-OAR-2004-
0008.

4
 National Research Council (NRC), 2008. Estimating Mortality Risk Reduction and Economic Benefits
from Controlling Ozone Air Pollution.  The National Academies Press: Washington, D.C.

5 Bates, D.V.; Baker-Anderson, M; Sizto, R. (1990)  Asthma attack periodicity: a study of hospital
emergency visits in Vancouver.  Environ. Res. 51: 51-70.

6 Thurston, G.D.; Ito, K.; Kinney, P.L.; Lippmann, M. (1992) A multi-year study of air pollution and
respiratory hospital admissions in three New York State metropolitan areas: results for 1988 and 1989
summers. J. Exposure Anal. Environ. Epidemiol. 2:429-450.

7 Thurston, G.D.; Ito, K.; Hayes, C.G.; Bates, D.V.; Lippmann, M. (1994) Respiratory hospital admissions
and summertime haze air pollution in Toronto, Ontario: consideration of the role of acid aerosols. Environ.
Res. 65: 271-290.

8 Lipfert, F.W.; Hammerstrom, T. (1992) Temporal patterns in air pollution and hospital admissions.
Environ. Res. 59: 374-399.

9 Burnett, R.T.; Dales, R.E.; Raizenne, M.E.; Krewski, D.; Summers, P.W.; Roberts, G.R.; Raad-Young,
M.; Dann,T.; Brook, J. (1994) Effects of low ambient levels of ozone and sulfates on the frequency of
respiratory admissions to Ontario hospitals. Environ. Res. 65: 172-194.

10 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

11 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

12 Devlin, R. B.; McDonnell, W. F.; Mann, R.; Becker, S.; House, D. E.; Schreinemachers, D.; Koren, H. S.
(1991) Exposure of humans to ambient levels of ozone for 6.6 hours causes cellullar and biochemical
changes in the lung. Am. J. Respir. Cell Mol. Biol. 4: 72-81.

13 Koren, H. S.; Devlin, R. B.; Becker, S.; Perez, R.; McDonnell, W. F. (1991) Time-dependent changes of
markers associated with inflammation in the lungs of humans exposed to ambient levels of ozone. Toxicol.
Pathol. 19:406-411.

14 Koren, H. S.; Devlin, R. B.; Graham, D.  E.; Mann, R.; McGee, M. P.; Horstman, D. H.; Kozumbo, W. J.;
Becker,  S.; House, D.  E.; McDonnell, W. F.; Bromberg, P. A. (1989a) Ozone-induced inflammation in the
lower airways of human subjects. Am. Rev. Respir. Dis. 139: 407-415.

15 Schelegle, E.S.;  Siefkin, A.D.; McDonald, R.J. (1991) Time course of ozone-induced neutrophilia in
normal humans. Am.  Rev. Respir. Dis. 143:1353-1358.

16 U.S. EPA (1996). Air Quality Criteria for Ozone and Related Photochemical Oxidants, EPA600-P-93-
004aF; (See page 7-171). This document is contained in Docket Identification EPA-HQ-OAR-2004-0008-
0455 to 0457.

17 Hodgkin, J.E.; Abbey, D.E.; Euler, G.L.; Magie, A.R. (1984) COPD prevalence in nonsmokers in high
and low photochemical air pollution areas.  Chest 86: 830-838.
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Regulatory Impact Analysis
18 Euler, G.L.; Abbey, D.E.; Hodgkin, J.E.; Magie, A.R. (1988) Chronic obstructive pulmonary disease
symptom effects of long-term cumulative exposure to ambient levels of total oxidants and nitrogen dioxide
in California Seventh-day Adventist residents. Arch. Environ. Health 43: 279-285.

19 Abbey, D.E.; Petersen, F.; Mills, P.K.; Beeson, W.L. (1993) Long-term ambient concentrations of total
suspended particulates, ozone, and sulfur dioxide and respiratory symptoms in a nonsmoking population.
Arch. Environ. Health 48: 33-46.

20 U.S. EPA, Review of the National Ambient Air Quality Standards for Ozone: Policy Assessment of
Scientific and Technical Information, OAQPS Staff Paper, Washington, DC, EPA-452/R-07-003, January
2007. This document is available in Docket EPA-HQ-OAR-2004-0008.

21 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants  (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

22 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants  (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

23 Avol, E. L.; Trim, S. C; Little, D. E.; Spier, C. E.; Smith, M. N.; Peng, R.-C; Linn, W. S.; Hackney, J.
D.; Gross, K. B.; D'Arcy, J. B.; Gibbons, D.; Higgins, I. T. T. (1990) Ozone exposure and lung function in
children attending a southern California summer camp. Presented at: 83rd annual  meeting and exhibition of
the Air & Waste Management Association; June; Pittsburgh, PA. Pittsburgh, PA:  Air & Waste
Management Association; paper no. 90-150.3.

24 Higgins, I. T.  T.; D'Arcy, J. B.; Gibbons, D. I.; Avol, E. L.; Gross, K. B. (1990) Effect of exposures to
ambient ozone on ventilatory lung function in children. Am. Rev. Respir. Dis. 141:  1136-1146.

25 Raizenne, M.  E.; Burnett, R. T.; Stern, B.; Franklin, C. A.; Spengler, J. D. (1989)  Acute lung function
responses to ambient acid aerosol exposures in children. Environ. Health Perspect. 79: 179-185.

26 Raizenne, M.; Stern, B.; Burnett, R.; Spengler, J. (1987) Acute respiratory function and transported air
pollutants: observational studies. Presented at: 80th annual meeting of the Air Pollution Control
Association; June; New York, NY. Pittsburgh, PA: Air Pollution Control Association; paper no. 87-32.6.

27 Spektor, D. M.; Lippmann, M. (1991) Health effects of ambient ozone on healthy children at a summer
camp. In: Berglund, R. L.;  Lawson, D. R.; McKee, D. J., eds. Tropospheric ozone and the environment:
papers from an international conference; March 1990; Los Angeles, CA. Pittsburgh, PA: Air & Waste
Management Association; pp. 83-89. (A&WMA transaction series no. TR-19).

28 Spektor, D. M.; Thurston, G. D.; Mao, J.; He, D.; Hayes, C.; Lippmann, M. (1991) Effects of single- and
multiday ozone  exposures on respiratory function in active normal children. Environ. Res. 55: 107-122.

29 Spektor, D. M.; Lippman, M.; Lioy, P. J.; Thurston, G. D.; Citak, K.; James, D. J.; Bock, N.; Speizer, F.
E.; Hayes, C. (1988a) Effects of ambient ozone on respiratory function in active, normal children. Am.
Rev. Respir. Dis. 137: 313-320.

30 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants  (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

31 Hazucha, M. J.; Folinsbee, L. J.; Seal, E., Jr. (1992) Effects of steady-state and  variable ozone
concentration profiles on pulmonary function. Am. Rev. Respir. Dis. 146: 1487-1493.
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32 Horstman, D.H.; Ball, B.A.; Folinsbee, L.J.; Brown, I; Gerrity, T. (1995) Comparison of pulmonary
responses of asthmatic and nonasthmatic subjects performing light exercise while exposed to a low level of
ozone. Toxicol. Ind. Health.

33 Horstman, D.H.; Folinsbee, L.J.; Ives, P.J.; Abdul-Salaam, S.; McDonnell, W.F. (1990) Ozone
concentration and pulmonary response relationships for 6.6-hour exposures with five hours of moderate
exercise to 0.08, 0.10, and 0.12 ppm. Am. Rev. Respir. Dis. 142: 1158-1163.

34 AQ modeling TSD (EPA Doc #)

35 Intergovernmental Panel on Climate Change (2007). Fourth Assessment Report of the Intergovernmental
Panel on Climate Change. Cambridge University Press, NY.

36 U.S. EPA. 1999.  The Benefits and Costs of the Clean Air Act, 1990-2010. Prepared for U.S. Congress
by U.S. EPA, Office of Air and Radiation, Office of Policy Analysis and Review, Washington, DC,
November; EPA report no. EPA410-R-99-001. Error! Main Document Only.This document is
contained in Docket Identification EPA-HQ-OAR-2004-0008-0485.

37 Winner, W.E., and CJ. Atkinson. 1986. "Absorption of air pollution by plants, and consequences for
growth." Trends in Ecology and Evolution 1:15-18.

38 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006.  This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

39 Tingey, D.T., and Taylor, G.E. 1982. "Variation in plant response to ozone:  a conceptual model of
physiological events." In: Effects of Gaseous Air Pollution in Agriculture and Horticulture (Unsworth,
M.H., Omrod, D.P., eds.) London, UK: Butterworth Scientific, pp. 113-138.

40 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006.  This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

41 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

42 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006.  This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

43 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

44 Ollinger, S.V., J.D. Aber and P.B. Reich. 1997. "Simulating ozone effects on forest productivity:
interactions between leaf canopy and stand level processes." Ecological Applications 7:1237-1251.
45
  Winner, W.E., 1994. "Mechanistic analysis of plant responses to air pollution." Ecological Applications,
4(4) :651-661.

46 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006.  This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.


                                             2-51

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Regulatory Impact Analysis
47 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

48 Fox, S., and R. A. Mickler, eds. 1996.  Impact of Air Pollutants on Southern Pine Forests. Springer-
Verlag, NY, Ecol. Studies, Vol. 118, 513 pp.

49 De Steiguer, J., J. Pye, C. Love. 1990. "Air Pollution Damage to U.S. Forests." Journal of Forestry, Vol
88 (8) pp. 17-22.

50 Pye, J.M. 1988. "Impact of ozone on the growth and yield of trees: A review." Journal of Environmental
Quality 17 pp.347-360.

51 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

52 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

53 McBride, J.R., P.R. Miller, andR.D. Laven. 1985. "Effects of oxidant air pollutants on forest succession
in the mixed conifer forest type of southern California." In:  Air Pollutants Effects On Forest Ecosystems,
Symposium Proceedings, St.  P, 1985, p. 157-167.

54 Miller, P.R., O.C. Taylor, R.G. Wilhour. 1982. Oxidant air pollution effects on a western coniferous
forest ecosystem. Corvallis, OR: U.S. Environmental Protection Agency, Environmental Research
Laboratory (EPA600-D-82-276).

55 U.S. EPA. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). U.S. EPA,
Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document is contained in Docket Identification
EPA-HQ-OAR-2004-0008-0455 to 0457.

56 Kopp, R. J.; Vaughn, W. J.; Hazilla, M.; Carson, R. 1985.  "Implications of environmental policy for
U.S. agriculture: the case of ambient ozone standards." J. Environ. Manage.  20:321-331.

57 Adams, R. M.; Hamilton, S. A.; McCarl, B. A. 1986. "The benefits of pollution control: the case of
ozone and U.S. agriculture."  Am. J. Agric. Econ. 34:3-19.

58 Adams, R. M.; Glyer, J. D.; Johnson, S. L.; McCarl, B. A. 1989. "A reassessment of the economic
effects of ozone on U.S. agriculture." JAPCA 39:960-968.

59 Abt Associates, Inc.  1995. Urban ornamental plants: sensitivity to ozone and potential economic losses.
U.S. EPA, Office of Air Quality Planning and Standards, Research Triangle Park. Under contract to
RADIAN Corporation, contract no. 68-D3-0033, WA no. 6.  pp. 9-10.

60 U.S. EPA (2004)  Air Quality Criteria for Paniculate Matter (Oct 2004),  Volume I Document No.
EPA600/P-99/002aF and Volume II Document No. EPA600/P-99/002bF.  Error! Main Document
Only.This document is available in Docket EPA-HQ-OAR-2004-0008-0042 and EPA-HQ-OAR-2004-
0008-0043.
                                            2-52

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61 U.S. EPA (2005) Review of the National Ambient Air Quality Standard for Paniculate Matter: Policy
Assessment of Scientific and Technical Information, OAQPS Staff Paper. EPA-452/R-05-005. Error!
Main Document Only.This document is available in Docket EPA-HQ-OAR-2004-0008-0454.

62 U.S. EPA 2006. Provisional Assessment of Recent Studies on Health Effects of Paniculate Matter
Exposure. EPA/600/R-06/063.  Error! Main Document Only.This document is available in Docket
EP A-HQ-OAR-2004-0008-0461.

63 Laden F; Neas LM; Dockery DW; et al. 2000. "Association of fine paniculate matter from different
sources with daily mortality in six U.S. cities."  Environ Health Perspectives 108(10):941-947.

64 Schwartz J; Laden F; Zanobetti A.  2002. "The concentration-response relation between PM(2.5) and
daily deaths." Environ Health Perspect 110(10): 1025-1029.

65 Janssen NA; Schwartz J; Zanobetti A.; et al.  2002. "Air conditioning and source-specific particles as
modifiers of the effect of PM10 on hospital admissions for heart and lung disease." Environ Health
Perspect 110(l):43-49.

66 Dockery, DW; Pope, CA, III; Xu, X; et al.  1993. "An association between air pollution and mortality in
six U.S. cities." N Engl J Med 329:1753-1759.

67 Pope, CA, III; Burnett, RT; Thun, MJ; Calle, EE; et al.  2002. "Lung cancer, cardiopulmonary mortality,
and long-term exposure to fine paniculate air pollution."  J Am Med Assoc 287: 1132-1141.

68 Krewski, D; Burnett, RT; Goldberg, M S; et al. 2000. "Reanalysis of the Harvard Six Cities study and the
American Cancer Society study of paniculate air pollution and mortality. A special report of the Institute's
Particle Epidemiology Reanalysis Project." Cambridge, MA: Health Effects Institute.
69
  Jerrett, M; Burnett, RT; Ma, R; et al. 2005. "Spatial Analysis of Air Pollution and Mortality in Los
Angeles." Epidemiology. 16(6):727-736.
70
  Ktinzli, N.; Jerrett, M.; Mack, W.J.; et al.(2004) Ambient air pollution and atherosclerosis in Los
Angeles. Environ Health Perspect doi: 10. 1289/ehp.7523 [Available at http://dx.doi.org/] .

71 Riediker, M.; Cascio, W.E.; Griggs, T.R.; et al. 2004. "Paniculate matter exposure in cars is associated
with cardiovascular effects in healthy young men." Am JRespir Crit Care Med 169: 934-940.

72 Maynard, D.; Coull, B.A.; Gryparis, A.; Schwartz, J. (2007) Mortality risk associated with short-term
exposure to traffic particles and sulfates. Environmental Health Perspectives 115: 751-755.

73 Ryan, P.H.; LeMasters, O.K.; Biswas, P.; Levin, L.; Hu, S.; Lindsey, M.; Bernstein, D.I.; Lockey, J.;
Villareal, M.; Khurana Hershey, O.K.; Grinshpun, S.A. (2007) A comparison of proximity and land use
regression traffic exposure  models and wheezing in infants. Environ Health Perspect 115:  278-84.

74 Morgenstern, V.; Zutavern, A.;  Cyrys, J.; Brockow, I.; Gehring, U.; Koletzko, S.; Bauer, C.P.; Reinhart,
D; Wichmann, H-E.; Heinrich, J. (2007) Respiratory health and individual estimated expousure to traffic-
related air pollutant in a cohort of young children. Occupational and Environmental Medicine 64:  8-16.

75 Franco Suglia, S.; Gryparis, A.; Wright, R.O.; Schwartz, J.; Wright, R.J. (2007) Association of black
carbon with cognition among children in a prospective birth cohort  study.  American Journal of
Epidemiology 167: 280-286.
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Regulatory Impact Analysis
76 National Research Council, 1993. Protecting Visibility in National Parks and Wilderness Areas.
National Academy of Sciences Committee on Haze in National Parks and Wilderness Areas. National
Academy Press, Washington, DC. This book is available electronically at
http://www.nap.edu/books/0309048443/html/ and is available in Docket EPA-HQ-OAR-2004-0008.

77 U.S. EPA, National Ambient Air Quality Standards for Paniculate Matter; Proposed Rule; January 17,
2006, Vol71  p 2676. Error! Main Document Only.This document is available in Docket EPA-
HQ-OAR-2004-0008-0466. This information is available electronically at: http://epa.gov/fedrgstr/EPA-
AIR/2006/January/Day-17/al77.pdf

78 U.S. EPA (2004) Air Quality Criteria for Paniculate Matter (Oct 2004), Volume I Document No.
EPA600/P-99/002aF and Volume II Document No. EPA600/P-99/002bF. This document is available in
Docket EPA-HQ-OAR-2004-0008.

79 U.S. EPA (2005) Review of the National Ambient Air Quality Standard for Paniculate Matter: Policy
Assessment of Scientific and Technical Information, OAQPS  Staff Paper.  EPA-452/R-05-005. This
document is available in Docket EPA-HQ-OAR-2004-0008.

80 U.S. EPA.  1993. Effects of the 1990 Clean Air Act Amendments on Visibility in Class I Areas: An EPA
Report to Congress. EPA452-R-93-014. Error! Main Document Only.This document is available
in Docket EPA-HQ-OAR-2004-0008-0483.

81 U.S. EPA (2002) Latest Findings on National Air Quality - 2002 Status and Trends. EPA 454/K-03-001.
Error! Main Document Only.This document is available in Docket EPA-HQ-OAR-2004-0008-
0482.

82 National Park Service. Air Quality in the National Parks, Second edition. NFS, Air Resources Division.
D 2266. September 2002.  Error! Main Document Only.This document is available in Docket
EPA-HQ-OAR-2004-0008-0481.

83 U.S. EPA (2002) Latest Findings on National Air Quality - 2002 Status and Trends. EPA 454/K-03-001.
This document is available in Docket EPA-HQ-OAR-2004-0008-0482.

84 Environmental Protection Agency (2003). Response of Surface Water Chemistry to the Clean Air Act
Amendments of 1990. National Health and Environmental Effects Research Laboratory, Office of Research
and Development, U.S. Environmental Protection Agency. Research Triangle Park, NC. EPA 620/R-
03/001.

85 Fenn, M.E. and Blubaugh, TJ. (2005) Winter Deposition of Nitrogen and Sulfur in the Eastern Columbia
River Gorge National Scenic Area, USDA Forest Service.

86 Galloway, J. N.;  Cowling, E. B. (2002). Reactive nitrogen and the world: 200 years of change. Ambio
31:64-71.

87 Bricker, Suzanne B., et al., National Estuarine Eutrophication Assessment,  Effects of Nutrient
Enrichment in the Nation's Estuaries, National Ocean Service, National Oceanic and Atmospheric
Administration, September, 1999.

88 Smith, W.H. 1991. "Air pollution and Forest Damage." Chemical Engineering News, 69(45):  30-43.

89 Gawel, J.E.; Ahner, B.A.; Friedland, A.J.; and Morel, F.M.M. 1996. "Role for heavy metals in forest
decline indicated by phytochelatin measurements." Nature, 381: 64-65.
                                            2-54

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90 Cotrufo, M.F.; DeSanto, A.V.; Alfani, A.; et al. 1995. "Effects of urban heavy metal pollution on organic
matter decomposition in Quercus ilix L. woods." Environmental Pollution, 89: 81-87.

91 Niklinska, M.; Laskowski, R.; Maryanski, M. 1998. "Effect of heavy metals and storage time on two
types of forest litter: basal respiration rate and exchangeable metals." Ecotoxicological Environmental
Safety, 41: 8-18.

92 Mason, R.P. and Sullivan, K.A. 1997. "Mercury in Lake Michigan." Environmental Science &
Technology, 31: 942-947.  (from Delta Report "Atmospheric deposition of toxics to the Great Lakes").

93 Landis, M.S. and Keeler, G.J. 2002. "Atmospheric mercury deposition to Lake Michigan during the Lake
Michigan Mass Balance Study." Environmental Science & Technology, 21: 4518-24.

94 U.S. EPA. 2000. EPA453/R-00-005, "Deposition of Air Pollutants to the  Great Waters: Third Report to
Congress," Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.
Error! Main Document Only.This document is available in Docket EPA-HQ-OAR-2004-0008.

95 NSTC 1999

96 Callender, E. and Rice, K.C. 2000. "The Urban Environmental Gradient: Anthropogenic Influences on
the Spatial and Temporal Distributions of Lead and Zinc in Sediments." Environmental Science &
Technology, 34: 232-238.

97 Rice, K.C. 1999. "Trace Element Concentrations in Streambed Sediment Across the Conterminous
United States." Environmental Science & Technology, 33: 2499-2504.

98 Ely, JC; Neal, CR; Kulpa, CF; et al. 2001. "Implications of Platinum-Group Element Accumulation
along U.S. Roads from Catalytic-Converter Attrition." Environ. Sci. Technol. 35: 3816-3822.

99 U.S. EPA. 1998. EPA454/R-98-014, "Locating and Estimating Air Emissions from Sources of
Poly cyclic Organic Matter," Office of Air Quality Planning and Standards, Research Triangle Park, North
Carolina. Error! Main Document Only.This document is available  in Docket EPA-HQ-OAR-
2004-0008.

100U.S. EPA. 1998. EPA454/R-98-014, "Locating and Estimating Air Emissions from Sources of
Poly cyclic Organic Matter," Office of Air Quality Planning and Standards, Research Triangle Park, North
Carolina. Error! Main Document Only.This document is available  in Docket EPA-HQ-OAR-
2004-0008.

101 Simcik, M.F.; Eisenreich, S.J.; Golden, K.A.; et al. 1996. "Atmospheric Loading of Polycyclic Aromatic
Hydrocarbons to Lake Michigan as Recorded in the Sediments." Environmental Science and Technology,
30: 3039-3046.

102 Simcik, M.F.; Eisenreich, S.J.; and Lioy, P.J. 1999. "Source apportionment and source/sink relationship
of PAHs in the coastal atmosphere of Chicago and Lake Michigan." Atmospheric Environment, 33: 5071-
5079.

103 Arzayus, K.M.; Dickhut, R.M.; and Canuel, E.A. 2001. "Fate of Atmospherically Deposited Polycyclic
Aromatic Hydrocarbons (PAHs) in Chesapeake Bay." Environmental Science & Technology, 35, 2178-
2183.

104 Park, J.S.; Wade, T.L.; and Sweet, S. 2001. "Atmospheric distribution of polycyclic aromatic
hydrocarbons and deposition to Galveston Bay, Texas, USA." Atmospheric Environment, 35: 3241-3249.
                                            2-55

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Regulatory Impact Analysis
105 Poor, N.; Tremblay, R.; Kay, H.; et al. 2002. "Atmospheric concentrations and dry deposition rates of
poly cyclic aromatic hydrocarbons (PAHs) for Tampa Bay, Florida, USA." Atmospheric Environment 38:
6005-6015.

106 Arzayus, K.M.; Dickhut, R.M.; and Canuel, E.A. 2001. "Fate of Atmospherically Deposited Polycyclic
Aromatic Hydrocarbons (PAHs) in Chesapeake Bay." Environmental Science & Technology, 35, 2178-
2183.

107 U.S. EPA. 2000. EPA453/R-00-005, "Deposition of Air Pollutants to the Great Waters: Third Report to
Congress," Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina. This
document is available in Docket EPA-HQ-OAR-2004-0008.

108 Van Metre, P.C.; Mahler, B.J.; and Furlong, E.T. 2000. "Urban Sprawl Leaves its PAH Signature."
Environmental Science & Technology, 34: 4064-4070.

109 Cousins, I.T.; Beck, A.J.; and Jones, K.C. 1999. "A review of the processes involved in the exchange of
semi-volatile organic compounds across the air-soil interface." The Science of the Total Environment, 228:
5-24.

110 Tuhackova, J. et al. (2001) Hydrocarbon deposition and soil microflora as affected by highway traffic.
Environmental Pollution,  113: 255-262.

111 U.S. EPA, Technical Support Document for the Final Small Si/Marine SI Rule: Air Quality Modeling,
Research Triangle Park, NC

112 U.S. EPA, Byun, D.W., and Ching, J.K.S., Eds, 1999. Science algorithms of EPA Models-3 Community
Multiscale Air Quality (CMAQ modeling system, EPA/600/R-99/030, Office of Research and
Development).

113 Byun, D.W., and Schere, K.L., 2006. Review of the Governing Equations, Computational Algorithms,
and Other Components of the Models-3 Community Multiscale Air Quality (CMAQ) Modeling System, J.
Applied Mechanics Reviews, 59 (2), 51-77.

114 Dennis, R.L., Byun, D.W., Novak, J.H., Galluppi, K.J., Coats, C.J., and Vouk, M.A., 1996. The next
generation of integrated air quality modeling: EPA's Models-3, Atmospheric Environment, 30, 1925-1938.

115 Amar, P., Bornstein, R., Feldman, H., Jeffries, H., Steyn, D., Yamartino, R., Zhang, Y., 2004. Final
Report Summary:  December 2003 Peer Review of the CMAQ Model, p. 7.

116 Grell, G., J. Dudhia, andD. Stauffer, 1994: A Description of the Fifth-Generation Perm State/NCAR
Mesoscale Model (MM5), NCAR/TN-398+STR., 138 pp, National Center for Atmospheric Research,
Boulder CO.

117 U.S. Environmental Protection Agency, Byun, D.W., and Ching, J.K.S., Eds, 1999. Science algorithms
of EPA Models-3 Community Multiscale Air Quality (CMAQ) modeling system, EPA/600/R-99/030,
Office of Research and Development). Please also see: http://www.cmascenter.org/
118
   Yantosca, B., 2004. GEOS-CHEMv7-01-02 User's Guide, Atmospheric Chemistry Modeling Group,
Harvard University, Cambridge, MA, October 15, 2004.
119
   U.S. EPA, (2004), "Procedures for Estimating Future PM2.5 Values for the CAIR Final Rule by
Application of the (Revised) Speciated Modeled Attainment Test (SMAT)- Updated 11/8/04".
120 Sisler 1996
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121 U.S. EPA, Guidance on the Use of Models and Other Analyses For Demonstrating Attainment of Air
Quality Goals for Ozone, PM2.5, and Regional Haze; EPA-454/B-07-002; Research Triangle Park, NC;
April 2007.

122
   U. S. EPA. 1999 National-Scale Air Toxics Assessment.
http://www.epa.gov/ttn/atw/natal999/risksum.html

123 Baldauf, R.; Fortune, C.; Weinstein, J.; Wheeler, M; Blanchard, F. (2006) Air contaminant exposures
during the operation of lawn and garden equipment. J Exposure Sci & Environ Epidemiol 16:  362-370.
124
   Volckens, J.; Olson, D.A.; Hays, M.D. (2008) Carbonaceous species emitted from handheld two-stroke
engines.  Atmos Environ 42:  1239-1248.

125 Isbell, M.; Ricker, J.; Gordian, M.E.; Duff, L.K. (1999) Use of biomarkers in an indoor air study: lack
of correlation between aromatic VOCs with respective urinary biomarkers.  Sci Total Environ 241: 151-
159.

126 Batterman, S.; Jia, C.; Hatzivasilis, G. (2007) Migration of volatile organic compounds from attached
garages to residences:  a major exposure source. Environ Res 104:  224-240.

127 Philips, M.L.; Esmen, N.A.; Hall, T.A.; Lynch, R. (2005) Determinants of exposure to volatile organic
compounds in four Oklahoma cities.  J Exposure Anal Environ Epidemiol 15: 35-46.

128 U.S. EPA (2003) Integrated Risk Information System File of Acrolein. National Center for
Environmental Assessment, Office of Research and Development, Washington, D.C. 2003. This material
is available electronically at http://www.epa.gov/iris/subst/0364.htm.

129 U.S. EPA (2006) National-Scale Air Toxics Assessment for 1999. This material is available
electronically at http://www.epa.gov/ttn/atw/natal999/risksum.html.

130 U.S. EPA (2006) National-Scale Air Toxics Assessment for 1999.
http://www.epa.gov/ttn/atw/natal999.

131 U.S. EPA. 2000. Integrated Risk Information System File for Benzene. This material is available
electronically at: http://www.epa.gov/iris/subst/0276.htm.

132 International Agency for Research on Cancer, IARC monographs on the evaluation of carcinogenic risk
of chemicals to humans, Volume 29, Some industrial chemicals and dyestuffs, International Agency for
Research on Cancer, World Health Organization, Lyon, France, p. 345-389, 1982.

133 Irons, R.D.; Stillman,  W.S.; Colagiovanni, D.B.; Henry, V.A. (1992) Synergistic action of the benzene
metabolite hydroquinone on myelopoietic stimulating activity of granulocyte/macrophage colony-
stimulating factor in vitro, Proc. Natl. Acad. Sci. 89:3691-3695.

134 International Agency for Research on Cancer (IARC). 1987. Monographs on the evaluation of
carcinogenic risk of chemicals to humans, Volume 29, Supplement 7,  Some industrial chemicals  and
dyestuffs, World Health Organization, Lyon, France.

135 U.S. Department of Health and Human Services National Toxicology Program 11th Report on
Carcinogens available at: http://ntp.niehs.nih.gov/go/16183.

136 Aksoy, M.  (1989). Hemato to xicity and  carcinogenicity of benzene.  Environ. Health Perspect. 82:
193-197.
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Regulatory Impact Analysis
137 Goldstein, B.D.  (1988). Benzene toxicity. Occupational medicine. State of the Art Reviews. 3:541-
554.

138 Rothman, N., G.L. Li, M. Dosemeci, W.E. Bechtold, G.E. Marti, Y.Z. Wang, M. Linet, L.Q. Xi, W. Lu,
M.T. Smith, N. Titenko-Holland, L.P. Zhang, W. Blot, S.N. Yin, andR.B. Hayes (1996) Hematotoxicity
among Chinese workers heavily exposed to benzene. Am. J. Ind. Med. 29: 236-246.

139 U.S. EPA 2002 Toxicological Review of Benzene (Noncancer Effects). Environmental Protection
Agency, Integrated Risk Information System (IRIS), Research and Development, National Center for
Environmental Assessment, Washington DC. This material is available electronically at
http://www.epa.gov/iris/subst/0276.htm.

140 Qu, O.; Shore, R.; Li, G.; Jin, X.; Chen, C.L.; Cohen, B.; Melikian, A.; Eastmond, D.; Rappaport,  S.; Li,
H.; Rupa, D.; Suramaya, R.; Songnian, W.; Huifant,  Y.;  Meng, M.;  Winnik, M.; Kwok, E.; Li, Y.; Mu,
R.;Xu, B.; Zhang, X.; Li, K. (2003). HEI Report 115, Validation & Evaluation of Biomarkers in Workers
Exposed to Benzene in China.

141 Qu, Q., R. Shore, G. Li, X. Jin, L.C. Chen, B. Cohen, et al. (2002).  Hematological changes among
Chinese workers with a broad range of benzene exposures. Am. J. Industr. Med. 42: 275-285.
142
   Lan, Qing, Zhang, L., Li, G., Vermeulen, R., et al. (2004). Hematotoxically in Workers Exposed to
Low Levels of Benzene.  Science 306: 1774-1776.

143 Turtletaub, K.W. and Mani, C.  (2003). Benzene metabolism in rodents at doses relevant to human
exposure from Urban Air. Research Reports Health Effect Inst. Report No.113.

144 U.S. EPA. 2002. Health Assessment of 1,3-Butadiene. Office of Research and Development, National
Center for Environmental Assessment, Washington Office, Washington, DC. Report No. EPA600-P-98-
00IF. This document is available electronically at http://www.epa.gov/iris/supdocs/buta-sup.pdf.

145 U.S. EPA. 2002 "Full IRIS Summary for 1,3-butadiene (CASRN 106-99-0)" Environmental Protection
Agency, Integrated Risk Information System (IRIS), Research and Development, National Center for
Environmental Assessment, Washington, DC http://www.epa. gov/iris/subst/013 9.htm.

146 International Agency for Research on Cancer (IARC) (1999) Monographs on the evaluation of
carcinogenic risk of chemicals to humans, Volume 71, Re-evaluation of some organic chemicals, hydrazine
and hydrogen peroxide and Volume 97 (in preparation), World Health Organization, Lyon, France.

147 U.S. Department of Health and Human Services National Toxicology Program 11th Report on
Carcinogens available at: http://ntp.niehs.nih.gov/go/16183.

148 Bevan, C.; Stadler, J.C.; Elliot, G.S.; et al. (1996) Subchronic toxicity of 4-vinylcyclohexene in rats and
mice by inhalation. Fundam. Appl. Toxicol. 32:1-10.

149 U.S. EPA. 1987. Assessment of Health Risks to Garment Workers and Certain Home Residents from
Exposure to Formaldehyde, Office of Pesticides and Toxic Substances, April 1987.

150 Hauptmann, M..; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.; Blair, A. 2003. Mortality from
lymphohematopoetic malignancies among workers in formaldehyde industries.  Journal of the National
Cancer Institute 95: 1615-1623.

151 Hauptmann, M..; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.; Blair, A. 2004. Mortality from solid
cancers among workers in formaldehyde industries. American Journal of Epidemiology 159: 1117-1130.
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152 Pinkerton, L. E. 2004. Mortality among a cohort of garment workers exposed to formaldehyde: an
update.  Occup. Environ. Med. 61: 193-200.

153 Coggon, D, EC Harris, J Poole, KT Palmer. 2003. Extended follow-up of a cohort of British chemical
workers exposed to formaldehyde. J National Cancer Inst. 95:1608-1615.

154 Conolly, RB, JS Kimbell, D Janszen, PM Schlosser, D Kalisak, J Preston, and FJ Miller. 2003.
Biologically motivated computational modeling of formaldehyde carcinogenicity in the F344 rat. Tox Sci
75: 432-447.

155 Conolly, RB, JS Kimbell, D Janszen, PM Schlosser, D Kalisak, J Preston, and FJ Miller. 2004. Human
respiratory tract cancer risks of inhaled formaldehyde: Dose-response predictions derived from
biologically-motivated computational modeling of a combined rodent and human dataset. Tox Sci 82: 279-
296.

156 Chemical Industry Institute of Toxicology (CUT). 1999. Formaldehyde: Hazard characterization and
dose-response assessment for carcinogenicity by the route of inhalation. CUT, September 28, 1999.
Research Triangle Park, NC.

157 International Agency for Research on Cancer (2006) Formaldehyde, 2-Butoxyethanol and 1-tert-
Butoxypropan-2-ol.  Monographs Volume 88. World Health Organization, Lyon, France.

ICO
   Agency for Toxic Substances and Disease Registry (ATSDR). 1999. Toxicological profile for
Formaldehyde. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service.
http://www.atsdr.cdc.gov/toxprofiles/tpl 11.html

159
   WHO (2002) Concise International Chemical Assessment Document 40: Formaldehyde. Published
under the joint sponsorship of the United Nations Environment Programme, the International Labour
Organization, and the World Health Organization, and produced within the framework of the Inter-
Organization Programme for the Sound Management of Chemicals.  Geneva.

160 U.S. EPA (1988).  Integrated Risk Information System File of Acetaldehyde.  Research and
Development, National Center for Environmental Assessment, Washington, DC. This material is available
electronically at http://www.epa.gov/iris/subst/0290.htm.

161 U.S. Department of Health and Human Services National Toxicology Program 11th Report on
Carcinogens available at: http://ntp.niehs.nih.gov/go/16183.

162 International Agency for Research on Cancer (IARC). 1999. Re-evaluation of some organic chemicals,
hydrazine, and hydrogen peroxide.  IARC Monographs on the Evaluation of Carcinogenic Risk of
Chemical to Humans, Vol 71. Lyon, France.

163 U.S. EPA (1988).  Integrated Risk Information System File of Acetaldehyde.  This material is available
electronically at http://www.epa.gov/iris/subst/0290.htm.

164 U.S. EPA. 2003. Integrated Risk Information System File of Acrolein.  Research and Development,
National Center for Environmental Assessment, Washington, DC. This material is available electronically
at http://www.epa.gov/iris/subst/0364.htm.

165 Appleman, L.M., R.A. Woutersen, and V.J. Feron. (1982). Inhalation toxicity of acetaldehyde in rats. I.
Acute and subacute studies. Toxicology. 23: 293-297.
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Regulatory Impact Analysis
166 Myou, S.; Fujimura, M; Nishi K.; Ohka, T.; and Matsuda, T. (1993) Aerosolized acetaldehyde induces
histamine-mediated bronchoconstriction in asthmatics. Am. Rev. Respir.Dis. 148(4 Pt 1): 940-943.

167 Integrated Risk Information System File of Acrolein.  Research and Development, National Center for
Environmental Assessment, Washington, DC. This material is available at
http://www.epa.gov/iris/subst/0364.htm

168 International Agency for Research on Cancer (IARC). 1995. Monographs on the evaluation of
carcinogenic risk of chemicals to humans, Volume 63, Dry cleaning, some chlorinated solvents and other
industrial chemicals, World Health Organization, Lyon, France.

169 Weber-Tschopp, A; Fischer, T; Gierer, R; et al.  (1977) Experimentelle reizwirkungen von Acrolein auf
den Menschen. Int Arch Occup Environ Hlth 40(2): 117-130. In German

170 Sim, VM; Pattle, RE. (1957) Effect of possible smog irritants on human subjects. J Am Med Assoc
165(15):1908-1913.

171 Morris JB, Symanowicz PT, Olsen JE, et al.  2003. Immediate sensory nerve-mediated respiratory
responses to irritants in healthy and allergic airway-diseased mice. J Appl Physiol 94(4): 1563-1571.

172 Sim VM, Pattle RE. Effect of possible smog irritants on human subjects JAMA165:  1980-2010, 1957.

173 Perera, P.P.; Rauh, V.; Tsai, W-Y.; et al. (2002) Effect of transplacental exposure to environmental
pollutants on birth outcomes in a multiethnic population.  Environ Health Perspect.  Ill: 201-205.

174 Perera, P.P.; Rauh, V; Whyatt, R.M.; Tsai, W.Y.; Tang, D.; Diaz, D.; Hoepner, L.; Barr, D.; Tu, Y.H.;
Camann, D.; Kinney, P. (2006) Effect of prenatal exposure to airborne polycyclic aromatic hydrocarbons
on neurodevelopment in the first 3 years of life  among inner-city children. Environ Health Perspect 114:
1287-1292.

175 U. S. EPA.  2004.  Toxicological Review of Naphthalene (Reassessment of the Inhalation Cancer Risk),
Environmental Protection Agency, Integrated Risk Information System, Research and Development,
National Center for Environmental Assessment, Washington, DC.  This material is available electronically
at http://www.epa.gov/iris/subst/0436.htm.

176 Oak Ridge Institute for Science and Education.  (2004). External Peer Review for the IRIS
Reassessment of the Inhalation Carcinogenicity of Naphthalene. August 2004.
http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=84403

177 National Toxicology Program (NTP). (2004). 11th Report on Carcinogens. Public Health Service, U.S.
Department of Health and Human Services, Research Triangle Park, NC. Available from: http://ntp-
server.niehs.nih.gov.

178 International Agency for Research on Cancer (IARC). (2002).  Monographs on the Evaluation of the
Carcinogenic Risk of Chemicals for Humans. Vol.82. Lyon, France.

179 U. S. EPA. 1998. Toxicological Review of Naphthalene, Environmental Protection Agency, Integrated
Risk Information System, Research and Development, National Center for Environmental Assessment,
Washington, DC. This material is available electronically at http://www.epa.gov/iris/subst/0436.htm

1 80
   US EPA (2004) Characterization of Emissions from Small, Hand-Held,In-Use 2-Cycle Engines Internal
Report, EPA/600/X-04/191.
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181 U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide. EPA600-P-99-001F. June 1, 2000. U.S.
Environmental Protection Agency, Office of Research and Development, National Center for
Environmental Assessment, Washington, D.C. This document is available online at
http://www.epa.gov/ncea/pdfs/coaqcd.pdf. A copy of this document is available in Docket Identification
EPA-HQ-OAR-2004-0008-0050.

182 U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide. EPA600-P-99-001F. June 1, 2000. U.S.
Environmental Protection Agency, Office of Research and Development, National Center for
Environmental Assessment, Washington, D.C. This document is available online at
http://www.epa.gov/ncea/pdfs/coaqcd.pdf. A copy of this document is available in Docket Identification
EPA-HQ-OAR-2004-0008-0050.

183 Coburn, R.F. (1979) Mechanisms of carbon monoxide toxicity. Prev. Med. 8:310-322.

184 Helfaer, M.A., and Traystman, R.J.  (1996) Cerebrovascular effects of carbon monoxide. In: Carbon
Monoxide (Penney, D.G., ed). Boca Raton, CRC Press, 69-86.
185
   Benignus, V. A.  (1994) Behavioral effects of carbon monoxide: meta analyses and extrapolations. J.
Appl. Physiol.  76:1310-1316.

186 U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide. EPA600-P-99-001F. June 1, 2000. U.S.
Environmental Protection Agency, Office of Research and Development, National Center for
Environmental Assessment, Washington, D.C. This document is available online at
http://www.epa.gov/ncea/pdfs/coaqcd.pdf. A copy of this document is available in Docket Identification
EPA-HQ-OAR-2004-0008-0050.

187 U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide. EPA600-P-99-001F. June 1, 2000. U.S.
Environmental Protection Agency, Office of Research and Development, National Center for
Environmental Assessment, Washington, D.C. This document is available online at
http://www.epa.gov/ncea/pdfs/coaqcd.pdf. A copy of this document is available in Docket Identification
EPA-HQ-OAR-2004-0008-0050.

188 U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide. EPA600-P-99-001F. June 1, 2000. U.S.
Environmental Protection Agency, Office of Research and Development, National Center for
Environmental Assessment, Washington, D.C. This document is available online at
http://www.epa.gov/ncea/pdfs/coaqcd.pdf. A copy of this document is available in Docket Identification
EPA-HQ-OAR-2004-0008-0050.

189 U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide. EPA600-P-99-001F. June 1, 2000. U.S.
Environmental Protection Agency, Office of Research and Development, National Center for
Environmental Assessment, Washington, D.C. This document is available online at
http://www.epa.gov/ncea/pdfs/coaqcd.pdf. A copy of this document is available in Docket Identification
EPA-HQ-OAR-2004-0008-0050.

190 National Academy of Sciences (2003). Managing Carbon Monoxide Pollution in Meteorological and
Topographical Problem Areas. The National Academies Press, Washington, D.C. This document is
available on the internet at http://www.nap.edu.

191 National Academy of Sciences (2003). Managing Carbon Monoxide Pollution in Meteorological and
Topographical Problem Areas. The National Academies Press, Washington, D.C. This document is
available on the internet at http://www.nap.edu.

192 National Park Service: Department of Interior; National Institute for Occupational Safety and Health.
(2004) Boat-related carbon monoxide (CO) poisonings.  Updated: October 2004 [Online at


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Regulatory Impact Analysis
http://safetynet.smis.doi.gov/thelistbystatelO-19-04.pdf]  A copy of this document is available in Docket
Identification EPA-HQ-OAR-2004-0008-0106.

193 U.S. Department of Interior. (2004) Carbon monoxide dangers from generators and propulsion engines.
On-board boats - compilation of materials. [Online at http://safetynet.smis.doi.gov/COhouseboats.htm] A
copy of this document is available in Docket Identification EPA-HQ-OAR-2004-0008-0110.

194 Letter dated April 5, 2001 to Mr.  John Stenseth, Fun Country Marine Industries,  Inc., from Ronald M.
Hall, NIOSH.

195 Gabele, P. (1997) Exhaust emissions from four-stroke lawn mower engines. Air Waste Manage Assoc.
47: 945-952.

196 Priest, M.W.; Williams, D.J.; and Bridgman, H.A. (2000) Emissions from in-use lawn-mowers in
Australia. Atmos Environ. 34:657-664.

197 Hunger, J.; Bombosch, F.; Mesecke, U.; and Hairier, E. (1997) Monitoring and analysis of occupational
exposure to chain saw exhausts. Am IndHyg Assoc J. 58:747-751.

198 Baldauf, R.; Fortune, C.; Weinstein, J.; Wheeler, M.; and Blanchard, F.  (2006) Air contaminant
exposures during the operation of lawn and garden equipment. Journal of Exposure Science and
Environmental Epidemiology. 16(4):362-370.
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                                                                     Emission Inventory
                   CHAPTER 3: Emission Inventory

       This chapter presents our analysis of the emission impact of the final Phase 3 standards
for spark ignition (SI) small nonroad engines (<25 horsepower (hp) or < 19 kilowatts (kW) used
in land-based or auxiliary marine applications (hereafter collectively termed small nonroad SI
engines) and marine SI engines. The control requirements include exhaust and evaporative
emission standards for small non-handheld SI engines (Class I <225 cubic centimeters (cc) and
Class II >225 cc), an evaporative emission standards for small handheld SI engines (Classes III-
V), and exhaust and evaporative emission standards for all marine SI engines.

       Section 3.1 presents an overview of methodology used to develop the emission
inventories for the small nonroad and marine engines that are subject to the final rulemaking.
Section 3.2 identifies the specific modeling inputs that were used to develop the baseline
scenario emission inventories.  The resulting baseline emission inventories are also presented in
that section. Section 3.3 then describes the contribution of the small nonroad and marine SI
engines to national baseline inventories.  Section 3.4  describes the development of the controlled
inventories, specifically the changes made to the baseline modeling inputs to incorporate the new
standards.  The control  inventories are also presented in this section.  Section 3.5 follows with
the projected emission reductions resulting from the final rule.  Section 3.6 describes the
emission inventories used in the air quality modeling  described in Chapter 2. This discussion
includes a description of the changes in the inputs and resulting emission inventories between the
preliminary baseline and control scenarios used for the air quality modeling and the slightly
refined baseline and control scenarios reflected in the actual final rule.

       The emission inventory estimates contained in Sections 3.2, 3.4, 3.5, and 3.6, for small
nonroad and marine SI  engines are reported for the 50-state geographic area that comprises the
United States (including the District of Columbia). These inventories reflect the emissions from
the engines subject to the final Phase 3  standards,  i.e., federal engines. As such, they exclude the
emissions from engines that are regulated by the State of California as provided for by section
209 of the Clean Air Act.

       More specifically, California has been granted a waiver under the Clean Air Act to
regulate the emissions from all nonroad SI engines, except for engines with less than 175
horsepower that are used in farm and construction equipment. Therefore, these latter engines are
subject to federal regulation and are included in our 50-state inventories. By contrast, we do  not
include any of the emissions from California marine  SI engines in these inventories.  As with
certain nonroad engine  classes, the State has been granted a waiver to regulate the exhaust
emissions from all marine SI engines and evaporative emissions from outboard and personal
watercraft SI engines.  That State also has indicated its intent to adopt the final Phase 3 standards
for evaporative emissions from sterndrive engines. Therefore, the 50-state inventories presented
in Sections 3.2, 3.4, 3.5, and 3.6 only reflect the emissions from small nonroad and marine SI
engines that are subject to federal regulation.
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Final Regulatory Impact Analysis
       Section 3.3 presents a nationwide comparison of the emissions from small nonroad and
marine SI engines to those from other source categories, i.e., stationary, area, and other mobile
sources. Unlike the 50-state inventories described earlier, these inventories reflect the emissions
from all sources, whether they are separately regulated by a state government or the federal
government, e.g., all of California's small SI and marine SI engines are included.

       Inventories are generally presented for the following pollutants: exhaust and evaporative
hydrocarbons reported as total hydrocarbons (THC) and volatile organic compounds (VOC),
oxides of nitrogen (NOX), particulate matter (PM25 and PM10), and carbon monoxide (CO). The
VOC category is a broader class of hydrocarbon compounds than THC that is primarily
important for air quality modeling purposes. The additional compounds  that comprise this
category are reactive oxygenated species represented by aldehydes (RCHO) and alcohols
(RCOH), and less reactive species represented by methane (CH4) and ethane (CH3CH3).  The PM
inventories for particle sizes of <2.5 microns or <10 microns in diameter include directly emitted
PM only, although secondary sulfates are taken into account in the air quality modeling as noted
below. Toxic pollutant inventories are also presented because the final Phase 3 requirements
will reduce hazardous air pollutants such as benzene, formaldeyde, acetaldehyde,  1,3-butadiene,
acrolein, napthalene, and 15 other compounds grouped together as poly cyclic organic matter
(POM).

       Finally, none of the controlled inventory estimates include the potential uses of the
averaging, banking, and trading (ABT) program for engine manufacturers, since these are
flexibilities that would be difficult to predict and model. More information regarding these
provisions can be found in the preamble for this final rule that is published in the Federal
Register.

3.1 Overview of Small Nonroad and Marine SI Engine Emissions Inventory
Development

       This section describes how the final emission inventories were modeled for the small
nonroad and marine SI engines that are affected by the Phase 3 standards. Generally, the
inventories were generated using a modified version of our NONROAD2005 model. More
specifically, we started with the most recent public version of the model, i.e., NONROAD2005a,
which was released in February 2006. A copy of that model and the accompanying technical
reports that detail of the modeling inputs (e.g., populations, activity, etc.) are available in the
docket for this final rule.1  They can also be accessed on our website at:
http ://www. epa. gov/otaq/nonrdmdl .htm.

       The NONROAD2005a model was modified to incorporate new emission test data and
other improvements for this rulemaking.  This special version is named NONROAD2005d. A
copy of the model and the accompanying documentation are available in the docket.2'3'4   The
inputs we used to model the effects of the Phase 3 standards are also described in  Chapter 4 for
exhaust emissions and Chapter 5  for evaporative emissions. Finally, the modifications we made
to NONROAD2005a to reflect the baseline and control  scenarios related to the final rule are
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                                                                    Emission Inventory
summarized in Sections 3.2 and 3.4, respectively.

       The nonroad model estimates emission inventories of important air pollutant species from
a diverse universe of nonroad equipment. The model's scope includes all off-highway sources
with the exception of locomotives, aircraft and commercial marine vessels. The model can
distinguish emissions on the basis of equipment type, horsepower, and technology group. For
the engines subject to the final rule, the nonroad model evaluates numerous equipment types
with each type containing multiple horsepower categories and technology groups. A central
feature of the model is the projection of past, present, or future emissions between 1970 and
2050.

       The chemical species NOx, PM, and CO are exhaust emissions, i.e., pollutants emitted
directly as exhaust from the combustion of fuel (both liquid and gaseous fuels) in the engine.
Hydrocarbon species, e.g., THC and VOC, consist of both exhaust and evaporative emissions.
The exhaust component represents hydrocarbons emitted as products of combustion, which can
also include emissions vented from the crankcase.  The evaporative hydrocarbon component
includes compounds from unburned fuel that are emitted either while the engine is being
operated  or when the equipment is not in use. The various categories of evaporative emissions
that are included in the nonroad model are:

       Diurnal. These emissions result from changes in temperature during the day.  As the day
gets warmer there is a  concomitant rise in the temperature of the liquid fuel in the fuel tank.  This
causes the vapor pressure inside the tank to increase, forcing vaporized fuel to escape into the
atmosphere. For modeling purposes, this category also includes diffusion losses that come from
fuel vapor exiting the orifice of a vented fuel tank cap regardless of temperature.

       Permeation.  These emissions occur when fuel molecules transfuse through plastic or
rubber fuel-related components (fuel lines and fuel tanks) into the atmosphere.

       Hot Soak.  These emissions occur after the  engine is shut off and the engine's residual
heat causes fuel vapors from the fuel tank or fuel metering device to be released into the
atmosphere.

       Running Loss.  Similar in form to diurnal losses, these emissions are caused from the
engine's heat during equipment operation.

       Vapor Displacement or Refueling Loss. These are vapors displaced from the fuel tank
when liquid fuel is being added during a refueling event.

       Liquid Spillage. This refers to the liquid fuel that is spilled when equipment is refueled
either from a portable fuel container or fuel pump,  which subsequently evaporates into the
atmosphere.

       Equipment fueled by compressed natural gas, liquified petroleum gas, or diesel fuel are
assumed to have zero evaporative emissions. Consequently, all evaporative emissions are from

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Final Regulatory Impact Analysis
gasoline or gasoline blends, i.e., ethanol and gasoline.

       The control scenario analyzed in Section 3.4 reflects the final Phase 3 standards for
exhaust hydrocarbons, CO, and NOx from small nonhandheld nonroad and marine SI engines.a
New standards to control evaporative emissions from hose permeation and tank permeation from
these engine classes and handheld equipment are also included. Further, the final requirements
also establish new standards for running loss and diffusion emissions from small nonhandheld
nonroad SI engines and diurnal emissions from marine SI engines. Finally, we expect that the
technology necessary to achieve the final exhaust emission standards will indirectly lower
exhaust PM.  All of these effects are reflected in the controlled emission inventories presented in
this chapter.

3.2 Baseline Emission Inventory Estimates

       This section describes more specifically how we developed the baseline exhaust and
evaporative inventories for small nonroad and marine SI engines.  The resulting baseline
inventories are also presented.  Section 3.2.1 provides this information for exhaust and
evaporative emissions.

       The inventory estimates presented throughout this section  include only equipment that
would be subject to the final standards. For small nonroad SI equipment, California's Air
Resources Board (ARE) has promulgated standards that are roughly equivalent in stringency
overall to final Phase 3  federal standards, although  some of the specific requirements and test
procedures are different. However, the Clean Air Act prohibits California from regulating
engines used in farm and construction equipment with maximum power levels below 175 hp or
130 kW.  Therefore, the requirements contained in this final rule for small nonroad SI engines
will apply in California to the above farm and construction equipment power levels.  As a  result,
these engines are included in the inventories presented in this chapter. However, the majority of
the small nonroad SI equipment in California is subject to ARE regulations, so the effect of the
federal Phase 3 standards for these engines in that State is rather limited.

       For marine SI engines, ARB also has its own exhaust emission standards that are roughly
equivalent overall to the final Phase 3 federal standards.  In addition, ARB has stated its intend
to develop evaporative emissions standards for marine SI equipment in California. Therefore,
the exhaust and evaporative inventory estimates for marine SI engines/equipment completely
exclude California.

3.2.1 Baseline Exhaust and Evaporative Emissions Estimates  for THC, VOC, NOx, PM2 5,
PM10, and CO

       The baseline exhaust and evaporative emission inventories for small nonroad and marine
SI engines include the effects of all existing applicable federal emission standards. We
        The CO standard applies to small nonhandheld SI engines used in auxiliary marine applications.

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                                                                    Emission Inventory
generated these inventories by starting with the NONROAD2005a emissions model, which was
released to the public in February 2006. That model was then modified to incorporate new
emission test data and other improvements for this rulemaking.  This special version of the
model is named NONROAD2005d.  The modifications to the base model are described below.

       3.2.1.1 Changes from NONROAD2005a to NONROAD2005d

       As already mentioned, a number of improvements to the most publically available
nonroad emissions inventory model were made to develop the NONROAD2005d, which is used
in this final rulemaking.  These revisions were based on recent testing programs, other
information, and model enhancements. The changes are summarized below for small nonroad
and marine  SI engines. Many of the most important revisions are discussed in greater detail in
the following  sections.

       3.2.1.1.1 Revisions for Small SI Engines

       The modifications that we made to the NONROAD2005a model for Small SI engines
that are most relevant to the final rule are summarized below:

       1.      Revised fuel tank and hose permeation emission factors;
       2.      Added new fuel tank diffusion losses to the diurnal emission estimates;
       3.      Updated or corrected exhaust emission factors and deterioration rates, and
              technology-type sales fractions for Phase 2 engines;
       4.      Adjusted equipment populations to properly account for the application of federal
              emission requirements to engines in California;
       5.      Added the ability to specifically model the effects of ethanol blends on exhaust
              emissions and  on fuel tank and hose permeation  losses;
       6.      Added hot soak and running losses for handheld equipment;
       7.      Corrected snowblower technology types to include 4-stroke engines; and
       8.      Corrected running loss emission factors for Class 1 snowblowers to account for
              cold weather applications.

       3.2.1.1.2 Revisions for Recreation Marine  SI Engines

       The modifications that we made to the NONROAD2005a model for marine  SI engines
that are most relevant to the final rule are summarized below:

       1.      Revised brake-specific fuel consumption factors;
       2.      Revised PM emission factors for 2-stroke technology engines;
       3.      Revised fuel tank and hose permeation emission factors and temperature effects;
       4.      Updated modeling inputs for high performance sterndrive and inboard (SD/I)
              engines; and
       5.      Added the ability to specifically model the effects of ethanol blends on exhaust
              emissions and  fuel tank and hose permeation losses.
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Final Regulatory Impact Analysis
       3.2.1.2 Baseline Exhaust Emission Calculations

       3.2.1.2.1 Small SI Exhaust Calculations

       We revised the Phase 2 exhaust emission factors in the NONROAD2005d inventory
model to reflect new information and our better understanding of the in-use emissions of these
engines, as discussed further below.

       The nonroad model estimates exhaust emissions in a given year by applying an
appropriate emission factor based on the engines age or hours of use.  This reflects the fact that
an engine's exhaust emissions performance degrades over its lifetime due to normal use or
misuse (i.e., tampering or neglect). More specifically, the emission factor is a combination of a
"zero-hour" emission level (ZHL) and a deterioration factor (DF).  The ZHL represents the
emission rate for recently manufactured engines, i.e., engines with few operating hours. The DF
to the degree  of emissions degradation per unit of activity. Nonroad engine activity is expressed
in terms of hours of use or fraction of its median life. This later term refers to the age at which
50 percent of the engines sold in a given year ceased to function and have been scrapped.  The
following formula describes the basic form of the calculation:

       EFaged = ZHLxDF

              where:  EFaged is the emission factor for an aged engine
                     ZML is the zero hour emission factor for a new engine
                     DF is the deterioration factor

       The form of the DF for nonroad SI engines is as follows:

       DF =  1 + A x  (Age Factor)   for Age Factor  < 1
       DF =  1 + A                for Age Factor > 1

       where:  Age Factor  =   [Cumulative Hours x Load Factor]
                               Median Life at Full Load, in Hours

               A,             =   constants for a given technology type; b < 1.

       The constants A and b can be varied to approximate a wide range of deterioration
patterns.  "A" can be varied to reflect differences in maximum deterioration. For example,
setting A equal to 2.0 would result in emissions at the engine's median life being three times the
emissions when new.  The shape  of the deterioration function is determined by the second
constant, b. This constant can be set at any level between zero and 1.0; currently, the
NONROAD model sets b equal to either 0.5 or 1.0. The first case results in a curvilinear
deterioration rate in which most of the deterioration occurs in the early part of an engine's life.
The second case results in a linear deterioration pattern in which the rate of deterioration is
constant throughout the median life of an engine.  In both cases, we previously decided to cap
deterioration at the end of an engine's median life, under the assumption that an engine can only

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                                                                      Emission Inventory
deteriorate to a certain point beyond which it becomes inoperable. For spark ignition engines at
or below 25 horsepower, which are the subject of this final rule, the nonroad model sets the
constant b equal to 0.5. The emission factor inputs for Phase 2 small nonroad SI engines used in
this analysis are shown in Table 3.2-1.

      Table 3.2-1: Phase 2 Modeling Emission Factors for Small SI Engines(g/kW-hr)b
Class/
Tprhnnlnpy
Class I - SV
Class I - OHV
Class II
THCZML
10.30
8.73
5.58
THC "A"
1.753
1.753
1.095
NOxZML
2.57
3.28
3.71
NOx "A"
0.180
0.180
0.000
COZML
386.53
392.93
472.80
CO "A"
0.070
0.070
0.080
PM10
7MT,
0.35
0.05
0.08
PM10
"A"
1.753
1.753
1.095
       Some of the values shown in Table 3.2-1 have been updated from the NONROAD2005a
inventory model based on data collected by EPA on in-use engines as well as
manufacturer-supplied certification data. The ZHL emission factors for Class I engines were
updated based on testing performed by EPA on 16 in-use walk-behind lawnmowers.  The Class I
side-valve engine A values were revised to be the same as the Class I overhead engine A values
based on the same in-use testing of lawnmowers which showed similar in-use deterioration
characteristics between overhead valve and sidevalve Class I engines. The Class I and Class II
engine A values for CO emissions were revised to better reflect the level of deterioration seen in
both the in-use lawnmower testing noted above as well as certification data provided by
manufacturers to EPA. Finally, based on data collected from another test program of in-use
lawnmowers, the assumption that there was no deterioration of Class I and II emissions after the
median life was reached was revised to reflect further continued emissions deterioration after
that point.

       Also, the model was modified to acknowledge the continued use of side-valve engine
designs in Class I nonhandheld engines meeting Phase 2 standards. In the rulemaking that
established those regulatory requirements, side-valve technology was assumed to be superceded
by overhead valve designs and was modeled accordingly. In reality, side-valve technology has
continued to be used in small nonroad SI engines.  The resulting technology mixture is shown in
Table 3.2-2. The estimated sales fractions by engine class and technology are based on sales
information provided by engine manufacturers to EPA for the 2005 model year. A full
description of the emission modeling information for Phase 2 engines and the basis for the
estimates can be found in the docket for this rule.
       b The nonroad model calculates VOC by multiplying THC by an adjustment factor depending on engine
and fuel type for exhaust emissions as follows: 2-stroke gasoline = 1.034; 4-stroke gasoline = 0.933; liquified
petroleum (LPG) = 0.995; and compressed natural gas (CNG) = 0.004. Crankcase and evaporative VOC for all fuels
other than CNG is assumed to be equivalent to THC. CNG fueled equipment do not emit crankcase and evaporative
VOC emissions because CNG is comprised almost exclusively of methane.  PM2 5 is calculated by multiplying PM10
0.92.
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Final Regulatory Impact Analysis
            Table 3.2-2:  Phase 3 Small Nonroad SI Engine Technology Classes
Engine Class
Class I
Class I
Class II
Technology Class
Side Valve
Overhead Valve
Overhead Valve
Percent Sales (%)
60
40
100
       3.2.1.2.2 Marine SI Exhaust Calculations

       The NONROAD2005a model included a number of updates to the emission rates and
technology mix of marine SI engines.5  These updates were largely based on data submitted to
EPA by marine engine manufacturers as part of the certification process and on new test data
collected by EPA.6 However, NONROAD2005a did not include high-performance SD/I marine
engines. High-performance marine engines are niche product and were not included in the data
set used to develop the engine populations for the NONROAD2005a model.

       Manufacturers have more recently commented that approximately 1,500 high-
performance engines are produced in the U.S. per year.  These engines range from 500 to 1500
horsepower and are used in both racing and non-racing applications. Based on conversations
with individual high-performance engine manufacturers, we estimate that about two thirds of
these engines are sold for use in the U.S. with an  average power of about 650 horsepower. These
engines are designed to sacrifice service life for power, but with rebuilds, generally are used for
7-8 years (we use 8 years for our modeling). Based on these estimates and the growth rate in the
NONROAD2005a model, we estimate  a 1998 population of SD/I engines >600 horsepower of
7500 units. One manufacturer stated that they performed a survey on the annual use of these
engines for warranty purposes and the result was  an average annual use of about 30 hours per
year. We also updated the baseline emission factors for high performance marine engines based
on the emission data presented in Chapter 4. Note that no changes were made to the PM
emission factors because no new data was available. Table 3.2-3 presents the updated emission
factors for high-performance SD/I marine engines.

     Table 3.2-3: Emission Factors for High-Performance Marine Engines [g/kW-hr]
Pollutant
HC
CO
NOx
PM
BSFC
Carbureted Engines
(MS4C, Bin 12)
13.8
253
8.4
0.08
400
Fuel-Injected Engines
(MS4D, Bin 12)
13.8
207
6.8
0.08
362

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                                                                     Emission Inventory
       3.2.1.3 Baseline Evaporative Emission Calculations

       Chapter 5 presents a great deal of information on evaporative emission rates from fuel
systems used in nonroad equipment.  Much of this information was incorporated into the
NONROAD2005a model.7 However, we have continued to collect evaporative emission data
and incorporate the new information into our evaporative emission inventory calculations.
These updates are described below. A technical memorandum that documents the methodology
and input values for modeling the effects of ethanol blends on nonroad engine fuel hose and tank
permeation is also available in the docket for this final rulemaking.8

       3.2.1.3.1 Fuel Ethanol Content

       Currently, about 55 percent of fuel sold in the U.S. contains ethanol. With the recent
establishment of the Energy Policy Act of 2005,9 this percentage is expected to increase.  The
significance of the use of ethanol in fuel, for the inventory calculations, is that ethanol in fuel can
affect both exhaust and evaporative emissions from nonroad equipment. The oxygen content of
the ethanol tends to make combustion mixtures leaner, which can decrease exhaust HC and CO
emissions while increasing NOx. Also, fuel blends containing ethanol typically increase the
permeation rate for most materials used in gasoline fuel systems. This is discussed in more
detail below.

       Title XV, section 1501, of the Energy Policy Act requires that the total volume of
renewable fuel increase from 4.0 to 7.5 billion gallons per year from 2006 to 2012, and the
Energy Information Administration (EIA) predicts that production will actually surpass  11
billion gallons per year by then. Based on these figures and projected gasoline sales from the
Energy Information Administration,10'11 we estimate that about three-fourths of gasoline sold in
2009 and later will contain ethanol. Table 3.2-4 presents our estimates for ethanol blended fuels
into the future.  The blend market shares shown in the last column of this table assume 10
percent for ethanol content of blended gasoline in all areas except California, where it is 5.7
volume percent until switching to 10 percent in 2010.
                                           3-9

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Final Regulatory Impact Analysis
             Table 3.2-4: Estimated Fraction of Gasoline Containing Ethanol
Calendar Year
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
U.S. Gasoline Sales
[109gal.]
129.9
132.0
135.6
137.0
140.1
140.2
142.2
141.7
142.5
144.1
145.4
147.1
149.0
U.S. Ethanol Sales
[109gal.]
1.6
1.8
2.1
2.8
3.5
4.0
5.5
6.1
7.6
10.0
10.9
11.0
11.2
Fraction of Gas with
Ethanol
12.5%
13.4%
15.7%
22.2%
27.3%
31.0%
41.5%
46.3%
57.5%
75.1%
78.8%
78.8%*
78.8%*
        ethanol fraction projected to be constant after 2010
       3.2.1.3.2 Hose Permeation

       We developed hose permeation emission factors based on the permeation data and hose
requirements presented in Chapter 5.  Because permeation is a function of surface area and
because hose lengths and inner diameters are defining parameters, hose permeation rates are
based on g/m2/day. These emission factors incorporate a more complete set of data than those in
the NONROAD2005a model. In addition, distinctions are now made between permeation rates
for liquid fuel versus fuel vapor exposure and between permeation rates for gasoline versus
ethanol-blend fuels.  The updated hose emission factors are discussed below and presented in
Table 3.2-5.

       Fuel hoses in small nonroad SI applications vary greatly in construction depending on the
individual specifications of the engine and equipment manufacturers. However most fuel hose
used on non-handheld  equipment meets the SAE J30 R7 hose requirements which includes a
permeation requirement of 550 g/m2/day on Fuel C at 23C.12 Chapter 5 presents data on several
hose constructions that range from 190 to 450 g/m2/day on Fuel C. As discussed in Chapter 5,
permeation is typically lower on gasoline than on Fuel C.  At the same time, blending ethanol
into the fuel increases permeation. Based on data presented in Chapter 5, we estimate that non-
handheld fuel hose permeation rates range from 27 to 180 g/m2/day on gasoline and 80-309
g/m2/day on gasoline blended with 10 percent ethanol (E10). Of the data presented in Chapter 5,
the lowest two permeation rates for SAE J30 R7 hose were from an unknown fuel hose
construction and from  a hose (used in some small nonroadSI applications) that was specially
constructed of fuel resistant materials to facilitate painting. Dropping the unknown hose
construction (which  is not known to be used in Small SI applications), we get average
permeation rates of 122 g/m2/day on gasoline and 222 g/m2/day on E10 at 23C.
                                          3-10

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                                                                     Emission Inventory
       Chapter 5 also presents permeation data on fuel lines used in handheld equipment tested
using E10 fuel.  Based on this data, we estimate an average permeation rate at 23C, on fuel
containing 10 percent ethanol of 255 g/m2/day. To determine an emission factor for handheld
fuel lines on gasoline, we used the ratio of permeation rates for NBR rubber samples on E10
versus gasoline. The resulting permeation rate for handheld hose on gasoline was estimated to
bel40g/m2/dayat23C.

       Fuel hose for portable marine fuel tanks is not subject to any established recommended
practice.  For this reason, we consider fuel hose used on portable marine fuel tanks to be
equivalent to the hose used in Small SI applications. The supply hose for each portable marine
fuel tank is modeled to include a primer bulb with the same permeation rate as the hose.

       Recommended practices for marine hose on SD/I vessels include a permeation rate of
100 g/m2/day on Fuel C and 300 g/m2/day on fuel CM15 (15 percent methanol).13'14
Accordingly, these vessels have fuel hose with lower permeation. Rather than using the
recommended permeation rate limits for this hose, we base the permeation emission factors for
this hose on the data presented in Chapter 5 on gasoline with ethanol which is more
representative of in-use fuels. Chapter 5 also includes data on commercially available low
permeation fuel hose which is used by some manufacturers.  However, we do not include this in
the baseline emission factor calculation because its use is primarily in anticipation of upcoming
permeation standards and would therefore not be expected to remain in the baseline without
enactment of this final rule.

       For other vessels with installed fuel tanks (OB and PWC), we based the permeation
emission factors on the test data in Chapter 5 on marine hose not certified to Coast Guard Class I
requirements.

       The Coast Guard specifications for fill neck hose call for a permeation limit of 300
g/m2/day on Fuel C and 600 on Fuel CM15. However, fill neck hose are not usually exposed to
liquid fuel. Therefore, we used the vapor line data presented in  Chapter 5 for both fill neck and
vent line permeation rates. Hose permeation rates for both gasoline and E10 are presented in
Table3.2.-5.

            Table 3.2-5: Hose Permeation Emission Factors at 23"C [g/m2/day]
Hose Type
Handheld equipment fuel hose
Non-handheld equipment fuel hose
Portable fuel tank supply hose*
Installed system OB/PWC fuel lines
Installed system SD/I fuel lines
Fill necks and vent lines (vapor exposure)
Gasoline
140
122
122
42
22
2.5
E10
255
222
222
125
40
4.9
 * this permeation rate is used for primer bulbs as well
                                          3-11

-------
Final Regulatory Impact Analysis
       The above permeation rates do not include any effects of deterioration.  Over time, the
fuel can draw some of the plasticizers out of the rubber in the hose, making it more brittle and
subject to cracking.  This is especially true for higher permeation fuel hoses which are generally
less fuel resistant. Exposure to ozone over time can also deteriorate the hose.  This deterioration
would presumably increase the permeation rate over time. However, we do not have any data to
quantify this effect and are not including deterioration in this analysis at this time. Lower
permeation fuel hose, such as that designed to meet the final standard would likely have much
lower deterioration due to the use of more fuel resistant materials. Therefore, this analysis may
underestimate the inventory and benefits associated with the final fuel permeation standards.

       3.2.1.3.3 Hose Lengths

       The hose lengths used in NONROAD2005a are based primarily on confidential
information supplied by equipment manufacturers.  Hose lengths for handheld equipment are
based on survey data provided by the Outdoor Power Equipment Institute.15 Recently, we
received comment from a boatbuilder using outboard motors that the hose lengths in our
calculations were too short.16 Because our existing data set did not include outboard boats with
installed fuel tanks, we updated the hose lengths for these vessels based on the data supplied by
this boat builder. In addition, the vent line lengths in  the NONROAD2005a were divided by two
to account for a vapor gradient throughout the fuel line caused by diurnal breathing and
diffusion. This  factor has been removed in lieu of the new emission factors for vent lines based
on vapor exposure. Table 3.2-6 presents the updated hose lengths for outboard boats with
installed fuel tanks.

    Table 3.2-6: Updated Hose Lengths for Outboard Boats with Installed Fuel Systems
Engine Power
Category
18.7-29.8 kW
29.9-37.3 kW
37.4.74.6 kW
74.7-130.5 kW
130.6+ kW
Fill Neck
Length [m]
1.8
2.4
3.1
3.7
4.3
Fuel Supply Hose
Length [m]
1.8
2.4
3.1
3.7
4.3
Vent Hose
Length [m]
1.5
1.8
2.1
2.4
2.7
       3.2.1.3.4 Tank Permeation

       For fuel tanks, the NONROAD2005a model does not include a fuel ethanol effect on
permeation.  Data in Chapter 5 suggest that even polyethylene fuel tanks see a small increase in
permeation on E10 compared to gasoline.  This increase is much larger for nylon fuel tanks like
those used in handheld equipment with structurally-integrated fuel tanks.  Table 3.2-7 presents
the updated emission factors on E10 fuel and compares them to the emission factors based on
gasoline permeation rates. The primary difference between the permeation rates for installed
marine tanks, compared to smaller HDPE fuel tanks, is largely due to the wall thickness of the
different constructions rather than material permeation properties. Permeation rate is a function
                                          3-12

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                                                                     Emission Inventory
of wall thickness, so as tank thickness doubles, permeation rate halves.  The model considers
permeation from metal fuel tanks to be zero.

            Table 3.2-7: Tank Permeation Emission Factors at 29C [g/mVday]
Tank Type
Nylon handheld fuel tanks
Small SI HOPE <0.25 gallons
Small SI HOPE >0.25 gallons
Portable and PWC HOPE fuel tanks
Installed non-metal marine fuel tanks
Metal tanks
Gasoline
1.25
6.5
9.7
9.9
8.0
0
E10
2.5
7.2
10.7
10.9
8.8
0
       3.2.1.3.5 Diffusion

       The NONROAD2005a model includes an adjustment factor to diurnal emissions to
account for diffusion.  The data used to create this adjustment factor is included in Chapter 5.
This adjustment factor is applied to all small nonroad SI equipment in the NONROAD2005a
model. However, we believe that handheld equipment are all produced with either sealed fuel
tanks or slosh/spill resistant fuel caps. Therefore, we do not include diffusion emissions for
handheld equipment in this analysis.

       3.2.1.3.6 Modeling of Nonlinear Ethanol Blend Permeation Effects

       Based on the limited available test data it appears that the effect of alcohol-gasoline
blends on permeation is nonlinear, tending to increase permeation at lower alcohol
concentrations up to about 20 percent ethanol, but then decreasing permeation at higher alcohol
concentrations.
              17
       Starting with the zero and 10 percent ethanol points described above, a simple
exponential curve was selected to connect the zero and 10 percent points continuing up to the 20
percent ethanol level.  Then to get a nonlinear decreasing curve above 20 percent a simple
decreasing exponential curve was used.  Since effects above 85 percent are especially uncertain,
and no such fuels are foreseen for use in nonroad equipment, the effect above 85 percent was set
equal to the E85  effect. The equations used are shown here, and an example curve based on
these equations is shown in Figure 3.2-1.
                                          3-13

-------
Final Regulatory Impact Analysis
Hose and Tank Permeation for zero to 20 percent ethanol volume percent:

  Permeation EF = GasEF + GasEF x (ElOfac - 1) x [ (EthVfrac / 0.10) A 0.4 ]

Hose and Tank Permeation for ethanol volume percent greater than 20 percent:

  Permeation EF = GasEF x { 1 + (ElOfac - 1) x [ (20 / 10) A 0.4 ] }
                    x { 1 - [ (MIN(EthVfrac, 0.85) - 0.20 ) / 0.80 ] A (1 / 0.4 ) }

       where:
       Permeation EF = Permeation emission factor for modeled fuel (grams per meter2 per day)
       GasEF = Gasoline hose permeation emission factor from input EF data files (grams per
       meter2 per day)
       ElOfac = permeation emission adjustment factor for E10 relative to gasoline.  This is the
       ratio of the E10 to gasoline permeation emission factors (unitless)
       EthVfrac = Volume fraction ethanol in the fuel being modeled. El0 = 0.10
       0.4 = exponent chosen to yield a reasonable shape of curve.

          Figure 3.2-1: Ethanol Blend Hose Permeation Example Curve
        300.0
               0    0.1  0.2   0.3  0.4   0.5   0.6  0.7   0.8  0.9
                            Ethanol Volume Fraction
       It should be noted that all ethanol blends currently modeled with the NONROAD model
are less than or equal to E10, so no parts of this curve above E10 are used. Also, the value of
ElOfac used in the modeling of the control case is 2.0 for all the tank and hose permeation
sources listed above in Tables 3.2-6 and 3.2-7.
                                         3-14

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                                                                    Emission Inventory
       3.2.1.3.7 Modeling Effect ofEthanol Blend Market Share on Permeation

       The effect of ethanol blend market share is modeled linearly. In most areas the ethanol
blend market share is either zero or 100 percent, but in areas where it is between those two
market shares,  or when doing a nationwide model run, the effect is calculated as a simple
proportion. For instance a 30 percent market share of E10 would be modeled using a permeation
rate 30 percent of the way between the EO permeation rate and the E10 permeation rate.

       3.2.1.4  Baseline Exhaust and Evaporative Inventory Results for THC, VOC, NOx,
       PM2 5, PM10, and CO

       Table 3.2-8 presents the 50-state baseline emission inventories, respectively, for small
nonroad SI engines.  Table 3.2-9 provides the same information for marine SI engines.
                                          3-15

-------
Final Regulatory Impact Analysis
      Table 3.2-8: Baseline 50-State Annual Exhaust and Evaporative Emissions for
                  Small Nonroad Spark-Ignition Engines (short tons)
Year
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
THC
1,064,625
1,026,922
963,709
886,524
825,413
768,239
718,564
682,088
665,762
663,620
665,666
671,328
679,634
689,045
699,225
709,899
720,944
732,284
743,755
755,254
766,782
778,333
789,900
801,493
813,217
824,971
836,736
848,508
860,287
872,069
883,856
895,645
907,437
919,232
931,029
942,828
954,629
966,431
978,235
voc
1,047,374
1,009,822
945,601
867,081
804,926
747,552
700,010
665,890
650,954
649,358
651,743
657,539
665,819
675,131
685,164
695,658
706,498
717,615
728,853
740,118
751,412
762,727
774,056
785,411
796,890
808,397
819,915
831,439
842,970
854,504
866,042
877,583
889,126
900,672
912,219
923,769
935,321
946,874
958,429
NOx
106,804
106,852
106,610
106,847
109,233
109,439
111,235
116,329
118,376
119,424
120,820
122,506
124,400
126,395
128,468
130,573
132,701
134,846
137,002
139,160
141,317
143,475
145,636
147,806
150,003
152,209
154,418
156,628
158,840
161,053
163,266
165,479
167,692
169,906
172,119
174,332
176,546
178,759
180,973
PM2.5
23,382
23,480
23,483
23,417
23,498
23,804
24,335
24,882
25,402
25,888
26,364
26,832
27,291
27,747
28,202
28,655
29,107
29,558
30,009
30,460
30,911
31,362
31,813
32,265
32,718
33,173
33,627
34,081
34,535
34,990
35,444
35,898
36,353
36,807
37,261
37,716
38,170
38,625
39,079
PM10
25,416
25,522
25,525
25,453
25,541
25,874
26,451
27,045
27,611
28,139
28,657
29,165
29,664
30,160
30,654
31,146
31,638
32,128
32,618
33,109
33,599
34,089
34,579
35,070
35,563
36,057
36,551
37,045
37,538
38,032
38,526
39,020
39,514
40,008
40,502
40,995
41,489
41,983
42,477
CO
15,091,835
14,351,829
13,690,337
12,923,819
12,252,479
11,711,607
10,861,441
9,992,801
9,623,727
9,568,610
9,579,040
9,644,512
9,751,728
9,879,027
10,020,040
10,169,185
10,324,079
10,483,706
10,645,870
10,808,929
10,972,659
11,136,954
11,301,731
11,467,292
11,634,934
11,803,402
11,972,207
12,141,251
12,310,505
12,479,899
12,649,385
12,818,940
12,988,554
13,158,228
13,327,954
13,497,732
13,667,556
13,837,424
14,007,335
                                       3-16

-------
                                                           Emission Inventory
Table 3.2-9: Baseline 50-State Annual Exhaust and Evaporative Emissions for
               Marine Spark-Ignition Engines (Short Tons)
Year
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
THC
906,318
873,287
836,493
796,279
756,781
717,924
680,702
645,730
612,180
580,750
553,441
530,682
511,166
495,178
481,650
470,667
462,602
455,864
451,176
447,624
445,371
443,951
443,203
443,196
443,770
444,806
446,152
447,768
449,626
451,666
453,836
456,159
458,592
461,115
463,691
466,323
468,999
471,706
474,437
voc
931,132
896,969
858,916
817,340
776,480
736,303
697,795
661,588
626,901
594,415
566,191
542,671
522,503
505,981
492,000
480,648
472,308
465,336
460,481
456,799
454,457
452,972
452,179
452,151
452,720
453,764
455,126
456,766
458,656
460,733
462,943
465,310
467,790
470,363
472,990
475,674
478,403
481,164
483,949
NOx
46,311
49,694
53,397
57,862
63,366
67,730
73,894
82,123
87,140
90,516
93,662
96,528
99,197
101,703
104,022
106,158
108,084
109,885
111,525
113,063
114,479
115,802
117,052
118,228
119,344
120,401
121,411
122,387
123,335
124,260
125,166
126,052
126,922
127,777
128,621
129,454
130,278
131,095
131,907
PM2.5
15,092
14,417
13,679
12,886
12,090
11,311
10,553
9,824
9,149
8,525
7,983
7,534
7,144
6,823
6,549
6,324
6,156
6,012
5,908
5,826
5,768
5,726
5,696
5,680
5,675
5,678
5,687
5,701
5,719
5,741
5,765
5,792
5,821
5,851
5,883
5,915
5,948
5,982
6,016
PM10
16,404
15,670
14,869
14,007
13,142
12,295
11,470
10,678
9,945
9,266
8,678
8,189
7,766
7,416
7,118
6,874
6,691
6,535
6,422
6,333
6,270
6,224
6,191
6,174
6,168
6,172
6,182
6,197
6,217
6,240
6,266
6,296
6,327
6,360
6,394
6,429
6,465
6,502
6,539
CO
2,472,251
2,407,992
2,346,538
2,266,733
2,170,374
2,103,059
2,007,804
1,885,970
1,823,844
1,788,830
1,758,115
1,732,653
1,710,005
1,690,755
1,673,978
1,660,415
1,650,631
1,642,841
1,638,114
1,635,047
1,634,065
1,634,672
1,636,603
1,639,914
1,644,492
1,650,159
1,656,748
1,663,933
1,671,627
1,679,753
1,688,228
1,697,074
1,706,229
1,715,675
1,725,343
1,735,210
1,745,240
1,755,400
1,765,651
                                  3-17

-------
Final Regulatory Impact Analysis
3.2.2  Baseline Hazardous Air Pollutant Estimates

       The analysis of toxic air pollutants from small nonroad and marine SI engines focuses on
seven major pollutants: benzene, formaldehyde, acetaldehyde, 1,3-butadiene, acrolein,
naphthalene, and 15 other compounds grouped together as poly cyclic organic matter (POM) for
this analysis.0  All of these compounds, except acetaldehyde, were identified as national or
regional cancer or noncancer "risk" drivers in the 1999 National Scale Air Toxics Assessment
(NATA)18 and have significant inventory contributions from mobile sources. That is, for a
significant portion of the population, these compounds pose a significant portion of the total
cancer or noncancer risk from breathing outdoor air toxics. The health effects of these hazardous
pollutants are specifically discussed in Chapter 2. Many of these compounds are also part of the
THC and VOC inventories.  An exception is formaldehyde, which is not measured by the
analytic technique used to measure THC, and part of the mass of other aldehydes as well.
However, all are included in the VOC inventories presented in this chapter.

       The baseline inventories for each of the toxic air pollutants  described above were
developed using EPA's National Mobile Inventory Model (NMIM). This model is an analytical
framework that links a county-level database to our NONROAD model and collates the output
into a single database table.  The resulting estimates for small nonroad and marine SI engines
account for local differences in fuel characteristics and temperatures on a much finer scale than
is possible when running the standalone NONROAD model. Emissions were modeled for all of
the small nonroad and marine SI equipment categories in the continental United States, including
California. Hence, the hazardous emission inventories presented here include the emissions
from engines that are regulated by that State. As a result, the emission inventories are slightly
overstated relative to the those from the small nonroad and marine  SI engines subject to the
federal Phase 3 requirements.

       Table 3.2-10 presents the 50-state baseline inventories for toxic air emissions from small
nonroad SI engines in 2002, 2020, 2030. Table 3.2-11 provides the same information for marine
SI engines.

                 Table 3.2-10: Baseline 50-State Air Toxic Emissions for
                   Small Nonroad Spark-Ignition Engines (short tons)
Year
2002
2020
2030
Benzene
35,086
23,216
26,776
1,3
Butadiene
5,561
3,468
3,999
Formalde-
hyde
8,664
5,802
6,691
Acetalde-
hyde
2,900
2,792
3,217
Acrolein
505
291
336
Naphthalene
447
638
739
POM
97
131
152
       0 The 15 POMs summarized in this chapter are acenaphthylene, anthracene, benz(a)anthracene,
benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, beno(k)fluoranthene, chrysene, dibenzo(a,h)anthracene,
fluoranthene, fluorene, ideno(l,2,3-c,d)pyrene, phenanthrene, andpyrene.
                                           3-18

-------
                                                                    Emission Inventory
                 Table 3.2-11: Baseline 50-State Air Toxic Emissions for
                       Marine Spark-Ignition Engines (short tons)
Year
2002
2020
2030
Benzene
23,110
8,417
8,476
1,3
Butadiene
2,053
763
751
Formalde-
hyde
2,153
535
525
Acetalde-
hyde
1,543
818
811
Acrolein
211
27
27
Naphthalene
37
42
46
POM
31
16
16
3.3  Contribution of Small Nonroad and Marine SI Engines to National
Emissions Inventories

       This section describes the nationwide contribution of small nonroad and marine SI
engines to the emissions of other source categories.  Information is presented for the pollutants
that are directly controlled by the final standards, i.e., VOC, NOX, and CO, and those that are
indirectly reduced by some of the requisite control technology, i.e., PM25 and PM10.  The VOC
inventories includes both exhaust and evaporative hydrocarbon emissions.

       The national inventories are presented for 2002, 2020,  and 2030 for all 50-states and the
District of Columbia.19  The stationary, highway, and aircraft inventories were taken directly
from EPA's National Emissions Inventory (NEI) modeling platform for 2002.20 The emission
inventories for locomotives, and Classes 1 and 2 commercial marine engines were taken from
our recent final rule for these mobile source categories.21 The  inventories for Class 3
commercial marine engines was take from our recent advance  notice of final rulemaking for that
category of engines.22 The emission estimates for portable fuel containers was taken from the
recent final MS AT rule.23 All of the land-based nonroad engine emission inventories was
developed using the NONROAD2005d model, as previously described.d Finally, these
inventories account for the future use of renewable fuels as required by the Energy Policy Act of
2005.

3.3.1 VOC Emissions Contribution

       Table 3.3-1 provides the contribution of small nonroad SI engines, marine SI engines and
other source categories to nationwide VOC emissions. The emissions from small nonroad
(<19kW) and marine SI engines are 26 percent of the mobile source inventory and 12 percent of
the total manmade VOC emissions in 2002. These percentages decrease slightly to 23 percent
and 10 percent, respectively, by 2030.
       d  The modeling inputs for diesel nonroad engines that were used in NONROAD2005d for this final rule
are the same as those contained in the NONROAD2005a public.
                                          3-19

-------
Final Regulatory Impact Analysis
3.3.2  NOx Emissions Contribution

       Table 3.3-2 provides the contribution of nonroad small nonroad SI engines, marine SI
engines and other source categories to nationwide NOx emissions. The emissions from small
nonroad and marine SI engines are about 1 percent of the mobile source inventory and about 1
percent of the total manmade NOx emissions in 2002. These percentages increase to 6 percent
and 3  percent, respectively, by 2030.

3.3.3 PM Emissions Contribution

       Table 3.3-3 and 3.3-4 provide the contribution of small nonroad SI engines, marine SI
engines and other source categories to nationwide PM2 5 and PM10 emissions, respectively. Both
particle size categories from small nonroad and marine  SI engines are about 8 percent of the
mobile source inventory and approximately 1 percent of the total manmade PM25 emissions in
2002.  The mobile source percentage increases to about 12 percent and the total manmade
percentage stay about the same at 1 percent by 2030.

3.3.4 CO Emissions Contribution

       Table 3.3-5 provides the contribution of small nonroad SI engines, marine SI engines,
and other source categories to nationwide CO emissions. The emissions from small nonroad and
marine SI engines are 23 percent of the mobile source inventory and 10 percent of the total
manmade CO emissions in 2002.  These percentages decrease to 30 percent and increase to 25
percent, respectively, by 2030.
                                          3-20

-------
Table 3.3-1: 50-State Annual VOC Baseline Emission Levels for
            Mobile and Other Source Categories
Category
Small Nonroad SI total
A Tsnuan -Hi "\-i Small SI
Handheld S"iall SI
Recreational Marine SI
Locomotive
Recreational Marine Diesel
Commercial Marine (Cl & C2)
Land-Based Nonroad Diesel
Commercial Marine (C3)
SI Recreational Vehicles
Large Nonroad SI (>25hp)
Portable Fuel Containers
Aircraft
Total Off Highway
Highway Diesel
Highway Non-Diesel
Total Highway
Total Diesel (distillate) Mobile
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources
2002
short tons
1,165,257
675,311
489,946
1,003,325
50,665
1,538
17,229
184,868
26,175
551,285
134,950
243,994
52,651
3,431,938
191,514
4,684,391
4,875,904
445,814
8,307,843
9,433,356
17,741,198
%of
mobile
14.0%
8.1%
5.9%
12.1%
0.6%
0.0%
0.2%
2.2%
0.3%
6.6%
1.6%
2.9%
0.6%
41.3%
2.3%
56.4%
58.7%
5.4%
100%
-
-
% of total
6.6%
3.8%
2.8%
5.7%
0.3%
0.0%
0.1%
1.0%
0.1%
3.1%
0.8%
1.4%
0.3%
19.3%
1.1%
26.4%
27.5%
2.5%
46.8%
53.2%
100%
2020
short tons
808, 8 73
590,186
218,688
496,183
27,974
2,485
11,478
76,817
53,204
442,121
11,957
38,185
63,251
2,032,530
129,321
1,973,180
2,102,501
248,075
4,135,030
8,740,057
12,875,088
%of
mobile
19.6%
14.3%
5.3%
12.0%
0.7%
0.1%
0.3%
1.9%
1.3%
10.7%
0.3%
0.9%
1.5%
49.2%
3.1%
47.7%
50.8%
6.0%
100%
-
-
% of total
6.3%
4.6%
1.7%
3.9%
0.2%
0.0%
0.1%
0.6%
0.4%
3.4%
0.1%
0.3%
0.5%
15.8%
1.0%
15.3%
16.3%
1.9%
32.1%
67.9%
100%
2030
short tons
935,619
684,057
251,562
494,217
17,722
2,912
6,911
63,342
79,697
382,468
9,953
43,375
67,730
2,103,947
140,959
1,800,856
1,941,815
231,847
4,045,762
8,740,057
12,785,819
%of
mobile
23.;%
16.9%
6.2%
12.2%
0.4%
0.1%
0.2%
1.6%
2.0%
9.5%
0.2%
1.1%
1.7%
52.0%
3.5%
44.5%
48.0%
5.7%
100%
-
-
% of total
7.3%
5.4%
2.0%
3.9%
0.1%
0.0%
0.1%
0.5%
0.6%
3.0%
0.1%
0.3%
0.5%
16.5%
1.1%
14.1%
15.2%
1.8%
31.6%
68.4%
100%

-------
Table 3.3-2: 50-State Annual NOx Baseline Emission Levels
         for Mobile and Other Source Categories

Category
Small Nonroad SI
AT, U, ,,;,; f,,;; or
Hctn^h"!"1 ^mall e/
Recreational Marine SI
Locomotive
Recreational Marine Diesel
Commercial Marine (Cl & C2)
Land-Based Nonroad Diesel
Commercial Marine (C3)
SI Recreational Vehicles
Large Nonroad SI (>25hp)
Aircraft
Total Off Highway
Highway Diesel
Highway Non-Diesel
Total Highway
Total Diesel (distillate) Mobile
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources

short tons
119,833
116,743
3,090
49,902
1,118,786
40,437
834,025
1,555,812
745,224
10,614
336,292
103,591
4,914,515
3,529,046
4,293,733
7,822,779
7,078,105
12,737,294
8,613,718
21,351,012
2002
%of
mobile
source
0.9%
0.9%
0.0%
0.4%
8.8%
0.3%
6.5%
12.2%
5.9%
0.1%
2.6%
0.8%
38.6%
27.7%
33.7%
61.4%
55.6%
100%
-
-

% of total
0.6%
0.5%
0.0%
0.2%
5.2%
0.2%
3.9%
7.3%
3.5%
0.0%
1.6%
0.5%
23.0%
16.5%
20.1%
36.6%
33.2%
59.7%
40.3%
100%

short tons
753,872
148,004
5,867
120,172
669,405
43,579
499,798
683,481
1,368,420
30,108
48,270
132,278
3,749,382
681,142
1,270,269
1,951,411
2,577,404
5,700,793
5,773,927
11,474,721
2020
%of
mobile
source
2.7%
2.6%
0.1%
2.1%
11.7%
0.76%
8.77%
12.0%
24.00%
0.5%
0.8%
2.32%
65.8%
11.9%
22.3%
34.2%
45.2%
100%
-
-

% of total
1.3%
1.3%
0.1%
1.0%
5.8%
0.38%
4.36%
5.96%
11.93%
0.3%
0.42%
1.15%
32.7%
5.9%
11.1%
17.0%
22.5%
49.7%
50.3%
100%

short tons
178,406
171,650
6,756
132,898
437,245
43,665
308,614
435,774
2,023,974
34,318
47,766
143,986
3,786,645
355,817
1,144,199
1,500,016
1,581,115
5,286,661
5,773,927
11,060,589
2030
%of
mobile
source
3.4%
3.2%
0.1%
2.5%
8.3%
0.8%
5.8%
8.2%
38.3%
0.6%
0.9%
2.7%
71.6%
6.7%
21.6%
28.4%
29.9%
100%
-
-

% of total
1.6%
1.6%
0.1%
1.2%
4.0%
0.4%
2.8%
3.9%
18.3%
0.3%
0.4%
1.3%
34.2%
3.2%
10.3%
13.6%
14.3%
47.8%
52.2%
100%

-------
Table 3.3-3: 50-State Annual PM2 5 Baseline Emission Levels
         for Mobile and Other Source Categories

Category
Small Nonfood SI
^onHan^h"!^ ^mcdl e/
Hctn^h"!"1 ^mall e/
Recreational Marine SI
Locomotive
Recreational Marine Diesel
Commercial Marine (Cl & C2)
Land-Based Nonroad Diesel
Commercial Marine (C3)
SI Recreational Vehicles
Large Nonroad SI (>25hp)
Aircraft
Total Off Highway
Highway Diesel
Highway non-diesel
Total Highway
Total Diesel (distillate) Mobile
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources

short tons
25, 700
4,841
20,859
16,262
29,660
1,096
28,730
159,111
54,667
13,710
1,652
17,979
348,568
94,982
51,694
146,676
313,581
495,245
3,025,244
3,520,488
2002
%of
mobile
source
5.2%
1.0%
4.2%
3.3%
5.99%
0.22%
5.80%
32.1%
11.04%
2.8%
0.3%
3.63%
70.4%
19.2%
10.4%
29.6%
63.3%
100%
-
-

% of total
0.7%
0.1%
0.6%
0.5%
0.84%
0.03%
0.82%
4.52%
1.55%
0.4%
0.05%
0.51%
9.9%
2.7%
1.5%
4.2%
8.9%
14.1%
85.9%
100%

short tons
32,905
6,957
25,947
6,367
15,145
973
15,787
46,056
110,993
11,901
2,421
22,176
264,722
20,145
45,329
65,474
98,106
330,196
3,047,714
3,377,911
2020
%of
mobile
source
10.0%
2.1%
7.9%
1.9%
4.59%
0.29%
4.78%
13.9%
33.61%
3.6%
0.7%
6.72%
80.2%
6.1%
13.7%
19.8%
29.7%
100%
-
-

% of total
7.0%
0.2%
0.8%
0.2%
0.45%
0.03%
0.47%
1.36%
3.29%
0.4%
0.07%
0.66%
7.8%
0.6%
1.3%
1.9%
2.9%
9.8%
90.2%
100%

short tons
37,878
8,065
29,813
6,163
8,584
1,053
10,017
17,902
166,161
10,090
2,844
24,058
284,749
18,802
51,621
70,423
56,358
355,172
3,047,714
3,402,887
2030
%of
mobile
source
10.7%
2.3%
8.4%
1.7%
2.42%
0.30%
2.82%
5.0%
46.78%
2.8%
0.8%
6.77%
80.2%
5.3%
14.5%
19.8%
15.9%
100%
-
-

% of total
1.1%
0.2%
0.9%
0.2%
0.25%
0.03%
0.29%
0.53%
4.88%
0.3%
0.08%
0.71%
8.4%
0.6%
1.5%
2.1%
1.7%
10.4%
89.6%
100%

-------
Table 3.3-4: 50-State Annual PM10 Baseline Emission Levels
         for Mobile and Other Source Categories

Category
Small Nonfood SI
^onHan^h"!^ ^mcdl e/
Hctn^h"!"1 ^mall e/
Recreational Marine SI
Locomotive
Recreational Marine Diesel
Commercial Marine (Cl & C2)
Land-Based Nonroad Diesel
Commercial Marine (C3)
SI Recreational Vehicles
Large Nonroad SI (>25hp)
Aircraft
Total Off Highway
Highway Diesel
Highway non-diesel
Total Highway
Total Diesel (distillate) Mobile
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources

short tons
27,935
5,262
22,673
17,676
30,578
1,130
29,619
164,032
59,409
14,902
1,672
24,622
371,575
109,097
92,531
201,628
334,456
573,203
3,158,011
3,731,215
2002
%of
mobile
source
4.9%
0.9%
4.0%
3.1%
5.33%
0.20%
5.17%
28.6%
10.36%
2.6%
0.3%
4.30%
64.8%
19.0%
16.1%
35.2%
58.3%
100%
-
-

% of total
0.7%
0.1%
0.6%
0.5%
0.82%
0.03%
0.79%
4.40%
1.59%
0.4%
0.04%
0.66%
10.0%
2.9%
2.5%
5.4%
9.0%
15.4%
84.6%
100%

short tons
35, 766
7,562
28,204
6,920
15,613
1,003
16,275
47,480
120,617
12,936
2,441
30,211
289,263
32,733
96,380
129,113
113,105
418,376
3,194,610
3,612,986
2020
%of
mobile
source
8.5%
1.8%
6.7%
1.7%
3.73%
0.24%
3.89%
11.3%
28.83%
3.1%
0.6%
7.22%
69.1%
7.8%
23.0%
30.9%
27.0%
100%
-
-

% of total
1.0%
0.2%
0.8%
0.2%
0.43%
0.03%
0.45%
1.31%
3.34%
0.4%
0.07%
0.84%
8.0%
0.9%
2.7%
3.6%
3.1%
11.6%
88.4%
100%

short tons
41,172
8,767
32,406
6,699
8,849
1,086
10,327
18,455
180,566
10,967
2,866
32,714
313,702
34,746
110,796
145,542
73,464
459,244
3,194,610
3,653,854
2030
% of mobile
source
9.0%
1.9%
7.1%
1.5%
1.93%
0.24%
2.25%
4.0%
39.32%
2.4%
0.6%
7.12%
68.3%
7.6%
24.1%
31.7%
16.0%
100%
-
-

% of total
1.1%
0.2%
0.9%
0.2%
0.24%
0.03%
0.28%
0.51%
4.94%
0.3%
0.08%
0.90%
8.6%
1.0%
3.0%
4.0%
2.0%
12.6%
87.4%
100%

-------
Table 3.3-5: 50-State Annual CO Baseline Emission Levels
        for Mobile and Other Source Categories

Category
Small Nonfood SI
Ar,zj,,,,,;,7 e,,;; er
fjan^h"^ ^mall e/
Recreational Marine SI
Locomotive
Recreational Marine Diesel
Commercial Marine (Cl & C2)
Land-Based Nonroad Diesel
Commercial Marine (C3)
SI Recreational Vehicles
Large Nonroad SI (>25hp)
Aircraft
Total Off Highway
Highway Diesel
Highway non-diesel
Total Highway
Total Diesel (distillate) Mobile
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources

short tons
16,943,267
15,884,854
1,058,413
2,663,932
123,210
6,467
151,331
860,257
59,515
1,741,702
1,801,104
557,820
24,908,605
940,898
59,178,847
60,119,745
2,082,164
85,028,351
11,354,201
96,382,552
2002
%of
mobile
source
19.9%
18.7%
1.2%
3.1%
0.1%
0.0%
0.2%
1.0%
0.1%
2.0%
2.1%
0.7%
29.3%
1.1%
69.6%
70.7%
2.4%
100%
-
-

% of total
17.6%
16.5%
1.1%
2.8%
0.1%
0.0%
0.2%
0.9%
0.1%
1.8%
1.9%
0.6%
25.8%
1.0%
61.4%
62.4%
2.2%
88.2%
11.8%
100%

short tons
11,934,654
11,084,472
850,181
1,765,122
167,488
9,374
139,712
310,250
120,889
1,910,030
289,382
677,930
17,324,829
260,238
29,211,716
29,471,955
887,061
46,796,783
11,049,239
57,846,022
2020
%of
mobile
source
25.5%
23.7%
1.8%
3.8%
0.4%
0.0%
0.3%
0.7%
0.3%
4.1%
0.6%
1.4%
37.0%
0.6%
62.4%
63.0%
1.9%
100%
-
-

% of total
20.6%
19.2%
1.5%
3.1%
0.3%
0.0%
0.2%
0.5%
0.2%
3.3%
0.5%
1.2%
29.9%
0.4%
50.5%
50.9%
1.5%
80.9%
19.1%
100%

short tons
13,803,668
12,826,965
976,703
1,801,234
195,882
10,930
143,791
155,576
181,032
1,916,102
270,827
723,842
19,202,883
219,594
32,038,635
32,258,229
725,772
51,461,112
11,049,239
62,510,350
2030
% of mobile
source
26. 8%
24.9%
1.9%
3.5%
0.4%
0.0%
0.3%
0.3%
0.4%
3.7%
0.5%
1.4%
37.3%
0.4%
62.3%
62.7%
1.4%
100%
-
-

% of total
22.1%
20.5%
1.6%
2.9%
0.3%
0.0%
0.2%
0.2%
0.3%
3.1%
0.4%
1.2%
30.7%
0.4%
51.3%
51.6%
1.2%
82.3%
17.7%
100%

-------
Final Regulatory Impact Analysis
3.4  Controlled Nonroad Small Spark-Ignition and Marine Engine Emission
Inventory Development

       This section describes how the controlled emission inventories were developed for the
small nonroad and marine SI engines that are subject to the Phase 3 standards. The resulting
controlled emission inventories are also presented. Section 3.4.1 provides this information for
exhaust and evaporative emissions.

       Once again, the inventory estimates presented throughout this section only include
equipment that would be subject to the final standards.  Specifically for California, this includes
small nonroad SI engines used in farm and construction equipment with maximum power levels
below 175 hp or 130 kW. For marine SI engines, our analysis assumes that the final standards
have no effect because that state already has equivalent exhaust emission standards and is
expected to adopt equivalent evaporative hydrocarbon requirements.

3.4.1 Controlled Exhaust and Evaporative Emissions Estimates for THC, VOC, NOx,
PM2 5, PM10, and CO

       The controlled exhaust and evaporative emission inventories for small nonroad and
marine SI engines were generated by modifying the input files for NONROAD2005d to account
for the  engine and equipment controls associated with the Phase 3 standards.  (See the baseline
emission inventory discussion in Section 3.2 for the changes we made to the publically available
NONROAD2005a model to develop NONROAD2005d.) The modifications  that were made to
estimate the controlled emissions inventories are described below.

       3.4.1.1 Controlled Exhaust Emission Standards, Zero-Hour Emission Factors and
       Deterioration Rates

       3.4.1.1.1 Small SI Exhaust Emission Calculations

       The final Phase 3 emission standards and implementation schedule are shown in Table
3.4-1. While the new standards take effect in 2011 for Class II engines and 2012 for Class  I
engines, we providing a number of flexibilities for engine and equipment manufacturers that will
allow the continued production and use of Class II engines meeting the Phase 2 standards in
limited numbers over the first four years of the Phase 3 program. The implementation schedule
shown in the table is used for modeling purposes only. It is based on our assumption that engine
and equipment manufacturers take full advantage of these flexibilities.
                                         3-26

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                                                                    Emission Inventory
    Table 3.4-1: Phase 3 Emission Standards and Estimated Implementation Schedule
                for Class I and II Small SI Engines3 (g/kW-hr or Percent)
Engine
Class


Class I




Class II



Requirement
HC+NOx
CO (marine generator
sets only)
Estimated Sales
Percentage
HC+NOx
CO (marine generator
sets only)
Estimated Sales
Percentage

2011
~

~

~
8

5

83

2012
10

5

95
8

5

83

2013
10

5

95
8

5

93

2014
10

5

100
8

5

93

2015+
10

5

100
8

5

100
a Reflects maximum use of compliance flexibilities by engine and equipment manufacturers. Used for modeling
purposes only.
       The modeled emission factors corresponding to the final Phase 3 standards are shown in
Table 3.4-2. (See Section 3.2.1.2.1 for a discussion of how the model uses zero hour emission
levels (ZML) and deterioration rates (A values.) We developed these new emission factors
based on testing of catalyst-equipped engines both in the laboratory and in-use.  A full
description of the emission factor information for Phase 3 engines and the basis for the estimates
can be found in the docket for this rule.

      Table 3.2-2: Phase 3 Modeling Emission Factors for Small SI Engines (g/kW-hr)
Class/
Technology
Class f - SV
Class f - OHV
Class ff
HCZML
5.60
5.09
4.25
HC "A"
0.797
0.797
0.797
NOxZML
1.47
1.91
1.35
NOx "A"
0.302
0.302
0.302
CO ZML
319.76
325.06
431.72
CO "A"
0.070
0.070
0.080
PM10
ZML
0.24
0.05
0.08
PM10 "A"
1.753
1.753
1.095
       We left the proportion of sales in each technology classification unchanged from those
used for Phase 2 engines.  The technology mix was previously shown Table 3.2-2.

       Finally, as discussed in more detail in Chapter 6, were developed a new brake-specific
fuel consumption (BSFC) estimate for Class II engines to reflect the expected fuel consumption
benefit associated with the use of additional electronic fuel injection technology on Phase 3
compliant engines. The resulting BFSC for Phase 3 Class II engines is 0.735 pounds per
horsepower-hour (Ib/hp-hr).
                                          3-27

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Final Regulatory Impact Analysis
       3.4.1.1.2 Marine SI Exhaust Emission Calculations

       For the control case, we developed new technology classifications for engines meeting
the final standards. For outboards and personal watercraft, we no longer will attempt to
determine the technology mix between low emitting technology options (such as DI 2-stroke
versus 4 stroke).  The new technology classifications for these engines are simply tied to the
standard.  These new technology classifications are titled MO09 and MP09 for outboards and
personal watercraft, respectively.  In determining the combined HC+NOx emission factor, we
used the final emission standards with a 10 percent compliance margin (with deterioration factor
applied).  To determine the NOx emission factors,  we used certification data to determine the
sales weighted average NOx for low emission technologies in each power bin. HC was then
determined as the difference between the HC+NOx and the NOx emission factors.  Because we
are establishing the same standards for OB and PWC and because they use similar engines, we
use the same HC+NOx emission factors and deterioration factors for both engine types.

       Because the final CO  standard primarily acts as a cap on CO, the CO emission factors
were determined based on the emission factors for existing low emission engines in each power
bin.  Fuel consumption factors were calculated in the same manner. Therefore, some differences
are seen between the projected CO and BSFC factors for OB and PWC. No changes were made
to the PM emission factors. Also, the existing deterioration factors for 4-stroke carbureted
engines were applied to the control case (1.05 for HC, NOx, and CO).  Table 3.4-3  presents the
zero-hour OB/PWC emission factors  for the control case.

           Table 3.4-3: Control Case Emission Factors for OB/PWC (g/kW-hr)
Power Bin
0-2.2 kW
2.3-4.5 kW
4.6-8.2 kW
8.3-11.9 kW
12.0-18. 6 kW
18. 7-29.8 kW
29.9-37.3 kW
37.4-55. 9 kW
55. 9-74.6 kW
74.7-130.5 kW
130.6+ kW
HC
20.9
22.1
15.5
11.6
12.5
10.2
9.3
9.2
9.2
9.2
10.2
NOx
4.8
3.6
5.6
6.8
4.3
5.7
5.9
5.4
5.4
5.0
3.7
CO
OB PWC
542
357
292
248
205
189
167
169
169
173
137
640
538
243
231
218
206
206
206
206
202
178
BSFC
OB PWC
563
560
555
552
543
528
507
471
471
415
387
563
560
555
552
543
528
507
486
486
394
380
       For sterndrive and inboards, we developed a new engine classification similar to the
OB/PWC discussion above. SD/I engines at or below 373 kW are modeled to meet the final
standard through the use of aftertreatment.  HC and NOx emission factors are based on test data
presented in Chapter 4 for SD/I engines equipped with catalysts.  High performance engines
have two tiers of standards that can be achieved through the use of engine-based technology.
Although the standards distinguish between two power ranges for high-performance, a single
                                          3-28

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                                                                     Emission Inventory
weighted EF is used here. CO emission factors are based on meeting the final standard at the
end of useful life (with the deterioration factor applied). No emission reductions are modeled for
PM. The fuel consumption factor for fuel-injected 4-stroke SD/I engines is applied to the control
case.  Deterioration factors for catalyst-equipped engines are the same as those used in the
NONROAD2005a model for catalyst-equipped large SI engines. Table 3.4-4 presents the zero-
hour emission factors and the accompanying deterioration factors for the control case.

                Table 3.4-4: Control Case EFs  (g/kW-hr) and DFs for SD/I
Engine Category
kW <373 kW
> 373 kW, Tier 1
>373kW, Tier 2
HC
EF
1.80
11.80
8.58
DF
1.64
1.69
1.69
NOx
EF
1.60
6.70
6.80
DF
1.15
1.38
1.38
CO
EF
55.0
207
207
DF
1.36
1.81
1.81
BSFC
345
362
362
       3.4.1.2 Controlled Evaporative Emission Rates

       Below, we present the effect of the final Phase 3 evaporative emission standards on hose
permeation, tank permeation, diurnal, and running loss emission inventories.

       3.4.1.2.1 Hose Permeation

       Similar to the baseline case, hose permeation rates are based on g/m2/day and are
modeled as a function of temperature. The fuel hose test procedures are based on Fuel CE10 as a
test fuel. Based on data presented in Chapter 5, we would expect in-use emissions on gasoline-
based E10 to be about half of the measured level on Fuel CE10. In addition, we believe that
hose designed to meet the final  15 g/m2/day standard on 10 percent ethanol fuel will permeate at
least 50 percent less when gasoline is used. Therefore, we model permeation from hoses
designed to meet 15 g/m2/day on Fuel CE10 to be 3.75 g/m2/day on gasoline at 23C.  Consistent
with the baseline emission case, we weight the gasoline and E10 emission factors by our
estimates of gasoline sales with and without ethanol added. The same correction factors used to
account for the effect of ethanol on permeation are used in the control and baseline cases.

       Fill neck and vent hose containing vapor rather than liquid fuel are not subject to the final
standards. No emission reductions are modeled for these hose types. In addition, no emission
reductions are modeled for hose on handheld equipment used in cold weather applications (e.g.
Class V chainsaws).

       3.4.1.2.2 Tank Permeation

       Similar to the baseline case, fuel tank permeation rates are based on units of g/m2/day and
are modeled as a function of temperature.  We believe that fuel tanks using alternative materials
                                          3-29

-------
Final Regulatory Impact Analysis
to meet the final 1.5 g/m2/day standard on 10 percent ethanol fuel will typically permeate at least
50 percent less when gasoline is used.  Therefore, we model permeation from fuel tanks to be
0.75 g/gal/day at 29C on gasoline. Consistent with the baseline emission case, we weight the
gasoline and E10 emission factors by our estimates of gasoline sales with and without ethanol
added. The same correction factors used to account for the effect of ethanol on permeation are
used in the control and baseline cases.

       One exception to the above discussion is metal  tanks. For these fuel tanks, we do not
include any emissions reductions from baseline.

       3.4.1.2.3 Diurnal

       We are not establishing a diurnal emission requirement for small nonroad SI equipment.
Therefore, we do not model direct reductions in diurnal emissions.  However, we are placing a
limit on diffusion emissions.  As a result, we set the diffusion multiplier to 1.0 for all non-
handheld Small SI equipment for the control case. Note that this multiplier was already set to
1.0 for handheld equipment in the baseline case.  This is equivalent to applying a 32 percent
reduction to the diurnal emission factors.

       In the control case for marine SI engines, we model portable fuel tanks as having 90
percent lower diurnal emissions than an open vent system.  Also, we set the diffusion multiplier
to 1.0 because the tanks would be sealed. Presumably, the diurnal temperature cycles would
build some pressure in the fuel tank causing hydrocarbons to be released when the tank is
opened. Therefore, we do not model these tanks as having zero diurnal emissions. For PWC, we
use the baseline scenario of sealed systems with a 1.0 psi pressure relief valve.  For installed fuel
tanks, we model a 60 percent reduction due to a carbon canister in the fuel line with passive
purge.  This reduction is based on data presented in Chapter 5. As in the baseline case, no
diffusion is modeled for PWC and installed fuel tanks.

       3.4.1.2.4 Running Loss

       For Class I engines, we believe that the final running loss control requirement will be met
by routing vapor from the fuel take to the engine air intake system. Therefore, all vapor
generated in the fuel tank should be consumed by the engine, thereby eliminating running loss
emissions.  However, there may be some inefficiencies in the system such as vapor escaping out
the intake at idle. Therefore, we model the  running loss emission reduction as only 90 percent.
For Class II equipment, we believe that some equipment will inherently meet the final standard
because they will have low enough temperature fluctuation in the fuel tanks during operation to
certify by design. Based on the data presented in Chapter 5  on fuel tank temperatures during
operation, we estimate an 80 percent reduction in running loss for Class II equipment.

       3.4.1.3 Controlled Exhaust and Evaporative Inventory Results for THC, VOC,
       NOx,  PM2 5, PM10, CO and SO2

       Tables 3.4-5 presents the 50-state controlled emission inventories  for small nonroad SI

                                          3-30

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                                                                  Emission Inventory
engines. Tables 3.4-6 provides the same information for marine SI engines.

     Table 3.4-5: Controlled 50-State Annual Exhaust and Evaporative Emissions for
                   Small Nonroad Spark-Ignition Engines (short tons)
Year
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
THC
1,064,625
1,026,922
963,709
886,524
825,413
768,239
713,266
669,782
646,659
618,463
573,611
535,035
509,895
495,565
486,951
484,102
485,460
488,969
493,763
499,618
506,071
512,988
520,130
527,386
534,763
542,202
549,676
557,179
564,711
572,261
579,823
587,396
594,978
602,567
610,167
617,776
625,391
633,010
640,633
voc
1,047,374
1,009,822
945,601
867,081
804,926
747,552
694,712
653,584
631,851
604,977
562,317
525,722
501,985
488,517
480,492
477,989
479,510
483,092
487,905
493,736
500,141
506,990
514,054
521,227
528,516
535,864
543,246
550,657
558,094
565,549
573,015
580,492
587,978
595,471
602,974
610,486
618,003
625,525
633,050
NOx
106,804
106,852
106,610
106,847
109,233
109,439
111,235
116,329
118,376
107,135
96,222
86,623
81,011
76,412
73,517
72,202
71,768
71,822
72,175
72,848
73,667
74,592
75,564
76,578
77,629
78,700
79,782
80,875
81,977
83,086
84,197
85,312
86,429
87,547
88,669
89,795
90,922
92,051
93,181
PM2.5
23,382
23,480
23,483
23,417
23,498
23,804
24,335
24,882
25,402
25,888
26,364
26,832
27,291
27,747
28,202
28,655
29,107
29,558
30,009
30,460
30,911
31,362
31,813
32,265
32,718
33,173
33,627
34,081
34,535
34,990
35,444
35,898
36,353
36,807
37,261
37,716
38,170
38,625
39,079
PM10
25,416
25,522
25,525
25,453
25,541
25,874
26,451
27,045
27,611
28,139
28,445
28,747
29,071
29,473
29,896
30,336
30,795
31,259
31,727
32,198
32,671
33,146
33,622
34,098
34,576
35,055
35,534
36,013
36,492
36,971
37,450
37,929
38,408
38,887
39,366
39,845
40,324
40,803
41,282
CO
15,091,835
14,351,829
13,690,337
12,923,819
12,252,479
11,711,607
10,861,441
9,992,801
9,623,727
9,427,359
9,240,448
9,125,886
9,107,104
9,135,515
9,201,411
9,298,167
9,415,010
9,543,762
9,679,462
9,820,562
9,964,572
10,110,794
10,258,216
10,406,862
10,557,631
10,709,373
10,861,555
11,014,081
11,166,921
11,319,980
11,473,166
11,626,453
11,779,824
11,933,276
12,086,826
12,240,473
12,394,188
12,547,962
12,701,792
                                        3-31

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Final Regulatory Impact Analysis
     Table 3.4-6: Controlled 50-State Annual Exhaust and Evaporative Emissions for
                      Marine Spark-Ignition Engines (short tons)
Year
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
THC
906,318
873,287
836,493
796,279
756,781
717,924
680,702
644,330
593,432
543,080
495,189
452,028
412,280
376,203
342,807
312,281
285,067
259,742
238,704
219,826
203,027
188,065
175,954
166,147
157,943
151,063
145,397
140,670
136,990
134,079
131,797
130,067
128,766
127,853
127,275
126,952
126,816
126,828
126,959
voc
931,132
896,969
858,916
817,340
776,480
736,303
697,795
660,187
607,656
555,760
506,468
462,066
421,190
384,108
349,793
318,441
290,507
264,519
242,957
223,621
206,427
191,121
178,752
168,751
160,391
153,384
147,624
142,822
139,083
136,124
133,803
132,045
130,723
129,798
129,212
128,888
128,753
128,769
128,906
NOx
46,311
49,694
53,397
57,862
63,366
67,730
73,894
82,123
84,822
85,353
85,673
85,732
85,609
85,334
84,890
84,279
83,468
82,546
81,398
80,081
78,657
77,197
75,802
74,424
73,057
71,713
70,421
69,236
68,639
68,339
68,148
68,038
67,985
67,975
68,009
68,077
68,174
68,302
68,461
PM2.5
15,092
14,417
13,679
12,886
12,090
11,311
10,553
9,824
8,832
7,891
7,035
6,275
5,577
4,951
4,376
3,856
3,399
2,978
2,640
2,341
2,081
,851
,673
,534
,419
,323
,247
,185
,137
,099
,067
,043
,024
,010
,001
995
991
989
989
PM10
16,404
15,670
14,869
14,007
13,142
12,295
11,470
10,678
9,600
8,577
7,647
6,820
6,062
5,381
4,756
4,191
3,695
3,237
2,869
2,545
2,262
2,012
1,818
1,668
1,542
1,438
1,355
1,288
1,236
1,194
1,160
1,134
1,113
1,098
1,088
1,081
1,077
1,075
1,075
CO
2,472,251
2,407,992
2,346,538
2,266,733
2,170,374
2,103,059
2,007,804
1,885,970
1,808,304
1,755,638
1,707,370
1,664,442
1,624,423
1,587,889
1,553,983
1,523,443
1,496,863
1,472,528
1,452,196
1,433,655
1,417,440
1,403,195
1,391,146
1,380,739
1,371,913
1,364,592
1,358,936
1,354,638
1,353,989
1,355,439
1,357,905
1,361,273
1,365,343
1,370,010
1,375,199
1,380,822
1,386,805
1,393,116
1,399,715
                                        3-32

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                                                                       Emission Inventory
3.4.2 Controlled Hazardous Air Pollutant Estimates

       The final hydrocarbon emission standards for small nonroad and marine SI engines will
also reduce toxic air pollutants.  To calculate the controlled toxic air emission inventories, we
multiplied the baseline hazardous air pollutant estimates (Section 3.2.2) by the ratio of control
and baseline emission inventories (Section 3.2.1.4 and 3.4.1.3, respectively) for VOC or PM, as
appropriate. More specifically, we used the VOC ratio for all toxic pollutant species that are
found in the gas phase.  The gas phase pollutants are all the species described below, except for
naphthalene and the polycyclic organic matter (POM) compounds that are found in both the gas
and particulate phase. In these cases, we used the PM ratio to estimate the controlled
inventories.
       Controlled inventories were calculated for the seven major types of air toxic emissions:
benzene, formaldeyde, acetaldehyde, 1,3-butadiene, acrolein, naphthalene, and 15 other
compounds grouped together as POM for this analysis.6 Table 3.4-7 presents the 50-state
controlled inventories, respectively, small nonroad SI engines. Table 3.4-8 provides the same
information for marine SI engines.

                 Table 3.4-7: Controlled 50-State Air Toxic Emissions for
                    Small Nonroad Spark-Ignition Engines (short tons)
Year
2002
2020
2030
Benzene
35,086
15,413
17,577
1,3
Butadiene
5,561
2,504
2,859
Formalde-
hyde
8,664
4,189
4,784
Acetalde-
hyde
2,900
2,015
2,300
Acrolein
505
210
240
Naphthalene
447
620
718
POM
97
128
147
                 Table 3.4-8: Controlled 50-State Air Toxic Emissions for
                        Marine Spark-Ignition Engines (short tons)
Year
2002
2020
2030
Benzene
23,110
4,453
2,582
1,3
Butadiene
2,053
390
216
Formalde-
hyde
2,153
273
151
Acetalde-
hyde
1,543
418
234
Acrolein
211
14
8
Naphthalene
37
19
9
POM
31
7
3
       e  The 15 POMs summarized in this chapter are acenapthylene, anthracene, benz(a)anthracene,
benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, beno(k)fluoranthene, chrysene, dibenzo(a,h)anthracene,
fluoranthene, fluorene, indeno(l,2,3-c,d)-pyrene, phenanthrene, andpyrene.
                                            3-33

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Final Regulatory Impact Analysis
3.5  Projected Emissions Reductions from the Final Rule

       This section presents the projected total emission reductions associated with the final
Phase 3 standards. We calculated the reductions by subtracting the baseline inventories from
Section 3.2 by the controlled inventories from Section 3.4.

3.5.1  Results for THC, VOC, NOx, PM25, PM10, and CO

        Tables 3.5-1 presents the 50-state exhaust and evaporative emission inventories and
percent reductions, respectively, for small nonroad SI engines.  Tables 3.5-2 provides the same
information for marine SI engines. Tables 3.5-3 summarizes the combined emission reductions
for the final rule. The earliest Phase 3 evaporative standards for small nonroad SI engines begin
in 2008.  Similar final evaporative standards affect Marine SI engines one year later. Therefore
the emission reductions are shown beginning in 2008 for small nonroad SI engines and 2009 for
Marine SI engines.  Figures 3.5-1 though 3.5-5 show the combined baseline, controlled, and by
contrast the reduction emission inventories over time for small nonroad and Marine SI engines.
                                          3-34

-------
Table 3.5-1: Total 50-State Annual Exhaust
                 for Small Spark-Ignition
and Evaporative Emission Reductions
Engines (short tons)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
THC
Tons
5,298
12,306
19,103
45,157
92,055
136,293
169,739
193,479
212,274
225,797
235,483
243,315
249,991
255,636
260,711
265,345
269,770
274,107
278,455
282,769
287,060
291,328
295,576
299,808
304,033
308,250
312,460
316,665
320,862
325,052
329,238
333,421
337,602
%
1
2
3
7
14
20
25
28
30
32
33
33
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
35
35
voc
Tons
5,298
12,306
19,103
44,381
89,426
131,817
163,834
186,614
204,672
217,669
226,988
234,523
240,948
246,382
251,271
255,737
260,002
264,185
268,375
272,533
276,668
280,782
284,876
288,955
293,027
297,091
301,148
305,201
309,246
313,284
317,318
321,349
325,379
%
1
2
3
7
14
20
25
28
30
32
33
33
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
35
35
NOx
Tons
0
0
0
12,289
24,598
35,882
43,389
49,983
54,951
58,371
60,933
63,024
64,827
66,312
67,650
68,883
70,072
71,228
72,374
73,509
74,635
75,753
76,863
77,967
79,068
80,167
81,264
82,359
83,450
84,537
85,623
86,708
87,792
%
0
0
0
10
20
29
35
40
43
45
46
47
47
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
48
49
49
PM2.5
Tons
0
0
0
0
195
385
546
632
697
745
776
800
820
838
854
868
881
894
908
922
936
949
963
977
990
1,004
1,018
1,031
1,045
1,059
1,072
1,086
1,100
%
0
0
0
0
1
1
2
2
2
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
PM10
Tons
0
0
0
0
212
419
594
687
758
810
843
870
892
911
928
943
958
972
987
1,002
1,017
1,032
1,047
1,062
1,076
1,091
1,106
1,121
1,136
1,151
1,166
1,181
1,195
%
0
0
0
0
1
1
2
2
2
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
CO
Tons
0
0
0
141,251
338,592
518,625
644,624
743,512
818,628
871,019
909,068
939,944
966,407
988,367
1,008,088
1,026,161
1,043,515
1,060,430
1,077,303
1,094,028
1,110,652
1,127,170
1,143,584
1,159,920
1,176,219
1,192,487
1,208,730
1,224,953
1,241,128
1,257,259
1,273,368
1,289,462
1,305,543
%
0
0
0
1
4
5
7
8
8
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9

-------
Table 3.5-2: Total 50-
                for
State Annual Exhaust and Evaporative Emission Reductions
Marine Spark-Ignition Engines (short tons)
Year
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
THC
Tons
1,400
18,748
37,670
58,252
78,654
98,886
118,974
138,843
158,386
177,535
196,122
212,471
227,798
242,345
255,886
267,248
277,049
285,828
293,743
300,755
307,097
312,636
317,588
322,039
326,092
329,826
333,261
336,417
339,371
342,183
344,878
347,477
%
0
3
6
11
15
19
24
29
34
38
43
47
51
54
58
60
63
64
66
67
69
70
70
71
71
72
72
73
73
73
73
73
voc
Tons
1,400
19,245
38,656
59,723
80,605
101,313
121,873
142,207
162,207
181,801
200,818
217,524
233,178
248,030
261,851
273,428
283,400
292,329
300,379
307,503
313,944
319,573
324,609
329,140
333,265
337,067
340,565
343,778
346,786
349,649
352,395
355,043
%
0
3
7
11
15
19
24
29
34
38
43
47
51
55
58
60
63
65
66
68
69
70
70
71
72
72
72
73
73
73
73
73
NOx
Tons
0
2,318
5,163
7,989
10,796
13,588
16,369
19,131
21,879
24,617
27,340
30,128
32,981
35,822
38,605
41,250
43,803
46,286
48,689
50,990
53,151
54,696
55,921
57,018
58,015
58,937
59,802
60,611
61,377
62,104
62,793
63,445
%
0
3
6
9
11
14
16
18
21
23
25
27
29
31
33
35
37
39
40
42
43
44
45
46
46
46
47
47
47
48
48
48
PM2.5
Tons
0
317
634
948
1,259
1,567
1,872
2,173
2,468
2,756
3,034
3,269
3,485
3,688
3,875
4,023
4,146
4,256
4,355
4,440
4,516
4,582
4,642
4,698
4,749
4,797
4,841
4,882
4,920
4,957
4,993
5,027
%
0
3
7
12
17
22
27
33
39
45
50
55
60
64
68
71
73
75
77
78
79
80
81
81
82
82
83
83
83
83
83
84
PM10
Tons
0
344
689
1,031
1,369
1,703
2,035
2,362
2,683
2,996
3,298
3,553
3,788
4,008
4,212
4,373
4,506
4,626
4,734
4,826
4,909
4,981
5,046
5,107
5,162
5,214
5,262
5,306
5,348
5,388
5,427
5,464
%
0
3
7
12
17
22
27
33
39
45
50
55
60
64
68
71
73
75
77
78
79
80
81
81
82
82
83
83
83
83
83
84
CO
Tons
0
15,540
33,192
50,745
68,211
85,582
102,867
119,995
136,972
153,767
170,313
185,917
201,392
216,625
231,477
245,457
259,174
272,579
285,568
297,811
309,295
317,638
324,313
330,323
335,801
340,886
345,665
350,145
354,388
358,435
362,283
365,936
%
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
17
18
19
19
19
20
20
20
20
20
20
21
21
21

-------
Table 3.5-3: Total 50-State Annual Exhaust and Evaporative Emission Reductions
       for Small Nonroad and Marine Spark-Ignition Engines (short tons)
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
THC
Tons
5,298
13,706
37,851
82,827
150,307
214,947
268,625
312,454
351,117
384,183
413,019
439,437
462,463
483,433
503,056
521,231
537,018
551,156
564,282
576,512
587,814
598,426
608,211
617,396
626,072
634,342
642,286
649,926
657,279
664,423
671,421
678,299
685,079
%
0
1
3
7
12
18
23
26
30
33
35
37
39
40
42
43
44
44
45
45
46
46
46
47
47
47
47
47
47
47
47
47
47
voc
Tons
5,298
13,706
38,348
83,037
149,149
212,422
265,147
308,487
346,879
379,875
408,789
435,340
458,472
479,560
499,301
517,588
533,430
547,584
560,704
572,913
584,171
594,726
604,449
613,565
622,167
630,356
638,215
645,766
653,024
660,069
666,967
673,744
680,422
%
0
1
3
7
12
18
22
26
29
32
35
37
39
40
41
43
44
44
45
45
46
46
46
47
47
47
47
47
47
47
47
47
47
NOx
Tons
0
0
2,318
17,451
32,587
46,679
56,977
66,353
74,082
80,250
85,550
90,363
94,954
99,293
103,472
107,488
111,322
115,031
118,660
122,198
125,625
128,904
131,559
133,888
136,087
138,182
140,201
142,161
144,061
145,914
147,727
149,501
151,237
%
0
0
1
8
15
21
25
29
32
34
36
37
38
39
40
41
42
43
44
45
46
46
47
47
47
47
48
48
48
48
48
48
48
PM2.5
Tons
0
0
317
634
1,143
1,644
2,113
2,504
2,870
3,213
3,532
3,834
4,089
4,323
4,541
4,743
4,905
5,040
5,164
5,277
5,376
5,465
5,545
5,619
5,688
5,753
5,814
5,872
5,927
5,979
6,029
6,079
6,127
%
0
0
1
2
3
5
6
7
8
9
10
11
11
12
12
13
13
13
13
14
14
14
14
14
14
14
14
14
14
14
14
14
14
PM10
Tons
0
0
344
689
1,243
1,787
2,297
2,722
3,120
3,493
3,839
4,168
4,444
4,698
4,936
5,155
5,331
5,479
5,613
5,736
5,843
5,940
6,027
6,107
6,183
6,253
6,320
6,383
6,442
6,499
6,554
6,607
6,660
%
0
0
1
2
3
5
6
7
8
9
10
11
11
12
12
13
13
13
13
14
14
14
14
14
14
14
14
14
14
14
14
14
14
CO
Tons
0
0
15,540
174,444
389,337
586,836
730,206
846,379
938,623
1,007,991
1,062,836
1,110,258
1,152,325
1,189,759
1,224,712
1,257,637
1,288,972
1,319,604
1,349,882
1,379,596
1,408,463
1,436,465
1,461,222
1,484,233
1,506,542
1,528,288
1,549,616
1,570,618
1,591,273
1,611,647
1,631,803
1,651,746
1,671,479
%
0
0
0
2
3
5
6
7
8
9
9
9
9
10
10
10
10
10
10
10
10
10
10
10
11
11
11
11
11
11
11
11
11

-------
Final Regulatory Impact Analysis
                    Figure 3.5-1:  50-State Annual THC Exhaust and Evaporative Emissions for Small SI and
                                                 Marine SI Engines
                      2,000,000 - -.
                      1,500,000
                   in
                   O
                       500,000
                                    2005     2010    2015     2020     2025     2030     2035     2040
                       Figure 3.5-2: 50-State Annual VOC Exhaust and Evaporative Emissions for

                                            Small SI and Marine SI Engines
                         2,500,000
                         2,000,000
ra


(A
                         1,500,000
                         1,000,000
                          500,000
                               2000    2005     2010    2015     2020    2025    2030    2035    2040
                                                            Year
                                                        3-38

-------
                                                                        Emission Inventory
Figure 3.5-2: 50-State Annual NOx Exhaust Emissions for Small SI and Marine SI
                                Engines
300,000
     2000     2005     2010      2015     2020     2025     2030     2035      2040
 Figure 3.5-3: 50-State Annual PM2.5 Exhaust Emissions for Small SI and
                           Marine SI Engines
50,000
45,000
 5,000
    2000
             2005
                                                               2035
                                                                       2040
                                     3-39

-------
Final Regulatory Impact Analysis
                      Figure 3.5-4: 50-State Annual PM10 Emissions for Small SI and Marine SI
                                                   Engines
                    60,000
                    50,000
                    40,000
                 cu
                 
-------
                                                                      Emission Inventory
3.5.2  Results for Hazardous Air Pollutants

       Table 3.5-4 presents the 50-state exhaust and evaporative hazardous air pollutant
emission reductions for small nonroad SI engines that are expected as a result of the final
standards. Table 3.5-5 provides the same information for marine SI engines.  Table 3.5-6
summarizes the combined hazardous air pollutant reductions for the final rule. These results are
displayed for 2020 and 2030, when most or all of the engines subject to the standards are
represented in the respective fleets.
                                           3-41

-------
   Table 3.5-4: 50-State Air Toxic Emission Reductions for
      Small Nonroad Spark-Ignition Engines (short tons)
Year
2020
2030
Benzene
Tons
7,803
9,200
%
34
34
1,3 Butadiene
Tons
965
1,140
%
28
29
Formaldehyde
Tons
1,614
1,907
%
28
29
Acetaldehyde
Tons
777
917
%
28
29
Acrolein
Tons
81
96
%
28
29
Napthalene
Tons
17
21
%
3
29
POM
Tons
4
4
%
3
3
   Table 3.5-5: 50-State Air Toxic Emission Reductions for
         Marine Snark-Tgnition Engines (short tnns>
Year
2020
2030
Benzene
Tons
3,964
5,893
%
47
70
1,3 Butadiene
Tons
373
535
%
49
71
Formaldehyde
Tons
261
374
%
49
71
Acetaldehyde
Tons
400
577
%
49
71
Acrolein
Tons
13
19
%
49
71
Napthalene
Tons
23
37
%
55
80
POM
Tons
9
13
%
55
80
   Table 3.5-6: 50-State Air Toxic Emission Reductions for
Small Nonroad and Marine Snark-Tgnition Engines (short tnns>
Year
2020
2030
Benzene
Tons
11,767
15,093
%
37
43
1,3 Butadiene
Tons
1,338
1,675
%
32
35
Formaldehyde
Tons
1,875
2,281
%
30
32
Acetaldehyde
Tons
1,176
1,494
%
33
37
Acrolein
Tons
94
115
%
30
32
Napthalene
Tons
41
57
%
6
7
POM
Tons
9
57
%
11
10

-------
                                                                     Emission Inventory
3.6  Emission Inventories Used for Air Quality Modeling

       This section briefly summaries the methodology we used for air quality modeling
purposes and to develop the emission inventories for that modeling. It also describes the
changes to our emission inventory modeling inputs and resulting emission inventories that were
made between the preliminary baseline and control scenarios used for the air quality modeling,
and the updated final baseline and control scenarios for the final Phase 3 rule. These differences
often occur because the emission inputs for the air quality modeling are required early in the
analytical process to ensure there is adequate time to complete the analysis and incorporate the
results into the rulemaking.  Given that lead time requirement, air quality modeling is often
based on analytical methods and inputs that may be superceded, or on a control scenario that
does not specifically match the final set of emission standards.

3.6.1 General Description of the Air Quality Modeling

       Air quality modeling was performed for the 48 contiguous states and the District of
Columbia to estimate the effect of the final rule on future annual fine particulate matter (PM25)
concentrations, 8-hour ozone concentrations, and visibility levels. The analysis was performed
for calendar years 2002, 2020, and 2030 using the Community Multiscale Air Quality (CMAQ)
model. The model simulates the multiple physical and chemical processes involved in the
formation, transport, and destruction of fine parti culate and ozone.

       The air quality modeling for the final rule was predominately taken directly from the
work performed for EPA's recent final rulemaking to  control air emissions from locomotive
engines and marine compression-ignition engines less than 20 liters per cylinder (the
locomotive/marine rule). This approach was adopted  to ensure that the air quality modeling for
this rule included the effects all EPA's most recent air pollution control regulations and to
conserve resources by taking advantage of the existing inventory preparation (i.e., input files),
analytical methods, and results.

       More specifically, we used the locomotive/marine rule's "control" scenario as our starting
point.  The resulting baseline for the Phase 3 final rule was then modified to include more recent
modeling updates for small nonroad and marine  SI engines based on the NONROAD2005d core
model  and a set of input files that closely  matches those used in this final rule. (The differences
in the input files used in the preliminary inventories and those for the final  rule, which also used
NONROAD 2005d core model, are  specifically described later in this section.)  For air quality
modeling purposes, the nonroad model was  executed within the framework of EPA's National
Mobile Inventory Model (NMEVI) that links a county-level database to the model and collates the
output into a single database table. The resulting NMIM inventory estimates for nonroad and
marine SI engines account for local  differences in fuel characteristics and temperatures. By
contrast, if NONROAD2005d is run as a stand alone model,  results are based on a somewhat less
accurate, but much less resource intensive approach that uses national average daily temperatures
and fuel characteristics.
                                          3-43

-------
Final Regulatory Impact Analysis
       The NMIM emissions inventory methodology and results for the highway vehicles and all
nonroad sources (including those for small nonroad and marine SI engines) that were used in the
air quality assessment are in the docket for this final rule.24

3.6.2  Methodology for Comparing the Preliminary Air Quality Emission Inventories and
the Final Inventories

       The simplest method for comparing the preliminary emission inventories and the
inventories represented in the final rule is to compare the emission results from using the
NONROAD2005d core model  with the national average inputs for temperature and fuel that
reflect the modeling assumptions for the preliminary and final rule inventories. This is possible
because of the similarities in the underlying use of the NONROAD2005d model. More
specifically, even though the two modeling approaches, i.e., NMIM and the stand alone
NONROAD2005 model, use different temperature and fuel characteristics, the computational
method is the same/  This consistency means that the results of the two modeling approaches
will be proportional in nature, i.e., the relative changes in the inventories will be similar. Also,
as is explained in more detail later, the other basic modeling scenario inputs, e.g., emission
factors and deterioration rates,  are nearly identical.  Taken together, the modeling results from
using the NONROAD2005d model with national average inputs for temperature and fuels will
closely mirror the differences in inventories produced with NMIM. This avoids the more time
and resource intensive approach of rerunning the NMIM model for the final rule scenarios, while
still providing a good comparison of the differences in the absolute inventories, i.e., tons, and
more  importantly for air quality considerations, the percent reduction between the baseline and
control cases.  Therefore, the comparisons of the preliminary and final emission scenarios that
are  presented in the following sections are based on comparing 50-state inventories using the
nonroad model with national average inputs.

3.6.3  Comparison of the Baseline Scenario Emission Inventories

       As described in Section 3.2., the final emission inventories for the Phase 3 rule are based
on the use of a special version of the nonroad model, i.e., NONROAD2005d.  Similarly, the
preliminary emission inventories for air quality modeling were also constructed using the same
version NONROAD2005d core model.  Therefore, the only difference between the preliminary
and final baseline scenarios are the modeling inputs. These differences and a comparison of the
respective inventory results are presented below.

       3.6.3.1 Differences Between the Preliminary and Final Baseline Scenarios

       The modeling inputs for the final baseline scenario are described in Section 3.2.1.  The
only difference in the inputs for small nonroad SI engines between the preliminary and the final
baseline scenarios is that the preliminary results did not include correction of the running loss
       f The difference between the preliminary emission inventories using NMIM and final rule emission
inventories using NONROAD2005d is that the NMIM results, which use county-level data for temperatures and fuel
characteristics, are generally 10-15 percent greater depending on the pollutant.

                                           3-44

-------
                                                                     Emission Inventory
emission factors for Class 1 snowblowers to account for cold weather applications as described
in Section 3.2.1.1.1, number 8. There were no differences in the inputs for marine SI engines.
       3.6.3.2 Comparison of Preliminary and Final Baseline Emission Inventories

       Table 3.6-1 compares the preliminary and final 50-state baseline scenario inventories for
small nonroad and marine SI engines. As shown, the differences in the baseline scenarios are
insignificant.
                                          3-45

-------
Table 3.6-1: Comparison of 50-State Baseline Scenario Emissions for
         Preliminary Air Quality Modeling and Final Rule
Applications
Small Nonroad
SI Subject to
the Final rule
Marine SI
Total
Year
2020
2030
2020
2030
2020
2030
VOC [short tons]
Final
728,853
842,970
460,481
458,656
1,189,334
1,301,626
Preliminary
729,235
843,410
460,481
458,656
1,189,716
1,302,066
Difference
(382)
(440)
0
0
(382)
(440)
NOX [short tons]
Final
137,002
158,840
111,525
123,335
248,527
282,175
Preliminary
137,002
158,840
111,525
123,335
248,527
282,175
Difference
0
0
0
0
0
0
PM25 [short tons]
Final
30,009
34,535
5,908
5,719
35,917
40,254
Preliminary
30,009
34,535
5,908
5,719
35,917
40,255
Difference
0
0
0
0
0
0

-------
                                                                     Emission Inventory
                                  Table 3.6-1 (Cont'd)
                 Comparison of 50-State Baseline Scenario Emissions for
                    Preliminary Air Quality Modeling and Final Rule
Applications
Small Nonroad
SI Subject to the
Final rule
Marine SI
Total
Year
2020
2030
2020
2030
2020
2030
PM10 [short tons]
Final
32,618
37,538
6,422
6,217
39,041
43,755
Preliminary
32,618
37,538
6,422
6,217
39,041
43,755
Difference
0
0
0
0
0
0
CO [short tons]
Final
10,645,870
12,310,505
1,638,114
1,671,627
12,283,983
13,982,132
Preliminary
10,645,870
12,310,505
1,638,114
1,671,627
12,283,983
13,982,132
Difference
0
0
0
0
0
0
3.6.4  Comparison of the Control Scenario Emission Inventories

       As noted above, the preliminary and final emission inventories for the Phase 3 rule are
based on the same version of the nonroad model, i.e., NONROAD2005d. Therefore, the only
difference between the scenarios are the modeling inputs.  These differences and a comparison
of the respective inventory results are presented below.

       3.6.4.1 Differences Between the Preliminary and Final Control Scenarios

       The modeling inputs for the final control scenario are described in Section 3.4.1. The
only difference in the inputs for small nonroad SI engines between the preliminary and the final
control scenarios is that the preliminary results excluded the following:

       1.     Update of the Phase 3 Class II zero-hour emission factor for CO from 391.13 to
             431.72 g/kW-hr (321.9 g/hp-hr); and
       2.     Update of the Phase 3 Class II brake specific fuel consumption values from 0.666
             to 0.735 Ib/hp-hr to reflect a lower use of electronic fuel injection systems.

       For marine SI engines, the only difference in the inputs between the preliminary and the
final control scenarios is that the preliminary results excluded the following:

       1.     Revised several of the HC and NOx emission factors for outboards, personal
             watercraft, and sterndrive/inboards;
       2.     Revised the Phase 3 standard phase-in dates for high performance
             sterndrive/inboards (>600 hp);
       3.     Delayed by one year the implementation dates for outboards, personal watercraft,
             and stern  drive/inboards: and
                                          3-47

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Final Regulatory Impact Analysis
       4.     Delayed by one year the implementation of diurnal Phase 3 controls for portable
             fuel tanks to 2010 and installed fuel tanks to 2011.

       3.6.4.2 Comparison of Preliminary and Final Control Emission Inventories

       Table 3.6-2 compares the preliminary and final 50-state control scenario inventories for
small nonroad and marine SI engines.   As shown, the difference in the control scenarios are
insignificant.
                                          3-48

-------
 Table 3.6-2: Comparison of 50-State Control Scenario Emissions for
Preliminary Air Quality Modeling Scenario and Final Rule (Tons/Year)
Applications
Small Nonroad
SI Subject to
the Final rule
Marine SI
Total
Year
2020
2030
2020
2030
2020
2030
VOC [short tons]
Final
487,905
558,094
242,957
139,083
730,862
697,177
Preliminary
487,663
557,805
241,216
136,650
728,879
694,455
Difference
242
289
1,741
2,433
1,983
2,722
NOX [short tons]
Final
72,175
81,977
81,398
68,639
153,573
150,616
Preliminary
72,175
81,977
81,162
68,538
153,336
150,515
Difference
0
0
236
101
237
101
PM2 , [short tons]
Final
29,189
33,572
2,640
1,137
31,829
34,709
Preliminary
29,189
33,572
2,640
1,137
31,829
34,709
Difference
0
0
0
0
0
0

-------
Final Regulatory Impact Analysis
                                 Table 3.6-2 (Cont'd)
                 Comparison of 50-State Control Scenario Emissions for
                   Preliminary Air Quality Modeling and Final Rule
Applications
Small Nonroad
SI Subject to the
Final rule
Marine SI
Total
Year
2020
2030
2020
2030
2020
2030
PM10 [short tons]
Final
31,727
36,492
2,869
1,236
34,596
37,728
Preliminary
31,727
36,492
2,869
1,236
34,596
37,728
Difference
0
0
0
0
0
0
CO [short tons]
Final
9,679,462
11,166,921
1,452,196
1,353,989
11,131,658
12,520,910
Preliminary
9,029,001
10,393,508
1,447,553
1,345,079
10,476,554
11,738,587
Difference
650,461
773,413
4,643
8,910
655,104
782,323
3.6.5 Comparison of the Emission Reduction Inventories

       Table 3.6-3 compares the emission reductions for preliminary and final 50-state
inventories for small nonroad and marine SI engines. As shown, the differences are
insignificant.
                                         3-50

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    Table 3.6-3: Comparison of 50-State Emissions Reductions for
Preliminary Air Quality Modeling Scenario and Final Rule (Tons/Year)
Applications
Small Nonroad
SI Subject to
the Final rule
Marine SI
Total
Year
2020
2030
2020
2030
2020
2030
VOC [short tons]
Final
240,948
284,876
217,524
319,573
458,472
604,449
Preliminary
241,572
285,605
219,265
322,006
460,837
607,611
Difference
(624)
(729)
(1,741)
(2,433)
(2,365)
(3,162)
NOX [short tons]
Final
64,827
76,863
30,128
54,696
94,955
131,559
Preliminary
64,827
76,863
30,364
54,797
95,191
131,660
Difference
0
0
(236)
(101)
(236)
(101)
PM2 5 [short tons]
Final
820
963
1,287
3,269
4,082
5,545
Preliminary
820
963
3,269
4,582
4,089
5,545
Difference
0
0
(1,982)
(1,313)
(7)
0

-------
Final Regulatory Impact Analysis
                                Table 3.6-3 (Cont'd)
                    Comparison of 50-State Emission Reductions for
                   Preliminary Air Quality Modeling and Final Rule
Applications
Small Nonroad
SI Subject to the
Final rule
Marine SI
Total
Year
2020
2030
2020
2030
2020
2030
PM10 [short tons]
Final
892
1,047
3,553
4,981
4,445
6,028
Preliminar
y
892
1,047
3,553
4,981
4,445
6,028
Difference
0
0
0
0
0
0
CO [short tons]
Final
966,407
1,143,584
185,917
317,638
1,152,325
1,461,222
Preliminar
y
1,616,868
1,916,997
190,560
326,548
1,807,428
2,243,545
Difference
(650,461)
(773,413)
(4,643)
(8,910)
(655,103)
(782,323)
                                        3-52

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                                                                              Emission Inventory
Chapter 3 References
1.   "NONROAD2005a Emissions Inventory Model and Documentation," Memorandum and attachment from
Richard S. Wilcox to Docket EPA-HQ-OAR-2004-0008, U.S. Environmental Protection Agency, Office of
Transportation and Air Quality, Ann Arbor, Michigan, February 5, 2007. Docket Identification EPA-HQ-OAR-
2004-0008-0517.

2.  "NONROAD2005d missions Inventory Model," Memorandum and attachment from Richard S. Wilcox to Docket
EPA-HQ-OAR-2004-0008, U.S. Environmental Protection Agency, Office of Transportation and Air Quality, Ann
Arbor, Michigan, February 5, 2007. Docket Identification EPA-HQ-OAR-2004-0008-0719.

3.  "Updates to Phase 2 Technology Mix, Emission Factors, and Deterioration Rates for Spark-Ignition Nonroad
Nonhandheld Engines at or below 19 Kilowatts for the NONROAD Emissions Inventory Model," Memorandum
from Phil Carlson to Docket EPA-HQ-OAR-2004-0008, U.S. Environmental Protection Agency, Office of
Transportation and Air Quality, Ann Arbor, Michigan, March 6, 2000. Docket Identification EPA-HQ-OAR-2004-
0008-0543.

4.  "Phase 3 Technology Mix, Emission Factors, and Deterioration Rates for Spark-Ignition Nonroad Nonhandheld
Engines at or below  19 Kilowatts for the NONROAD Emissions Inventory Model," Memorandum from Phil Carlson
to Docket EPA-HQ-OAR-2004-0008, U.S. Environmental Protection Agency, Office of Transportation and Air
Quality, Ann Arbor, Michigan, May 21, 2008. Docket Identification EPA-HQ-OAR-2004-0008-0842.

5. "Exhaust Emission Factors for Nonroad Engine Modeling; Spark-Ignition, Report No. OlOe,"  U.S. Environmental
Protection Agency, Office of Transportation and Air Quality, Ann Arbor, Michigan, EPA420-R-05-019,  December
2005. Docket Identification EPA-HQ-OAR-2004-0008-0398.

6.  "Updates to Technology Mix, Emissions Factors, Deterioration Rates, Power Distribution, and Fuel Consumption
Estimates for SI Marine Engines in the NONROAD Emissions Inventory Model," Memorandum from Michael
Samulski to Docket EPA-HQ-OAR-2004-0008, U.S. Environmental Protection Agency, Office of Transportation
and Air Quality, Ann Arbor, November 30, 2005. Docket Identification EPA-HQ-OAR-2004-0008-0361.

7.  "Nonroad Evaporative Emission Rates, Report No. 012c," U.S. Environmental Protection Agency, Office of
Transportation and Air Quality, Ann Arbor, Michigan, December 2005. Docket Identification EPA-HQ-OAR-2004-
0008-0362.

8.  "Modeling of Ethanol Blend Effects on Nonroad Fuel Hose and Tank Permeation - Updated," Memorandum from
Craig Harvey to Docket EPA-HQ-OAR-2004-0008, U.S. Environmental Protection Agency, Office of
Transportation and Air Quality, Ann Arbor, Michigan, February 22, 2008. Docket Identification EPA-HQ-OAR-
2004-0008-0698.

9.  "Domenici-Barton Energy Policy Act of 2005," 109th Congress, U.S. House of Representatives and U.S. Senate,
July 26, 2005. Docket Identification EPA-HQ-OAR-2004-0008-0268.

10. "Annual Energy Outlook 2007; With Projections to 2030, Table 11: Liquid Fuels Supply and Disposition,"
Energy Information Administration, U.S. Department of Energy, Report # DOE/EIA-0383(2007), 2007.
Http://www.eia.doe.gov/oiaf/archive/aeo07/pdf/aeotab_l 1 .pdf. Docket Identification EPA-HQ-OAR-2004-0008-
0695.

11. "Annual Energy Outlook 2007; With Projections to 2030, Table 17: Renewable Energy, Consumption, by
Sector and Source," Energy Information Administration, U.S. Department of Energy, Report #
DOE/EIA-0383(2007), 2007. Http://www.eia.doe.gov/oiaf/archive/aeo07/pdf/aeotab 17.pdf. Docket Identification
EPA-HQ-OAR-2004-0008-0696.


                                               3-53

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Final Regulatory Impact Analysis
12. "Fuel and Oil Hoses," Recommended Practice J30, Society of Automotive Engineers, June 1998. Docket
Identification EPA-HQ-OAR-2004-0008-0176.

13. "Personal Watercraft Fuel Systems,"  Recommended Practice J2046, Society of Automotive Engineers, January,
19, 2001. Docket Identification EPA-HQ-OAR-2004-0008-0179.

14. "Marine Fuel Hoses," Recommended Practice J1527, Society of Automotive Engineers, Revised February 1993.
Docket Identification EPA-HQ-OAR-2004-0008-0177.

15. "Handheld Fuel Lines," email from William Guerry, representing Outdoor Power Equipment Institute, to Glenn
Passavant and Mike Samulski, U.S. Environmental Protection Agency, Office of Transportation and Air Quality,
Ann Arbor, Michigan, July 6, 2005. Docket Identification EPA-HQ-OAR-2004-0008-0126.

16. Letter from Jim Hardin, Grady-White Boats, to Phil Carlson, U.S. Environmental Protection Agency, Office of
Transportation and Air Quality, Ann Arbor, Michigan, July 25, 2006. Docket Identification EPA-HQ-OAR-2004-
0008-0437.

17. "Permeation of Gasoline and Gasoline-Alcohol Fuel Blends Through High-Density Polyethylene Fuel Tanks
with Different Barrier Technologies,"  D. Kathios and R. Ziff, SAE Paper 920164, 1992, Docket Identification
EPA-HQ-OAR-2004-0008-0172.

18. "List of 177 Pollutants in the Assessment," National-Scale Air Toxics Assessment for 1999, U. S.
Environmental Protection Agency, 2006. Http://www.epa.gov/ttn/atw/natal999/177poll.html.

19. "Comparison of Small Nonroad and Marine Spark-Ignition Emissions to Stationary and Other Mobile Source
Emission Inventories," Memorandum and attachment from Richard Wilcox, U.S. Environmental Protection Agency,
Office of Transportation and Air Quality, Ann Arbor, Michigan, March 12, 2007.  Docket Identification EPA-HQ-
OAR-2004-0008-0540.

20. "Technical Support Document: Preparation of Emissions Inventories for the 2002-Based Platform, Version 3,
Criteria Pollutants," U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, Research
Triangle Point, North Carolina, January 2008.
Http://www.epa.gov/scram001/reports/Emissions%20TSD%20Voll_02-28-08.pdf. Docket Identification EPA-HQ-
OAR-2004-0008-0699.

21. "Regulatory Impact Analysis: Control of Emissions or Air Pollution from Locomotives and Marine
Compression-Ignition Engines Less Than 30 Liters per Cylinder," U.S. Environmental Protection Agency, Office of
Transportation and Air Quality, Ann Arbor, Michigan, May 2008. EPA Report Number:  EPA420-R-08-001a.

22. "Control of Emissions From New Marine Compression-Ignition Engines at or Above 30 Liters per Cylinder,"
Advanced Notice of Proposed Rulemaking, U.S. Environmental Protection Agency, Office of Transportation and
Air Quality, Ann Arbor, Michigan, 72 Federal Register 69521, December 7, 2007.

23. "Control of Hazardous Air Pollutants from Mobile Sources: Regulatory Impact Analysis," U.S. Environmental
Protection Agency, Office of Transportation and Air Quality, Ann Arbor, Michigan, February 2007.  EPA Report
Number: EPA420-R-07-002.

24. "Electronic Media Supporting Development of Air Quality Modeling Emissions Inventories for the Small
Nonroad and Marine Spark-Ignition Engine Final Rulemaking," Memorandum and attachments from Harvey
Michaels, U.S. Environmental Protection Agency, Office of Transportation and Air Quality, Ann Arbor, Michigan,
July 22, 2008. Docket Identification EPA-HQ-OAR-2004-0008-0694.
                                                 3-54

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                                                Feasibility of Exhaust Emission Control
     CHAPTER 4: Feasibility of Exhaust Emission Control

       Section 213(a)(3) of the Clean Air Act presents statutory criteria that EPA must evaluate
in determining standards for nonroad engines and vehicles including marine vessels.  The
standards must "achieve the greatest degree of emission reduction achievable through the
application of technology which the Administrator determines will be available for the engines
or vehicles to which such standards apply, giving appropriate consideration to the cost of
applying such technology within the period of time available to manufacturers and to noise,
energy, and safety factors associated with the application of such technology." This chapter
presents the technical analyses and information that form the basis of EPA's belief that the
exhaust emission standards are technically achievable accounting for all the above factors.

       The exhaust emission standards for Small SI engines and Marine SI engines are
summarized in the Executive Summary.  This chapter begins with a current state of technology
for spark-ignition (SI) engines and the  emission control technologies expected to be available for
manufacturer and continues with a presentation of available emissions data on baseline
emissions  and on emission reductions achieved through the application of emission control
technology. In addition, this chapter provides a description of new test procedures including
not-to-exceed requirements.

4.1  General Description of Spark-Ignition Engine Technology

       The two most common types of engines are gasoline-fueled engines and diesel-fueled
engines. These engines have very different combustion mechanisms. Gasoline-fueled engines
initiate combustion using spark plugs, while diesel fueled engines initiate combustion by
compressing the fuel and air to high pressures. Thus these two types of engines are often more
generally referred to as "spark-ignition" and "compression-ignition" (or SI and CI) engines, and
include similar engines that use other fuels.  SI engines include engines fueled with liquid
petroleum gas (LPG)  and compressed natural gas (CNG).

4.1.1  Basics of Engine Cycles

       Spark ignition engines may be of two-stroke or four-stroke which refers to the number of
piston strokes per combustion cycle. Handheld Small SI equipment typically use two-stroke
engines while larger non-handheld equipment use four-stroke engines.  Outboard and personal
watercraft (OB/PWC) engines, until the advent of recent environmental regulations, were
generally two-stroke engines.  They are now a mix of two- and four-stroke engines.  Sterndrive
and inboard (SD/I) engines are primarily SI four-stroke engines.

       4.1.1.1 Two-Stroke Engines

       "Two-stroke"  refers to the  number of piston strokes per combustion cycle. These two
strokes, compression and expansion, occur in one revolution of the crankshaft. During the

                                         4-1

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Final Regulatory Impact Analysis
expansion stroke the piston moves downward.  As the piston nears its lowest position, the intake
and exhaust ports are opened.  While these ports are open, a fresh charge of fuel and air is
pushed into the cylinder which, in turn, helps force the burned gases from the previous cycle out
of the exhaust port. During the compression stroke, the intake and exhaust ports close and the
fresh charge is compressed. As the piston approaches its highest position, a spark-plug ignites
the fresh charge to generate combustion.  The force from the combustion acts on the piston to
move it downward, thereby causing the expansion stroke and generating power.

       In traditional two-stroke engine designs, the engines are crankcase-scavenged and
carbureted with intake and exhaust ports on the cylinder walls.  The advantage of this engine
design is simplicity (low number of moving parts) and a high power to weight ratio of the
engine.  In this design, the carburetor meters fuel into the intake air which is then routed to the
crankcase.  The motion of the drive shaft then pressurizes the charge. Oil is typically blended
into the fuel to provide cylinder and reciprocating assembly lubrication. When the piston lowers,
it exposes the intake port on the side of the cylinder wall which allows the pressurized fuel/air
charge to enter the cylinder. At the same time, the exhaust port is exposed allowing burned
gases to escape the cylinder. Because both ports are open at the same time, some of the fresh
charge can  exit the exhaust port. These fuel losses  are known as "short-circuiting" or
"scavenging" losses and can result in 25 percent or more of the fuel passing through the cylinder
unburned.  As the piston moves up, the intake and exhaust ports are covered and combustion is
initiated.

       An emerging technology for reducing emissions and scavenging losses from two-stroke
engines is direct-injection. This is used primarily on larger outboard  and personal watercraft
engines (37 kW and up) to meet exhaust emission standards. In a direct-injected engine,  charge
air is used to scavenge the exhaust gases. Once the exhaust valve closes, fuel is injected into the
charge air and ignited with a spark-plug.  Because the exhaust valve is closed during most or all
of the injection event, short-circuiting losses are minimized. Also, because the fuel is not used to
lubricate the crankcase, oil does not need to be blended into the fuel.  As a result, much less oil is
used.

       4.1.1.2 Four-Stroke Engines

       Four-stroke engines are used in many different applications. Virtually all gasoline-
powered highway motorcycles, automobiles, trucks and buses are powered by four-stroke
engines. Four-stroke engines are  also common in off-road motorcycles, all-terrain vehicles
(ATVs), boats, airplanes, and numerous nonroad applications such as lawn mowers, lawn and
garden tractors, and generators, pressure washers and water pumps to name just a few.

       A "four-stroke" engine gets its name from the fact that the piston makes four passes or
strokes in the cylinder to complete an entire cycle.  The strokes are intake, compression,
expansion or power, and exhaust. Two of the strokes are downward (intake & expansion) and
two of the strokes are upward (compression &  exhaust).  The four strokes are completed in two
revolutions of the crankshaft. Valves in the combustion chamber open and close to route gases
into and out of the combustion chamber or create compression.

                                           4-2

-------
                                                 Feasibility of Exhaust Emission Control
                              Figure 4.1-1: 4-Stroke Cycle
2, Compression      3. Expansion
                                                                   4,  Exhaust
       The first step of the cycle is for an intake valve to open during the intake stroke allowing
a mixture of air and fuel to be drawn into the cylinder while an exhaust valve is closed and the
piston moves down the cylinder.  The piston moves from top dead center (TDC) or the highest
piston position to bottom dead center (BDC) or lowest piston position. This displacement of the
piston draws air and fuel past the open intake valve into the cylinder.

       During the compression stroke, the intake valve closes and the momentum of the
crankshaft moves the piston up the cylinder from BDC to TDC, compressing the air and fuel
mixture. As the piston nears TDC, at the very  end of the compression stroke, the air and fuel
mixture is ignited by a spark plug and the air and fuel mixture begins to burn.  As the air and fuel
mixture burns, pressures and temperatures increase and the products of combustion expand in the
cylinder, which causes the piston to move back down the cylinder, transmitting power to the
crankshaft during the expansion or power stroke. Near the bottom of the expansion stroke, an
exhaust valve opens and as the piston moves back up the cylinder, exhaust gases are pushed out
through the exhaust valve to the exhaust manifold to complete the exhaust stroke, finishing a
complete four-stroke cycle.

4.1.2 Exhaust Emissions from Nonroad SI Engines

       Hydrocarbon (HC) and carbon monoxide (CO) emissions are products of incomplete
combustion. The level of CO exhaust emissions is primarily a function of the air-to-fuel ratio at
which an engine is operated. Hydrocarbon emissions formation mechanisms are somewhat more
complex, and appear to be primarily related to:

1.     Quenching of the air/fuel mixture at the walls of the combustion chamber
2.     Filling  of crevice volumes with the air/fuel mixture that remains unburned due to flame
       quenching at the entrance to the  crevice
3.     Lubricant absorption and desorption  of fuel compounds
4.     Partial combustion during an operating cycle or even complete misfiring of the air/fuel
       mixture during the cycle
5.     Entrainment and incomplete combustion of lubricant
                                          4-3

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Final Regulatory Impact Analysis
       As a result, a number of design and operational variables have an impact on HC
emissions, including air-to-fuel ratio; combustion chamber design and geometry; homogeneity of
the air/fuel charge; intake port geometry and the degree of induced air/fuel charge motion;
ignition energy, dwell, and timing; the effectiveness of the cooling system; and oil  consumption.

       NOx emissions from SI engines are primarily emissions of nitric oxide (NO). Nitrogen
in the intake air reacts with  oxygen at high temperatures primarily via the Zeldovich mechanism
to form NO. Thus variables that impact combustion temperatures can have a significant impact
on NO formation and NOx exhaust emissions. These include air-to-fuel ratio, spark timing and
the quantity of residual exhaust gases carried over between engine firing cycles (either through
external exhaust gas recirculation or inefficient cylinder scavenging).

       Particulate matter (PM) emissions from SI engines consists primarily of semi-volatile
organic compounds from the engine lubricant together with elemental-carbon soot  formed from
pyrolysis of fuel and lubricant during combustion.

              4.1.2.1 Air-to-fuel ratio

       The calibration of engine air-to-fuel ratio affects torque and power output, fuel
consumption (often indicated  as Brake Specific Fuel  Consumption or BSFC), engine
temperatures, and emissions for SI engines.  The effects of changing the air-to-fuel ratio on
emissions, fuel consumption and torque (indicated as Brake Mean Effective  Pressure or BMEP,
which is torque corrected for engine volumetric displacement) are shown in  Figure 3-1.l

       In the past, manufacturers have calibrated fuel systems of nonroad SI engines for rich
operation. This was done in part to reduce the risk of lean misfire due to imperfect mixing of the
fuel and air and variations in the air-fuel mixture from cylinder to cylinder.  Rich operation at
between approximately 12.5:1 and 13:1 air-to-fuel ratio also generally increased engine torque
output (figure 4.1-1) and prevented lean air-to-fuel ratio excursions during application of
transient loads to the engine.  Rich operation  also has been used to reduce piston, combustion
chamber, cylinder and exhaust port temperatures, thus reducing the thermal load on the cooling
system, a particularly important issue with air-cooled engines.  Operation at air-to-fuel ratios
richer than approximately 13:1 or 13.5:1 can  limit the effectiveness of, or pose design challenges
for, post-combustion catalytic exhaust emission controls for HC and CO emissions but work well
for catalytic reduction of NOx. At the same time, because a rich mixture lacks sufficient oxygen
for complete combustion, it results in increased fuel consumption rates and higher HC and CO
emissions.

       As can be seen from the figure, the best fuel consumption rates occur when the engine is
running lean of the stoichiometric air-to-fuel  ratio (approximately 14.6:1 air-to-fuel ratio for
typical gasolines), but lean operational limits are bounded by the onset of abnormal combustion
(e.g.,  lean misfire and combustion knock), the ability to pick up load, and exhaust port
temperatures (particularly with air-cooled engines).  Many air-cooled engines are limited by
heat-rejection to operation that starts approximately at stoichiometry for light loads, and is rich

                                           4-4

-------
                                                 Feasibility of Exhaust Emission Control
of stoichiometry as load is increased.

       With the use of more advanced fuel systems, manufacturers would be able to improve
control of the air-fuel mixture in the cylinder. This improved control allows for leaner operation
that is closer to a stoichimetric air-to-fuel ratio without increasing the risk of abnormal
combustion. This can be enhanced through careful selection of intake port geometry and
combustion chamber shape to induce turbulence into the air/fuel cylinder charge.  The leaner air-
to-fuel ratios (e.g., operating just rich of stoichiometry) resulting from advanced fuel systems
and intake charge turbulence can significantly reduce HC and CO emissions and fuel
consumption, and can provide more oxygen in the exhaust for improved catalytic control of HC
and CO.  Leaner air-to-fuel ratios, however, can increase NOx emissions due to higher
combustion temperatures, particularly for engines that are not equipped with exhaust catalysts.
More advanced fuel systems would allow tailoring of the air to fuel ratio to  allow good transient
response and to add enrichment at higher load conditions for engine and catalyst protection and
to reduce engine-out NOx emissions.  High-load enrichment is particularly important for air-
cooled engines, since high-load operation at leaner air-to-fuel ratios could also increase
hydrocarbon emissions and PM emissions if the higher cylinder temperatures encountered result
in a significant increase in cylinder-bore distortion and lubricating oil consumption.

   Figure  4.1-2:  Effects of Air-to-Fuel Ratio on Torque Output, Fuel Consumption and
                Emissions for Naturally Aspirated Spark Ignition Engines.
       4.1.2.2 Spark-timing

       For each engine speed and air-fuel mixture, there is an optimum spark-timing that results
in peak torque ("Maximum Brake Torque" or "MET" timing). If the spark is advanced from
MET, more combustion occurs during the compression stroke. If the spark is retarded from
MET, peak cylinder pressure is decreased because too much combustion occurs later in the
expansion stroke generating less useable torque.  Timing retard may be used as a strategy for
reducing NOx emissions, because it suppresses peak cylinder temperatures that lead to high NOx
levels.  Timing retard also results in higher exhaust gas temperatures, because less mechanical
work is extracted from the available energy.  This may have the benefit of warming catalyst
material to more quickly reach the temperatures needed to operate effectively during light-load
operation.2 Some automotive engine designs rely on timing retard at start-up to reduce cold-start
                                           4-5

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Final Regulatory Impact Analysis
emissions.

       Advancing the spark-timing at higher speeds gives the fuel more time to burn. Retarding
the spark timing at lower speeds and loads avoids misfire. With a mechanically controlled
engine, a fly-weight or manifold vacuum system adjusts the timing. Mechanical controls,
however, limit the manufacturer to a single timing curve when calibrating the engine. This
means that the timing is not completely optimized for most modes of operation.

4.1.3  Marinization

       Gasoline sterndrive and inboard (SD/I) engines are generally derived from land-based
counterparts. Engine marinizers buy automotive engine blocks and modify them for use on
boats.  Because of the good power/weight ratio of gasoline engines, most SD/I  engines are not
modified to produce more power than the base engines were originally designed to produce. In
some airboat applications, aircraft engines are used.

       4.1.3.1 Typical SD/I marinization  process

       Marine SI engines are typically built from base engines designed for use in cars and
trucks. Currently, the vast majority of base engines are General Motor (GM) engines that range
in size from  a 3.0  L in-line four cylinder engine to an 8.1 L V8  engine and range in power from
about 100 to 300 kW.  These engines are sold without front  accessory drives or intake and
exhaust manifolds. Also, no carbureted versions of these engines are offered; they are either
sold with electronic fuel  injection, or no fuel system at all.  Relatively small numbers of custom
blocks and Mazda rotary engines are also used.

       Marinizers convert the base  engines into marine engines in the following ways:

       - Choose and optimize the fuel management system.
       - Configure a marine cooling system.
       - Add intake and exhaust manifolds, and accessory drives and units.

       Fuel and air management: Historically, Marine SI engines have been carbureted.  Today
this technology seems to be going away but is still offered as cheaper alternative to electronic
fuel injection.  Less than half of new engines are sold with carburetors. GM does not offer
carburetors or their associated intake manifolds because they are not used in the higher volume,
automotive applications. Therefore, marinizers who produce carbureted engines must purchase
the fuel systems and intake manifolds elsewhere.

       The 3.0 L  and 4.3 L base engines are offered with throttle body fuel injection systems as
an option. All of the larger engines are offered with multi-port fuel injection as an option.
Although GM offers a base marine calibration for its electronic control module, it  also offers
software allowing marinizers to perform their own engine calibrations. For most engines sold,
the marinizers will alter the calibrations to optimize engine operation. Except for some small
market niches, the marinizers do not calibrate the engines for more power.

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                                                 Feasibility of Exhaust Emission Control
       Cooling system: Marine SI engines are generally packaged in small compartments
without much air flow for cooling. In addition, Coast Guard safety regulations require that
surface temperatures be kept cool on the engine and exhaust manifold. Typically, marine
exhaust systems are designed with surface temperatures below 93C (200F).  To do this,
manufacturers use ambient (raw) water to cool the engine and exhaust. Most sterndrive and
inboard engines use raw water to cool the engine.  This water is then used, in a water jacket, to
cool the exhaust manifold. Finally, the water is dumped into the exhaust stream.

       Most Marine SI engines are cooled with raw water.  This means that ambient water is
pumped through the engine, to the exhaust manifold, and mixed with the exhaust. The
exhaust/water mixture is then dumped under water. Mixing the water with exhaust has three
advantages:

       - cools the exhaust and protects rubber couplings in sterndrives
       - acts as a muffler  to reduce noise
       - helps tune the exhaust back pressure

       An alternative to raw water cooling is fresh water cooling. In a fresh water system, raw
water is used to cool the recirculated engine coolant ("fresh water"). The raw water is generally
still used to cool the exhaust manifold and exits the engine with the exhaust.  However, some
systems use the engine coolant to cool the exhaust manifold.

       Some gasoline engines, mostly inboards, have fresh water cooling systems which provide
two advantages.  1) Engine corrosion problems are reduced, especially when the boat is used in
saltwater. Fresh water systems keep saltwater, which can be corrosive, out of the engine.
Because salt emulsifies at about 68C, thermostats in fresh water systems are set around 60-
62C. 2) Marinizers can achieve much better control of the engine temperature.  By reducing
variables in engine operation, combustion can be better optimized.3

       There are trade-offs with using a fresh water system. The fresh water system costs more
because of the added pump and heat exchanger. Also, this system is not as efficient for cooling
the engine as pumping raw water directly to the engine

       Other additions: As mentioned above, marinizers add intake manifolds to carbureted
engines.  As part of the cooling system, marinizers must add water jacketed exhaust manifolds,
pumps, and heat exchangers. SD/I engines may also have larger oil pans to help keep oil
temperatures down. Because of the unique marine engine designs, marinizers also add their own
front accessory drive assembly. Finally, sterndrive engines also must be  coupled with the lower
drive unit.

       4.1.3.2 High performance SD/I marinization process

       There is a niche in the SD/I market where customers are willing to sacrifice engine
durability for a high power to weight ratio. Marinizers who address this niche do so by
increasing the fueling of the engine, optimizing the spark-timing for power, increasing the peak

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Final Regulatory Impact Analysis
engine speed (rpm), and modifying the exhaust manifold for better tuning. In some cases, the
marinizers may actually increase the displacement of the engine by boring out the cylinders.
Other components such as camshafts and pistons may also be modified. Superchargers may also
be added.  As an example, GM's largest base engine for this market is rated at 309 kW. One
high performance SD/I engine with a bored cylinder, a high performance fuel injection
calibration, and a supercharger achieves more than 800 kW.

4.1.4 Gaseous Fuels

       Engines operating on LPG or natural gas carry compressed fuel that is gaseous at
atmospheric pressure. The technical challenges for gasoline related to an extended time to
vaporize the fuel do not apply to gaseous-fuel engines. Typically, a mixer introduces the fuel
into the intake system. Manufacturers are pursuing new designs to inject the fuel directly into
the intake manifold. This improves control of the air-fuel ratio and the combustion event, similar
to the improvements in gasoline injection technology.

4.2  General Description of Exhaust Emission  Control Technologies

       HC and CO emissions from spark-ignition engines  are primarily the result of poor in-
cylinder combustion.  This is intensified in carbureted two-stroke engines with the very high HC
emissions due to short-circuiting losses.  Higher levels of NOx emissions are the result of leaner
air-fuel ratios and the resulting higher  combustion temperatures.  Combustion chamber
modifications can help reduce HC emission levels, while using improved air-fuel ratio and spark
timing calibrations, as discussed in Sections 4.1.2.1 and 4.1.2.2, can further reduce HC emissions
and lower CO emissions. The conversion from carburetor to electronic fuel injection will also
help reduce HC and CO emissions.  Exhaust gas recirculation could be used to reduce NOx
emissions.  The addition of secondary  air into the exhaust can significantly reduce HC and CO
emissions.  Finally, the use catalytic converters can further reduce all three emissions.

4.2.1 Combustion chamber design

       Unburned fuel can be trapped momentarily in crevice volumes (especially the space
between the piston and cylinder wall) before being released into the exhaust.  Reducing crevice
volumes decreases this amount of unburned fuel, which reduces HC emissions.  One way to
reduce crevice volumes is to design pistons with piston rings closer to the top of the piston.  HC
may be reduced by  3 to 10 percent by reducing crevice volumes, with negligible effects on NOx
emissions.4

       HC emissions also come from lubricating oil that leaks into the combustion chamber.
The heavier hydrocarbons in the oil generally do not burn completely.  Oil in the combustion
chamber can also trap gaseous HC from the fuel and prevent it from burning.  For engines using
catalytic control, some components in  lubricating oil can poison the catalyst and reduce its
effectiveness, which would further increase emissions over time. To reduce oil consumption,
manufacturers can tighten tolerances and improve surface finishes for cylinders and pistons,
improve piston ring design and material, and improve exhaust valve stem seals to prevent

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                                                  Feasibility of Exhaust Emission Control
excessive leakage of lubricating oil into the combustion chamber.

4.2.2  Fuel injection

       Fuel injection has proven to be an effective and durable strategy for controlling emissions
and reducing fuel consumption from highway gasoline engines. Comparable upgrades are also
available for gaseous fuels. This section describes a variety of technologies available to improve
fuel metering.

       Throttle-body gasoline injection: A throttle-body system uses the same intake manifold
as a carbureted engine. However, the throttle body replaces the carburetor. By injecting the
fuel into the intake air stream, the fuel is better atomized than if it were drawn through with a
venturi. This results in better mixing and more efficient combustion. In addition, the fuel can be
more precisely metered to achieve benefits for fuel economy, performance, and emission control.

       Throttle-body designs have the drawback of potentially large cylinder-to-cylinder
variations with multi-cylinder engines.  Like  a carburetor, TBI injects the fuel into the intake air
at a single location upstream of all the cylinders. Because the air-fuel mixture travels different
routes to each  cylinder, and because the fuel "wets" the intake manifold, the amount of fuel that
reaches each cylinder will vary. Manufacturers account for this variation in their design and may
make compromises such as injecting extra fuel to ensure that the cylinder with the leanest
mixture will not misfire.  These compromises affect emissions and fuel consumption.

       Port gasoline injection: As the name suggests, port (single cylinder) or multi-port (multi-
cylinder-port)  fuel injection means that a fuel injector is placed in close proximity to each of the
intake ports. The intake manifold, if used, flows only air.  Sequentially-timed systems inject a
quantity of fuel each time the intake valve opens for each cylinder, but multi-port injection
systems can also be "batch fired" (all injectors pulsed simultaneously on a multicylinder engine)
or continous (e.g., the Bosch CIS automotive systems of the 1970's and 80's).  Port injection
allows manufacturers to more precisely control the amount of fuel injected for each combustion
event.  This control increases the manufacturer's ability to optimize the air-fuel ratio for
emissions, performance, and fuel consumption. Because of these benefits, multi-port injection is
has been widely used in automotive applications for decades.

       Sequential injection has further improved these systems by more  carefully timing the
injection event with the intake valve opening. This improves fuel atomization and air-fuel
mixing, which further improves performance and control of emissions.

       A newer development to improve injector performance is air-assisted fuel injection. By
injecting high pressure air along with the fuel spray, greater atomization  of the fuel droplets can
occur.  Air-assisted fuel injection is especially helpful in improving  engine performance and
reducing emissions at low engine  speeds. In  addition, industry studies have shown that the short
burst of additional fuel needed for responsive, smooth transient maneuvers can be reduced
significantly with air-assisted fuel injection due to a decrease in wall wetting in the intake
manifold. On  a highway 3.8-liter engine with sequential fuel injection, the air assist was shown

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Final Regulatory Impact Analysis
to reduce HC emissions by 27 percent during cold-start operating conditions. At wide-open-
throttle with an air-fuel ratio of 17, the HC reduction was 43 percent when compared with a
standard injector.5

4.2.3  Exhaust gas recirculation

       Exhaust gas recirculation (EGR) has been in use in cars and trucks for many years. The
recirculated gas acts as a diluent in the air-fuel mixture, slowing reaction rates and absorbing
heat to reduce combustion temperatures.  These lower temperatures can reduce the engine-out
NOx formation rate by as much as 50 percent.6 HC is increased slightly due to lower
temperatures for HC burn-up during the late expansion and exhaust strokes.

       Depending on the burn rate of the engine and the amount of recirculated gases, EGR can
improve fuel consumption.  Although EGR slows the burn rate, it can offset this effect with
some benefits for engine efficiency. EGR reduces pumping work of SI engines because the
addition of nonreactive recirculated gases forces larger throttle openings for the same power
output.  Because the burned gas temperature  is decreased, there is also less heat loss to the
exhaust and cylinder walls.  In effect, EGR allows more of the chemical energy in the fuel to be
converted to useable work.7

       Electronic EGR control: Many EGR systems in today's automotive applications utilize a
control valve that requires vacuum from the intake manifold to regulate EGR flow. Under part-
throttle operation where EGR is needed, engine vacuum is sufficient to open the valve.
However, during throttle applications near or at wide-open throttle, engine vacuum is too low to
open the EGR valve.  While EGR operation only during part-throttle driving conditions has been
sufficient to control NOx emissions for vehicles in the past, more stringent NOx standards and
emphasis on controlling off-cycle emission levels may require more precise EGR control and
additional EGR during heavy throttle operation to reduce NOx emissions. Automotive
manufacturers now use electronic control of EGR. By using electronic solenoids  to directly
open and close the EGR valve or by modulating the vacuum signal to vacuum actuated valves,
the flow of EGR can be precisely controlled.

       Stratified EGR. Another method of increasing the engine's tolerance to EGR is to
stratify the  reicirculated gases in the cylinder. This stratification allows high amounts of dilution
near the spark plug for NOx reduction while  making undiluted air available to the crevices, oil
films, and deposit areas so that HC emissions may be reduced. Stratification may be induced
radially or laterally through control of air and mixture motion determined by the geometry of the
intake ports. Research on a one cylinder engine has shown that stratified EGR will result in
much lower fuel consumption at moderate speed and load (6 percent EGR at 2400 rpm, 2.5 bar
BMEP) while maintaining low HC and NOx emissions when compared to homogeneous EGR.8

       For catalyst systems with high conversion efficiencies, the benefit of using EGR becomes
proportionally smaller, although it can offer cost savings by reducing catalyst rhodium loadings.
Including EGR as a design variable for optimizing the engine can add significantly to the
development time needed to fully calibrate the electronic controls of engines or vehicles.

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                                                 Feasibility of Exhaust Emission Control
4.2.4  Multiple valves and variable valve timing

       Four-stroke engines generally have two valves for each cylinder, one for intake of the air-
fuel mixture and the other for exhaust of the combusted mixture. The duration and lift (distance
the valve head is pushed away from its  seat) of valve openings is constant regardless of engine
speed. As engine  speed increases, the aerodynamic resistance to pumping air in and out of the
cylinder for intake and exhaust also increases.  Automotive engines have started to use two
intake and two exhaust valves to reduce pumping losses and improve their volumetric efficiency
and useful power output.

       In addition to gains in volumetric efficiency, four-valve designs allow the spark plug to
be positioned closer to the center of the combustion chamber, which decreases the distance the
flame must travel inside the chamber.  This decreases the likelihood of flame-quenching
conditions in the areas of the combustion chamber farthest from the spark plug.  In addition, the
two streams of incoming gas can be used to achieve greater mixing of air and fuel, further
increasing combustion efficiency and lowering engine-out emissions.

       Control of valve timing and lift  take full advantage of the four-valve configuration for
even greater improvement in combustion efficiency.  Engines normally use fixed-valve timing
and lift across all engine speeds. If the valve timing is optimized for low-speed torque, it may
offer compromised performance under  higher-speed operation. At light engine loads, for
example, it is desirable to close the intake valve early to reduce pumping losses. Variable-valve
timing can enhance both low-speed and high-speed performance with less compromise.
Variable-valve timing can allow for increased swirl and intake charge velocity, especially during
low-load operating conditions where this is most problematic. By providing a strong swirl
formation in the combustion chamber, the air-fuel mixture can mix sufficiently, resulting in a
faster, more complete combustion, even under lean air-fuel conditions, thereby reducing
emissions.  Automotive engines with valve timing have also replaced external EGR systems with
"internal EGR" accomplished via variable valve overlap, generally with improved EGR rate
control over external systems and improved engine-out NOx emissions.

4.2.5  Secondary air

       Secondary injection of air into exhaust ports or pipes after cold start (e.g., the first 40-60
seconds) when the engine is operating rich, coupled with spark retard, can promote combustion
of unburned HC and CO in the exhaust manifold and increase the warm-up rate of the catalyst.
By means of an electrical or mechanical pump, or by using a passive venturi or check-valve,
secondary air is injected into the exhaust system, preferably in close proximity of the exhaust
valve.  Together with the oxygen of the secondary air and the hot exhaust components of HC and
CO, net oxidizing conditions ahead of the catalyst can bring about an efficient increase in the
exhaust temperature which helps the catalyst to heat up quicker.  The exothermic reaction that
occurs is dependent on several parameters (secondary air mass, location of secondary air
injection, engine A/F ratio, engine air mass, ignition timing, manifold and headpipe construction,
etc.), and ensuring reproducibility demands detailed individual application for each vehicle or
engine design.

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Final Regulatory Impact Analysis
       Secondary air injection was first used as an emission control technique in itself without a
catalyst, and still is used for this purpose in many highway motorcycles and some off-highway
motorcycles to meet federal and California emission standards. For motorcycles, air is usually
provided or injected by a system of check valves which uses the normal pressure pulsations in
the exhaust manifold to draw in air from outside, rather than by a pump.9

       Secondary air injection can also be used in continuous operation with rich-jetted
carbureted engines to a achieve an exhaust chemistry just rich of stoichiometry to improve the
efficiency of 3-way catalysts.10'11

4.2.6  Catalytic Aftertreatment

       Over the last several years, there have been tremendous advances in exhaust
aftertreatment systems. Catalyst manufacturers have increased the use of palladium (Pd),
particularly for close-coupled positions in automotive catalyst applications.12 Improvements to
catalyst thermal stability and washcoat technologies, the design of higher cell densities, and the
use of two-layer washcoat applications are just some of the advances made in catalyst
technology.13 Current Pd catalysts are capable of withstanding prolonged exposure to
temperatures approaching 1100C.14 The light-off temperature of these advanced catalysts is in
the range of 250 to 270C.

       There are two types of catalytic converters commonly used: oxidation and three-way.
Oxidation catalysts use platinum and/or palladium to increase the rate of reaction between
oxygen in the exhaust and unburned HC and CO.  Ordinarily, this reaction would proceed very
slowly at temperatures typical of engine exhaust. The effectiveness of the catalyst depends on its
temperature, on the air-fuel ratio of the mixture, and on the mix of HC present. Highly reactive
species such as formaldehyde and olefins are oxidized more effectively than less-reactive
species. Short-chain paraffins such as methane, ethane, and propane are among the least reactive
HC species, and are more difficult to oxidize.

       Three-way catalysts use a combination of platinum and/or palladium and rhodium. In
addition to promoting  oxidation of HC and CO, these metals also promote the reduction of NO to
nitrogen and oxygen.  In order for the NO reduction to occur efficiently, an overall rich or
slightly-rich of stoichiometric air-fuel ratio is required. The NOx efficiency drops rapidly as the
ai-fuel ratio becomes leaner than stoichiometric. If the air-fuel ratio can be maintained precisely
at or just rich of stoichiometic, a three-way catalyst can simultaneously oxidize HC and CO and
reduce NOx.  The window of air-fuel  ratios within which this is possible is very narrow and
there is a trade-off between NOx and HC/CO control even within this window.  The window can
be broadened somewhat through the use of oxygen storage components, such as cerium oxide,
within the catalyst washcoating. Cerium oxide also promotes CO and HC removal via steam
reformation with water vapor in the exhaust, and the hydrogen liberated by these reactions
promotes further NOx reduction.

       Manufacturers are developing catalysts with substrates that utilize thinner walls in order
to design higher cell density, low thermal mass catalysts for close-coupled applications

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                                                  Feasibility of Exhaust Emission Control
(improves mass transfer at high engine loads and increase catalyst surface area). The cells are
coated with washcoat which contain the noble metals which perform the catalysis on the exhaust
pollutants.  The greater the number of cells, the more surface area with washcoat that exists,
meaning there is more of the catalyst available to convert emissions (or that the same catalyst
surface area can be put into a smaller volume). Cell densities of 900 cells per square inch (cpsi)
have already been commercialized, and research on 1200 cpsi catalysts has been progressing.
Typical cell densities for conventional automotive catalysts are 400 to 600 cpsi.

       There are several issues involved in designing catalytic control systems for the engines
covered by this rule.  The primary issues are the cost of the system, packaging constraints, and
the durability of the catalyst. This section addresses these issues.

       4.2.6.1 System cost

       Sales volumes of recreational vessels are small compared to automotive sales and while
sales of Small SI engines <19kW are similar, the price of equipment is much less than
automotive.  Manufacturers therefore have a limited ability to recoup large R&D expenditures
for these applications. For these reasons, we believe it is not appropriate to consider highly
refined catalyst systems that are tailored  specifically to nonroad applications. Catalyst
manufacturers have assured us that automotive-type catalysts can easily be built to any  size
needed for Small SI and marine applications. We are considering catalyst packaging designs
that do not require the manufactures to incur the costs of reworking the entire exhaust system
and, for Marine SI engines, the lower power unit. The cost of these systems will decrease
substantially when catalysts become commonplace. Chapter 6 describes the estimated costs for
nonroad catalyst systems for Small SI and Marine SI engines.

       4.2.6.2 Differences in emission  control system application  and design by engine
       category

       One challenge in the use of catalytic control for Small SI and Marine  SI engines lies in
acceptable design and packaging of the exhaust catalysts onto a wide variety  of different types of
equipment. This section discusses specific issues related to these applications.

       4.2.6.2.1 Small SI Class I engines

       Class I engines typically are equipped with integral exhaust and fuel systems and are
air-cooled. Significant applications include walk-behind lawn mowers (largest segment),
pressure washers, generator sets and pumps. There are both overhead valve (OHV) and
side-valve (SV) engines used in Class I, but  side-valve engines are the predominant type in Class
I, particularly in lawn mower applications.  They currently represent about 60 percent of Class I
sales. Exhaust catalyst design for Class I engines must take into account several important
factors that differ from automotive applications:

1.      Air-cooled engines run rich of stoichiometry to prevent overheating when under load.
       Because of this, CO and HC emissions can be high. Catalyst induced oxidation of a high

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Final Regulatory Impact Analysis
       percentage of available reactants in the exhaust in the presence of excess oxygen (i.e.,
       lean of stoichiometric conditions) can result in highly exothermic exhaust reactions and
       increase heat rejection from the exhaust.  For example, approximately 80 to 90 percent of
       the energy available from catalyst-promoted exhaust reactions is via oxidation of CO.
2.      Air-cooled engines have significant HC and NOx emissions that are typically much
       higher on a brake-specific basis than water-cooled automotive engine types.  Net heat
       available from HC oxidation and NOx reduction at rich of stoichiometric conditions is
       considerably less than that of oxidation of CO at near stoichiometric or lean of
       stoichiometric conditions due to the much lower concentrations of NO and HC in the
       exhaust relative to CO.
3.      Most Class I engines do not have 12-volt DC electrical systems to power auxiliaries and
       instead are pull  start. Electronic controls relying on 12-volt DC power would be difficult
       to integrate onto Class I engines without a significant cost increase.
4.      Most Class I engines use inexpensive stamped mufflers with internal baffles.  Mufflers
       are typically integrated onto the engine and may or may not be placed in the path of
       cooling air from the cooling fan.
5.      The regulatory emission test cycles (A-cycle, B-cycle), manufacturer's durability cycles
       and some limited in-use operation data indicate that emissions control should focus
       primarily on light and part load operation for the highest volume applications
       (lawnmowers).

       These factors would lead to exhaust catalyst designs for small engines that should differ
somewhat from those of light duty gasoline vehicle exhaust catalyst designs. Design elements
specific to Class I Phase 3 exhaust catalysts would include:

1.      Catalyst substrate volume would be sized relatively small so as to be space-velocity
       limited. Catalyst volume for Class I Phase 3 engines would be approximately 18 to 50
       percent of the engine cylinder displacement, depending on cell count, engine-out
       emission levels, and oil consumption. Catalyst substrate sizes would be compact, with
       typical catalyst substrate volumes of approximately 2 to 5 cubic inches.  This would
       effectively limit mass transport to catalyst sites at moderate-to-high load conditions and
       reduce exothermic reactions occurring when exhaust temperature is highest. This is
       nearly the opposite of the case of typical automotive catalyst designs.  Automotive
       catalyst volume is typically 50 to 100 percent of cylinder displacement, with the chief
       constraints on catalyst volume being packaging and cold-start light-off performance.
2.      Catalyst precious metal loading (Pt-platinum, Pd-palladium, Rh-rhodium) would be kept
       relatively low, and formulations would favor NOx and HC selectivity over CO
       selectivity. We estimate that typical loading ratios for Phase 3 would be approximately
       in the range of 40 to 50 g/ft3 (approximately 50 percent of typical automotive loadings at
       light-duty vehicle Tier 2 emission levels) and can be Pt:Rh, Pd:Rh or tri-metallic.
       Tri-metallic platinum group metal (PGM) loadings that replace a significant fraction of Pt
       with Pd would be less selective for CO oxidation and would also reduce the cost of the
       catalyst. Loading ratios would be similar or higher in Rh than what is typically used for
       automotive applications (20-25 percent of the total PGM mass in Small SI) to improve
       NOx selectivity, improve rich of stoichiometry HC reactions and reduce CO selectivity.

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                                                  Feasibility of Exhaust Emission Control
3.      Catalysts would be integrated into the muffler design.  Incorporating the catalyst into the
       muffler would reduce surface temperatures, and would provide more surface area for heat
       rejection.  This is nearly the opposite of design practice used for automotive systems,
       which generally try to limit heat rejection to improve cold-start light-off performance.
       The muffler design for Class I Phase 3 engines would have somewhat higher surface area
       and somewhat larger volume than many current Class I muffler designs in order to
       promote exhaust heat rejection and to package the catalyst, but would be similar to some
       higher-end "quiet" Class I muffler designs. Appropriately positioned stamped
       heat-shielding and touch guards would be integrated into Class I Phase 3 catalyst-muffler
       designs in a manner similar to many Class I Phase 2 mufflers.  A degree of heat rejection
       would be available via forced convection from the cooling fan, downstream of cooling
       for the cylinder and cylinder head. This is the case with many current muffler designs.
       Heat rejection to catalyst muffler surfaces to minimize "hot spots" can also be enhanced
       internally by turning the flow through multiple chambers and baffles that serve  as sound
       attenuation within the muffler, similar to the designs used with catalyst-equipped lawn
       mowers sold in Sweden and Germany.
4.      Many Class I Phase 3 catalysts would include passive secondary air injection to enhance
       catalyst efficiency and allow the use of smaller catalyst volumes. Incorporation of
       passive secondary air allows halving of catalyst substrate volume for the same catalyst
       efficiency over the regulatory cycle. A system for Class I Phase 3 engines would be sized
       small enough to provide minimal change in exhaust stoichiometry at high  load conditions
       so as to limit heat rejection, but would be provide approximately 0.5 to 1.0 points of
       air-to-fuel ratio change at conditions of 50 percent of peak torque and below in  order to
       lower HC emissions effectively in engines operating at air-to-fuel ratios similar to those
       of current Class I Phase 2 engines. Passive secondary  air systems are preferred.
       Mechanical or electrical air pumps are not necessary. Passive systems include stamped
       or drawn Venturis or ejectors integrated into the muffler, some of which may incorporate
       an air check-valve, depending on the application. Pulse-air injection is also a form of
       passive secondary air injection.  Pulse air draws air into the exhaust port through a
       check-valve immediately following the closure of the exhaust valve. Active secondary
       air (air pump) systems were not considered in this analysis since they may be cost
       prohibitive for use in Class I applications due to the need for a mechanical accessory
       drive or 12-volt DC power.
5.      Catalyst durability in side valve engines can be enhanced through two catalyst design
       ideas. First, the use of a pipe catalyst upstream of the main catalyst brick can "catch" the
       oil in the exhaust thereby limiting the amount seen in the catalyst and thereby catalyst
       poisoning.  Second, the catalyst brick can be lengthened to allow poisoning to some
       degree yet allow for catalyst  conversion for the regulatory life of the engine.
6.      Class I engines are typically turned off via a simple circuit that grounds the input side of
       the ignition coil.  Temperature fail-safe capability could, if appropriate, be incorporated
       into the engine by installing a bimetal thermal switch in parallel with the ignition
       grounding circuit used for turning the engine  off. The switch can be of the inexpensive
       bimetal disc type in wide-spread use in numerous consumer products (furnaces,
       water-heaters, ovens, hair dryers, etc.). To reduce cost, the bimetal switch could be a
       non-contact switch mounted to the engine immediately behind the muffler, similar to the

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Final Regulatory Impact Analysis
       installation of bimetal sensors currently used to actuate automatic chokes on current
       Phase 2 Class I lawn mower engines.

       4.2.6.2.2 Small SI Class II engines

       Almost all Class II engines are air-cooled. Unlike Class I engines, Class II engines are
not typically equipped with integral exhaust systems and fuel tanks.  Significant applications
include lawn tractors (largest segment), commercial turf equipment, generator sets and pumps.
Overhead valve engines have largely replaced side-valve engines in Class II, with the few
remaining side-valve engines certifying to the Phase II standards using emissions credits or
being used in snow thrower type applications where the HC+NOx standards do not apply. Class
II engines are typically built more robustly than Class I engines. They often use cast-iron
cylinder liners, may use either splash lubrication or full-pressure lubrication, employ high
volume cooling fans and in some cases, use significant shrouding to direct cooling air. Exhaust
catalyst design practice for Class II engines will differ depending on the level of emission
control. Class II engine designs are more suitable for higher-efficiency emission control systems
than most Class I engine designs. The design factors are somewhat similar to Class I:

1.      Class II engines are mostly air-cooled, and thus must run rich of stoichiometry at high
       loads. The ability to operate at air-to-fuel ratios rich of stoichiometry  at high load may
       be more critical for some Class II engines than for Class I engines  due to the longer
       useful life requirements in Class II. The larger displacement Class II engines have better
       efficiency combustion and some engines incorporate more advanced fuel metering and
       spark control than is typical in Class I, in order to meet the more stringent Class II Phase
       2 emission standards (12.1 g/kW-hr HC+NOx in Class II versus 16.1 g/kW-hr in Class I).
       The heat energy available from CO oxidation is typically somewhat less than the case in
       Class I because of slightly lower average emission rates.
2.      Class II engines have HC and NOx emissions that are generally in more equal portions,
       or have the potential to be, in the total regulated HC+NOx emissions and lower CO
       emissions than is the case for Class I engines.
3.      Most Class II engines are equipped with 12-volt DC electrical systems for starting.
       Electronic controls relying on 12-volt DC power could be integrated into Class II engine
       designs. Low-cost electronic engine management systems are extensively used in motor
       scooter applications in Europe and Asia.  Both Kohler and Honda have introduced Class
       II engines in North America that use electronic engine management systems.
4.      Class II engines use inexpensive stamped mufflers with internal baffles similar to Class I,
       but the mufflers are often not integrated onto the engine design and may be remote
       mounted in a manner more typical of automotive mufflers. Class II mufflers are often not
       placed in the direct path of cooling air from the cooling fan.
5.      As with Class I, the regulatory cycles (A-cycle, B-cycle), manufacturer's durability  cycles
       and some limited in-use operation data indicate that emissions control should focus
       primarily on light and part load operation for the high volume sales of garden tractor
       equipment.

       Taking these factors into account  would point towards exhaust catalyst designs that differ

                                           4-16

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                                                  Feasibility of Exhaust Emission Control
from those of light duty gasoline exhaust catalysts and differ in some cases from Class I systems.
Elements specific to Class II Phase 3 emission control system design using carburetor fuel
systems would include:

1.      Catalyst substrate volume would be sized relatively small so as to be space-velocity
       limited.  Catalyst volume for Class II Phase 3 engines would be approximately 33-50
       percent of the engine cylinder displacement, depending on cell  count, engine-out
       emission levels, oil consumption and the useful life hours to which the engine's emissions
       are certified. Catalyst substrate sizes would be very compact within typical mufflers used
       in Class II, with typical catalyst substrate volumes of approximately 8 to 10 cubic inches
       (based on sales weighting within useful life categories).  This would effectively limit
       mass transport to catalyst sites at moderate-to-high load conditions and reduce
       exothermic reactions occurring when exhaust temperature is highest.
2.      Catalyst precious metal loading would be kept relatively low, and formulations would
       favor NOx and HC selectivity over CO selectivity to minimize  heat concerns.  We
       estimate that typical loading ratios for Phase 3 would be approximately in the range of 30
       to 50 g/ft3 (approximately 50 percent of typical automotive loadings) and could be Pt:Rh,
       Pd:Rh or tri-metallic. Tri-metallic PGM loadings that replace a significant fraction of Pt
       with Pd would be less selective for CO oxidation and would also reduce the cost of the
       catalyst. Loading ratios would be similar or higher in Rh than what is typically used for
       automotive applications (20-25 percent of the total PGM mass in Small SI).
3.      Catalysts would be integrated into the muffler design. Incorporating the catalyst into the
       muffler would reduce surface temperatures relative to the use of a separate catalyst
       component. The catalyst for Class II Phase 3 engines would be integrated into mufflers
       that are similar in volume to today's Class II Phase 2 mufflers.  Appropriately positioned
       stamped heat-shielding and touch guards would be integrated into Class II Phase 3
       catalyst-muffler designs in a manner similar to current product. Class II engines typically
       have a much higher volume of cooling air available downstream of the cylinder than
       Class I engines. Heat rejection from the cylinder and cylinder head increases the
       temperature of the cooling air, but it is still sufficiently below the temperature of exhaust
       system components to allow its use for forced cooling.  Thus a  degree of heat rejection
       would be available via forced convective cooling of exhaust components via the cooling
       fan. However, this would require some additional ducting to supply cooling air to exhaust
       system surfaces along with careful layout of engine and exhaust components within the
       design of the equipment that it is used to power.  Integrated catalyst-mufflers can also use
       exhaust energy for ejector cooling (see chapter 6).  Heat rejection to catalyst muffler
       surfaces to minimize "hot spots" can also be enhanced internally by turning the flow
       through multiple chambers and baffles that serve as sound attenuation within the muffler.
4.      Some applications may include secondary air injection to enhance catalyst efficiency.
       Incorporation of passive secondary air allows halving of catalyst substrate volume for the
       same catalyst efficiency over the regulatory cycle. In many cases, this may not be
       necessary due to the lower engine-out emissions of Class II engines. In cases where
       secondary air is used, it could either be a passive system similar to the previously
       described Class I systems, or an active system with an engine driven pump. Pump drive
       for active systems could be  either 12-volt DC electric or via crankcase pulse, and pump

                                           4-17

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Final Regulatory Impact Analysis
       actuation could be actively controlled using an electric solenoid or solenoid valve.  The
       use of active systems is an option but seems unlikely. The most likely control scenario
       for Class II would be a combination of engine out emission control, use of a small
       catalyst, and no use of secondary air.

Higher catalyst efficiency, considerably lower exhaust emissions levels, and improved fuel
consumption are possible with Class II engines, but heat rejection and safety considerations
might necessitate the use of electronic engine management and open-loop fuel injections
systems. In such a case, the design and integration of the emission control system would more
closely resemble automotive applications with the use of electronic engine management and
larger catalyst volumes with higher precious metal loadings.

       4.2.6.2.3Marine SI

       Due to the design of marine exhaust systems, fitting a catalyst into the exhaust system
raises unique application issues for many boat/engine designs.  Often boat builders will strive to
minimize the space taken up in the boat by the engine compartment.  In addition, these exhaust
systems are designed, for safety reasons, to avoid hot surface temperatures. For most Marine SI
engines, the surface temperature is kept low by running raw water through a jacket around the
exhaust system.  This raw water is then mixed with the exhaust before being passed out of the
engine.  To avoid a major redesign of the exhaust system, the catalyst must be placed upstream
of where the water and exhaust mix. In addition, the catalyst must be insulated and/or water-
jacketed to keep  the surface temperatures of the exhaust low.
       As discussed later in this chapter,
testing has been performed on prototype
systems where small catalysts have been placed
in the exhaust manifolds of SD/I engines.
Figure 4.2-1 illustrates one installation design.
For outboard engines, this packaging
arrangement would be less straightforward
because of the very short exhaust path between
the cylinder exhaust ports  and where the
cooling water and exhaust mix. However, it
may be possible to engineer a packaging
solution for outboards as well similar to that
shown for SD/I in Figure 4.2-1.
                                             Figure 4.2-1: Placement of Marine Catalyst
                                                   
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                                                  Feasibility of Exhaust Emission Control
       Another issue is maintaining high enough temperatures with a water-jacketed catalyst for
the catalyst to react properly.  The light-off temperature of these advanced catalysts is in the
range of 250 to 270C which was low enough for the catalysts to work effectively in our
laboratory tests.  However, it could be necessary for manufacturers to retard the spark timing at
idle and low load for some engines to maintain this minimum temperature in the catalyst.

       The matching of the catalyst to the engine may have to be compromised to fit it into the
exhaust manifold.  However, significant reductions are still achievable.  One study on a 4.3 liter
automotive engine looked at three different Pd-only catalyst displacements. The smallest of
these catalysts had a displacement ratio of 0.12 to 1.  The HC+NOx downstream of the catalyst
was measured to be from 1.2 to 2.6 grams per mile, depending on the severity of the catalyst
aging.15 This is equivalent to about 1.5 to 3.2 g/kW-hr based on highway operation.16 This work
suggests that significant reductions are achievable with an "undersized" catalyst. As discussed
later in this chapter, significant reductions in exhaust emissions have been demonstrated for
catalysts packaged in SD/I exhaust systems.

       4.2.6.3 Catalyst Durability

       Two aspects of marine applications that could affect catalyst durability are thermal load
and vibration. Because the catalyst would be coupled close to the exhaust ports, it would likely
see temperatures as high as 750 to 850C when the engine is operated at full power. The bed
temperature of the  catalyst would be higher due to the reactions in the catalyst.  However, even
at full power, the bed temperature of the catalyst most likely would not exceed the exhaust
temperature by more than 50-100C. In our laboratory testing, we minimized the temperature at
full load by operating the engine with a rich air-fuel mixture. The temperatures seen were well
within the operating range  of new Pd-only catalysts which are capable of withstanding prolonged
exposure to temperatures approaching 1100C.17

       In on-highway applications, catalysts are designed to operate in gasoline vehicles for
more than 100,000 miles.  This translates to about 4,000-5,000 hours of use on the
engine/catalyst.  We estimate that, due to low annual hours of operation, the average useful life
of Small SI and Marine SI  engines is only a fraction percent of this value. This suggests that
catalysts designed for automotive use should be durable over the useful life of a Small SI and
Marine SI engines. Use of catalysts in automotive, motorcycle, and hand-held equipment
applications suggests that catalysts can be packaged to withstand the vibration in the exhaust
manifold.  As discussed later in this chapter, catalysts have recently been demonstrated, through
in-use testing, to be durable over the useful lives of SD/I marine vessels.

       4.2.6.4 Water Reversion

       Another aspect of marine applications that could affect catalyst durability is the effect of
water contact with the catalyst. There is concern that, in some designs, water could creep back
up the exhaust passages, due to pressure pulses in the exhaust, and damage the catalyst and
oxygen sensor.  This damage could be due to thermal shock from cold water coming into contact
with a hot catalyst  or due to salt deposition on the catalyst.  One study was performed, using a

                                          4-19

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Final Regulatory Impact Analysis
two-stroke outboard equipped with a catalyst, to investigate the effect of water exposure on a
catalyst.18 The results of this study are summarized in Table 4.2-1.

               Table 4.2-1:  Summary of Marine Catalyst Durability Study
Issue
high catalyst
temperatures
saltwater effects
fresh water effects
thermal shock of hot
catalyst with cold
water
deterioration factor
Investigation
- compared base catalyst to catalysts aged for 10
hrs at 900 and 1050C
- soaked catalysts in two seawater solutions and
compared to base catalyst
- used intake air with a salt-water mist
- soaked catalyst in fresh water and compared to
base catalyst
- flushed out catalyst with fresh water that was
soaked in saltwater
- as part of the catalyst soaking tests, 900C
catalysts were soaked in both salt and fresh
water
- operated engine with catalyst for 300 hours of
E4 operation
Result
- little change in conversion efficiency
observed
- large drop in conversion efficiency
observed
- no effect on catalyst
- little change in conversion efficiency
observed
- washing catalyst removes salt and
restores some performance
- no damage to the catalysts was
reported
- 20% loss in conversion efficiency for a
2-stroke engine
       The above study on catalysts in marine applications was performed supplemental to an
earlier study.19 The earlier study also showed that immersing the catalysts in saltwater would
hurt the conversion efficiency of the catalyst, but that operating in a marine environment would
not.  In addition, this earlier study showed that much of the efficiency loss due to salt on the
catalyst could be reversed by flushing the catalyst with water. This paper also showed that with
the catalyst activated, temperatures at full power were less than at mid power because the space
velocity of the exhaust gases at rated speed was high enough to reduce the conversion efficiency
of the catalyst.

       A study of water reversion was performed on a vessel powered by a sterndrive engine.20
However, it was found that the water found in the exhaust system upstream of where the exhaust
and water mix was due to condensation.  This condensation was a result of cool surfaces in the
exhaust pipe due to the water-jacketing of the exhaust. This  study found that the condensation
could be largely resolved by controlling the exhaust cooling water temperature with a thermostat.
Since that time, data has been collected on a number of catalyst-equipped SD/I vessels operated
either in salt or fresh-water. This data, which showed no significant catalyst deterioration, is
discussed later in this chapter. These engines were designed to prevent water reversion by
placing the catalyst near the engine and away from the water/exhaust mixing point.  In addition,
some of the prototype designs used either a water dam or mist barrier to help limit any potential
water reversion.
                                           4-20

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                                                  Feasibility of Exhaust Emission Control
4.2.7  Advanced Emission Controls

       On February 10, 2000, EPA published new "Tier 2" emissions standards for all passenger
vehicles, including sport utility vehicles (SUVs), minivans, vans and pick-up trucks.  The new
standards will ensure that exhaust VOC emissions be reduced to less than 0.1 g/mi on average
over the fleet, and that evaporative emissions be reduced by at least 50 percent. Onboard
refueling vapor recovery requirements were also extended to medium-duty passenger vehicles.
By 2020, these standards will reduce VOC emissions from light-duty vehicles by more than 25
percent of the projected baseline inventory. To achieve these reductions, manufacturers will
need to incorporate advanced emission controls, including: larger and improved close-coupled
catalysts, optimized spark timing and fuel control, improved  exhaust systems.

       To reduce emissions, gasoline-fueled vehicle manufacturers have designed their engines
to achieve virtually complete combustion and have installed catalytic converters in the exhaust
system. In order for these controls to work well for gasoline-fueled vehicles, it is  necessary to
maintain the mixture of air and fuel at a nearly stoichiometric ratio (that is, just enough air to
completely burn the fuel).  Poor air-fuel mixture can result in significantly higher  emissions of
incompletely combusted fuel. Current generation highway vehicles are able to maintain
stoichiometry by using closed-loop electronic feedback control of the fuel systems. As part of
these  systems, technologies have been developed to closely meter the amount of fuel  entering the
combustion chamber to promote complete combustion. Sequential multi-point fuel injection
delivers a more precise amount of fuel to each cylinder independently and at the appropriate time
increasing engine efficiency  and fuel economy.  Electronic throttle control offers a faster
response to engine operational changes than mechanical throttle control can achieve,  but it is
currently considered expensive and only used on some higher-price vehicles. The greatest gains
in fuel control can be made through engine calibrations - the algorithms contained in the
powertrain control  module (PCM) software that control the operation of various engine and
emission control components/systems. As microprocessor speed becomes faster, it is possible to
perform quicker calculations and to increase response times for controlling engine parameters
such as fuel rate and spark timing. Other advances in engine design have also been used to
reduce engine-out emissions, including: the reduction of crevice volumes in the combustion
chamber to prevent trapping  of unburned fuel; "fast burn" combustion chamber designs that
promote swirl and flame propagation; and multiple valves with variable-valve timing to reduce
pumping losses and improve efficiency.  These  technologies  are discussed in more detail in  the
RIA for the Tier 2 FRM.21

       As noted above, manufacturers are also using aftertreatment control devices to control
emissions. New three-way catalysts for highway vehicles are so effective that once a TWC
reaches its operating temperature, emissions are virtually undetectable.22 Manufacturers are now
working to improve the durability of the TWC and to reduce light-off time (that is, the amount of
time necessary after starting the engine before the catalyst reaches its operating temperature and
is effectively controlling VOCs and other pollutants).  EPA expects that manufacturers will  be
able to design their catalyst systems so that they light off within less than thirty seconds of
engine starting. Other potential exhaust aftertreatment systems that could further  reduce cold-
start emissions are  thermally insulated catalysts, electrically heated  catalysts, and  HC adsorbers

                                          4-21

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Final Regulatory Impact Analysis
(or traps). Each of these technologies, which are discussed below, offers the potential for VOC
reductions in the future.  There are technological, implementation, and cost issues that still need
to be addressed, and at this time, it appears that these technologies would not be a cost-effective
means of reducing nonroad emissions on a nationwide basis.

       Thermally insulated catalysts maintain sufficiently high catalyst temperatures by
surrounding the catalyst with an insulating vacuum. Prototypes of this technology have
demonstrated the ability to store heat for more than 12 hours.23 Since ordinary catalysts typically
cool down below their light-off temperature in less than one hour, this technology could reduce
in-use emissions for vehicles that have multiple cold-starts in a single day.  However, this
technology would have less impact on emissions from vehicles that have only one or two cold-
starts  per day.

       Electrically-heated catalysts reduce cold-start emissions by applying an electric current to
the catalyst before the engine is started to get the catalyst up to its operating temperature more
quickly.24 These systems require  a modified catalyst, as well as an upgraded battery and
charging system.  These can greatly reduce cold-start emissions, but could require the driver to
wait until the catalyst is heated before the engine would start to achieve optimum performance.

       Hydrocarbon adsorbers are designed to trap VOCs while the catalyst is cold and unable
to sufficiently convert them.  They accomplish this by utilizing an adsorbing material which
holds  onto the VOC molecules. Once the catalyst is warmed up, the trapped VOCs are
automatically released from the adsorption material and are converted by the fully functioning
downstream three-way catalyst. There are three principal methods for incorporating an adsorber
into the exhaust system.  The first is to coat the adsorber directly on the catalyst substrate.  The
advantage is that there are no changes to the exhaust system required, but the desorption process
cannot be easily controlled and usually occurs before the catalyst has reached light-off
temperature.  The second method locates the adsorber in another exhaust pipe parallel with the
main exhaust pipe, but in front of the catalyst and includes a series of valves that route the
exhaust through the adsorber in the first few seconds after cold start, switching exhaust flow
through the catalyst thereafter.  Under this system,  mechanisms to purge the adsorber are also
required. The third method places the trap at  the end of the exhaust system, in another exhaust
pipe parallel to  the muffler, because of the low thermal tolerance of adsorber material. Again a
purging mechanism is required to purge the adsorbed VOCs back into the catalyst, but adsorber
overheating is avoided. One manufacturer who incorporates a zeolite hydrocarbon adsorber in
its California SULEV vehicle found that an electrically heated catalyst was necessary after the
adsorber because the zeolite acts as a heat sink and nearly negates the cold start advantage of the
adsorber. This  approach has been demonstrated to effectively reduce cold start emissions.

4.3 Feasibility of Small SI Engine Standards

       We are establishing new, more stringent HC+NOx standards for Small SI engines
(<19kW) used in nonhandheld, terrestrial applications (we are also setting a CO std for Small SI
engines used in marine applications that is discussed in Section 4.4). The standards differ by
engine size. Class I engines have a total  cylinder displacement of < 225cc. Class II engines

                                          4-22

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                                                  Feasibility of Exhaust Emission Control
have a total displacement of >225cc. We are also making changes to the emission certification
protocols for durability testing and test fuel specifications for both classes.  The new certification
requirements will improve emissions performance of these engines over their regulatory lifetime
and better align the test fuel with in-use fuel characteristics.

       Table 4.3-1 shows the existing Phase 2 exhaust emission standards for Class I and II
small spark ignition engines as well as the new Phase 3 standards. The Phase 3 standards
represent a nominal 35-40 percent reduction from current standards.

                     Table 4.3-1: Comparison of Phase 2 and Phase 3
                       Standards for Small Spark-Ignition Engines
Engine Class
Class I (<225 cc)
Class II (>225cc)
Phase 2 Standards
(HC+NOx g/kW-hr)
16.1
12.1
Phase 3 Standards
(HC+NOx g/kW-hr)
10.0
8.0
Percent Reduction
(%)
38
34
       The following sections present the technical analyses and information that support our
view that the Phase 3 exhaust emission requirements are technically feasible. We begin with a
review of the current state of compliance with the Phase 2 standards relative to the Phase 3
standards and conclude with a more in depth assessment of the technical feasibility of the
requirements for Class I gasoline-fueled engines, Class II single-cylinder gasoline-fueled
engines, Class II multi-cylinder gasoline-fueled engines, and both classes of gaseous-fueled (e.g.,
liquid propane gas) engines.

4.3.1  Current Technology and 2008 Certification Test Data

       In the 2008 model year manufacturers certified engines to the Phase 2 standards using a
variety of engine designs and  emission control technology.  Table 4.3-2 shows manufacturers'
projected engine sales by technology type.  For Class I engines, side-valve designs represent the
majority of sales, although there are also a significant number of overhead-valve sales.  An
extremely small number of engines used catalyst-based emission control technology. Class II is
dominated by overhead-valve engine designs.  A limited number of these engines used catalyst
technology, electronic fuel injection, or were water cooled.
                                          4-23

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Final Regulatory Impact Analysis
                Table 4.3-2: 2005 Engine Sales by Technology Market Mix
Engine Technology
Side Valve
Overhead Valve
With Catalyst
With Other (Electronic Fuel
Injection and/or water cooled)
Class I
66%
34%
0.003%
0
Class II
2%
98%
0.4%
1%
       Looking at the industry from an engine family rather than a sales perspective, shows that
68 and 212 engine families were emission certified in Class I and II, respectively for 2008. The
range of technology types is shown in Table 4.3-3. The majority of engine families in Class I are
overhead-valve, carbureted engines, with only 14 families using side-valve, carbureted designs
(the side-valve engines still account for the bulk of Class I sales). Five families utilized catalytic
exhaust aftertreatment.

                         Table 4.3-3: 2005 Small Spark-Ignition
                Engine Technology Types and Number of Engine Families





Engine
Class
I
II
Side-Valve



Single-
Cylinder
Carburetor
yes (14)
yes (2)


Single-
Cylinder
Carburetor
w. Catalyst
no
yes (0)
Overhead Valve



Single-
Cylinder
Carburetor
yes (48)
yes (43)


Single-
Cylinder
Carburetor
w. Catalyst
yes (4)
no



Multi-
Cylinder
Carburetor
no
yes (105)


Multi-
Cylinder
Carburetor
w. Catalyst
no
yes (6)


Multi-
Cylinder
Fuel
Injection
no
yes (6)
Multi-
Cylinder
Fuel
Injection
w.
Catalyst
no
yes (8)
       In Class II, the majority of the engine families use multi-cylinder (predominately v-twins)
designs incorporating overhead-valve technology. Most of these multi-cylinder families utilized
carburetors, with a few using catalytic exhaust aftertreatment, fuel injection, or electronic engine
controls.  There are relatively fewer single-cylinder engine families using the older, less
sophisticated side-valve technology. None of these engines were certified with catalytic
aftertreatment.

       Figures 4.3-1 and 4.3-2 present the 2008 certification results at full life for Class I and II
                                            4-24

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                                                       Feasibility of Exhaust Emission Control
engine families, respectively, by technology type.1 One striking feature of these figures, especially
Figure 4.3-2, is that there are a number of engine families displaying emission levels well above
the existing, i.e., Phase 2, standards.  Generally, these families represent somewhat older
technology, low production engines that have been certified using preexisting emission credits.
Under the conditions of the final Phase 3 rules, these engine families will be unable to be certified
using existing credits. As a consequence, we expect these families will be eliminated in favor of
newer designs when the Phase 3 standards become effective.

       Looking at the remaining engine families,  several families were certified at levels
necessary to comply with the Phase 3 standards.  Also, a number of families are very close to the
requisite emission levels.  This suggests that, even accounting for the relative increase in
stringency associated with our certification protocols, a number of families will either not need to
do anything or require only modest reductions in their emission performance to meet the new
standards.
        1 The data presented in Figure 4.3-1 and Figure 4.3-2 are consistent with the 2008 certification data used for the cost
analysis in Chapter 6. This data does not include certification data from the nearly 90 Chinese manufacturers that have started
certifying nonhandheld engines with EPA in the last few years. (As noted in Chapter 6, EPA has chosen not include data from
Chinese manufacturers because we have no information on actual sales of their engines in the United States. Based on
discussions with nonhandheld engine manufacturers that have been certifying with EPA for over ten years now, it is our
understanding that sales of nonhandheld engines from Chinese manufacturers are relatively small at this time.) The certification
levels of the engines certified by Chinese manufacturers generally fall within the same range as the engines presented in Figure
4.3-1 and Figure 4.3-2.
                                                4-25

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Final Regulatory Impact Analysis
                 Figure 4.3-l:Class I HC+NOx Full Life Certification Results for
                                            2008
                         100
                                  120
                                           140      160
                                         Displacement (cc)
                                                            180
                                                                     200
                                                                              220


-


1 10
-- _ o
o
? 6
O
I
9

n
(
Figure 4.3-2: Class II HC+NOx Full Life Certification Results for
2008
X

4 ^ Phase 2
^S^ Standard
ff
A*^AA A A *
AA AA/ * A * A ^ A A Phase 3
A AA AAA|AAA A .X'' Standard
..A A A A ^^ ^ ^ ^f
AA A ^^ A AA A^IA ^ A v- *
AAA AAA
^ A *SVCarb
A A OHV Harh
BOHV Fuel Inj
X *,

X
D 200 400 600 800 1000 1200 1400
Displacement (cc)













                                            4-26

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                                                  Feasibility of Exhaust Emission Control
4.3.2  Technology Assessment and Demonstration

       As described above, a number of engine families already are certified to emission levels
that likely would comply with the Phase 3 standards.  However, many engine families clearly will
have to do more to improve emission performance. Generally, we believe the new requirements
will require many engine manufacturers to adopt exhaust aftertreatment technology using
catalyst-based systems. Other likely changes include improved engine designs and fuel delivery
systems.  Finally, adding electronic controls or fuel injection systems may obviate the need for
catalytic aftertreatment for some engine families, with the most likely candidates being
multi-cylinder engine designs.

       Many of the technical design considerations for adapting advanced emission controls to
Small SI engines were presented in Section 4.2. These included redirected air from the cooling
fan, redirected exhaust flow through multiple chamber and baffles within the catalyst muffler, or
other design considerations.  (These are also the kinds of design elements that engine
manufacturers will need to consider for safe and durable emission control systems.) In the
remainder of this section we describe the specific results of our emission control assessment based
on engine testing of exhaust catalyst systems, as well as a more specific discussion of other
potential emission reduction technology for certain engine types such as electronic engine controls
and fuel injection. The results of our safety assessment are described later in section 4.8 of this
chapter.

       4.3.2.1 Overview of Technology Assessment

       Our feasibility assessment began by evaluating the emissions performance of current
technology for Small SI engines and equipment.  These initial efforts focused on developing a
baseline for emissions and general engine performance  so that we could assess the potential for
new emission standards for engines and equipment in this category. This process involved
laboratory and field evaluations of the current engines and equipment.  We reviewed engineering
information and data on existing engine designs and their  emissions performance.  We also
reviewed patents of existing catalyst/muffler designs for Class I engines.  We engaged engine
manufacturers and suppliers of emission control-related engine components in discussions
regarding recent and expected advances in emissions performance beyond that required to comply
with the current Phase 2  standards. Finally, we purchased catalyst/muffler units that were already
in mass production by an original equipment manufacturer for use on European walk-behind lawn
mowers and conducted engineering and chemical analysis on the design and materials of those
units.

       We used the information and experience gathered in the above effort along with the
previous catalyst design experience of our engineering staff to design and build prototype
catalyst-based emission control systems that were capable of effectively and safely achieving the
Phase 3 requirement based on dynamometer and field testing. We also used the information and
the results of our engine testing to assess the potential need for improvements to engine and fuel
system designs, and the selective use of electronic engine  controls and fuel injection on some
engine types. A great deal of this effort was conducted in association with our more exhaustive

                                           4-27

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Final Regulatory Impact Analysis
study regarding the efficacy and safety of implementing advanced exhaust emission controls on
Small SI engines, as well as new evaporative requirements for these engines.25  In other testing, we
evaluated advanced emission controls on a multi-cylinder Class II engine with electronic fuel
injection.26

       In designing our engine testing program, we selected engines certified to the Phase 2
emission standards that were expected to remain compliant with those standards for the duration of
their useful life based on our low-hour emission testing and the manufacturer's declared
deterioration factor from the certification records for that engine family.  We also selected engine
families that represented:  1) a cross section of Class I and Class II side-valve and overhead-valve
technologies; and 2) higher sales volume families.  Each engine was maintained based on the
manufacturer's specifications.2  The results of our specific technical feasibility assessment are
presented below.

       4.3.2.2 Class I Gasoline-Fueled Engines

       We tested six side-valve and six overhead-valve Class I engines that used gasoline fuel
with prototype catalyst/muffler control systems. The primary design target for selecting the
catalyst configuration, e.g., volume, substrate, platinum group metal (PGM), was to achieve
emission levels below the  limit of 10 g/kW-hr HC+NOx for this class at  125 hours of engine
operation.  That time period represents the useful life requirement for the most common
application in this category, i.e., residential walk-behind lawn mowers. A maximum of about 7
g/kW-hr HC+NOx was set as the low-hour performance target with a catalyst system to allow for
engine and emission control degradation over the engine's useful life. This level assumes a
certification cushion at low hours of 1 g/kW-hr HC+NOx  and a multiplicative deterioration factor
of 1.3. Secondary design targets were primarily safety related and included minimizing CO
oxidation at moderate to high load conditions to maintain exhaust system surface temperatures
comparable to those of the original Phase 2 compliant systems.  The test  engine, size,  and salient
catalyst features are shown in Table 4.3-4.

       Table 4.3-5 presents the results of our catalyst testing on Class I engines.27'28 Three of the
engines were tested at high hours. The high-hour results for the remaining engines  were  projected
from their low-hour emission performance. We projected high-hour emission results for  these
engines by applying the multiplicative deterioration factor from the manufacturer's Phase 2
certification application to the low-hour emission test results. The certification deterioration
factors ranged from 1.097 to 1.302 g/kW-hr HC+NOx.3 As shown, each of the engines achieved
the requisite emission limit of 10 g/kW-hr HC+NOx at the end of their useful lives.
       2 The specific test engines were generally used in residential lawn mower and lawn tractor applications.
These applications were chosen for field testing as part of our safety study because they represented certain
potentially unique and challenging safety concerns connected with operation and storage in environments with
combustible debris.

       3 These results were taken from the 2005 certification results.

                                            4-28

-------
Table 4.3-4: Class I Test Engine and Control Technology Description
Engine ID
236
246
248
249
6820
258
241
255
2982
243
244
245
Displace-
ment
(L)
0.20
0.20
0.20
0.20
0.19
0.19
0.19
0.19
0.19
0.16
0.16
0.16
Valve
Train
Side
Side
Side
Side
Side
Side
Overhead
Overhead
Overhead
Overhead
Over-head
Overhead
Fuel
Metering
Carburetor
Carburetor
Carburetor
Carburetor
Carburetor
Carburetor
Carburetor
Carburetor
Carburetor
Carburetor
Carburetor
Carburetor
Passive
(Venturi)
Secondary
Air?
Yes
Yes
Yes

Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Catalyst Type
Metal monolith
Metal monolith
Metal monolith
Wire-mesh
Cordierite
Ceramic
Monolith
Cordierite
Ceramic
Monolith
Cordierite
Ceramic
Monolith
Coated tube pre-
catalyst, Metal
monolith main-
body catalyst
Metal monolith
Cordierite
Ceramic
Monolith
Metal monolith
Metal monolith
Catalyst
Volume
44 cc
44 cc
44 cc
60 cc
40 cc
40 cc
40 cc
20 mm dia. X 73
mm long exhaust
tubing, 22 cc
metal monolith
34 cc
30 cc
44 cc
44 cc
Catalyst Cell
Density
200 cpsi
200 cpsi
200 cpsi
N/A
400 cpsi
400 cpsi
400 cpsi
Tube: 2 channels
(annular shape),
Main body: 200
cpsi
100 cpsi
400 cpsi
200 cpsi
200 cpsi
PGM Loading
(mass/catalyst volume,
Pt:Pd:Rh ratio)
30 g/ft3, 4:0:1
30 g/ft3, 4:0:1
30 g/ft3, 0.33:3.66:1
proprietary, 0:0:1
30 g/ft3, 5:0:1
30 g/ft3, 5:0:1
30 g/ft3, 5:0:1
Tube: Proprietary
Main body: 30 g/ft3,
3:1:1
50 g/ft3, 5:0:1
30 g/ft3, 5:0:1
30 g/ft3, 1:3:1
30 g/ft3, 3:1:1

-------
Final Regulatory Impact Analysis
     Table 4.3-5: Class I Emission Results with Advanced Catalytic Control Technology
Engine
236

246

248

249

6820

258

241

255

2982

243

244

245

Age
(hours)1
10-20
Projected High
10-20
Projected High
10-20
Projected High
10-20
Projected High
Not Tested
>110
10-20
>110
10-20
>110
10-20
Projected High
10-20
>110
10-20
Projected High
10-20
Projected High
10-20
Projected High
HC+NOx
(g/kW-hr)
4.90.62
6.1
5.6
7.0
4.6
5.7
6.3
7.8
na
9.4
6.7
8.2
3. 9 0.2
6.6  0.2
5.0
6.5
4.9 0.3
7.0  0.4
7 1
7.7
7.2
7.9
5.6
6.1
1 Projected high hour results estimated by multiplying the low hour test results by the
manufacturer's certification deterioration rate.
2 "" values represent the 95% confidence intervals of 3 tests using a 2-sided t-test.
                                           4-30

-------
                                                   Feasibility of Exhaust Emission Control
       The above method for projecting high-hour emission results using a certification
deterioration factor assumes that the catalyst system will control engine-out emissions to the same
extent, i.e., proportional reduction, over the useful life of the engine.  For some engines this may
not always be the case depending on oil consumption, air-to-fuel ratio and other factors that may
change the effectiveness of the catalyst over time.4 Our approach also did not explicitly account
for the fact that manufacturers will generally design the engine and catalyst to provide some
certification cushion.  It appears that most of the engines in Tables 4.3-5 would accommodate the
above design considerations. However, the projected high-hour results  are uncomfortably close to
the 10 g/kW-hr HC+NOx standard for engine number 6820. In these cases, such factors can be
accounted for by the engine manufacturer in the engine family's research and design phase by
either improving the durability of the engine (see the discussion below) or designing the catalyst to
account for degradation in catalyst effectiveness over time, e.g, more precious metal loading,
larger catalyst volume, dividing the catalyst into two separate pieces within the exhaust stream,
etc.

       The technical feasibility of the Phase 3 standard for Class I engines is supported by a
number of Small SI engine manufacturers.29'30'31'32  Also, a manufacturer of emission controls
specifically indicated the types of hardware that may be needed to comply with new standards.33
That manufacturer concluded that, depending on the application and engine family, either catalyst
or electronic engine controls should be able to achieve emission standards as low as 9 g/kW-hr
HC+NOx. As demonstrated above, we believe the standard of 10 g/kW-hr HC+NOx can be
achieved using  catalysts only.  However,  based on our engineering judgment, we agree that it may
be possible to achieve the standard with the sole use of electronic engine controls because of the
more precise management of air-fuel mixtures and ignition spark timing offered by that
technology.

       We conducted a design and process Failure Mode and Effects Analysis study to assess the
safety of implementing advanced exhaust emission controls on Small SI engines.34  That work,
which was based in part on our engine test program, suggests that manufacturers of Class I may
need to improve the durability of basic engine designs, ignition systems, or fuel  metering systems
for some engines in order to comply with the emission regulations at full useful  life. Some of
these emission-related improvements may include:

       1.  Adding a fuel filter or improving the needle and seat design in the  carburetor to
       minimize fuel metering problems  caused by debris from the fuel tank;
       2.  Improving intake manifold design or materials to reduce air leaks;
       3.  Upgrading the ignition system  design for better ignition spark reliability and durability;
       4.  Improving design and manufacturing processes for carburetors to reduce the production
       variability in air-fuel mixtures; and
       4  Catalyst performance degradation can occur from thermal sintering and catalyst poisoning due to oil
consumption. Catalyst performance can also improve as engine air-to-fuel ratio slowly drifts towards stoichiometry
over the useful life of the engine. Air-cooled engines are typically designed with air-to-fuel ratio calibrations that
take into account lean-drift with extended operation, and are designed with a sufficiently rich air-to-fuel ratio to
prevent net-lean operation at high hours that could result in engine damage or deteriorating engine performance.

                                            4-31

-------
Final Regulatory Impact Analysis
       5.  Enhancing exhaust manifold design for better reliability and durability.

       4.3.2.3 Class II Single-Cylinder Gasoline-Fueled Engines

       Class II single-cylinder engines that use gasoline fuel are currently certified and sold under
the Phase 2 standard in both side-valve and overhead-valve configurations. In 2008, only 2 out of
107 Class II single-cylinder engine families used side-value designs. Manufacturers certified these
families under the averaging provisions of the applicable regulations with emission credits that
were generated by (low emitting) overhead-valve engines. We believe that the Phase 3 standard
will reduce the number of emission credits available for the certification of side-valve technology.
As a result, we assume that a number of the remaining Class II side-valve engines may be phased
out of applicable manufacturer's product line in the future.

       Based on the above, we did not directly assess the technical feasibility of the  standard for
side-valve Class II engines in our test program. Instead we assessed only single-cylinder,
overhead-valve Class II engines with prototype catalyst/muffler control systems. The primary
design target for selecting the catalyst configuration for these engines, e.g., volume, substrate,
design and PGM loading, was to achieve emission levels well below the limit of 8 g/kW-hr
HC+NOx for this class to accommodate the longer useful life of many of these engines.  The
emission regulations allow useful lives ranging from 250 tolOOO hours.  For two of the engines
families, we selected emission control technology with a target of meeting a 3.5 g/kW-hr
HC+NOx.  This included the use of electronic engine and fuel controls to improve  the
management of air-fuel mixtures and ignition spark timing that allow, among other advantages, the
use of larger catalyst volumes and higher precious metal loading. Secondary design targets were
primarily safety related and included minimizing CO oxidation at moderate to high load conditions
to maintain exhaust system surface temperatures comparable to those of the original Phase 2
compliant systems.  The test engines, size, salient catalyst parameters, and use of electronic engine
controls are shown in Table 4.3-6.
                                           4-32

-------
                                                  Feasibility of Exhaust Emission Control
   Table 4.3-6: Class II Single-Cylinder Test Engine and Control Technology Description
Engine
142
231
251
253
254
232
Displac
ement
(L)
0.40
0.50
0.50
0.50
0.59
0.49
Useful
Life
500 hour
250 hour
250 hour
250 hour
250 hour
1,000 hour
Fuel
Metering
Carburetor
Electronic
Fuel
Injection
Carburetor
Carburetor
Carburetor
Electronic
Fuel
Injection
Catalyst
Type
Cordierite
Ceramic
Monolith
Metal
monolith
Cordierite
Ceramic
Monolith
Cordierite
Ceramic
Monolith
Cordierite
Ceramic
Monolith
Metal
monolith
Catalyst
Volume
250 cc
280 cc
250 cc
250 cc
250 cc
250 cc
Catalyst
Cell
Density
400 cpsi
200 cpsi
400 cpsi
400 cpsi
400 cpsi
200 cpsi
Catalyst Loading
40 g/ft3, 5:0:1'
70 g/ft3, 0:5:1
40 g/ft3, 5:0:1
40 g/ft3, 5:0:1
40 g/ft3, 5:0:1
40 g/ft3, 5:0:1
1 Metal loading expressed as a ratio of platinum:palladium:rhodium.
       Table 4.3-7 shows the results of our catalyst testing on single cylinder Class II engines.
Only one of the engines was tested at high hours. As explained above for the Class I engines, the
high-hour results for the remaining engines were projected from their low-hour emission
performance. We projected high-time emission results for these engines by applying the
multiplicative deterioration factor from the manufacturer's Phase 2 certification application to the
low-hour emission test results.  The certification deterioration factors ranged from 1.033 to 1.240
g/kW-hr HC+NOx.5 As shown, each of the engines achieved the requisite emission limit of 8
g/kW-hr HC+NOx.
       5 These results were taken from the 2005 certification results.

                                           4-33

-------
Final Regulatory Impact Analysis
                   Table 4.3-7: Class II Single-Cylinder Emission Results
                       with Advanced Catalytic Control Technology
Engine
231 (w/EFI)

232 (w/ EFI)

251

253

254

142

Age
(hours)1
10-40
Projected High
10-40
Projected High
10-40
Projected High
10-40
Projected High
10-40
Projected High
50
500
HC+NOx
(g/kW-hr)
1.80.42
2.2
2.2 0.1
2.3
3.1 .3
3.8
4. 5 0.1
5.6
4.0 0.3
4.5
2.5 0.6
2.8
1 Projected high-hour results estimated by multiplying the low-hour test results by the manufacturer's 2005
certification deterioration rate.
2 "" values represent the 95% confidence intervals of 3 tests using a 2-sided t-test.
       Again, as with Class I engines, the technical feasibility of the Class II standard was
supported by a number of Small SI engine manufacturers.35363738 Also, a manufacturer of emission
controls specifically indicated the types of hardware that may be needed to comply with new
standards.39 That manufacturer concluded that, depending on application and engine family, a
catalyst and  electronic engine controls should be capable of achieving emission standards as low
as 7 g/kW-hr HCNOx.  Also,  as described above, that same manufacturer concluded that, again
depending on the application and engine family, either catalyst or electronic engine controls
should be able to achieve emission standards as low as 9 g/kW-hr HCNOx.  Our standard of 8
g/kW-hr HCNOx is in between these two regions. Therefore, based solely on that manufacturer's
conclusions, complying with the standard may require control technology  ranging from either a
catalyst or electronic engine controls, or a combination of both.

       Based on the above information, especially our testing as discussed previously, we
conclude that catalysts do not necessarily need to be used in conjunction with electronic engine
controls to achieve our standard of 8 g/kW-hr HCNOx.  Either one of those technologies appear
sufficient. In fact, market forces may cause some manufacturers to shift to electronic controls in
the absence of more stringent emission standards. Nonetheless, we can not discount the possibility
that both technologies may be used by some manufacturers to meet the standard on single-cylinder
Class II engines. (See section 4.2.3.4 for more on electronic engine control and fuel injection.)

       The design and process Failure Mode and Effects Analysis study mentioned previously
suggests that manufacturers of Class II may need to improve the durability of basic engine designs,
                                           4-34

-------
                                                   Feasibility of Exhaust Emission Control
ignition systems, or fuel metering systems for some engines in order to comply with the emission
regulations at full useful life.40 Some of these emission-related improvements may include:

       1.  Reducing the variability in air-fuel mixtures with tighter manufacturing tolerances for
       fuel metering components; and
       2.  Improving the ignition system design for better ignition spark reliability and durability.

       4.3.2.4 Class II Multi-Cylinder Gasoline-Fueled Engines

       Gasoline-fueled Class II multi-cylinder engines are very similar to their single-cylinder
counterparts. Beyond the difference in the number of cylinders, several more Class II multi-
cylinder engine families are currently certified with catalysts and electronic engine control
technology (either with or without a catalyst). Because of the direct similarities and the use of
more sophisticated emission control-related technology on some engine families, we find that our
conclusions regarding the technical feasibility of the 8 g/kW-hr HC+NOx standard for single-
cylinder Class II engines is directly transferable to multi-cylinder Class II engines.

       Nonetheless, we also tested two twin-cylinder gasoline-fueled Class II engines from
different engine families by the same manufacturer.41 The engines were basically identical except
for their fuel metering systems, i.e., carbureted or electronic fuel injection. We tested both without
modification and tested the electronic fuel injected engine with a catalyst system that we
developed. All the tests were conducted when the engines had accumulated  10-15 total hours of
operating time.

       The results of this testing are shown in Table 4.3-8.  As was done for the Class I and II
single-cylinder engines discussed earlier, we projected emission levels at the end of each  engine's
useful life using the multiplicative deterioration factors for each engine family as reported in the
manufacturer's Phase 2 certification application. As shown, the carbureted engine is projected to
have end of life emissions of approximately 9.1  g/kW-hr. Based on our experience with single-
cylinder engines, compliance with the new standard may require the use of a catalyst for this
engine family. The unmodified engine with electronic fuel injection is projected to achieve about
7.3 g/kW-hr. This engine is very close to complying with the standard and will most likely require
only additional fuel-air mixture and injection timing calibration changes for compliance.

-------
Final Regulatory Impact Analysis
                            Table 4.3-8: Class II Multi-Cylinder
               Emission Results with Advanced Catalytic Control Technology
             (V-Twin, Approximately 0.7 Liter Displacement, 3-Way Catalyst)
Engine
Configu
r-ation
OEM

OEM

OEMw/
catalyst
Fuel
Metering
Carburet

EFI

EFI

Age
(hours)1
10-40
Projected
10-40
Projected
10-40
Projected
HC+NO
X
(g/kW-
hr)
7.2
9.1
5.9
7.3
1.8
2.2
Catalyst
Type




Cordi erite
same
Catalyst
Volume




700cc
same
Catalyst
Cell
Density




400 cpsi
same
Catalyst
Loading




60 g/ft3,
same
1 Projected high-hour results estimated by multiplying the low-hour test results by the manufacturer's 2004
certification deterioration rate.
2 Metal loading expressed as a ratio of platinum:palladium:rhodium.

       Finally, the combination of electronic fuel injection and catalytic exhaust aftertreatment
clearly has the potential to reduce emissions well below the Phase 3 standard as shown in the table.

       We also evaluated emission control technology for twin-cylinder Class II engines, and by
analogy all multi-cylinder engines, as part of our safety study.42 Here again we did not find any
unique challenges in designing catalyst-based control systems for these multi-cylinder engines
relative to the feasibility of complying with the exhaust standards under normal  engine operation.
However, we did conclude that these engines may present unique concern with the application of
catalytic control  technology under atypical operation conditions. More specifically, the concern
relates to the potential consequences of combustion misfire or a complete lack of combustion in
one of the two or more cylinders when a single catalyst/muffler design is used. (A single muffler
is typically used in Class II applications.) In a single-catalyst system, the unburned fuel and air
mixture from the malfunctioning cylinder would combine with hot exhaust gases from the other,
properly operating cylinder.  This condition would create high temperatures within the muffler
system as the unburned fuel and air charge from the misfiring cylinder combusts within the
exhaust system.  This could potentially destroy the catalyst.

       One solution is simply to have a separate catalyst/muffler for each cylinder. Another
solution is to employ electronic engine controls to monitor ignition and either put the engine into
"limp-mode" or shut the engine down until the  condition clears on re-start  or until necessary
repairs are made, if appropriate. For engines using carburetors, this would effectively require the
addition  of electronic controls. For engines employing electronic fuel injection that may need to
also employ a small catalyst, it would require that the electronic controls incorporate ignition
misfire detection if they  do not already utilize the inherent capabilities within the engine
management system.
                                            4-36

-------
                                                  Feasibility of Exhaust Emission Control
       We expect some engine families will use electronic fuel injection to meet the Phase 3
standard without employing catalytic aftertreatment. As described earlier, engine families that
already use these fuel metering systems and are reasonably close to complying with the
requirement are likely to need only additional calibration changes to the engine management
system for compliance.  In addition, we expect that some engine families which currently use
carbureted fuel systems will convert directly to electronic fuel injection. Manufacturers may adopt
this strategy to couple achieving the standard without a catalyst and realizing other advantages of
using fuel injection such as easier starting, more stable and reliable engine operation, and reduced
fuel consumption. A few engine manufacturers have confidentially confirmed their plans to use
electronic fuel injection on some engine families in the future as part of an engine management
strategy in lieu of using catalysts.

       Our evaluation of electronic fuel injection systems that could be used to attain the new
standard found that a rather simple, low cost system should be sufficient. We demonstrated this
proof of concept as part of the engine test program we conducted for our safety study.  In that
program, we fitted two single-cylinder Class II engines with an electronic control unit and fuel
system components developed for Asian motor-scooters  and small-displacement motorcycles.
The sensors for the system were minimized to include a throttle position sensor, air charge
temperature sensor, oil temperature sensor, manifold absolute pressure sensor,  and a crankshaft
position sensor. This is in contrast to the original equipment manufacturer (OEM) fuel injection
systems currently used in some two-cylinder Class II engine applications that employ more
sophisticated and expensive automotive-based components.

       Regarding the electronic control unit and fuel system components referenced above and in
previous sections, at least two small engine manufacturers have developed simplified, compact,
low-cost electronically controlled fuel injection systems  for small motorcycles and scooters.4344
One manufacturer has also developed a general purpose  small engine with electronic engine speed
control technology that eliminates the need for a battery.45'46 These manufacturers have generally
reported a number of benefits for these advanced systems, including lower emissions and better
fuel economy.

       4.3.2.5 Class II Gaseous-Fueled Engines

       Engine manufacturers and equipment manufacturers certify engines to run on liquid
propane gas (LPG) or compressed natural gas (CNG) in a number of applications including indoor
floor buffers which require low CO emissions. The technology to reduce emissions to the Phase 3
levels is catalyst due the fact that most engines run closer to stoichiometry than gasoline engines
and further enleanment to reduce emissions may not be feasible. Due to the high amount of NOx
compared with HC, as seen from engine data in the certification database, the catalysts may  need
to be designed to reduce NOx and oxidize  a limited amount of CO.  The EPA 2008 Certification
Database lists 6 multi-cylinder engine families in the Class II 1000 useful life category as having
catalysts.  Due to this fact, it  is assumed that gaseous engines do not have the same concerns with
multi-cylinder engines and catalysts as gasoline engines.
                                           4-37

-------
Final Regulatory Impact Analysis
4.4  Feasibility of Outboard/Personal Watercraft Marine Engine Standards

       Outboard and personal watercraft (OB/PWC) engines are subject to exhaust emission
standards which require approximately a 75 percent reduction in hydrocarbon emissions compared
to conventional carbureted, crankcase-scavenged two-stroke engines. Because of the emission
credit program included in these requirements, manufacturers are able to sell a mix of old and new
technology engines to meet the standards on average.

       We are finalizing new exhaust emission standards for OB/PWC engines based on the
emissions results achievable from the newer technology engines. These technologies have
primarily been two-stroke direct injection and four-stroke engine designs. For a few model years,
one manufacturer certified PWC engines with catalytic aftertreatment.  This section presents
emission data for 2004 model year outboard and personal watercraft engines and includes a
description of the various emission control technologies used.  In addition, the possibility of using
catalytic aftertreatment on OB/PWC engines is discussed.

4.4.1  OB/PWC Certification Test Data

       When engine manufacturers apply for certification to exhaust emission standards, they
submit exhaust emission test data.  In the case of the OB/PWC engines, the emission standards are
based on the sum of hydrocarbons and oxides of nitrogen (HC+NOx). Manufacturers submit
emission test data on HC and NOx to demonstrate their emission levels. Although carbon
monoxide (CO) emissions are not currently regulated, manufacturers submit data on CO emissions
as well.

       Three primary technologies are used on Marine SI engines: conventional two-stroke
engines, direct injection two-stroke engines, and four-stroke engines. Conventional two-stroke
engines are primarily carbureted, but larger engines may have indirect fuel injection systems as
well (IDI). Four stroke engines come in carbureted, throttle-body fuel injected (TBI), and multi-
port fuel injection (MPI) versions.  These technologies are discussed in more detail in
Section 4.4.2.

       4.4.1.1 HC+NOx Certification Data

       Figure 4.4-1  presents HC+NOx certification levels for 2006 model year outboard engines
and compares this data to the existing and new exhaust emission standards.  These certification
levels are based on test data over the ISO E4 duty cycle with an adjustment for emissions
deterioration over the regulatory useful life. The certification data set includes engines well above
and below the emission standard. Manufacturers are able to certify to the standard by meeting it
on average.  In other words, clean engines generate emission credits which offset the debits
incurred by the engines emitting above the standard. Figure 4.4-2 presents only the data from
engines that meet the 2006 standard. As shown in these figures, two-stroke direct injection
engines and four-stroke engines easily meet the 2006 standard.
                                           4-38

-------
                                          Feasibility of Exhaust Emission Control
        Figure 4.4-1:  2006 MY Outboard HC+NOx Certification Levels


f
.c
i
2
X
O
z
+
O



400 -i
"^n
?nn -
9ciO
900

150
100 -

n -
C


#
1
^
% 
	 ^ ^ 	 V 	
*

h .  ^ .__ _ 	   .  -
^^  ^w"r^ w^ ~^w~~ p^^^^^
) 50 100 150 2(
Rated Power [kW]









DO


 2s Carb
 2s Dl
A 4s Carb
 Ac. PFI
'to cn
~   BasGlinG
	 2006



Figure 4.4-2: 2006 MY New Technology Outboard HC+NOx Certification Levels
                  50           100
                        Rated Power [kW]
150
200
                                                                    2s Carb
                                                                    2s Dl
                                                                  A  4s Carb
                                                                    4s EFI
                                                                  ^ proposed
 Figures 4.4-3 and 4.4-4 present similar data for personal watercraft engines.  These engines
                                    4-39

-------
Final Regulatory Impact Analysis
use similar technology, but the HC+NOx emissions are a little higher on average, presumably due
to higher average power densities for PWC engines. This difference in emissions is reflected in
the new HC+NOx standards.

        Figure 4.4-3:  2006 MY Personal Watercraft HC+NOx Certification Levels
400
ocn

^ 250
3)
X
9 i*n
Z 150
Q 100
50 -

n
(



1
1

*

^^
J0v ^^V
D 50 100 150 2(
Rated Power [kW]










DO


 2s Carb
 2s Dl
^ 2s Catalyst
 Ac PFI
'ts tri
	 2006
	 2010



        Figure 4.4-4: 2006 MY New Technology PWC HC+NOx Certification Levels
    1
    2
    x
    O
    O
    I
                       50           100
                            Rated Power [kW]
150
200
                         2s Carb
                         2s Dl
                         2s Catalyst
                         4s EFI
                         Baseline
                        2006
                        2010
                                         4-40

-------
                                                 Feasibility of Exhaust Emission Control
       4.4.1.2 CO Certification Data

       Although no exhaust emission standards for CO are currently in place for Marine SI
engines, the technological advances associated with the HC+NOx standards have resulted in lower
CO emissions for many engines. Figures 4.4-5 and 4.4-6 present reported CO exhaust emission
levels for certified outboard and personal watercraft engines. These engines use similar
technology as outboard engines and show similar emission results.

        Figure 4.4-5: Reported CO Emission Levels for 2006 MY Outboard Engines
600
500 -

1=1 400
= "300
2
R 200

100
n
(


V
X
*
  .


% 
) 50 100 150 2(
Rated Power [kW]









DO



 2s Carb
 2s Dl
ZS L/alaiyST
 4s EFI
2010



          Figure 4.4-6: Reported CO Emission Levels for 2006 MY PWC Engines
                        50           100           150
                              Rated Power [kW]
200
                                          4-41

-------
Final Regulatory Impact Analysis
4.4.2  OB/PWC Emission Control Technologies

       This section discusses the how general technologies discussed above apply to outboard and
PWC applications and discusses specific OB/PWC technology.

       4.4.2.1 Conventional Two-Stroke Engines

       As discussed earlier in this chapter, hydrocarbon emissions from two-stroke engines are
primarily the result of short-circuiting losses where unburned fuel passes through the engine and
out the exhaust during cylinder charging.  Even with an indirect injection system, the air and fuel
are mixed prior to entering the cylinder. Therefore, even though there is better metering of fuel
and air than with a carbureted engine, short-circuiting losses still occur. Because of the very rich
and cool conditions, little NOx  is formed. As shown in Figures 4.4-1 and 4.4-2, HC emissions can
range from 100 to 400 g/kW-hr. CO is formed as a product of incomplete combustion. As a
result, CO emissions range from 200 to 500 g/kW-hr from these engines.

       4.4.2.2 Direct Injection Two-Stroke Engines

       The primary advantage  of direct-injection (DI) for a two-stroke is that the exhaust gases
can be scavenged with fresh air and fuel can be injected into the combustion chamber after the
exhaust port closes.  As a result, hydrocarbon emissions, fuel economy, and oil consumption are
greatly improved. Some users prefer direct-injection two-stroke  engines over four-stroke engines
due to the higher power to weight ratio. Today, this technology is used on engines with power
ratings ranging from 35 to 220 kW.  One manufacturer has recently stated its plans to manufacture
DI two-stroke engines as low as 7.4 kW.

       Most of the DI two-stroke engines currently certified to the current OB/PWC emissions
standards have HC+NOx emissions levels somewhat higher than certified four-stroke engines.
These engines also typically have lower CO emissions due to the nature of a heterogeneous
charge.  By injecting the fuel directly into a charge of air in the combustion chamber, localized
areas  of lean air/fuel mixtures are created where CO is efficiently oxidized. PM emissions may be
higher for DI two-stroke engines than for four-stroke engines because oil is burned in the
combustion chamber and because of localized rich areas in the fuel injection stream.

       Recently, one manufacturer has introduced a newer technology DI two-stroke engine that
has comparable HC+NOx emission results as many of the certified four-stroke engines.47 This
engine makes use of a low-pressure fuel injection nozzle that relies on high swirl to produce
uniform fuel flow rates and droplet sizes.  Also, significant improvements have been made in oil
consumption.  As with the older DI two-stroke designs, CO emissions are much lower than
comparable four-stroke engines. What is unique about this design is that the manufacturer has
reported lower PM emissions than for a comparable four-stroke engine.
                                           4-42

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                                                 Feasibility of Exhaust Emission Control
       4.4.2.3 Four Stroke Engines

       Manufacturers currently offer four-stroke Marine SI engines with power ratings ranging
from 1.5 to 224 kW.  These engines are available with carburetion, throttle-body fuel injection, or
multi-point fuel injection. Carbureted engines are offered from 1.5 to 60 kW while fuel injected
engines are offered from 22 to 224 kW. One manufacturer has stated that the fuel injection
systems are too expensive to use on the smaller engine sizes. Most of the four-stroke outboard
engines above 19 kW have HC+NOx emissions below 16 g/kW-hr and many have emissions
below 13 g/kW-hr. CO emissions for these engines range from 150 to 250 g/kW-hr.  Based on the
certification data, whether the engine is carbureted or fuel injected does not have a significant
effect on combined HC+NOx emissions. For PWC engines, the HC+NOx levels are somewhat
higher. However, many of the four-stroke PWC engines are below 16 g/kW-hr.  CO emissions for
these engines are similar as those for four-stroke outboards.
       4.4.2.4 Catalysts

       One manufacturer has certified two PWC
engine models with oxidation catalysts. One engine
model uses the oxidation catalyst in conjunction with
a carburetor while the other uses throttle-body fuel
injection.  The engine with throttle-body fuel
injection has an HC+NOx emission rate of 25 g/kW-
hr which is significantly below the EPA 2006
standard. In this application, the exhaust system is
shaped in such a way to protect the catalyst from
water and is nearly as large as the engine (see Figure
4.4-7).  Manufacturers have recently begun efforts to
develop a three-way catalyst system for PWC
engines used in jet boats.
Figure 4.4-7: PWC Engine with Catalyst
               ^K  *v
                        ;
       Catalysts have not yet been packaged into the
exhaust system of production outboard marine engines.  In current designs, water and exhaust are
mixed in the exhaust system to help cool the exhaust and tune the engine.  Water often works its
way up through the exhaust system because the lower end in under water and due to pressure
pulses. As discussed above, salt-water can be detrimental to catalyst performance and durability.
In addition, the lower unit of outboards are designed to be as thin as possible to improve the ability
to turn the engine on the back of the boat and to reduce drag on the lowest part of the unit.
Certainly,  the success of packaging catalysts in sterndrive and inboard boats in recent development
efforts (see below) suggests that catalysts may be feasible for outboards.  However, this has not yet
been demonstrated and significant development efforts would be necessary.

4.5  Feasibility of Sterndrive/Inboard Marine Engine Standards

       We are establishing exhaust emission standards for spark-ignition sterndrive and inboard
(SD/I) engines. These new emission standards  are supported by data collected on SD/I engines
                                           4-43

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Final Regulatory Impact Analysis
equipped with catalysts.  This section presents exhaust emission data from baseline SD/I engines
as well as data from SD/I engines equipped with lean calibrations, exhaust gas recirculation, and
catalytic control.

4.5.1  Baseline SD/I Emissions Data

       The vast majority of SD/I engines are four-stroke reciprocating piston engines similar to
those used in automotive applications.  The exceptions are small sales of air boats using aircraft
piston-type engines and at least one marinizer that uses rotary engines.  More than half of the new
engines sold are equipped with electronic fuel injection while the rest still use carburetors.  The
majority of the electronic fuel injection systems are multi-port injection; however, throttle-body
injection is also widely used, especially on smaller engines.

       Table 4.5-1 presents baseline emissions for four-stroke SD/I engines built up from
automotive engine blocks.48'49'50'51'52'53'54 All these data were collected during laboratory tests over
the ISO E4 duty cycle. Five of these engines are carbureted, one uses throttle-body fuel injection,
and four use multi-port fuel injection. One of the multi-port fuel injected engines was tested with
three  calibrations.  Note that without emissions calibrations performed specifically for low
emissions, the HC+NOx emissions are roughly equal for the carbureted and fuel injected engines.
Using the straight average, HC+NOx from the carbureted engines is 15.6 g/kW-hr while it is 16.0
g/kW-hr from the fuel injected engines (15.1 g/kW-hr if the low HC calibration outlier is
excluded).
                                            4-44

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                                                 Feasibility of Exhaust Emission Control
                     Table 4.5-1: Baseline SD/I Exhaust Emission Data
Engine
#
1
2
3
4
5
6
7
8
9
9
9
10
11
Power
[kW]
79
91
121
153
158
167
196
159
185
181
191
219
229
Fuel Delivery System
carburetor
carburetor
carburetor
multi-port electronic fuel injection
carburetor
carburetor
carburetor
throttle -body fuel injection
multi-port electronic fuel injection
#9, low CO calibration
#9, low HC calibration
multi-port electronic fuel injection
multi-port electronic fuel injection
HC
[g/kW-hr]
11.2
4.4
8.5
4.9
7.3
8.0
4.4
2.9
5.2
5.8
3.3
4.7
2.7
NOx
[g/kW-hr]
8.0
13.9
6.0
11.7
6.0
5.7
10.3
8.7
9.7
11.7
18.2
9.4
13.1
CO
[g/kW-hr]
281
98
247
111
229
174
101
42
149
48
72
160
44
       A distinct class of SD/I engines are the high-performance engines. These engines are
similar to SD/I engines except that they are designed for high power output at the expense of
engine durability.  This high power output is typically achieved through higher fuel and air rates,
larger combustion chambers, and through higher peak engine speeds. In most cases, custom
engine blocks are used.  Even in the engines that use an automotive block, few stock automotive
engine components are used. Table 4.5-2 presents emission data collected by EPA on five high-
performance engines.55'56'57 This data also includes data submitted by a high performance engine
manufacturer in its public comments on the proposed rule.58
                                           4-45

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Final Regulatory Impact Analysis
      Table 4.5-2: Baseline High Performance SD/I Exhaust Emission Data [g/kW-hr]
Power
[kW]
391
550
634
778
802
466
410
466
Fuel Delivery System
multi-port electronic fuel injection
carburetor
multi-port electronic fuel injection, supercharger
throttle-body fuel-injection, supercharger,
intercooler
multi-port electronic fuel injection, supercharger
electronic fuel injection
electronic fuel injection
electronic fuel injection, low emission
calibration13
HC
14.7
13.23
16.9
7.6
16.1
15.43
14.83
4.3
NOx
3.8
8.4
9.1
4.9
9.4
3.2
3.9
10.8
CO
243
253
135
349
102
257
325
104
BSFC
354
376
348
448
299
~
~
~
       3 HC concentration at idle was out of measurement range
       b 15% load factor at idle
4.5.2  Exhaust Gas Recirculation Emission Data

       We collected data on three engines over the ISO E4 marine test cycle with and without the
use of exhaust gas recirculation (EGR).59'60'61  The first engine was a 6.8 L Ford heavy-duty
highway engine.  Although this was not a marine engine, it uses the same basic technology as SD/I
engines. The second and third engines were the 7.4 L and 4.3 L SD/I engines used in the catalyst
development program described below. These engines are marinized versions of GM heavy-duty
highway engines.  The baseline emissions from the 7.4 L engine are a little different than
presented below in the catalyst discussion because engine head was rebuilt prior to the catalyst
development work.

       This test data suggests that, through the use of EGR on a SD/I marine engine, a 40-50
percent reduction in NOx (30-40 percent reduction in HC+NOx) can be achieved. EGR was not
applied at peak power in this testing because the throttle is wide open at this point and displacing
fresh air with exhaust gas at this mode of operation would reduce power. We also did not apply
EGR at idle because the idle mode does not contribute significantly to the cycle weighted NOx.
                                          4-46

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                                                 Feasibility of Exhaust Emission Control
       Table 4.5-3: Exhaust Emission Data Using EGR on the E4 Marine Duty Cycle
EGR Scenario
6.8 L Engine: baseline
with EGR
7.4 L Engine: baseline
with EGR
4.3 L Engine: baseline
with EGR
HC
[g/kW-hr]
2.7
2.7
4.5
4.5
4.9
4.2
NOx
[g/kW-hr]
13.4
7.1
8.4
4.8
11.7
5.3
CO
[g/kW-hr]
26.5
24.3
171
184
111
92
Power
[kW]
145
145
209
209
153
148
BSFC
[g/kW-hr]
326
360
349
356
329
350
4.5.3  Catalytic Control Emission Data

       4.5.3.1 Engine Testing

       In a joint effort with the California Air Resources Board (ARE), we contracted with
Southwest Research Institute to perform catalyst development and emission testing on a SD/I
marine engine.62 This test program was performed on a 7.4 L electronically controlled Mercruiser
engine with multi-port fuel injection. Figure 4.5-1 illustrates the three primary catalyst packaging
configurations used in this test program. The upper right-hand picture shows a catalyst packaged
in a riser extension which would be placed between the lower exhaust manifold and the exhaust
elbow. This riser had the same outer dimensions as the stock riser extension produced by Mercury
Marine. The upper left-hand picture shows a catalyst packaged in the elbow. The lower picture
shows a larger catalyst that was packaged downstream of the exhaust elbow.  All of these catalyst
configurations were water jacketed to prevent high surface temperatures.
                                           4-47

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Final Regulatory Impact Analysis
          Figure 4.5-1:  Three Catalyst Configurations Used in SD/I Test Program
       Table 4.5-4 presents the exhaust emission results for the baseline test and three catalyst
packaging configurations.  In each case a pair of catalysts were used, one for each exhaust
manifold.  For the riser catalyst configuration, we tested the engine with two cell densities, 60 and
300 cells per square inch (cpsi), to investigate the effects of back-pressure on power.  The catalysts
reduced in HC+NOx in the range of 42 to 77 percent and reduced CO in the range of 46 to 54
percent. There were no significant impacts on power, and fuel consumption actually improved due
to the closed-loop engine calibrations necessary to optimize the catalyst effectiveness. At the full
power mode, we left the engine controls in open-loop and allowed it to operate rich to protect the
catalysts from over-heating.
                                           4-48

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                                                  Feasibility of Exhaust Emission Control
     Table 4.5-4: Exhaust Emission Data on a 7.4 L SD/I Engine with Various Catalysts
Catalyst Scenario*
(cell density, volume, location)
baseline (no catalyst)
60 cpsi, 0.7 L, riser
300 cpsi, 0.7 L, riser
400 cpsi, 1.3 L, elbow
200 cpsi, 1.7 L, downstream
HC
[g/kW-hr]
4.7
2.5
1.7
2.8
2.1
NOx
[g/kW-hr]
9.4
5.7
1.9
1.1
1.2
CO
[g/kW-hr]
160
81
87
81
83
Power
[kW]
219
214
213
217
221
BSFC
[g/kW-hr]
357
345
349
337
341
*Multiply volume by two for total catalyst volume per engine.
       Additional reductions in HC+NOx and CO can be achieved by using EGR in addition to a
catalyst.  However, the added benefit of EGR is small compared to the emission reductions
achieved by the catalysts. Regardless, the use of EGR could give manufacturers some flexibility
in the design of their catalyst. In the catalyst testing work described above on the 7.4 L SD/I
marine engine, each of the catalyst configurations were tested with and without EGR.  Table 4.5-5
presents these test results.

    Table 4.5-5: Exhaust Emission Data on a 7.4 L SD/I Engine with Catalysts and EGR
Catalyst Scenario*
(cell density, volume, location)
60 cpsi, 0.7 L, riser
300 cpsi, 0.7 L, riser
400 cpsi, 1.3 L, elbow
200 cpsi, 1.7 L, downstream
HC+NOx [g/kW-hr]
catalyst
8.2
3.6
3.9
o o
J.J
catalyst + EGR
6.8
2.8
3.3
2.5
CO [g/kW-hr]
catalyst
81
87
81
83
catalyst + EGR
74
77
76
73
* Multiply volume by two for total catalyst volume per engine.
       4.5.3.2 Freshwater Boat Testing

       The catalyst testing described above was a first step in developing and demonstrating
catalysts that can reduce emissions from Marine SI engines.  However, this program only looked at
catalysts operating in a laboratory. Additional efforts have been made to address issues with using
catalyst in marine applications by operating engines in boats with catalysts.  When the California
Air Resources Board finalized their catalyst-based emission standards for SD/I engines, they
agreed to further assessment of the durability of catalyst used in boats through technology review.

       To that end, ARB, industry and the U.S. Coast Guard recently performed a cooperative in-
                                           4-49

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Final Regulatory Impact Analysis
boat demonstration program designed to demonstrate the feasibility of using catalysts in SD/I
applications.63'64 This testing included four boats, two engine types, and four catalysts.  The
catalysts were packaged in the exhaust emission manifold in such a way that they were water-
jacketed and capable of fitting within the existing boat design.  Each of the boats were operated by
the U.S. Coast Guard for 480 hours on a fresh water lake. This service accumulation period,
which was intended to represent the useful life of typical SD/I engines, began in December of
2003 and was completed in September of 2004. Table 4.5-6 presents a description of the boats
that were used in the test program.

           Table 4.5-6: Vessel Configurations for Full Useful Life Catalyst Testing
Boat
Inboard Straight-Drive Ski Boat
Inboard V-Drive Runabout
22 ft, Sterndrive Bowrider
19 ft. Sterndrive Runabout
Engine
5.7L, V-8
5.7L, V-8
5. 7 L, V-8
4.3 L, V-6
Catalyst
Type
metallic
ceramic
metallic
ceramic
Catalyst
Volume*
1.4 L
1.7L
1.4 L
0.7 L
Catalyst Cell
Density
300 cpsi
400 cpsi
200 cpsi
400 cpsi
*Multiply volume by two for total catalyst volume per engine.
       Exhaust emissions were measured for each catalyst before and after the durability testing.65
No significant deterioration was observed on any of the catalysts. In fact, all of the 5.7 L engines
were below the standard of 5 g/kW-hr HC+NOx even after the durability testing.  Although the
zero hour emissions for the 4.3 L engine were less than half of the HC+NOx standard, the final
emissions for the 4.3 L engine were 15 percent above the HC+NOx standard. However, it should
be noted that the 4.3L engine was determined to have excessive fuel delivered to one cylinder bank
and low compression in one of the cylinders. These problems did not appear to be related to the
catalyst installations and would account for the increase in emissions even without catalyst
deterioration.  Once the calibration on this engine was corrected, a level of 5 g/kW-hr HC+NOx
was achieved.  In addition, no deterioration was observed in the oxygen sensors which were
installed upstream of the catalysts.

       Significant carbon monoxide emission reductions were achieved, especially at lower power
modes.  At wide-open-throttle, the engines operated in open-loop to prevent the exhaust valves
from overheating. Additional reductions in CO could be achieved through better fuel air ratio
control.  For instance, although the engines in this test program were fuel injected, batch injections
were used.  In other words, all of the fuel injectors for each bank were firing at the same time
rather than timing the fuel injection with the valve timing for each individual cylinder.  Because of
this strategy, the engine would need to be calibrated somewhat rich. The next generation of
electronics for these engines are expected to have more sophisticated control which would allow
for optimized timing for each  fuel injector.
                                           4-50

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                                                  Feasibility of Exhaust Emission Control
           Table 4.5-7: Vessel Configurations for Full Useful Life Catalyst Testing

Boat
5.7 L engine
4.3 L engine
Inboard Straight-
Drive Ski Boat
Inboard V-Drive
Runabout
22 ft, Sterndrive
Bowrider
19 ft. Sterndrive
Runabout

Catalyst Aging
baseline (no catalyst)
baseline (no catalyst)
0 hours
480 hours
0 hours
480 hours
0 hours
480 hours
0 hours
480 hours*
HC
[g/kW-hr]
5.4
4.9
1.7
2.1
1.8
1.7
1.8
1.5
1.9
2.9
NOx
[g/kW-hr]
6.7
11.7
1.0
1.7
0.5
1.0
0.5
0.9
0.5
2.1
CO
[g/kW-hr]
193
111
100
117
87
102
74
93
106
116
       * after calibration corrected
       4.5.3.3 Saltwater Boat Testing

       Two test programs were initiated to investigate the feasibility of using catalysts on boats
used in saltwater.  In the first program, a small boat with a catalyst was operated over a set of
operation conditions, developed by industry, to represent the worst case conditions for water
reversion. In the second test program, three boats were equipped with catalysts and operated for
an extended period similar to the fresh water testing.

       4.5.3.3.1 Safety, Durability, and Performance Testing

       We contracted with SwRI to test catalysts on a Sterndrive engine before and after operation
on a boat in saltwater.66  The purpose of the testing was to determine if the catalyst would be
damaged by water reversion in the exhaust manifold. This testing was performed on a 19 foot
runabout with a 4.3 L Sterndrive engine. On previous testing on this boat without a catalyst, SwRI
found that the only water collected in the exhaust manifold was due to condensation. They were
able to prevent this condensation by fitting the water jacket around the exhaust system with a
thermostat to keep the manifold walls from becoming too cool.

       The 4.3 L engine was fitted with a pair of riser catalysts similar to the one illustrated in
Figure 4.5-1.  These catalysts had a cell density of 300 cpsi and a combined volume of 1.4 L. The
catalysts were water-jacketed to maintain low surface temperatures and, to prevent any possible
water reversion, cones were inserted in the exhaust elbows.  These cones were intended to increase
the difficulty  for water to creep up the inner walls of the exhaust manifold.  The water jacketing
system was fitted with a 82C thermostat to keep the manifold wall temperatures above the dew
                                           4-51

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Final Regulatory Impact Analysis
point of the exhaust gas (~50C) thereby preventing water condensation in the exhaust manifold.

       Prior to testing, the catalysts were aged using a rapid aging cycle designed to represent
50,000 miles of vehicle operation.  SwRI estimated that this would likely be more severe than
would be seen over the useful life of an SD/I engine. The engine was then tested for emissions, in
a test cell, with and without the aged catalysts installed in the exhaust manifold risers. In addition
to adding the catalysts, the engine fueling was optimized using closed-loop electronic emission
control.

       After the baseline emission  tests, the catalysts were installed on a 19 foot runabout
equipped with a similar 4.3 L engine used in the emissions test cell. The boat was operated on
saltwater over a number of safety, durability, and performance tests that were developed by
industry for heat soak, water ingestion, and engine exhaust back-pressure. In addition, SwRI
operated the boat over tests that they designed to represent operation and use that would most
likely induce water reversion. After this boat testing, the catalyst was returned to the laboratory
for a repetition of the baseline emission tests.

       Table 4.5-8 presents the baseline, aged catalyst, and post boat operation catalyst emission
test results. No significant deterioration of the catalysts were observed. Prior to boat testing, the
aged catalysts  achieved a 75  percent reduction in HC+NOx and a 36 percent reduction in CO.
After the boat  operation in saltwater, the catalysts achieved a 73 percent reduction in HC+NOx
and a 34 percent reduction in CO. As described in Chapter 3, if saltwater  had reached the catalyst,
there would have been  a large reduction in catalyst efficiency. No salt deposits were observed on
the catalysts when they were removed from the boat.

         Table 4.5-8: Exhaust Emission Data on a 4.3 L SD/I Engine with Catalysts
Catalyst Scenario
open-loop, no catalyst
closed-loop, no catalyst
aged catalyst pre boat
aged catalyst post boat
HC
[g/kW-hr]
4.9
4.5
2.1
2.2
NOx
[g/kW-hr]
11.7
10.4
2.0
2.3
CO
[g/kW-hr]
111
101
70
73
Power
[kW]
153
153
154
150
BSFC
[g/kW-hr]
329
327
321
327
       4.5.3.3.2 Extended Period In-Use Testing

       We engaged in a test program with the California Resources Board, United States Coast
Guard, National Marine Manufacturers Association, the Texas Department of Parks and Wildlife,
and Southwest Research Institute to evaluate three additional engines with catalysts in vessels
operating on salt-water.  Early in the program, two of the three manifolds experienced corrosion in
the salt-water environment resulting in water leaks and damage to the catalyst.  These manifolds
were rebuilt with guidance from experts in the marine industry and additional hours were
                                           4-52

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                                                  Feasibility of Exhaust Emission Control
accumulated on the boats.  Although the accumulated hours are well below the 480 hours
performed on fresh water, the completed operation showed no visible evidence of water reversion
or damage to the catalysts. Table 4.5-9 presents initial exhaust emission results for the three
engines, equipped with catalysts, included in this test program.

    Table 4.5-9: Baseline Emission Data for Engines/Catalysts in Saltwater Test Program
Catalyst Scenario
Maxum, 4.3L V6, ceramic catalysts
Sea Ray, 5.7L V8, metal catalysts
Malibu, 5.7L V8, ceramic catalysts
HC
[g/kW-hr]
2.1
1.3
0.5
NOx
[g/kW-hr]
0.7
0.3
0.4
CO
[g/kW-hr]
136
114
107
Power
[kW]
150
191
194
BSFC
[g/kW-hr]
345
351
348
       4.5.3.4 Production Engines

       At the time of proposal, only one manufacturer was selling inboard Marine SI engines
equipped with catalysts. These engines are being sold nationwide. The engines are based on 5.7L
automotive blocks and use electronically controlled fuel injection, twin catalysts, and onboard
diagnostics. The manufacturer, Indmar, has also performed extended durability testing in a
saltwater environment.  Test data from this engine is presented in Table 4.5-10, with and without
an applied deterioration factor.67  One advantage that Indmar has promoted with this engine is very
low CO at part throttle. Part throttle operation is associated with lower boat speeds where the risk
of CO poisoning is highest. The measured CO over the marine duty  cycle is primarily due to
emissions at wide open throttle, where the engine goes to open loop rich operation to protect the
exhaust valves from overheating.

   Table 4.5-10:  Exhaust Emission Data on a 5.7L Production SD/I Engine with Catalysts

measured test results
with deterioration factor applied
HC
[g/kW-hr]
1.8
2.0
NOx
[g/kW-hr]
2.0
2.3
CO
[g/kW-hr]
46.6
51.8
       At this time, three manufacturers have certified engines, equipped with catalysts, to the 5
g/kW-hr HC+NOx California standards for SD/I engines. Table 4.5-11 presents the certification
data available from the California Air Resources Board's Off-Road Certification Database.68
                                           4-53

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Final Regulatory Impact Analysis
           Table 4.5-11: Catalyst-Equipped SD/I Engines Certified in California
Manufacturer
Indmar

Mercury Marine




Volvo Penta

Engine Disp.
[liters]
5.7
5.7
1.6
3.0
5.0
5.7
8.1
8.1
5.0
8.1
Rated Power
[kW]
230
230
75
101
194
246
280
317
239
298
HC+NOx
[g/kW-hr]
3.7
4.6
4.2
2.7
1.8
3.4
2.8
4.6
3.3
2.6
       4.5.3.5 CO Emissions Reductions at Low versus High Power

       Under stoichiometric or lean conditions, catalysts are effective at oxidizing CO in the
exhaust. However, under very rich conditions, catalysts are not effective for reducing CO
emissions.  SD/I engines often run at high power modes for extended periods of time. At these
temperatures, engine marinizers must calibrate the engine to run rich as an engine protection
strategy.  If the engine were calibrated for a stoichometric air-fuel ratio at high power, high
temperatures could lead to failures in exhaust valves and cylinder heads.

       All of the data presented above on SD/I engines equipped with catalysts were based on
engines that used open-loop engine control at high power.  As a result, the catalysts achieved little
reduction in HC and CO at full power (test mode 1). However, NOx reductions were achieved at
mode 1 because NOx is effectively reduced under rich conditions.

       The catalysts were effective in reducing CO in modes 2 through 5 of the test procedure. In
these lower power modes, the engines described above saw CO reductions on the order of 80
percent. However, the weighted values over the test cycle only show about a 50 percent reduction
in CO because of the high contribution of mode 1 to the total weighted CO value. Studies have
shown that there is a higher risk of operator exposure to CO at lower boat speeds69 which would
correspond  to lower engine power modes. This suggests that CO reductions at lower power modes
may be more beneficial  than CO reductions at full power.

       To look at the effect of mode 1 on the cycle weighted CO levels, we performed an analysis
in which we recalculated the CO level for ten catalyst-equipped SD/I engines without mode 1.  To
determine the weighted  value without mode 1, the weighting factor for mode 1 was set to zero
percent and the weighting factors for modes 2 and 3 were each increased so that weighting factors
would sum  to 100 percent.  Figure 4.5-2 compares the CO emissions with and without including
                                          4-54

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                                                 Feasibility of Exhaust Emission Control
mode 1 for these engines. Although mode 1 is only weighted as 6 percent of the test cycle, but
makes up the majority of the cycle weighted CO value. Based on this analysis, the weighed CO
level would be 70-90 percent lower if mode 1 were not included in the test procedure.

           Figure 4.5-2: CO Emissions for SD/I Engines Equipped with Catalysts
                with and without Including Mode 1 in the Weighted Results
      140
      120
      100
             DE4 Weighting
              Without Mode 1
                                                                               10
4.6  Feasibility of Standard for Marine Generator Sets

       Currently, SI marine generator sets are regulated as Small SI or Large SI engines,
depending on their size. Most SI marine generators are less than 25 hp and are therefore classified
as Small SI engines. Generator sets in marine applications are unique in that they use liquid-
cooled engines. Liquid cooling allows manufacturers to minimize the temperature of hot surfaces
on marine generators, thereby reducing the risk of fires on a boat. For marine applications, liquid
cooling is practical because of the nearly unlimited source of cooling water around the boat.

       Another safety issue that has become apparent in recent years is carbon monoxide
poisoning on boats.  Studies have  shown that exhaust emissions from engines on boats can lead to
user exposure of high levels of carbon monoxide.70  The marine industry, Coast Guard, American
Boat and Yacht Council, and other stakeholders have been meeting regularly over the past several
years in an attempt to mitigate the risk of CO poisoning in boating.71'72 Mitigation strategies that
have been discussed at these meetings include labeling, education, diverting the exhaust flow with
smoke stacks, CO detectors, low CO emission technologies, and emission standards.

       The vast majority of gasoline marine generators are produced by two engine
manufacturers.  Recently, these two manufacturers have announced that they are converting their
                                          4-55

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Final Regulatory Impact Analysis
marine generator product lines over to low CO engines.73'74 They have stated that this is to reduce
the risk of CO poisoning and that this action is a result of boat builder demand. Both
manufacturers are using a combination of closed-loop electronic fuel injection and catalytic
control. To date, both of these manufacturers have certified some low CO engines and have stated
their intent to convert their full product lines in the near future.  These manufacturers also make
use of the electronic controls to monitor catalyst function. Table 4.6-1 presents the 2005 model
year certification levels for these engines.

     Table 4.6-1: 2005 MY Certification Levels for Low CO Marine Generator Engines
Engine
Manufacturer
Kohler Power
Systems
Westerbeke
Power
[kW]
10.2
7.5
17.9
Emission Control System
throttle-body injection, O2 sensor, catalyst
throttle-body injection, O2 sensor, catalyst
throttle-body injection, O2 sensor, catalyst
HC+NOx
[g/kW-hr]
7.2
2.0
4.4
CO
[g/kW-hr]
5.2
0.01
0.0
       In-use testing has been performed on two marine generator engine equipped with catalysts.
These engines were installed on rental houseboats and operated for a boating season. Testing was
first performed with low hours of operation; 108 hours for the 14 kW engine and 159 hours for the
20 kW.75 The CO performance was reported to be "impressive with exhaust stack CO emissions of
approximately 200 ppm for a fully warmed generator."  The emissions measured around the boat
were much lower due to dilution.  According to the  manufacturer, no significant deterioration has
been found in the emission performance of the catalysts. Note that the manufacturer recommends
changing the catalysts at 2000 hours and inspecting for CO at 1000 hours.

4.7  Test Procedures

       We are making several technical amendments to the existing exhaust emission test
procedures for Small SI and OB/PWC engines. These amendments are part of a larger effort to
develop uniform test procedures across all of our programs. We including SD/I engines in these
test procedures.   In addition we are establishing not-to-exceed requirements for Marine SI engines.
These new procedures are discussed in this section.

4.7.1  SD/I Certification Test Procedure

       We are using the same certification duty cycle and test procedures for all Marine SI
engines, including sterndrives and inboards. Table 4.5-6 presents the certification test duty cycle.
This duty cycle is commonly referred to as the E4 duty cycle and was developed using operational
data on outboard and sterndrive marine gasoline engines.76 In addition, the E4 duty cycle is
recommended by the International Standards Organization for use with all spark-ignition
pleasurecraft less than 24 meters in length.77 Although some Marine SI engines may be used for
commercial activities, these engines would not likely be made or used differently than those used
                                           4-56

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                                                  Feasibility of Exhaust Emission Control
for pleasure.
             Table 4.7-1: SI Marine Certification Steady-State Test Duty Cycle
Mode
1
2
3
4
5
% of Maximum Test
Speed (MES)
100
80
60
40
idle
% of Maximum Torque at
MES
100
71.6
46.5
25.0
Ob
% of Maximum Power2 at
MES
100
57.2
27.9
10.1
Weighting
Factor
0.06
0.14
0.15
0.25
0.40
       a o,
        % power = (% speed) * (% torque)
        15% of maximum torque at MES for high-performance engines

       For high-performance engines, the above test procedure is modified slightly. These
engines typically have substantial auxiliary loads and parasitic losses even when the vessel does
not need propulsion power.  In addition, these engines are not designed to operate at a low load
idle and survey data suggests that operators do not spend significant time at zero power idle.78 To
account for this, for high-performance engines, we revised the test torque at idle speed to be 15
percent of maximum torque at maximum test speed.

4.7.2  SI Marine Not-To-Exceed Requirements

       EPA is concerned that if a marine engine is designed for low emissions on average over a
low number of discrete test points, it may not necessarily operate with low emissions in-use.  This
is due to a range of speed and load combinations that can occur on a vessel which do not
necessarily lie on the test duty cycle. For instance, the test modes on the E4 duty cycle lie on an
average propeller curve.  However, a propulsion engine may never be fitted with an "average
propeller."  In addition, a light planing hull boat may operate at much lower torques than a heavily
loaded boat.

       It is our intent that an engine operate with low emissions under all in-use speed and load
combinations that can occur on a boat, rather than just the discrete test modes in the five-mode
duty cycle.  To ensure this, we have requirements  that extend to typical in-use operation.  We are
establishing not-to-exceed (NTE) requirements similar to those established for marine  diesel
engines.  Under this approach, manufacturers would design their engines to comply with a not-to-
exceed limit, tied to the standard, for HC+NOx and CO, within the NTE zone. In the cases where
the engine is included in averaging, banking, and trading of credits, the NTE limits would be tied
to the family emission limits.  We would reserve the right to test an engine in a lab  or installed in a
boat to confirm compliance to this requirement.

       We believe there are significant advantages to taking this approach.  The test procedure is
very flexible so it can represent the majority of in-use engine operation and ambient conditions.
Therefore, the NTE approach takes all of the benefits of a numerical standard and test procedure
and expands it to cover a broad range of conditions.  Also, laboratory testing makes it harder to
perform in-use testing because either the engines would have to be removed from the vessel or
                                           4-57

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Final Regulatory Impact Analysis
care would have to be taken that laboratory-type conditions can be achieved on the vessel. With
the NTE approach, in-use testing and compliance become much easier because emissions may be
sampled during normal vessel use. Because this approach is objective, it makes enforcement
easier and provides more certainty to the industry of what is expected in use versus over a fixed
laboratory test procedure.

       Even with the NTE requirements, we believe it is still important to retain standards based
on the steady-state duty cycle. This is the standard that we expect the certified marine engines to
meet on average in use. The NTE testing is more focused on  maximum emissions for segments of
operation and should not require additional technology beyond what is used to meet the new
standards. We believe basing the emission standards on a distinct cycle and using the NTE zone to
ensure in-use control creates a comprehensive program. In addition, the steady-state duty cycles
give a basis for calculating credits for averaging, banking, and trading.

       We believe that the same technology that can be used  to meet the standards over the five-
mode certification duty cycle can be used to meet the NTE caps in the NTE zone. We therefore do
not expect the NTE standards to cause marinizers to need additional technology. We do not
believe the NTE concept results in a large amount of additional testing, because these engines
should be designed to perform as well in use as they do over the steady-state five-mode
certification test.

       4.7.2.1  Shape of the NTE Zone

       The NTE zone is intended to capture typical in-use operation for marine vessels. We used
two data sources to define this operation.  The first data source was the collection of data on
marine engine  operation that was used to develop the ISO E4 steady-state duty cycle.79 Speed and
torque data were collected on 33 outboards and three sterndrives.  This data showed that the
marine engines generally operated along a propeller curve with some variation due to differences
in boat design and operation. A propeller curve defines the relationship between engine speed and
torque for a marine engine and is generally presented in terms of torque as a function of engine
speed in RPM raised to an exponent. The paper uses an exponent of 1.5 as a general fit, but states
that the  propeller curves for Marine SI applications range from exponents of 1.15 to 2.0.

       The second source of data was a study of marine engine operation recently initiated by the
marine industry.80 In this study, sixteen boats were tested in the water at various engine speeds.
These boats included seven sterndrives, three inboards, four outboards, and two personal
watercraft. To identify the full range of loads at each engine  speed, boats were operated both fully
loaded and lightly loaded. Boats were operated at steady speeds to identify torque at each speed.
In some cases, the operation was clearly unsafe or atypical. We did not include these operating
points in our analysis. An example of atypical operation would be with a boat so highly loaded
that it was operating in an unstable displacement mode with its bow sticking up into the air.

       Figure 4.7-1 presents test data from the two studies as well as the NTE zone for Marine SI
engines. This zone includes operation above and below the theoretical propeller curve used in the
E4 duty cycle.  Operation below 25 percent of rated speed is excluded because brake-specific

                                           4-58

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                                                 Feasibility of Exhaust Emission Control
emissions at low loads becomes very high due to low power in the denominator. This approach is
consistent with the marine diesel NTE zone.  The upper and lower borders of the NTE zone are
designed to capture all of the typical operation that was observed in the two studies. The curve
functions for these boarders are presented in Figure 4.7-1.

                Figure 4.7-1: NTE Zone and Marine Engine Operation Data
D
k.
O
    0)
   _N
    re
                      1.5 x Speed-0.16
                                                                 Outboard
                                                                 PWC
                                                               A  Inboard
                                                                 Sterndrive
                                                               x  SAE901596
                                                               O  E4 Setpoints
                                                                  Prop Curve
                                                                  Torque Curve
                                                                  NTE
                                                                  Zone
                                                                  Atypical Points
                                                S peed A1.5-0.08
                                          25.3% Torque
                    20%
                             40%         60%         80%
                                  Normalized Speed
100%
120%
       When testing the engine within the NTE zone, only steady-state operation would be
considered. It is unlikely that transient operation is necessary under the NTE concept to ensure
that emissions reductions are achieved. We designed the NTE zone to contain the operation near
an assumed propeller curve that the steady-state duty cycle represents. We believe that the vast
majority of the operation in the NTE zone would be steady-state. When bringing a boat to plane,
marine engine operation would be transient and would likely be above the NTE zone. However
we do not have enough information to quantify this. Also we do not believe that the NTE zone
should be extended to include areas an engine may  see under transient operation, but not under
steady-state operation.  For this reason, we do not believe that adding transient operation to the
NTE requirements is necessary at this time. We would revise this opinion in the future if there
were evidence that in-use emissions were increased due to insufficient emission control under
transient operation
                                           4-59

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Final Regulatory Impact Analysis
       4.7.2.2 Modal Emission Test Data within the NTE Zone

       The NTE zone has emissions caps which represent a multiplier times the weighted test
result used for certification.  Although ideally the engine should meet the certification level
throughout the NTE zone, we understand that a cap of 1.0 times the standard is not reasonable
because there is inevitably some variation in emissions over the range of engine operation. This is
consistent with the concept of a weighted modal emission test such as the E4 duty cycle.

       In developing the emission caps in the NTE zone, we collected modal HC+NOx and CO
emission data on a large number of OB, PWC, and SD/I engines. Because limited modal data is
available in published literature,81'82'83 most of the modal data on outboards and personal watercraft
was provided confidentially by individual manufacturers. Data on SD/I engines with catalysts was
collected as part of the catalyst development efforts discussed earlier in this chapter.84'85'86'87 Our
analysis focuses only on engines using technology that could be used to meet the new standards.
The modal data is presented in Figures 4.7-2 through 4.7-9 in terms of the modal emission rate
divided by the weighted E4 average for that engine. Each color bar represents a different engine.
Because of the large volume of data and differences in engine operation and emissions
performance, data is presented separately for carbureted 4-stroke, fuel-injected 4-stroke, and
direct-injected 2-stroke OB/PWC, and for catalyst-equipped SD/I engines.

       Figures 4.7-2 and 4.7-4 present normalized HC+NOx modal data for carbureted and EFI 4-
stroke OB/PWC engines. Note that most of the data points are near or below the E4 weighted
average (represented by bars near or below 1.0). This is largely due to the exclusion of idle
operation from the NTE zone compared to the E4 duty cycle that is 40 percent weighted at idle.
As mentioned above, idle is excluded because brake-specific emissions become very large at low
power due to a low power figure in the denominator (g/kW-hr). Especially for the carbureted
engines, higher normalized HC+NOx emissions are observed at the low power end of the NTE
zone (40 percent speed, 25 percent torque).  As shown in Figures 4.7-3 and 4.7-5, a similar trend is
observed with normalized CO emissions from these engines.
                                           4-60

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                                          Feasibility of Exhaust Emission Control
   Figure 4.7-2: Normalized Modal HC+NOx for Carbureted 4-Stroke OB/PWC
LLJ

"re
o
o
X

O
O
I

-a
o>
_N

"re
             40%, 25%         60%, 47%         80%, 72%         100%, 100%


                       Normalized Speed, Torque [% of rated]
      Figure 4.7-3: Normalized Modal CO for Carbureted 4-Stroke OB/PWC
            40%, 25%         60%, 47%         80%, 72%         100%, 100%


                        Normalized Speed, Torque [% of rated]
                                    4-61

-------
Final Regulatory Impact Analysis
          Figure 4.7-4: Normalized Modal HC+NOx for EFI 4-Stroke OB/PWC
2n
.u
1 R
UJ 1 R
 I .O
re
i, n
x, 1 .2
o i f r n n
2 1 n l FT Hi fl
+ t ' i
0)
 0.6
 0.4
o
2 0.2
On




rTTl nfffl IHn rfl
' -Hjhl ntylgLl
|J| f fj






-pi
I


.U i i
40%, 25% 60%, 47% 80%, 72% 100%, 100%
Normalized Speed, Torque [% of rated]
            Figure 4.7-5: Normalized Modal CO for EFI 4-Stroke OB/PWC
     2.5
     2.0
   i
   ra
   o
     1.5
   O
   o


   a 1-0
     0.5
     0.0
f
                40%, 25%          60%, 47%         80%, 72%         100%, 100%



                           Normalized Speed, Torque [% of rated]
                                        4-62

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                                                Feasibility of Exhaust Emission Control
       Figures 4.7-6 through 4.7-9 present normalized HC+NOx and CO modal data for direct-
injected 2-stroke OB/PWC engines. Based on the data collected, there appear to be two distinct
types of direct-injection 2-stroke engines. One manufacturer uses a higher pressure fuel system
with a unique combustion chamber design for low emissions.  Because the modal variation in
emission results are significantly different for the two engine designs, we designate them headings
of Type 1 and Type 2 engines and look at them separately for the purposes of this analysis.  As
shown in Figure 4.7-6 and 4.7-7, Type 1 engines tend to have relatively high HC+NOx at low
power, then fairly low emissions over the rest of the modes. For CO, these engines show much
less variability between modes.  For Type 2 engines, HC+NOx is below the E4 average in the mid-
speed range as shown in Figure 4.7-8. However, there is a wide degree of variation in how these
engines behave at low and high speed. Most of these engines seem to have high normalized
HC+NOx emissions either at low or at high speed. Figure 4.7-9 presents CO values for Type 1
engines. These engines tend to have high CO at full power with decreasing CO at lower power
modes.

       Figure 4.7-6: Normalized Modal HC+NOx for Type 1 DI 2-Stroke OB/PWC
                40%, 25%          60%, 47%          80%, 72%          100%, 100%

                           Normalized Speed, Torque [% of rated]
                                          4-63

-------
Final Regulatory Impact Analysis
         Figure 4.7-7: Normalized Modal CO for Type 1 DI 2-Stroke OB/PWC
     0.0
               40%, 25%          60%, 47%         80%, 72%        100%, 100%



                           Normalized Speed, Torque [% of rated]
       Figure 4.7-8: Normalized Modal HC+NOx for Type 2 DI 2-Stroke OB/PWC
2C
.0
51
LLJ 9 D
 Z.U
re
o
o
s
1"~l -I c
X 1 .O
O
2.
+
O
I 1 n
I .U
o
0)
_N
"5
n ^
u.o
o
2.
n n
PI
PI






1

r

1 n-
-
Tl
J
ni4l

T
f


 I

U.U I
40%, 25% 60%, 47% 80%, 72%
Normalized Speed, Torque [% of
1
r




III


rn



100%, 100%
rated]
                                       4-64

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                                                 Feasibility of Exhaust Emission Control
          Figure 4.7-9: Normalized Modal CO for Type 2 DI 2-Stroke OB/PWC
      0.0
                40%, 25%          60%, 47%          80%, 72%         100%, 100%

                             Normalized Speed, Torque [% of rated]
       Figures 4.7-10 and 4.7-11 present normalized HC+NOx and CO modal data for SD/I
engines equipped with catalysts. All of these engines demonstrated HC+NOx emissions below the
E4 average in the mid-speed range. However, some of these engines show somewhat higher
normalized HC+NOx emissions at either the low-power or full power mode.  These differences are
likely a function of catalyst design and location as well as air/fuel calibration. At wide open
throttle, all of these engines were calibrated to run rich as an engine protection strategy, so
emission reductions at this mode are due to NOx reductions in the catalyst. Because these engines
are designed to run rich at full power, high CO emissions were observed at this mode. For the rest
of the power range, CO emissions were generally below the E4 average for these engines.  As part
of the catalyst development work for SD/I engines, one engine was tested over 26 modes, most of
which are contained in the NTE zone.88 This engine was tested in its baseline configuration (open-
loop fuel injection) as well as with three catalyst configurations. The three catalyst configurations
included one close-coupled to the engine (in the riser), one a little farther downstream (in the
exhaust elbow), and a larger catalyst external to the existing exhaust manifold. This data provided
insight into how exhaust emissions throughout the NTE zone for Marine SI engines compare to the
modal test data on the theoretical propeller curve. This data is presented in Appendix 4A.
                                          4-65

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Final Regulatory Impact Analysis
Figure 4.7-10: Normalized
1 R
I .O
1 A
 1.4
LLJ
"J5 -| 9
- 1-^
O
u 1 n
1  ' 1 .U
X,
O
O
n R
o u.o
0)
_N
_ U.4
1 n?
Z. U.Z
n n
Modal HC+NOx for SD/I with Catalysts









i


- n
_ _

Rw
r _
r -
L



Jl 	 Iff 1
" 41- 1 " fl-
: fl - :
: ..I.:...




i 	




-








40%, 25% 50%, 35% 60%, 47% 70%, 59% 80%, 72% 90%, 85% 100%, 100%
Normalized Speed, Torque [% of rated]
Figure 4.7-11: Normalized Modal CO for SD/I with Catalysts
2 C
o n
O.U
HI 9 c
^ z.o
ra
o
o
s 9 n
!=. Z.U
0
o
__ -I C
~ 1 .0
0)
o
Oc
.0
On











.
I
n n
II

IflaM [
u
n ^rn PI r-L_ F
1" idlL It



-


-












.U i i i
40%, 25% 50%, 35% 60%, 47% 70%, 59% 80%, 72% 90%, 85% 100%, 100%
Normalized Speed, Torque [% of rated]
                                         4-66

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                                                 Feasibility of Exhaust Emission Control
       4.7.2.3 NTE Zones and Standards

       As described above, the emissions characteristics of marine engines are largely dependent
on technology type.  Four-stroke engines tend to have relatively constant emission levels
throughout the NTE zone.  In contrast, two-stroke engine tend to have high variability in
emissions, not only within the NTE zone but between different engine designs as well. Catalyst-
equipped engines tend to have relatively flat emissions profiles, in the NTE zone, when operating
in closed-loop engine control mode. However, at higher engine power, the engines are calibrated
to operate with a rich fuel-air ratio, in open-loop control, to protect the exhaust valves and catalyst
from high exhaust temperatures. This reduces the catalyst efficiency at high power for oxidizing
HC and CO.

       Since the NPRM was published, we have worked with engine manufacturers to better
understand the design constraints, operation, and emissions characteristics of marine engines.
Based on this understanding, and the emission data presented above, we decided to develop
different NTE standards for three distinct types of engines; 4-stroke, 2-stroke, and catalyst-
equipped. These standards are discussed below.

       We used the modal  data presented above and the data on additional operation points
presented in Appendix 4A to develop NTE limits. These limits are presented as a multiplier times
the Family Emission Limit (FEL) developed using the 5-mode test procedure. The limits represent
the levels that can be  met by the majority of the marine engines tested.  In the case of engines that
have modal emissions that are somewhat higher than the NTE limits, we believe that these engines
can be  calibrated to meet these limits.  In addition, the limits are based on the FELs chosen by
manufacturers at certification. Therefore, manufacturers would have the option of increasing their
FELs, in  some cases,  to bring otherwise problem engines into compliance with the NTE limits.

       4.7.2.3.1 4-Stroke Engines

       The emissions data, presented above, for 4-stroke marine engines suggests that brake-
specific emissions rates are relatively constant throughout  the NTE zone.  One exception is slightly
higher HC+NOx emissions at low power. To account for this, we are subdividing the NTE zone to
have a  low power subzone below 50 percent of maximum test speed. In this low power subzone,
the HC+NOx NTE limit is  1.6, while it is 1.4 for the remainder of the NTE zone. The CO NTE
limit is 1.5 throughout the NTE zone. Figure 4.7-12 presents the NTE zone and subzones.  These
limits would apply to all non-catalyzed four-stroke marine engines.
                                           4-67

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Final Regulatory Impact Analysis
                  Figure 4.7-12: 4-Stroke Engine NTE Zone and Subzones
     120%
          0%
                                          25.3% Torque
                              SpeedA1.5 (theoretical propeller curve)
20%
40%         60%         80%
     Normalized Speed
100%
120%
       4.7.2.3.2  2-Stroke Engines

       The emissions data presented above, for 2-stroke direct-injection marine engines suggests
that these engines have high variability in emissions, not only within the NTE zone but between
different engine designs as well. Due to this variability, we do not believe that a flat (or stepped)
limit in the NTE zone could be effectively used to establish meaningful standards for these
engines.  At the same time, we believe that NTE standards are valuable for facilitating in-use
testing. Therefore, we developed a weighted NTE approach specifically for these engines. In the
long term, we may  consider further emission reduction based  on catalytic control applied to
OB/PWC engines.  In this case, we would revisit the appropriateness of the weighted NTE
approach in the context of those standards.

       Under the weighted NTE approach, emissions data is collected at five test points.  These
test points are idle,  full power, and the speeds specified in modes 2-4 of the 5-mode duty cycle.
Similar to the 5-mode duty cycle, the five test points are weighted to achieve a composite value.
This composite value must be no higher than 1.2 times the FEL for that engine.

       The difference  in this approach, from the 5-mode duty cycle, is that the test torque is not
specified. During an in-use test, the engine would be set to the target speed and the torque value
would be allowed to float. In addition, at wide open throttle, the engine speed would be based on
                                           4-68

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                                                 Feasibility of Exhaust Emission Control
actual performance on the boat. Because in-use engines installed in boats do not generally operate
on the theoretical propeller curve used to define the 5-mode duty cycle, this NTE approach helps
facilitate NTE testing.

       At each test mode, limits are placed on allowable engine operation.  These limits are
generally based on the NTE zone presented above for 4-stroke engines, but there are two
exceptions. First, the lower torque limit at 40 percent speed is lowered slightly to better ensure
that an engine on an in-use boat is capable of operating within the NTE zone.  Second, the speed
range is extended at wide-open throttle for the same reason. Figure 4.7-13 presents this approach.

                  Figure 4.7-13: 2-Stroke Engine Weighted NTE Concept
     120%
     100%
   =  80%
  I
  re

  o
60%
      40%
      20%
       0%
                Idle
                              SpeedA1.5 (theoretical propeller curve)
          o%
               20%
40%         60%         80%
     Normalized  Speed
100%
120%
       During laboratory testing, any point within each of the four non-idle subzones may be
chosen as test points. These test points do not necessarily need to lie on a propeller curve. It
should be noted that the actual power measured would be used in the calculation of the weighted
brake-specific emissions.

       4.7.2.3.3  Catalyst-Equipped Engines

       SD/I engines are  anticipated to make use of three-way catalysts to meet the new exhaust
emission standards.  These catalysts are most effective when the fuel-air ratio in the exhaust is near
stoichiometry. Engine manufacturers use closed-loop control to monitor and maintain the proper
fuel-air ratio in the exhaust for optimum catalyst efficiency. However, at high power, engine
                                           4-69

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Final Regulatory Impact Analysis
manufacturers must increase the fueling rate to reduce the temperature of the exhaust. Otherwise,
if the exhaust temperature becomes too high, exhaust valves and catalysts may be damaged.
During rich, open-loop operation at high power, the catalyst is oxygen-limited and less effective at
oxidizing HC and CO. To address the issue of open-loop catalyst efficiency, we created a high
power subzone in the NTE zone for catalyst-equipped engines.

       The majority of SD/I engines are based on engine blocks produced by General Motors. To
determine the appropriate threshold for the high power-subzone, we used temperature data
supplied by General Motors.89 This data was consistent with confidential data supplied by engine
marinizers on engine  control strategies for catalyst-equipped SD/I engines.  Figure 4.7-14 presents
the stoichiometric limits for engine protection, based on the General Motors study, for three
different engine designs.

           Figure 4.7-14: GM Study-Stoichiometric Limits for Engine Protection
                  Engine Torque Curve
     100%
   0)
   3
I-  90%
0)
_N
"re
  80%
o
      70%
                                                                      5.7L NA

                                                                   k  6.0L SC Base

                                                                   76.0L SC Hi Pert
                                                           \?
                   70%
                                80%            90%
                              Normalized Speed
100%
       Figure 4.7-15 presents the NTE zone and high power subzone for catalyst-equipped marine
engines.  The shape of the high power subzone is based on the General Motors engine protection
data. The emission limits are based on data discussed above on SD/I engines, with catalysts,
operating in open-loop versus closed-loop engine control.

       For catalyst-equipped engines, the largest contribution of emissions over the 5-mode duty
cycle comes from open-loop operation at Mode 1.  In addition, the idle point (Mode 5) is weighted
                                          4-70

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                                                 Feasibility of Exhaust Emission Control
40 percent in the 5-mode duty cycle, but not included in the NTE zone.  For this reason,
brake-specific emissions throughout most of the NTE zone are less than the weighted average from
the steady-state testing. For most of the NTE zone, we are therefore requiring a limit equal to the
duty-cycle standard (i.e., NTE multiplier = 1.0).

       Emission data on catalyst-equipped engines also show higher emissions near full-power
operation. As discussed above, this is due to the need for richer fuel-air ratios under high-power
operation to protect the engines from overheating.  We  are therefore establishing higher NTE
limits for subzone 1 based on emissions performance during open-loop operation.  Specifically, we
are establishing an HC+NOx limit of 1.5 times the duty-cycle standard.  Some HC+NOx control is
expected in subzone 1 because a three-way catalyst will effectively reduce NOx emissions under
rich conditions. However, for subzone 1, we are not setting a CO limit.  Under rich conditions, a
three-way catalyst is not at all effective for oxidizing HC or CO emissions. In addition, the cycle
weighted emission level for CO is primarily driven by Mode 1.

            Figure 4.7-15: Catalyst-Equipped Engine NTE Zone and Subzones
     120%
     100%
   g.  80%
   ft  60%
  "re

  Z  40%
      20%
       0%
                                         N 25.3% Torque
                              SpeedA1.5 (theoretical propeller curve)
         o%
20%
40%         60%         80%
     Normalized Speed
100%
120%
       4.7.2.4 Ambient Conditions

       Ambient air conditions, including temperature and humidity, may have a significant effect
on emissions from marine engines in-use. To ensure real world emissions control, the NTE zone
testing should include a wide range of ambient air conditions representative of real world
conditions. Because these engines are used in similar environments as marine diesel engines, we
                                           4-71

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Final Regulatory Impact Analysis
are applying the same ambient ranges to the Marine SI NTE requirements as already exist for
marine diesel engine NTE requirements.

       We believe that the appropriate ranges should be 13-30C (55-86F) for air temperature
and 7.1-10.7 grams water per kilogram dry air (50-75 grains/pound of dry air) for air humidity.
The air temperature ranges are based on temperatures seen during ozone exceedences, except that
the upper end of the temperature range has been adjusted to account for the cooling effect of a
body of water on the air above it.90 We are also aware, however, that marine engines  sometimes
draw their intake air from an engine compartment or engine room such that intake air temperatures
are substantially higher than ambient air temperatures. In this case, we would retain 35C as the
end of the NTE temperature range for engines that do not draw their intake air directly from the
outdoor ambient.

       For NTE testing in which the air temperature or humidity is outside the specified range, we
require that the emissions must be corrected back to the specified air temperature or humidity
range.  These corrections would be consistent with the equations in 40 CFR Part 91, Subpart E
except that these equations correct to 25C and 10.7 grams per kilogram of dry air while the NTE
corrections would be to the nearest outside edge of the specified ranges. For instance, if the
outdoor air temperature were higher than 30C for an engine that drew fresh outdoor air into the
intake, a temperature correction factor could be applied to the emissions results to determine what
emissions would be at 30C.

       Ambient water temperature also may affect emissions due to it's impact on engine cooling.
For this reason, we are requiring that the NTE testing include a range of ambient water
temperatures from 5 to 27C (41 to 80F).  The water temperature range is based on temperatures
that marine engines experience in the U.S. in-use.  At this time, we are not aware of an established
correction for ambient water temperature, therefore the NTE zone testing would have to be withing
the specified ambient water temperature range.

4.8 Impacts on Safety, Noise, and Energy

       Section 213 of the Clean Air Act directs us to consider the potential impacts on safety,
noise, and energy when establishing the feasibility of emission standards for nonroad engines.
Furthermore, section 205 of Public Law 109-54 requires us to assess potential safety issues,
including the risk of fire and burn to consumers in use, associated with the emission standards for
nonroad spark-ignition engines under 50 horsepower. As further detailed  in the following
sections, we expect that the exhaust emission standards will either have no adverse affect on
safety, noise, and energy or will improve certain aspects of these important characteristics.

4.8.1  Safety

       We conducted a comprehensive, multi-year safety study of nonroad SI engines that focused
on the following areas where we are finalizing new exhaust standards.91 These areas are:

              New catalyst-based HC+NOx exhaust emission standards for Class I and II

                                           4-72

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                                                 Feasibility of Exhaust Emission Control
             nonhandheld (NHH) engines; and

             New HC+NOx exhaust emission standards for outboard and personal watercraft
             (OB/PWC) engines and vessels, and a new CO exhaust emission standard for NHH
             engines used in marine auxiliary applications.

       Each of these four areas is discussed in greater detail in the next sections.

       4.8.1.1 Exhaust Emission Standards for Small Spark-Ignition Engines

       The technology approaches that we assessed for achieving the Small SI engine standards
included exhaust catalyst aftertreatment and improvements to engine and fuel system  designs.  In
addition to our own testing and  development effort, we also met with engine and  equipment
manufacturers to better understand their designs and technology and to determine the  state of
technological progress beyond EPA's Phase 2 standards.

       The scope of our safety  study included Class I and Class II engine systems that are used in
residential walk-behind and ride-on lawn mower applications, respectively. Residential lawn
mower equipment was chosen for the following reasons.

          Lawn mowers and the closely-related category of lawn tractors overwhelmingly
          represent the largest categories of equipment using Class I and Class II engines. We
          estimate that over 47 million walk-behind mowers and ride-on lawn and turf equipment
          are in-use in the US  today.
          These equipment types represent the majority of sales for Small SI engines.
       -   Consumer Product Safety Commission (CPSC) data indicates that more thermal burn
          injuries associated with lawn mowers occur than with other NHH equipment; lawn
          mowers therefore represent the largest thermal burn risk for these classes of engines.
       -   General findings regarding advanced emission control technologies for residential lawn
          and garden equipment carry over to commercial lawn and turf care equipment as well
          as to other NHH equipment using Class I and Class II engines.  Lawn  mower design
          and use characteristics pose unique safety implications not encountered by other NHH
          equipment using these engines (i.e. a mower deck collects debris during operation
          whereas a pressure washer collects no  debris). Thus, other NHH equipment may
          employ similar advanced emission control technologies for meeting the standards
          without a corresponding concern regarding the safety issues analyzed  in this  study.

       We conducted the technical study of the incremental risk on several fronts. First, working
with the CPSC, we evaluated their reports and databases and other outside sources to identify
those in-use situations which create fire and burn  risk for consumers. The  outside sources
included meetings, workshops,  and discussions with engine and  equipment manufacturers.  The
following scenarios were identified for evaluation:

       -   Thermal burns due to inadvertent contact with hot surface on engine or equipment;
       -   Fires from grass and leaf debris on the engine or equipment;

                                          4-73

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Final Regulatory Impact Analysis
          Fires due to fuel leaks on hot surfaces;
          Fires related to spilled fuel or refueling vapor;
       -   Equipment or structure fire when equipment is left unattended after being used;
          Engine malfunction resulting in an ignitable mixture of unburned fuel and air in the
          muffler (engine misfire);  and
       -   Fire due to operation with richer than designed air-fuel ratio in the engine or catalyst.

       These scenarios cover a comprehensive variety of in-use conditions or circumstances
which potentially  could lead to an increase in burns or fires. They may occur presently or not at
all, but were included in our study because of the potential impact on safety if they were to occur.
The focus of the analysis was, therefore, on the incremental impact on the likelihood and severity
of the adverse condition in addition to the  potential causes as it related to the use of more advanced
emissions control  technology.

       Second, we conducted extensive laboratory and field testing of both current technology
(Phase 2) and prototype  catalyst-equipped advanced-technology engines and equipment (Phase 3)
to assess the emission control performance and thermal characteristics  of the engines and
equipment. This testing included a comparison of exhaust system, engine, and equipment surface
temperatures using thermal imaging  equipment.

       Third, we contracted with Southwest Research Institute (SwRI) to conduct design and
process Failure Mode and Effects Analyses (FMEA).92  The SwRI FMEA focused on comparing
current Phase 2 and Phase 3 compliant engines and equipment to evaluate incremental changes in
risk probability as a way of evaluating the incremental risk of upgrading Phase 2 engines to meet
Phase 3 emission standards.  This is  an engineering analysis tool to help engineers and other
professional staff on the FMEA team to identify and manage risk. In a FMEA, potential failure
modes, causes of failure, and failure effects are identified and  a resulting risk probability is
calculated from these results.  This risk probability is used by  the FMEA team to rank problems
for potential action to reduce or eliminate the causal factors. Identifying these causal factors is
important because they are the elements that a manufacturer can consider reducing the adverse
effects that might  result from a particular failure mode.

       Our technical work and subsequent analysis of all of the data and information strongly
indicate that effective catalyst-based standards can be implemented without an incremental
increase in the risk of fire or burn to the consumer either during or after using the equipment.
Similarly, we did not find any increase in the risk of fire during storage near typical combustible
materials. In many cases, the designs used for catalyst-based technology can lead to an
incremental decrease in such risk.

       More specifically, our work included taking temperature measurements and infrared
thermal images of both OEM mufflers and prototype catalyst/mufflers on six Class 1 engines and
three Class 2 engines as  part of the safety study.  We integrated the emission reduction catalyst
into the muffler. In doing so, we generally designed heat management features into the
catalyst/muffler and cooling system. These heat  management design elements, all of which were
not used on every  prototype, included: 1) positioning the catalyst within the cooling air flow of the

                                           4-74

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                                                 Feasibility of Exhaust Emission Control
engine fan or redirecting some cooling air over the catalyst area with a steel shroud; 2) redirecting
exhaust flow through multiple chambers or baffles within the catalyst/muffler; 3) larger
catalyst/muffler volumes than the original equipment muffler; and 4) minimizing CO oxidation at
moderate to high load conditions to maintain exhaust system surface temperatures comparable to
those of the OEM systems. The measurements and images were taken during various engine
operating conditions and as the engines cooled down after being shut off. This latter event,
termed "hot soak," is an important  consideration since it is often when the operator is in close
proximity to the engine either performing maintenance or refueling the equipment.

       Figures 4.8-1 and 4.8-2 are  an example of the measurements and images taken to compare
Class 1 engine original equipment (OEM) mufflers to the same engines equipped with prototype
catalyst/mufflers.  The first figure depicts surface temperatures from engine number 244 while
operated on a laboratory dynamometer over three modes of EPA's A-cycle steady-state test cycle.
The second figure shows surface temperatures for the same engine at different times during hot
soak. The prototype catalyst/muffler system shown in these figures uses one of the most effective
heat management designs in the safety study.  As shown, the catalyst system in this example has
much lower surface temperatures during both engine operation and hot soak.

       Similar information was collected in the laboratory for Class 2 engines used in lawn
tractors. However, those tests were conducted on the "raw" engines without the chassis, which is
an integral part of the overall engine cooling system for most residential Class 2 applications.
Because of this, we believe it is more appropriate to compare the thermal measurements from field
testing of the integrated unit.

       The test results for engine 251 are fairly typical of the Class 2 lawn tractor test results.
During engine operation, the OEM muffler configuration had exposed surface temperatures of
approximately 200 C as viewed from both sides of the tractor when cutting moderate to heavy
grass and peak temperatures as high as 300 to 365  C. The lawn tractor equipped with engine 253,
which is from the same engine family as number 251, was fitted with a prototype catalyst/muffler
exhibited exposed surface temperatures of approximately 115 to 130 C and peaks of 160 to 190
C. The lower temperatures for the prototype catalyst system is in part due to the more effective
cooling of the catalyst/mufflers due to the re-routing of cooling air through the chassis and other
heat management design elements.

       The hot soak results for the above engines and two other related Class 2 lawn mowers are
shown in Figure 4.8-3. The two-minute nominal refueling point after engine shut-down following
30 minutes of grass-cutting operation is shown for reference. In these tests, both of the engines
with prototype catalyst/mufflers had lower peak surface temperatures than the OEM muffler
configurations.
                                           4-75

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Final Regulatory Impact Analysis
   Figure 4.8-1: Surface Temperature Infrared Thermal Images of Exhaust System
   Components for Class 1 Engine 244 with a Catalyst/Muffler (left) and an OEM Muffler
   (right) at Various Operating Modes.
             ygtfun f HCinduy *ir
                         >oi ThncCle
                 f3;e temperature: 230 C

              50% Load-Mode 3
       Maximum surface temperature: 102

              10% Load-Mode 5
                                                           OEMttufflar
  aximum surface temperature: 551 C

       50% Load-Mode 3
Maximum surface temperature: 421 C

       10% Load-Mode 5
                                                            ace temperature: 363 C
                                         4-76

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                                                 Feasibility of Exhaust Emission Control
Figure 4.8-2: Hot Soak Surface Temperature Infrared Thermal Images of Exhaust System
Components for Class 1 Engine 244 After Sustained Wide Open Throttle and 100 Percent
Load.
         Modified
      Maximum, surfeice tmf lenrjjre
      Ms-dmum surfeiie temf icntijre
      M^odmium. UEfi.ce
        OEMIiluffler
Mmnoim. suEfece taifiOTimK: 4-83 * C
                        mm
                                                       Maximumeurfiice temperature: 4-18 *
                                           4-77

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Final Regulatory Impact Analysis
 Figure 4.8-3: Hot Soak Peak Surface Temperatures Infrared Thermal Images for Class 2
 Lawn Tractors Following After Approximately 30-Minutes of Grass Cutting.
   o
   
   
-------
                                                  Feasibility of Exhaust Emission Control
use.  Based on the applicability of Coast Guard and ABYC safety standards and the good in-use
experience with advanced-technology engines in the current vessel fleet, we believe new emission
standards would not create an incremental increase in the risk of fire or burn to the consumer.

4.8.2 Noise

       As automotive technology demonstrates, achieving low emissions from spark-ignition
engines can correspond with greatly reduced noise levels. Direct-injection two-stroke and four-
stroke OB/PWC have been reported to be much quieter than traditional carbureted two-stroke
engines. Catalysts in the exhaust act as mufflers which can reduce noise. Additionally, adding a
properly designed catalyst to the existing muffler found on all Small SI engines can offer the
opportunity to incrementally reduce noise.

4.8.3 Energy

       Adopting new technologies for controlling fuel metering and air-fuel mixing, particularly
the conversion of some carbureted engines to advanced fuel injection technologies, will lead to
improvements in fuel consumption.  This is especially true for OB/PWC engines where we expect
the standards to result in the replacement of old-technology two stroke engines with more fuel
efficient technologies such as two-stroke direct injection or four-stroke engines. Carbureted
crankcase-scavenged two-stroke engines are inefficient in that 25 percent or more of the fuel
entering the engine may leave the engine unburned.  We estimate a fuel savings of about 61
million gallons of gasoline from marine engines in 2030, when most boats would be using engines
complying with the standard.

       The conversion of some carbureted Small SI engines to fuel injection technologies is also
expected to improve fuel economy.  We estimate approximately 7 percent of the Class II engines
will be converted to fuel injection and that this will result in a fuel savings of about 10 percent for
each converted engine. This translates to a fuel savings of about 22 million gallons of gasoline in
2030 when all of the Class II engines used in the U.S. will comply with the Phase 3 standards. By
contrast, the use of catalyst-based control systems on Small SI engines is not expected to change
their fuel consumption characteristics. These estimates are discussed in more detail in Chapter 6.
                                           4-79

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Final Regulatory Impact Analysis
     APPENDIX 4A: Normalized Modal Emissions for a 7.4 L MPI SD/I
           Figure 4A-1:  HC+NOx Ratios for 7.4L MPI Engine, Baseline
140%
120%
 6
0.6 a 
' 0.9 1.1
05 o
a 0.6
0.8
o
NA

% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%
Normalized Speed
               Figure 4A-2: CO Ratios for 7.4L MPI Engine, Baseline
140%
120%

-------
                                    Feasibility of Exhaust Emission Control
Figure 4A-3:  HC+NOx Ratios for 7.4L MPI Engine, Riser Catalysts
140%
120%
CD 100%
3
E
I 80%
^
N
ID 60%
o
~Z. 40%
20%
0%
0

07
0.7
O
0.6
0.8
n- -9 ^ no
<* oa7 a9 0^9
d5 07 07
0.9 ...  66 1.0
0 0.4 1 0 0
1.6 a V
f> Q 0
<> 0.4 05
V 0.3  
1.3
o
NA

% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%
Normalized Speed
   Figure 4A-4:  CO Ratios for 7.4L MPI Engine, Riser Catalysts
140%
120%
0 100%
3
E
I 80%
^
N
ID *
i_
o
Z 40%
20%
0%
0

1 8
18
1.9
0.7
 0.9 V
o 0.2 04 '-4
a '
o4 n^ 02
o3 n^  ^1 168
 0.3 n ^ 
0.3 a uod
 Q 0
<> 0.4 04
^5 o.o * 
c-6
NA

% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%
Normalized Speed
                              4-81

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Final Regulatory Impact Analysis
                Figure 4A-5: HC+NOx Ratios for 7.4L MPI Engine, Elbow Catalysts
140%
120%
CD 100%
E
I 80%
N
ID 60%
o
~Z. 40%
20%
0%
0

Dfi
 0.5
O
0.6
03 "6 '5 05
0 a3 064 6
0X6 0.5 63
<55 05 0.2 05
H 0.5 o <5
17 05 
15 o4 o
b 0,3
167
NA

% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%
Normalized Speed
                   Figure 4A-6: CO Ratios for 7.4L MPI Engine, Elbow Catalysts
140%
120%
0 100%
3
E
I 80%
^
N
ro s""/0
i_
o
Z 40%
20%
0%
0

1 R
1.7
O
1.8
0.5
1.2
Oo 0,7 c>
6 rf9 0.6
 ^0^4
0,4 0.3 0.1
^ V 04 ai
0,4 0 o
0 04 0.5
04 <> o
^ OJ
68
NA

% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%
Normalized Speed
                                            4-82

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                                    Feasibility of Exhaust Emission Control
Figure 4A-7:  HC+NOx Ratios for 7.4L MPI Engine, External Catalysts
CD
E

N
O
140%
120%
100%
80%
60%
40%
20%
0%
0

0.4
0.3
0.3
o3 
0.3
0.3 o
n ^ o n 
0^3 0^3 o
 0.2 04 o c
14 H
i..t n ^
0<56 <>6
A A
a 0.0
NA

% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%
Normalized Speed
   Figure 4A-8: CO Ratios for 7.4L MPI Engine, External Catalysts
140%
120%
0 100%
3
E
I 80%
^
N
ID *
i_
o
Z 40%
20%
0%
0

0.3
0.3
o
0.5
0,4 "
0.4
0.2 *
n ? o n ^
V 0,1 04 V
c8 0.3 CL1
0.4 " 0.2 06
 0 4 0.5 o
0,9 Q, d 
" ^ 0,7 0,7
a5 6
,1
NA

% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%
Normalized Speed
                             4-83

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Final Regulatory Impact Analysis
Chapter 4 References
1.  Internal Combustion Engine Fundamentals, Heywood, J., McGraw-Hill, Inc., New York, 1988, pp.829-836,
Docket Identification EPA-HQ-OAR-2004-0008-0203.

2.  Internal Combustion Engine Fundamentals, Heywood, J., McGraw-Hill, Inc., New York, 1988, pp.827-829,
Docket Identification EPA-HQ-OAR-2004-0008-0203.

3.  Conversation between Tim Fileman at Flagship Marine and Mike Samulski at U.S. EPA, February 10, 1999.

4.  "Benefits and Cost of Potential Tier 2 Emission Reduction Technologies," Energy and Environmental Analysis,
Final Report, November 1997,  Docket Identification EPA-HQ-OAR-2004-0008-0198.

5.  "Study on Air Assist Fuel Injector Atomization and Effects on Exhaust Emission Reduction," Saikalis, G., Byers,
R., Nogi., T.,SAE Paper 930323, 1993, Docket Identification EPA-HQ-OAR-2004-0008-0217.

6.  "Three-Way Catalyst Technology for Off-Road Equipment Powered by Gasoline and LPG Engines," Southwest
Research Institute, prepared for CARB, CEP A, and SCAQMD, (SwRI 8778), April 1999, Docket Identification
EPA-HQ-OAR-2004-0008-0224.

7.  Internal Combustion Engine Fundamentals, Heywood, J., McGraw-Hill, Inc., New York, 1988, pp. 836-839,
Docket Identification EPA-HQ-OAR-2004-0008-0203.

8.  "Improving the NOx/Fuel Economy Trade-Off for Gasoline Engines with the CCVS Combustion System,"
Stokes, J., Lake, T., Christie, M., Denbratt, I.,  SAE Paper 940482, 1994, Docket Identification EPA-HQ-OAR-2004-
0008-0498.

9.  Wu, H., Yang, S., Wang, A., Kao, H., "Emission Control Technologies for 50 and 125 cc Motorcycles in
Taiwan," SAE Paper 980938, 1998, Docket Identification EPA-HQ-OAR-2004-0008-0502.

10. Borland, M., Zhao, F., "Application of Secondary Air Injection for Simultaneously Reducing Converter-In
Emissions and Improving Catalyst Light-Off Performance," SAE Paper 2002-01-2803, 2001, Docket Identification
EPA-HQ-OAR-2004-0008-0497.

11. Koehlen, C., Holder, E., Guido, V., "Investigation of Post Oxidation and Its Dependency on Engine Combustion
and Exhaust Manifold Design," SAE Paper 2002-01-0744, 2002.

12. "Benefits and Cost of Potential Tier 2 Emission Reduction Technologies," Energy and Environmental Analysis,
Final Report, November 1997,  Docket Identification EPA-HQ-OAR-2004-0008-0198.


13. "Reduction of Exhaust Gas Emissions by Using Pd-based Three-way Catalysts," Lindner, D., Lox,  E.S.,
Kreuzer, T., Ostgathe, K., van Yperen, R., SAE Paper 960802, 1996, Docket Identification EPA-HQ-OAR-2004-
0008-0500.

14. "Overview of Recent Emission Control Technology Developments," Manufacturers of Emission Controls
Association, November 18, 1997, Docket Identification EPA-HQ-OAR-2004-0008-0206.

15. "Application of Accelerated Rapid Aging Test (RAT) Schedules with Poisons: The Effects of Oil Derived
Poisons, Thermal Degradation  and Catalyst Volume on FTP Emissions," Ball, D., Mohammed, A., Schmidt, W.,
SAE Paper 972846, 1997, Docket Identification EPA-HQ-OAR-2004-0008-0501.
                                                4-84

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                                                        Feasibility of Exhaust Emission Control
16. "Update Heavy-Duty Engine Emission Conversion Factors for MOBILE6; Analysis of Fuel Economy, Non-
Engine Fuel Economy Improvements, and Fuel Densities," prepared by Arcadis for U.S. EPA, EPA420-R-006,
January 2002, Docket Identification EPA-HQ-OAR-2004-0008-0251.

17. "Overview of Recent Emission Control Technology Developments," Manufacturers of Emission Controls
Association, November 18, 1997, Docket Identification EPA-HQ-OAR-2004-0008-0206.

18. "Catalytic Converter Applications for Two Stroke, Spark-Ignited Marine Engines," Fujimoto, H., Isogawa, A.,
Matsumoto, N., SAE Paper 951814, 1995, Docket Identification EPA-HQ-OAR-2004-0008-0220.

19. "Catalytic Converter Applications for Two Stroke, Spark-Ignited Marine Engines," Fujimoto, H., Isogawa, A.,
Matsumoto, N., SAE Paper 941786, 1994, Docket Identification EPA-HQ-OAR-2004-0008-0218.

20. "Public Meeting to Consider a Status Report on Catalyst Testing of Spark-Ignition Inboard/Sterndrive
Pleasurecraft:  Staff Report," State of California; Air Resources Board, October 28, 2004, Docket Identification EPA-
HQ-OAR-2004-0008-0236.

21. "Regulatory Impact AnalysisControl of Air Pollution from New Motor Vehicles: Tier 2 Motor Vehicle
Emissions Standards and Gasoline Sulfur Control Requirements," U.S. EPA, December 1999, EPA420-R-99-023,
http://www.epa.gov/otaq/regs/ld-hwy/tier-2/frm/ria/r99023.pdf

22. "Demonstration of Tier 2 Emission Levels for Heavy Light-Duty Trucks," J. McDonald and L. Jones, SAE
2000-01-1957, Docket Identification EPA-HQ-OAR-2004-0008-0496.

23. "SULEV and 'Off-Cycle' Emissions Benefits of a Vacuum-Insulated Catalytic Converter," Burch, S.D., and J.P.
Biel, SAE 1999-01-0461, Docket Identification EPA-HQ-OAR-2004-0008-0495.

24. "Development of an Alternator-Powered Electrically-Heated Catalyst System," Laing, P.M., SAE 941042,
Docket Identification EPA-HQ-OAR-2004-0008-0494.

25. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower", U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.

26. "Nonroad SI Manufacturer Discussion," Slide 26-700cc Class II/Phase 2 Horizontal V-Twin. U.S.
Environmental Protection Agency, November 22, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0087.

27. "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower", U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.

28. "Test Results for Small Spark-Ignition Engine Number 258," Memorandum and Excel spreadsheet from Richard
Wilcox, Office of Transportation and Air Quality, U.S. Environmental Protection Agency, January 23, 2007,  Docket
IdentificationEPA-HQ-OAR-2004-0008-0530.

29. Letter from David Raney, American Honda Motor Co., Inc., to Margo T. Oge, U. S. Environmental Protection
Agency, September 1, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0304.

30. Letter from Kent B. Herrick, Tecumseh Products Company, to Margo T. Oge,  U. S. Environmental Protection
Agency, September 7, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0306.

31. Letter from Jeffrey Cl Shetler, Kawasaki Motors Corp, U.S.A., to  Margo T.  Oge,  U. S. Environmental
Protection Agency, September 7, 2005,  Docket Identification EPA-HQ-OAR-2004-0008-0305.
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Final Regulatory Impact Analysis
32.  Letter from James P. Doyle, Kohler Co., to Margo T. Oge, U. S. Environmental Protection Agency, September
7, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0303.

33.  "Reducing Emissions From Gasoline Platforms at Less Then 20 kW," Slide 9, B. Walker and A. Gopalkrishna,
Delphi Automotive, Asian Vehicle Emission Control Conference, Jaipur, Japan, September 22, 2006. EPA-HQ-
OAR-2004-0008-0535.

34.  "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower", Appendix C - FMEA of Small SI Equipment and Engines, U.S. Environmental Protection Agency,
EPA420-R-06-006, March 2006,  Docket Identification EPA-HQ-OAR-2004-0008-0329.

35.  Letter from David Raney, American Honda Motor Co., Inc., to Margo T. Oge, U. S. Environmental Protection
Agency, September 1, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0304.

36.  Letter from  Kent B. Herrick, Tecumseh Products Company, to Margo T. Oge,  U. S. Environmental Protection
Agency, September 7, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0306.

37.  Letter from Jeffrey Cl Shetler, Kawasaki Motors Corp, U.S.A., to Margo T. Oge, U. S. Environmental
Protection Agency, September 7, 2005,  Docket Identification EPA-HQ-OAR-2004-0008-0305.

38.  Letter from James P. Doyle, Kohler Co., to Margo T. Oge, U. S. Environmental Protection Agency, September
7, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0303.

39.  "Reducing Emissions From Gasoline Platforms at Less Then 20 kW," Slide 9, B. Walker and A. Gopalkrishna,
Delphi Automotive, Asian Vehicle Emission Control Conference, Jaipur, Japan, September 22, 2006. EPA-HQ-
OAR-2004-0008-0535.

40.  "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower", Appendix C - FMEA of Small SI Equipment and Engines, U.S. Environmental Protection Agency,
EPA420-R-06-006, March 2006,  Docket Identification EPA-HQ-OAR-2004-0008-0329.

41.  "Nonroad SI Manufacturer Discussion,"  Slide 26-700cc Class II/Phase 2 Horizontal V-Twin. U.S.
Environmental Protection Agency, November 22, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0087.

42.  "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.

43.  "Research on the New Control Method Using Crankshaft Rotational Changes for Electronically Controlled FI
System of Small Motorcycle Single Cylinder Engine," Toichiro Hikichi, Tetsuya Kaneko, and Toshimitsu Nakajima,
Honda R&D Co., Ldt, SAE Paper 2006-32-0108, Small Engine Technology Conference and Exhibition, San
Antonio, Texas, November 13-16, 2006, Docket Identification EPA-HQ-OAR-2004-0008.

44.  "Fuel Injection System for Small Motorcycles," Michihisa Nakamure, Yuuichirou Sawada, and Shigeki
Hashimoto, Yamaha Motor Co., Ltd., SAE Paper 2003-32-0084, September 2003,Docket Identification EPA-HQ-
OAR-2004-0008.

45.  "Honda Releases the iGX440 Next-Generation General Purpose Engine with Electronic Control Technology-a
World's First," Honda Motor Co., Ldt., Press Release, April 20, 2005, Docket Identification EPA-HQ-OAR-2004-
0008.

46.  "Honda's iGX Intelligent Engine," Honda Motor Co., Ldt., Product Information, April 2007, Docket
IdentificationEPA-HQ-OAR-2004-0008.
                                                 4-86

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                                                        Feasibility of Exhaust Emission Control
47.  "Evinrude E-TEC Presentation; Ann Arbor Michigan," presented to U.S. EPA by Fernando Garcia of BRP on
September 30, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0246.

48.  "Exhaust Emissions from Marine Engines Using Alternate Fuels," Michigan Automotive Research Corporation,
Prepared for NMMA, October 8, 1992, Docket Identification EPA-HQ-OAR-2004-0008-0205.

49.  "Effects of Transience on Emissions from Inboard Marine Engines," EPA memo by Mike Samulski, May 30,
1996, Docket Identification EPA-HQ-OAR-2004-0008-0209.

50.  Letter from Jeff Carmody, Santa Barbara Air Quality management District, to Mike Samulski, U.S. EPA, July
21,  1997, Docket Identification EPA-HQ-OAR-2004-0008-0193.

51.  "National Marine Manufacturers Association's Small Business Boat Builder and Engine Manufacturers
Comments in Response to EPA's Initial Regulatory Flexibility Analysis Regarding EPA's Plans to Propose
Emission Regulations for Recreational Marine Gas and Diesel Powered Sterndrive/Inboard Engines," July 12, 1999,
Docket Identification EPA-HQ-OAR-2004-0008-0213.

52.  "Emissions from Marine Engines with Water Contact in the Exhaust System," Mace, et. al., SAE Paper 980681,
1998, Docket Identification EPA-HQ-OAR-2004-0008-0219.

53.  "Marine Gasoline Engine Testing," Carroll, J., White, J., Southwest Research Institute, Prepared for U.S. EPA,
September, 2001, Docket A-2000-01, Docket Identification EPA-HQ-OAR-2004-0008-0253.

54.  "Marine Gasoline Engine and Boat Testing," Carroll, J., Southwest Research Institute, Prepared for U.S. EPA,
September, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0254.

55.  "Exhaust Emission Testing of Two High-Performance SD/I Marine Engines," EPA Memo from Mike Samulski
and Matt Spears, June  23, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0349.

56.  Email from Mark Reichers, Mercury Marine, to Mike Samulski, US EPA, "1075 / 850 Test Data," June 9, 2005,
Docket Identification EPA-HQ-OAR-2004-0008-0295.

57.  Email from Mark Reichers, Mercury Marine, to Mike Samulski, US EPA, "525 EFI Baseline Emissions Data,"
June 10, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0296.

58. Ray, P., Brown, R., " Ilmor Comments on the Notice of Proposed Rulemaking for Control of Emissions from
Nonroad Spark-Ignited Engines and Equipment 72 Fed. Reg. 28,908 (May 18,2007)," August 3, 2007.

59.  "EGR Test Data from a Heavy-Duty Gasoline Engine on the E4 Duty Cycle," EPA Memo from Joe McDonald
and Mike Samulski, July 12, 1999, Docket Identification EPA-HQ-OAR-2004-0008-0199.

60.  "Marine Gasoline Engine Testing," Carroll, J., White, J., Southwest Research Institute, Prepared for U.S. EPA,
September, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0253.

61.  "Marine Gasoline Engine and Boat Testing," Carroll, J., Southwest Research Institute, Prepared for U.S. EPA,
September, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0254.

62.  "Marine Gasoline Engine Testing," Carroll, J., White, J., Southwest Research Institute, Prepared for U.S. EPA,
September, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0253.

63.  "Summary of SwRI Project for CARD entitled, 'Development of Low Emissions SD/I Boats," White, J.,
Southwest Research Institute, August 14, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0263.
                                                 4-87

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Final Regulatory Impact Analysis
64. "Development of Low Emissions; SD/I Boats; Project Update," Carrol, I, Southwest Research Institute,
September 11, 2003, Docket Identification EPA-HQ-OAR-2004-0008-0264.

65. "Public Meeting to Consider a Status Report on Catalyst Testing of Spark-Ignition Inboard/Sterndrive
Pleasurecraft: Staff Report," State of California; Air Resources Board, October 28, 2004, Docket Identification EPA-
HQ-OAR-2004-0008-0236.

66. "Marine Gasoline Engine and Boat Testing," Carroll, I, Southwest Research Institute, Prepared for U.S. EPA,
September, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0254.

67. E-mail from Rich Waggoner, Indmar, to Mike Samulski, U.S. EPA, "SBREFA notes from Indmar," July 24,
2006, Docket Identification EPA-HQ-OAR-2004-0008-0438.

68. http://www.arb.ca.gov/msprog/offroad/cert/cert_results.php?order=0, February 14, 2008.

69. Garcia, A., Beamer, B., Earnest, G., "In Depth Survey Report of Carbon Monoxide Emissions and Exposures on
Express Cruisers Under Various Operating Conditions," National Institute for Occupational Safety and Health,
Report No. EPHB 289-1 la, January 2006, Docket Identification EPA-HQ-OAR-2004-0008-0396.

70. Garcia, A., Beamer, B., Earnest, G., "In Depth Survey Report of Carbon Monoxide Emissions and Exposures on
Express Cruisers Under Various Operating Conditions," National Institute for Occupational Safety and Health,
Report No. EPHB 289-1 la, January 2006, Docket Identification EPA-HQ-OAR-2004-0008-0396.

71. "Summary of Government/Industry Carbon Monoxide Workshop and Two Follow-Up Meetings," Memo from
Mike Samulski, U.S. EPA to Docket OAR-2004-0008, March 31, 2004, Docket Identification EPA-HQ-OAR-2004-
0008-0008.

72. "Carbon Monoxide Follow-up Meeting; Miami FL - IBEX Show; Minutes," American Boat and Yacht Council,
October 19, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0286.

73. "News Release: Floating Environmental Laboratory Demonstrates Westerbeke's Safe-CO Ultra-Low CO
Emissions," Westerbeke Engines & Generators, September 26, 2005, Docket Identification EPA-HQ-OAR-2004-
0008-0298.

74. "Create the Right Atmosphere; Kohler Marine Generators Helping Make Boating Safer," Presented by Kohler
Power Systems at the 2005 International Boatbuilders' Exhibition and Conference, October 20, 2005,  Docket
IdentificationEPA-HQ-OAR-2004-0008-0292.

75. Zimmer, A., Earnest, G., Kurimo, R., "An Evaluation of Catalytic Emission Controls and Vertical Exhaust
Stacks to Prevent Carbon Monoxide Poisonings from Houseboat Generator Exhaust," National Institute for
Occupational Safety and Health, EPHB 171-36a, September 2005, Docket Identification EPA-HQ-OAR-2004-0008-
0397.

76. "Duty Cycle for Recreational Marine Engines," Morgan, E., Lincoln, R., SAE Paper 901596, 1990, Docket
IdentificationEPA-HQ-OAR-2004-0008-0216.

77. "Reciprocating Internal Combustion Engines - Exhaust Emission Measurement - Part 4: Test Cycles for
Different Engine Applications," ISO/DIS 8178-4, International Standards Organization, Docket Identification EPA-
HQ-OAR-2004-0008-0503.

78. Ray, P., Brown, R., " Ilmor Comments on the Notice of Proposed Rulemaking for Control of Emissions from
Nonroad Spark-Ignited Engines and Equipment 72 Fed. Reg. 28,908 (May  18,2007)," August 3, 2007.
                                                 4-8

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                                                        Feasibility of Exhaust Emission Control
79.  Morgan, E., Lincoln, R., "Duty Cycle for Recreational Marine Engines," SAE Paper 901596, 1990, Docket
IdentificationEPA-HQ-OAR-2004-0008-0216.

80.  Carroll, I, "Determination of Operating Ranges of Marine Engines," prepared by Southwest Research Institute
for the National Marine Manufacturers Association, August 2004, Docket Identification EPA-HQ-OAR-2004-0008-
0255.

81.  Samulski, M., "Exhaust Emission Testing of a Two-Stroke and a Four-Stroke Marine Engine; Results and
Procedures," U.S. EPA, Memo to Docket #A-92-98, Docket Identification EPA-HQ-OAR-2004-0008-0097.

82.  Wasil, I, Montgomery, D., Strauss, S., Bagley, S., "Life Assessment of PM, Gaseous Emissions, and Oil Usage
in Modern Marine Outboard Engines," SAE-GRAZ 43, Society of Automotive Engineers International, 2004,
Docket Identification EPA-HQ-OAR-2004-0008-0262.

83.  Klak, Joe, "Marine NTE Zones," Bombardier Recreational Products, October 26, 2006, Docket Identification
EPA-HQ-OAR-2004-0008-0508.

84.  "Marine Gasoline Engine Testing," Carroll, I, White, I, Southwest Research Institute, Prepared for U.S. EPA,
September, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0253.

85.  "Marine Gasoline Engine and Boat Testing," Carroll, I, Southwest Research Institute, Prepared for U.S. EPA,
September, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0254.

86.  "Summary of SwRI Project for CARB entitled, 'Development of Low Emissions SD/I Boats," White, J.,
Southwest Research Institute, August 14, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0263.

87.  "Development of Low Emissions;  SD/I Boats; Project Update," Carrol, J., Southwest Research Institute,
September 11, 2003, Docket Identification EPA-HQ-OAR-2004-0008-0264.

88.  "Marine Gasoline Engine Testing," Carroll, J., White, J., Southwest Research Institute, Prepared for U.S. EPA,
September, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0253.

89.  Mantey, C., "GMPT Study - Stoich Limits for Engine Protection," Presented by General Motors to EPA on
November 19, 2007.

90.  Memorandum from Mark Wolcott to Charles Gray, "Ambient Temperatures Associated with High Ozone
Concentrations," U.S. EPA, September 6, 1984, Docket Identification EPA-HQ-OAR-2004-0008-0235.

91.  "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.

92.  "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.
                                                 4-89

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                                             Feasibility of Evaporative Emission Control
  CHAPTER 5: Feasibility of Evaporative Emission Control

       Section 213(a)(3) of the Clean Air Act presents statutory criteria that EPA must evaluate
in determining standards for nonroad engines and vehicles including marine vessels.  The
standards must "achieve the greatest degree of emission reduction achievable through the
application of technology which the Administrator determines will be available for the engines
or vehicles to which such standards apply, giving appropriate consideration to the cost of
applying such technology within the period of time available to manufacturers and to noise,
energy, and safety factors associated with the application of such technology."  This chapter
presents the technical analyses and information that form the basis of EPA's belief that the new
evaporative emission standards are technically achievable accounting for all the above factors.

       The evaporative emission standards for Small SI equipment and Marine SI vessels are
summarized in the Executive Summary.  This chapter presents available emissions data on
baseline emissions and on emission reductions achieved through the application of emission
control technology.  In addition, this chapter provides a description of the test procedures for
evaporative emission determination.

       Evaporative emissions from equipment and vessels using spark-ignition (SI) engines can
be very high.  This is largely because Small SI and Marine SI applications generally have fuel
tanks that are vented to the  atmosphere and because materials used in the construction of the
plastic fuel tanks and hoses generally have high permeation rates. Evaporative emissions can be
grouped into five categories:

       DIURNAL: Gasoline evaporation increases as the temperature rises during the day,
heating the fuel tank and venting gasoline vapors. We also include, under this heading, diffusion
losses which are vapors that will escape from an open vent even without a change in
temperature.

       PERMEATION: Gasoline molecules can saturate plastic fuel tanks and rubber hoses,
resulting in a relatively constant rate of emissions as the fuel continues to permeate through these
components.

       RUNNING LOSSES: The hot engine and exhaust system can vaporize gasoline when the
engine is running.

       HOT SOAK: The engine remains hot for a period of time after the engine is turned off
and gasoline evaporation continues.

       REFUELING: Gasoline vapors are always present in typical fuel tanks. These vapors are
forced out when the tank is filled with liquid fuel.
                                          5-1

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Final Regulatory Impact Analysis
5.1  Diurnal Emissions

       In an open fuel tank, the vapor space is at atmospheric pressure (typically about 14.7 psi),
and contains a mixture of fuel vapor and air. At all temperatures below the fuel's boiling point,
the vapor pressure of the fuel is less than atmospheric pressure.  This is also called the partial
pressure of the fuel vapor. The partial pressure of the air is equal to the difference between
atmospheric pressure and the fuel vapor pressure. For example, in an open-vented fuel tank at
60F, the vapor pressure of typical gasoline is about 4.5 psi.  In this example, the partial pressure
of the air is about 10.2 psi. Assuming that the vapor mixture behaves as an ideal gas, then the
mole fractions (or volumetric fractions) of fuel vapor and air is equal to their respective partial
pressures divided by the total pressure; thus, the fuel would be 31 percent of the mixture
(4.5/14.7) and the air would be 69 percent of the mixture (10.2/14.7).

       Diurnal emissions occur when the fuel temperature increases, which increases the
equilibrium vapor pressure of the fuel. For example, assume that the fuel in the previous
example was heated to 90F, where the vapor pressure that same typical fuel is about 8.0 psi.  To
maintain the vapor space at atmospheric pressure, the partial pressure of the air would need to
decrease to 6.7 psi, which means that the vapor mixture must expand in volume. This forces
some of the fuel-air mixture to be vented out of the tank.  When the fuel later cools, the vapor
pressure of the fuel decreases, contracting the mixture, and drawing fresh air in through the vent.
When the fuel is heated again, another cycle of diurnal emissions occurs.  It is important to note
that this is generally not a rate-limited process.  Although the evaporation of the fuel can be
slow, it is generally fast enough to maintain the fuel tank in an essentially equilibrium state.

       As fuel is used by the engine, and the liquid fuel volume decreases, air is drawn into the
tank to replace the volume of the fuel.  (Note: the decrease in liquid fuel could be offset to some
degree by increasing fuel vapor pressure caused by increasing fuel temperature.) This would
continue while the engine was running.  If the engine was shut off and the tank was left
overnight, the vapor pressure of the fuel would drop as the temperature of the fuel dropped. This
would cause a small negative pressure within the tank that would cause it to fill with more air
until the pressure equilibrated.  The next day, the vapor pressure of the fuel would increase as the
temperature of the fuel increased. This would cause a small positive pressure within the tank
that would force a mixture of fuel vapor and air out. In poorly designed gasoline systems, where
the engine or exhaust is very close to the fuel tank the engine/exhaust heating may cause large
amounts of gasoline vapor to be vented directly to the atmosphere.

       Several emission-control technologies can be used to reduce diurnal evaporative
emissions.  Many of these technologies also control  running loss and hot soak emissions and
some could be used to control refueling emissions. We believe manufacturers will have the
opportunity use a wide variety  of technology approaches to meet the evaporative emission
standards. The advantages and disadvantages of the various possible emission-control strategies
are discussed below. This section summarizes the data and rationale supporting the diurnal
emission standard for Marine SI vessels and Small SI equipment presented in the Executive
Summary.
                                           5-2

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                                               Feasibility of Evaporative Emission Control
5.1.1  Baseline Emissions

       5.1.1.1  Marine Vessels

       We tested two aluminum marine fuel tanks in their baseline configurations for diurnal
emissions.  Aluminum fuel tanks were used so that permeation emissions would not occur during
the testing. The 17 gallon aluminum tank was constructed for this testing, but is representative
of a typical marine fuel tank;  the 30 gallon aluminum tank was removed from an 18 foot
runabout. The fuel tanks were tested with the venting through a length of 5/8 inch hose to ensure
that the emissions measured were a direct result of the fuel temperature heating and not diffusion
through the vent (see Section 5.1.3). The advantage of using the aluminum fuel tanks for this
testing was to exclude permeation emissions from the measured results.  All of the testing was
performed with fuel tanks filled to 40 percent of capacity with 9RVP1 test fuel.

       The diurnal test results are presented in units of grams per gallon capacity of the fuel tank
per day.  These units are used because gallons capacity is  a defining characteristic of the fuel
tank.  Diurnal vapor formation itself is actually a function of the vapor space above the fuel in
the fuel tank rather than the total capacity.

       Table 5.1-1 presents the test results compared to anticipated results. The anticipated
results are based on the Wade model which is a  set of theoretical calculations for determining
diurnal emissions based of fill level, fuel RVP, and temperature profile.  These calculations are
presented in Chapter 3. Although the Wade model over-predicts the vapor generation, it does
show a similar trend with respect to temperature. To account for this over prediction, we use a
correction factor of 0.78.  This correction factor is based on empirical data1, has historically been
used in our automotive emission models, and appears to be consistent with the data presented
below.
       1 Reid Vapor Pressure (psi). This is a measure of the volatility of the fuel.  9 RVP represents a typical
summertime fuel in northern states.

                                            5-3

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Final Regulatory Impact Analysis
     Table 5.1-1; Baseline Diurnal Evaporative Emission Results (varied temperature)
Temperatures
22-36C (72-96F)
22-36C (72-96F)
24-33C (74-91F)
22 - 30C (71 - 86F)
25-3TC (77-88F)
26 - 32C (78 - 90F)
28-31C(82-87F)
Capacity
[gallons]
17
30
30
30
30
30
30
Measured
[g/gallon/day]
1.40
1.50
1.13
0.88
0.66
0.85
0.47
Wade Model
[g/gallon/day]
2.30
2.30
1.33
1.02
0.88
1.04
0.43
Corrected Wade
[g/gallon/day]
1.79
1.79
1.04
0.80
0.69
0.81
0.34
       5.1.1.2 Small SI Equipment

       We contracted with an outside lab for the testing of thirteen Small SI fuel tanks over
various test temperature profiles.2'3  This testing was performed with the tanks filled to 50
percent capacity with certification gasoline and is discussed in more detail below in the
Section 5.2.1.  This data is presented in Table 5.1-2. In addition, in cases where the fuel
temperature profiles were within the input range of the Wade model for diurnal emissions,
theoretical emissions were also calculated using the same correction factor discussed above for
marine fuel tanks.  As shown below, the measured values are fairly consistent with the
theoretical values.
                                           5-4

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                                            Feasibility of Evaporative Emission Control
  Table 5.1-2: Fuel Temperature Measurements During Operation of Small SI Equipment
Equipment Type
Riding mower





Walk-behind
mower

Generator set

Pressure washer
Fuel Capacity
[gallons]
1.1
1.4x2
1.7
2.5
3.0
6.5
6.5x2
0.34
0.25
0.22
8.5
7.0
1.8
Temperature
Profile C
15.7-28.4
21.9-29.7
19.5-30.3
27.0-35.0
26.6-28.4
24.3 -33.2
20.5-23.9
23.3 -33.0
28.7-46.7
28.7-59.7
20.6-25.8
25.8-50.0
19.0-50.6
Measured HC
grams/gallon
0.92
0.88
0.82
1.29
0.25
1.20
0.26
0.76
4.92
36.9
0.45
9.90
11.6
Theoretical HC
grams/gallon
0.91
0.71
0.94
1.16
0.17
1.08
0.23
1.18
NA*
NA*
0.38
NA*
NA*
       * outside the temperature range of the model
       The California Air Resources Board performed diurnal testing on seven pieces of
handheld equipment and 20 pieces of non-handheld equipment by placing the whole equipment
in a SHED.4 They filled the fuel tanks to 50 percent with 7 RVP fuel and tested over their 65-
105 F summer day test cycle. Because the entire piece of equipment was included in these
tests, not only were diurnal venting emissions measured, but tank and hose permeation as well
(plus any potential leaks). Average test results by equipment type are presented in Table 5.1-3.

   Table 5.1-3: ARB Measurement of Evaporative Emissions from Small SI Equipment
                (7 RVP California Certification Fuel, 50% Fill, 65-105F)
Equipment Type
Handheld equipment
Walk-behind lawnmowers
Generators
Riding Mowers
Edgers
Tiller
Number of Data Points
7
12
2
O
2
1
Average Measured HC [grams/day]
1.04
3.51
11.2
8.70
1.53
4.12
                                         5-5

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Final Regulatory Impact Analysis
       ARB also performed tests on a subset of the equipment using fuel containing MTBE and
fuel containing ethanol to investigate fuel effects. They observed nearly a 50 percent increase in
emissions when an ethanol blend was used compared to an MTBE blend. The reason for this
increase was not discussed, but may have due to increases in permeation caused by the ethanol
or due to differences in fuel volatility. On five pieces of equipment, a California wintertime
cycle (51.6-69.5 F) was used as well. As would be expected, the emissions were reduced
significantly. The theoretical models predict about an 85 percent reduction in diurnal venting
emissions and about a 60 percent reduction in permeation. The observed results were about a 70
percent reduction which is in this range.

5.1.2  Insulation of the Fuel Tank

       The diurnal vapor generated in a fuel tank is directly related to the diurnal temperature
profile of the fuel in the tank.  A reduction in temperature variation causes less vapor to be
formed. To investigate this effect, we used insulation around the fuel tank to reduce the effect of
the ambient air temperature variation on the fuel temperature variation.  In our preliminary
testing, we insulated a 23 gallon rotationally molded marine fuel tank using 3 inch thick
construction foam with an R-value of 15  as defined by  16 CFR 460.5. This testing was
performed with the fuel tank vent open to atmosphere.  Table 5.1-4 presents the fuel
temperatures and evaporative emissions over the three day test.

       We tested this fuel tank over a three day diurnal test with  an ambient temperature of 72-
96F. This experiment resulted in a 50 percent reduction in emissions from baseline on the
highest of these three test days.  The baseline emissions were measured  to be 2.5 g/gallon/day;
however, it should be noted that for both the baseline test and the insulated tank tests we did not
control for permeation or diffusion.  Over this test, the emissions decreased for subsequent days.
We believe this was due to the fuel temperature cycle stabilizing. Although we did not control
for permeation or diffusion, the results from this preliminary experiment directionally show the
effect of insulation on diurnal emissions.
        Table 5.1-4:  Evaporative Emission Results for Insulated Flat, Plastic Tank
Test Day
Day#l
Day #2
Day #3
SHED Temperature
22-36C (72-96F)
22-36C (72-96F)
22-36C (72-96F)
Fuel Temperature
22-28C (72-82F)
26-30C (78-86F)
26-30C (80-86F)
Evaporative HC
1.2g/gal/day
l.Og/gal/day
0.8 g/gal/day
       In boats with installed fuel tanks, the fuel tank is generally hidden beneath the deck. As a
result, there is a certain amount of "inherent" insulation caused by the boat itself.  This effect is
increased for a boat that is stored in the water. The water acts as a cooling  medium for the fuel
tank, especially if it is installed in the bottom of the boat. In addition, the thermal inertia of the
fuel in the tank  can act to dampen temperature variation imposed from the diurnal heating of the
                                           5-6

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                                             Feasibility of Evaporative Emission Control
ambient air. To investigate this effect, we tested several boats by recording the ambient air
temperature and fuel temperatures over a series of days.  Two boats were tested on trailers
outside in the summer, two boats were tested on trailers in a SHED, and two boats were tested in
the water on summer days. Table 5.1-5 presents the average results of this testing.  The
temperature traces are presented in Appendix 5 A.

           Table 5.1-5:  Ratio of Fuel to Ambient Temperature Swing for Boats
Boat Type
9 ft. personal watercraft
16 ft. jet boat
18 ft. runabout
16 ft. jet boat
18 ft. runabout
21 ft. deck boat
Test Conditions
outside, on trailer
outside, on trailer
in SHED, on trailer
in SHED, on trailer
outside, in water
outside, in water
Capacity
[gallons]
13
40
30
40
30
20
Fuel Tank
Fill Level
50%
50%
40%
90%
100%
90%
Temperature
Ratio*
66%
52%
68%
33%
19%
27%
     * Average ratio of change in fuel temperature to change in ambient air temperature over test days.
       In their comments on the 2002 proposed rule, the National Marine Manufacturers
Association presented temperature data on 18 foot runabout, with a 32 gallon tank, tested in a
SHED with an ambient temperature of 72-96F.5  The average fuel to ambient temperature ratio
was 54 percent for this testing.  This ratio is in the range of EPA test results for boats tested on a
trailer. Brunswick also included temperature data in their comments.6 The average days test on
a boat on the water was 19 percent, which is consistent with our water tests.  Brunswick's
average for boats tested while stored out of the water was 27 percent which is considerably lower
than the EPA and NMMA testing. Combining all of the EPA and industry data, the average fuel
to ambient temperature ratio (based on test days) is about 20 percent for boats in the water and
50 percent for boats stored out of the water.

       During diurnal testing of lawnmowers, ARB found that the fuel and tank skin
temperature follow the ambient temperature closely.7  This same phenomenon would be expected
for other Small SI equipment as well (and portable fuel tanks) because of the small fuel volumes
and because these tanks are generally exposed to ambient air.  One issue that we considered was
that Small SI  equipment is often stored in garages or sheds. In  that case, we  were interested in if
the garage or  shed acts to insulate the fuel tanks from ambient temperature swings. ARB
collected data on four garages and one shed. This data included summer and winter California
temperature measurements.  For each test, the inside and outside temperature were measured for
five days.  This data is presented in Table 5.1-7. For the garages, the inside temperature was
generally warmer than outside, but the variable temperature swings were smaller.  For the shed,
the inside temperature was warmer and showed higher heat builds than the outside temperature.
                                          5-7

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Final Regulatory Impact Analysis
Table 5.1-6 also presents an estimate of the effect on diurnal emissions using the theoretical
equations presented in Chapter 3. No conclusive evidence of was observed to suggest that these
fuel tanks are generally subject to inherent insulation.

       Table 5.1-6: Comparison of Ambient to Inside Diurnal Temperature Swings
Season

Winter


Summer




Enclosure

garage D
garage G
garage J
garage A
garage D
garage G
garage J
shed
Inside Temperature C
Avg T Avg Delta T
13.8
12.1
13.5
27.4
35.9
27.4
27.6
27.1
6.4
9.2
2.4
3.6
11.7
15.7
8.9
20.1
Outside Temperature C
Avg T Avg Delta T
10.1
5.8
8.0
22.4
30.3
21.3
23.7
23.6
9.3
14.3
7.3
12.2
15.6
19.5
20.3
14.1
Emission
Effect
-8%
-9%
-55%
-63%
20%
23%
-61%
119%
       Some of the variance between the fuel temperature and ambient temperature, especially
for larger fuel tanks, is likely due to the thermal inertia of the fuel in the tank.  The fuel has mass
and therefore takes time to heat up.  ARB performed a study in which the fuel temperature and
ambient temperature were recorded for aboveground storage fuel tanks.8'9 Three fuel tanks sizes
were included in the study: 350, 550, and 1000 gallons.  Because of the large size of these tanks,
the thermal inertia effects would be expected to be larger than for typical fuel tanks used in
Marine SI and Small SI applications. For the 350 gallon fuel tank, ARB  also measured the effect
of insulating the fuel tank on temperature. Table 5.1-7 presents the results of this testing. Note
that the test results are the average of five days. Ambient temperature on these test days
typically had a minimum in the 60-70F range and a maximum temperature in the 95-105T
range.

      EPA performed testing on 17 gallon marine fuel tank in a SUED over a single 72-96T
diurnal test and measured both ambient and fuel temperature.10 This data is also included in
Table 5.1-7. Note that for the smaller tank, there is little difference between the ambient and fuel
temperature profiles.  However, for larger tanks, the fuel temperature has about a 25-30 percent
smaller temperature swing than the ambient temperature. Note that the insulated fuel tank had a
temperature ratio similar to the fuel tank stored in a boat in the water.
                                          5-8

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                                              Feasibility of Evaporative Emission Control
      Table 5.1.7: Ratio of Fuel to Ambient Temperature for Uninsulated Fuel Tanks
Fuel Tank Type
marine fuel tank
aboveground storage tank
(with insulation)
aboveground storage tank
aboveground storage tank
Tank Capacity [gallons]
17
350
550
1000
Temperature Ratio*
95%
75%
(18%)
70%
76%
     * Average ratio of change in fuel temperature to change in ambient air temperature over test days.
5.1.3  Diffusion Effect

       For the purposes of this discussion, diffusion refers to the process in which gasoline
vapor penetrates air in an attempt to equalize the concentration throughout the gas mixture.  This
transport phenomenon is driven by the concentration gradient and by effective area. In the case
of a mobile source fuel system that has a vent to atmosphere, the fuel vapor concentration is near
saturation in the fuel tank and near zero outside of the fuel system.  Therefore, the diffusion rate
is primarily a function of the path between the fuel tank and atmosphere. The following equation
describes the relationship between the flux of gasoline vapor out of the tank, the concentration
gradient, and the vent path:
                           Flux =
                                       mass
                                    area x time
= Dx
AC
A*
       where: D = diffusion coefficient (constant)
                    AC = concentration gradient
                    Ax = path length
                    area = cross sectional area of vent

       Based on the above equation, diffusion from a tank through a vent hose would be a
function of the cross-sectional area divided by the length of the hose.  Therefore a longer hose
would theoretically limit fuel vapor venting due to diffusion. Whenever a hydrocarbon (HC)
molecule escapes from the fuel tank, a new molecule of air enters the fuel tank to replace the
escaped HC.  This brings the concentration of HC vapor in the fuel tank out of equilibrium. To
balance the partial pressures in the fuel tank, more HC must evaporate as HC in the vapor space
is depleted. In this way, the vapor concentration in the fuel tank remains saturated.

       5.1.3.1 Marine Fuel Tank Data

       In testing diurnal emissions from fuel tanks with open vents, the configuration of the vent
can have a significant effect on the measured emissions due to the diffusion of vapor out of any
                                           5-9

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Final Regulatory Impact Analysis
opening in the fuel tank. Depending on the size and configuration of the vent, diffusion can
actually occur when the fuel temperature is cooling. Most marine vessels with an installed fuel
tank vent through a hose.  As shown below this configuration can minimize diffusion.

       To quantify the diffusion component for a typical fuel tank, we ran four 72-96F diurnal
tests on a 17 gallon aluminum marine fuel tank using various configurations for venting The
first configuration was with the fuel cap cracked open and the vent sealed, the second
configuration was with a 68 cm length of vent hose, and the third configuration was with a 1000
micron (1  mm) limiting flow orifice in the vent opening. This 1000 micron orifice was large
enough to allow venting without any measurable pressure increase in the fuel tank during the
diurnal test.  The fourth configuration was a combination of the limited flow orifice and the vent
hose.  Table 5.1-8 presents the results of this testing.

          Table  5.1-8: Diurnal Test Results with Varied Venting Configurations
Vent Configuration
cracked fuel cap
68 cm of 5/8" fuel hose
1000 micron orifice
1000
micron orifice + 68 cm of 5/8" fuel hose
Evaporative HC [g/gallon/day]
2.05
1.40
1.47
1.34
       The above testing showed a 50 percent higher emission rate for the tank vented through a
cracked fuel cap compared to one vented through a hose.  In the test with the cracked fuel cap,
an increase in HC concentration in the SHED was observed throughout the test, even when the
fuel temperature was cooling. For the other three tests, the HC concentration leveled off when
the temperature began to cool.  This suggests that the difference in measured emissions of 0.6 -
0.7 g/gal/day was due to diffusion losses.

       To further investigate this diffusion effect, we tested the 17 gallon aluminum tank with
several venting configuration, at two constant temperature settings. Under these conditions, all
of the measured evaporative  emissions would be expected to be due to diffusion.  As seen in
Table 5.1-9, diffusion can be very high with too large of a vent opening unless a vent hose is
used.  The two lengths of vent hose tested did not show a  significant difference in diffusion
emissions.  We believe that the vent hose limits diffusion  by creating a gradual gradient in fuel
vapor concentration.
                                          5-10

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                                              Feasibility of Evaporative Emission Control
   Table 5.1-9: Constant Temperature Test Results with Varied Venting Configurations
Vent Configuration
1/2" ID. fitting
68 cm of 5/8" fuel hose
137 cm of 5/8" fuel hose
1000 micron orifice
22 C (72F)
Evaporative HC [g/gal/day]
5.65
0.11
0.07
0.28
36C (96F)
Evaporative HC [g/gal/day]
10.0
0.18
0.24
0.41
       The above data suggest that, at least for open vent fuel systems, the size and
configuration of the venting system can have a significant effect on evaporative emissions. In
marine applications, there is typically a vent hose attached to the fuel tank. Diffusion emissions
appear to be minimal if the fuel tank is vented through a length of hose.  This is probably
because the long residence times in the hose cause more opportunities for molecular collisions
which direct the HC molecules back towards the fuel tank.

       One study looked at the evaporation of liquids from a tube filled to various fill heights.11
As the fill height decreased (effectively increasing the length of the tube above the liquid
surface) the evaporation  quickly decreased.  These results are consistent with the observed
effects of venting through a hose in our testing. Installed  marine fuel tanks typically vent
through a hose to the outside of the boat; therefore, diffusion losses are likely relatively small for
these applications.  Another study was performed on automotive fuel caps which suggests that a
crack in the gasket on the fuel cap of 1 percent of the gasket area can result in more than 2 grams
of HC emissions per day.12

       5.1.3.2 Small SI  Fuel Tank Data

       For Small SI applications (and portable marine fuel tanks), the tanks are typically vented
through an opening in the fuel cap.  Therefore, unless the  cap is sealed, we would expect
diffusion emissions to occur. The above data suggest that diffusion can account for a significant
portion of the evaporative HC emissions measured from a metal tank with a small vent in the cap
over a 72-96F diurnal test. Because diffusion would still occur at constant temperature, the
contribution of diffusion to measured diurnal emissions would increase, on a percentage basis, as
the diurnal temperature swing approached zero.

       To investigate the effect of fuel cap design on diffusion for Small SI applications, we
implemented a test program which included  four fuel tank configurations (one metal and three
plastic) and the corresponding fuel caps.  These four fuel tanks were taken from lawnmowers
using engines from the three  lawnmower engine manufacturers with the highest U.S. sales and
represent the majority of lawnmower fuel tanks on the market.  Table 5.1-10 presents a
description of these fuel  tanks.
                                          5-11

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Final Regulatory Impact Analysis
         Table 5.1-10: Lawnmower Fuel Tanks Used in Diurnal/Diffusion Testing
Tank
BM
BP
HP
TP
Tank description
metal, 800 ml
plastic, 1175 ml
plastic, 950 ml
plastic, 920 ml
Fuel Cap Vent Description
Three 1/16" dia. holes drilled in top of cap. Four similar holes
drilled in fibrous gasket
Three torturous pathways through plastic gasket, with venting
between tank/cap threads. (Also performed test using a
modified cap similar to the cap used on the metal tank.)
Pinhole in gasket center leading to two indentations in rubber
gasket at mating surface, with venting between tank/cap threads
Four indentations in rubber gasket at mating surface, with
venting between tank/cap threads
       We contracted with two outside laboratories to perform the diurnal/diffusion tests for the
Small SI equipment fuel tanks shown above.13'1445'16  In this effort, the fuel tanks were sealed,
except for the vents in the fuel cap, and filled to 40 percent of capacity with 9 RVP fuel. These
tanks were then tested in a mini-SHED over the EPA 72-96F 24-hour diurnal test procedure.
To minimize the effect of permeation on the test results, new fuel caps and plastic fuel tanks
were used for each test that had not been exposed to fuel or fuel vapor prior to the test.

       Under this testing, emissions continued to climb even when temperature was cooling
back from 96F to 72F.  These emissions were clearly not driven by temperature, so they were
determined to represent diffusion emissions. Total diffusion for the test was determined by
recording the HC emissions that occurred during the last 12 hours of the test (during the cooling
event)  and then multiplying these emissions by two to represent 24 hours. Although the peak
temperature occurs after nine hours, only the last 12 hours were used  to ensure that the fuel in
the tank was not still heating due to a thermal time lag. Diffusion was then subtracted off the
total HC measurement to determine non-diffusion  diurnal  emissions.  For the fuel cap with the
three holes drilled straight through it, the emissions were so high that it went out of measurement
range near the end of the tests performed by one of the contractors. However, all of the observed
diffusion rates were linear, making it simple to extrapolate the data where necessary.  Table 5.1-
11 presents the diurnal and diffusion data from these tests  and compares it to the theoretical
diurnal emissions using the corrected Wade equations discussed above. Charts in Appendix 5B
present the time series of the measured HC compared to the mini-SHED temperature.
                                          5-12

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                                             Feasibility of Evaporative Emission Control
  Table 5.1-11: Diurnal and Diffusion Emissions from Lawnmower Fuel Tanks (g/gal/day)
                over a 72-96-72 F (22.2-35.6-22.2 C) Temperature Profile
Tank
BM
BP
BP cap 2*
HP
TP
Total HC
47.8
2.1
24.1
1.6
2.1
Diffusion
43.6
0.1
19.3
0.1
0.2
Diurnal
4.2
2.0
4.8
1.5
2.0
Wade Diurnal
1.8
1.8
1.8
1.8
1.8
        modified to be similar to cap on metal tank (BM)
       The fuel caps in the above table for the lawnmower tanks labeled as BM and BP cap 2
resulted in very high diffusion emissions. Although this fuel cap type is a common design used
in Small SI applications, it may represent one of the worst case configurations for diffusion.
There are three small holes in the cap itself, and four small holes in the fibrous material
imbedded in the inside of the cap. Presumably, this design was intended to minimize fuel from
splashing out of the tank while still allowing the tank to breathe to prevent pressure or vacuum
from occurring in the tank. Because the carburetor on this lawnmower is gravity fed, too much
vacuum in the  fuel tank could cause the engine to stall from lack of enough fuel.  The reason that
this may be a worst case configuration is that there is a direct (and relatively large) path for fuel
vapor to escape from the fuel tank.

       The other three fuel cap designs were also from stock lawnmower fuel systems.  In all
three of these designs, the venting occurred through small grooves in the gasket that seals the
mating between the fuel cap and the fuel tank. The venting then occurs through the thread paths
between the cap and tank. As  a result, vapor and air must pass through a tortuous pathway to
enter or leave the tank. This tortuous pathway appears to limit diffusion in much the same way
as venting through a long hose does.

       The above emission testing was repeated except that the vents in the fuel cap were sealed
and the tank was vented through a 8 inch length of 1/4" ID. hose.  A lawnmower air intake filter
was attached to the end of this hose in order to simulate the venting configuration on a
lawnmower with running loss control. To minimize the effect of permeation, a low permeation
barrier hose was used that had never before been exposed to fuel or fuel vapor. The test results
in which the tanks were vented through hoses are presented in Table 5.1-12.
                                          5-13

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Final Regulatory Impact Analysis
  Table 5.1-12: Diurnal and Diffusion Emissions from Lawnmower Fuel Tanks (g/gal/day)
    with Modified Venting Through Hose/Air Filter to Simulate Running Loss Control
                over a 72-96-72 F (22.2-35.6-22.2 C) Temperature Profile
Tank
BM
BP
BP cap 2*
HP
TP
Total HC
vent through stock cap
47.8
2.1
24.1
1.6
2.1
Total HC
vent through hose/filter
12.9
1.9
1.9
2.0
2.9
Reduction in
Total HC
34.8
0.2
22.2
(0.4)
(0.7)
       * modified to be similar to cap on metal tank (BM)
       As shown in the table above, venting through the hose greatly reduced the measured
emissions compared to the BM cap vent. When vented through the hose configuration, diffusion
emissions were on roughly the same order as when the tortuous cap vents were used. This is
consistent with the data presented earlier on marine fuel tanks vented through a hose. In an in-
use running loss system, a valve or limited flow orifice would likely also be in the vent line.
These components would likely further reduce, or even eliminate, diffusion emissions.

       There was some concern that diffusion may  have been underestimated in the above tests
because air flowing back into the fuel tank during the cooling period may have limited diffusion
by pulling HC  molecules back into the fuel tank.  In addition, we believed that testing at constant
temperature would allow us to more directly measure diffusion. Therefore, the above testing
was repeated at a constant temperature of 29C.17'18'19  However, it should be noted that this
testing may have overestimated diffusion somewhat because of small temperature fluctuations
(less than 0.5 C) around the average during the test.  Therefore, any HC measurements from the
"constant" temperature testing may have overstated diffusion due to vapor generated by the
repeated mini-diurnal cycles during in the test.  These test results are presented in Table 5.1-13.
                                          5-14

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                                             Feasibility of Evaporative Emission Control
          Table 5.1-13: Isothermal [29 C] Diurnal and Diffusion Emissions from
                Lawnmower Fuel Tanks (g/gal/day) with Modified Venting
                Through Hose/Air Filter to Simulate Running Loss Control
Tank
BM
BP
BP cap 2*
HP
TP
Total HC
vent through stock cap
43.2
1.3
29.3
1.0
0.9
Total HC
vent through hose/filter
8.9
1.0
1.0
0.8
0.9
Reduction in
Total HC
34.3
0.3
28.3
0.2
0.0
       * modified to be similar to cap on metal tank (BM)
       At constant temperature, the relationship between measured diffusion emissions between
the venting configurations was consistent with the variable temperature testing. However, the
indicated diffusion results were somewhat higher. These higher results were influenced by two
effects.  In the variable temperature testing, the diffusion was measured during the cooling
period when air was being drawn into the fuel tank. This would reduce diffusion into the SHED
because escaping HC molecules would need to overcome the air flow into the tank.  At the same
time, the constant temperature test may have overstated diffusion due to the measured small
fluctuations in temperature that may have caused mini-diurnal cycles.  Likely, the actual
diffusion rates are somewhere in-between the results presented in Tables 5.1-11 and 5.1-12.
Appendix 5B contains data charts that present the results of the Small SI diffusion testing in
more detail.

       Although the results are presented above on a gram per gallon basis for comparison with
diurnal emissions, diffusion appears to be more a function of orifice size that fuel tank size.
Presumably, the diffusion rate on a grams per day basis would be the same through a given
orifice regardless of size of the vapor space. This is reflected in the data above in that the
permeation rates on a gram per gallon basis from the lawnmower fuel tanks with holes in the fuel
cap were much larger than for the marine fuel tank in the testing discussed earlier. At the same
time, larger fuel tanks may be designed with larger orifice sizes to account for higher amounts of
vapor expansion in the tank.

5.1.4  Carbon Canister

       The primary diurnal evaporative emission control device used in automotive applications
is a carbon canister. With this technology, vapor generated in the tank is vented through a
canister containing activated carbon (similar to charcoal).  The fuel tank must be otherwise
sealed; however, this only results in a minimal amount of pressure in the tank. The activated
carbon collects and stores the hydrocarbons. Once the engine is running, purge air is drawn
through the canister and the hydrocarbons are burned in the engine.  These carbon canisters
                                          5-15

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Final Regulatory Impact Analysis
generally are about a liter in size for an automotive tank and have the capacity to store three days
of vapor over the test procedure conditions. For automotive applications, this technology
reduces diurnal emissions by more than 95 percent.

       In a marine application, the vessel may sit for weeks without an engine purge; therefore,
canisters were not originally considered to be a practical technology for controlling diurnal vapor
from boats.  Since that time, however, we have collected information showing that, during
cooling periods, the canister is purged sufficiently enough so that it can be used effectively to
reduce diurnal emissions. When the fuel in the tank cools, fresh air is drawn back through the
canister into the fuel tank.  This fresh air will partially purge the canister and return
hydrocarbons back to the fuel tank.20'21 Therefore, the canister will have open sites available to
collect vapor during the next heating event. Test data presented below show that a canister that
starts empty is more than 90 percent effective at capturing hydrocarbons until it reaches
saturation.  Once the canister reaches saturation, it is still capable of achieving more than a 60
percent reduction in diurnal emissions due to passive purging. Passive purging occurs as a result
of fresh air that is pulled through the canister during fuel tank cooling periods. With the addition
of an engine (active) purge, greater reductions would be expected.

       We tested a 30 gallon aluminum fuel tank over three, multiple-day diurnal cycles with
and without a charcoal canister.  The carbon canister was 2.1 liters in size with a butane working
capacity (BWC) of 11 g/dL (based on  EPA test) and was aged using multiple 24 hour diurnal
cycles prior to testing. In our first test, the fuel temperature was cycled from 72-96F using a
heating blanket in a SUED for at total  of 28 days.  Because we were not able to test over
weekends, we brought the fuel temperature down to  72F and held it to prevent the generation or
purging of vapors.  On Mondays, we saw higher vapor rates than the rest of the week which was
likely due to the vapor redistributing itself equally through the canister over the weekend when
the temperature was held constant. Under normal conditions, the continued diurnal cycles would
maintain a gradient through the canister and this effect would not occur. Appendix 5C contains
graph showing the results of the 28 day test.  This test is interesting because we began with a
purged canister and were able to observe the loading of the canister over the first few days. It
took about five test days to achieve canister breakthrough  and another ten test days before  the
canister loading/purging cycle stabilized.

       Once the canister was saturated, the emissions results stabilized. Therefore, for the
subsequent canister tests, we began with a loaded canister and tested for four days. The results
were collected beginning after the first night so that the canister would have a cooling  cycle for
back-purge. Table 5.1-14 presents our test results for the baseline and stabilized with canister
diurnal emission rates.
                                           5-16

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                                              Feasibility of Evaporative Emission Control
      Table 5.1-14: EPA Diurnal Emission Test Results With and Without a Canister
                 on a 30 Gallon Aluminum Marine Fuel Tank [g/gal/day]
Temperature Range
22.2-35.6C (72-96F)
25.6-32.2C (78-90F)
27.8-30.6C (82-87F)
Baseline
1.50
0.85
0.47
With a Canister
0.52
0.28
0.14
Reduction
65%
67%
71%
       Marine manufacturers raised the concern that the high humidity in the areas where boats
are used would be detrimental to this technology.  They stated that the carbon could become
saturated with water vapor, thereby reducing the available sites for hydrocarbon capture. These
manufacturers also commented that carbon canisters may not be able to survive shocks and
vibration that would be seen on a boat. Carbon canisters have been used in automotive
applications for decades, which are subject to high humidity (rainy days)  and shocks and
vibration. In addition, one manufacturer, who is a primary supplier to the automotive industry,
has developed a new grade of carbon that has low moisture adsorption characteristics and about
40 percent harder than typical automotive carbon.22'23 This carbon has been designed specifically
for marine applications.  Based on this manufacturer's testing, more than  a 60 percent reduction
in diurnal vapor emissions can be achieved with a passive purge system.  This reduction is based
on a canister capacity of 0.03 to 0.04 liters of carbon per gallon of fuel tank capacity.

       The National Marine Manufacturers Association performed a test program has to
demonstrate the durability of carbon canisters in marine applications.  This test program included
installing carbon canisters on a total of fourteen boats made by four boat builders.24 These boat
types included cruisers, runabouts, pontoon boats, and fishing boats. The carbon canister design
used for these boats is a simple cylinder that can be cut to length with end caps and mounting
brackets.  The canisters were installed in the vent lines and a valve was added to prevent liquid
fuel from reaching the canister during refueling. These canisters use marine grade carbon.  At
the end of this test program, each of the  canisters were tested for working capacity and each
canister showed proper performance.25

       Another issue that has been raised has been the ability of carbon canisters to pass the
Coast Guard flame test.  The carbon canisters could be made out of a variety of materials,
including metal.  Even a thin-walled nylon  fuel  tank could be manufactured to pass the flame test
if a flame-resistant coating or cover were used.  One study attempted to ignite a carbon canister
that was loaded with fuel vapor.26  When an ignition source was applied to the canister vent, the
gases exiting the canister were ignited and burned as a small, steady flame until the canister tube
opening began to melt.  No explosion occurred. In any case, as with the vent line, if the carbon
canister is self-draining, then the canister would not  likely hold the five ounces of fuel, specified
in 33 CFR 183.558, to trigger the need for flame protection.

       Manufacturers have raised the concern that it is common for liquid fuel to pass out the
                                          5-17

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Final Regulatory Impact Analysis
                                   Fill neck
                                                                               Canister
vent line during refueling.  If there were a canister in the vent line it would become saturated
with fuel.  While this would not likely cause permanent damage to the canister, we believe
marine fuel systems should prevent liquid fuel from exiting the vent line for both environmental
and safety reasons. A float valve or small orifice in the entrance to the vent line from the fuel
tank would prevent liquid fuel from reaching the canister or escaping from the tank. Any
pressure build-up from such a valve would cause fuel to back up the fill neck and shut off the
fuel dispensing nozzle.  In addition,
a vapor space should be included to        Fiure 5A~1:  Canister Installation Example
account for fuel expansion. These                                            Vent line
fuel system design considerations are
straight-forward, long used in other
applications,27 are applicable to
boats,28 and would have the added
benefit of minimizing fuel spillage,
from boats, into the water. One
possible design for preventing fuel
from reaching the canister, due to
refueling, sloshing, or expansion, is
shown in Figure 5.1-1.

       Recently, the California Air Resources Board (ARE) performed diurnal emission testing
on a commercial mower and a generator with 6 gallon fuel tanks and 0.65 liter canisters.29 Their
testing showed better than 50 percent reductions, on average, in diurnal emissions through the
use of canisters without an engine purge. The testing was performed over two diurnal
temperature ranges,  53-71F and  65-105F which are intended to represent an average day and a
high temperature episode.

       Over a decade ago, testing performed on a car showed similar results.30 A 1988 Regency
98 with an 18 gallon fuel tank was subjected to an 8 day diurnal without driving. This diurnal
was performed using a 72-96F temperature profile, a tank filled to 40 percent with 9RVP
gasoline, and a purged canister at the beginning of testing.  The test results showed, that the
canister loading/purging cycle began to stabilize after 6 days. Due to the canister back-purge,
the stabilized diurnal emission rate about 11.5 grams per day which was more than a 50 percent
reduction compared to baseline.

       A manufacturer of activated carbon performed studies of ethanol fuel blend and carbon
bed temperature on carbon efficiency.31  Testing was performed with carbon canisters using
gasoline, E10, and E85 fuel for onboard vapor refueling emissions efficiency. The emissions
control was similar for each of the test fuels. Testing was also performed to measure gasoline
working capacity for carbon soaked at temperatures ranging from 25 to 80C.  Over this range
only a 10 percent decrease in working capacity was  observed with increasing temperature.  Over
the 25-40C range, which is more representative of boat or Small SI equipment use, the effect
was only 1-2 percent. Based on the results from these studies, carbon  canister efficiency would
be expected to be effective at reducing diurnal emissions over the range of fuels and
temperatures that may be seen in  use.
                                          5-18

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                                              Feasibility of Evaporative Emission Control
5.1.5  Sealed System with Pressure Relief

       Evaporative emissions are formed when the fuel heats up, evaporates, and passes through
a vent into the atmosphere. By closing that vent, evaporative emissions are prevented from
escaping. However, as vapor is generated, pressure builds up in fuel tank. Once the fuel cools
back down, the pressure subsides.  One way to control these emissions is to seal the fuel system.
However, depending on the fuel tank design, a pressure relief valve may be necessary which
would limit the control.

       5.1.5.1 Pressure Relief Valve

       For most marine applications, U.S. Coast Guard safety regulations require that fuel tanks
be able to withstand at least 3 psi and must be able to pass a pressure impulse test which cycles
the tank from 0 to 3 psi 25,000 times (33 CFR part 183).2 The Coast Guard also requires that
these fuel tanks must be vented such that the pressure in the tank in-use never exceeds 80 percent
of the pressure that the tank is designed to withstand without leaking.  The American Boat and
Yacht Council makes the additional recommendation that the vent line should have a minimum
inner diameter of 7/16 inch.32 However, these recommended practices also note that "there may
be EPA or state regulations that limit the discharge of hydrocarbon emissions into the
atmosphere from gasoline fuel systems.  The latest version of these regulations should be
consulted."

       To prevent pressure from building too high in marine tanks, we first considered a 2 psi
pressure relief valve. This is a typical automotive rating and is below  the Coast Guard
requirements.  With this valve, vapors would be retained in the tank until 2 psi of pressure is
built up in the tank due to heating of the fuel.  Once the tank pressure reached 2 psi, just enough
of the vapor would be vented to the atmosphere to maintain  2 psi of pressure. As the fuel cooled,
the pressure would decrease.  In our August 14, 2002 proposal (67 FR 53050) we considered
standards based on a 1 psi valve which would only achieve a modest reduction over the diurnal
test procedure. However this reduction would be significantly greater in use because the test
procedure is designed to represent a hotter than average day. On a more mild day, there would
be less pressure buildup in the tank and the valve may not even need to open. With the use of a
sealed system, a low pressure vacuum relief valve would also be necessary so that air could be
drawn into the tank to replace fuel drawn from the tank when the engine is running.

       Manufacturers of larger plastic fuel tanks have expressed concern that their tanks are not
designed to operate under pressure. For instance, although they will not leak at 3 psi,
rotationally molded fuel tanks with large flat surfaces could begin deforming at pressures as low
as 0.5 psi. At 2.0 psi, the deformation would be greater. This deformation would affect how the
tank is mounted in the boat.  Also, fuel tank manufacturers commented that some of the fittings
       2 These regulations only apply to boats with installed fuel tanks and exclude outboard boats.
However, ABYC recommended practice effectively extends many of these requirements to outboard
boats as well.

                                          5-19

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Final Regulatory Impact Analysis
or valves used today may not work properly under 2 psi of pressure.  Finally, they commented
that backup pressure-relief valves would be necessary for safety.  For smaller fuel tanks, such as
used in personal watercraft, portable fuel tanks, and Small SI equipment, pressure is less of an
issue because of the smaller internal surface area of these fuel tanks.  In addition, the
construction of these fuel systems are generally vertically integrated which allows for more
precise control of design parameters.  For instance, personal watercraft manufacturers are
already sealing their fuel systems to prevent fuel from spilling into the water. These systems
generally have pressure relief valves ranging from 0.5 to 4.0 psi.  In addition, portable fuel tanks
are designed to be sealed without any pressure relief.

      We looked at two types of pressure relief strategies: pressure relief valves and limited
flow orifices. Because the Coast Guard requires that  fuel systems not exceed 80 percent of their
design capacity of 3 psi, we only looked at pressure relief strategies that would keep the pressure
below 2.4 psi under worst case conditions.

      For the pressure relief valve testing, we looked at several pressures ranging from 0.5 to
2.25 psi.  The 2.25 psi valve was an off-the-shelf automotive fuel cap with a nominal 2 psi
pressure relief valve and 0.5 psi vacuum relief valve.  For the other pressure settings, we used
another automotive cap modified to allow adjustments to the spring tension in the pressure relief
valve. We performed these tests on the 17 gallon aluminum fuel tank to remove the variable of
permeation.  Emissions were vented through a hose to prevent diffusion losses from affecting the
measurements.  We operated over two temperature profiles. The first set of tests were performed
in a variable temperature SUED with a 72-96F air temperature profile.  This temperature profile
was based on the existing automotive cycle which is intended to represent a typical summer day
on which a high ozone event may occur. The second set of tests were performed using a heating
blanket to create a 78-90F fuel temperature profile.  This testing was intended to represent a
fuel tank in a boat, where the tank may be inherently  insulated, during the same ambient
temperature profile.  This inherent insulation creates a time lag on the heating and cooling of the
fuel and reduces the amplitude of the temperature profile by half.

      As shown in Figure 5.1-2, there was a fairly linear relationship between the pressure
setting of the valve and the emissions measured over  the variable-temperature test procedure. In
addition, the slopes of the lines are similar for both test temperature scenarios. This suggests that
over a smaller temperature profile, a greater percent reduction in HC can be achieved at a given
pressure setting. This is reasonable because, in each case, a constant amount of vapor is
captured.  In other words, regardless of the temperature profile, the same amount of vapor must
be generated to create a given pressure. For instance, with a  1 psi valve, about 0.4 grams/gallon
of HC are captured over each temperature profile. However, this represents a 50 percent
reduction over a 78-90F temperature profile while only about a 25 percent reduction over the
72-96F temperature profile.
                                          5-20

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                                             Feasibility of Evaporative Emission Control
                Figure 5.1-2: Effect of Pressure Cap on Diurnal Emissions
        0.0
0.5            1.0            1.5
          pressure relief setting [psi]
2.0
2.5
       Portable marine fuel tanks are generally equipped with a valve that allows the tank to be
sealed when not in use. The valve must be opened during engine operation or the draw of fuel
from the fuel tank can create a vacuum in the fuel tank.  If the vacuum becomes too great, the
engine will not be able to draw sufficient fuel from the tank and therefore stall.  During storage,
the valve may be closed to prevent fuel vapors from escaping. These fuel tanks are designed to
withstand pressurization much greater than would be experienced when a fuel tank is heated by
ambient temperature changes.  However, this vapor control strategy relies heavily on user
behavior. According to one survey, the majority of boat owners store their portable marine  fuel
tanks with fuel in them, and many do not close the vent  during storage.33 Therefore, significant
emission reductions may be achieved with a sealed fuel  tank with an automatic vacuum relief
valve.  This is discussed further in section 5.1.5.3 below.

       The California Air Resources Board tested a lawnmower in a  SHED for diurnal
emissions in a baseline configuration, a sealed system, and with various pressure relief settings.34
Because the whole lawnmower was tested, permeation (and potentially leakages) were measured
as well as diurnal venting emissions. The testing was performed over a 65-105F temperature
cycle with the fuel tank filled to 50 percent with 7 RVP  fuel. For the system as a whole, they
measured a 76 percent reduction in emissions when the tank was fully sealed compared to the
open vent configuration. This suggests that diurnal venting made up  about 76 percent of the
evaporative emissions measured.  Testing using 2, 3, and 4 psi pressure relief valves showed
reductions of 43 percent, 43 percent, and 63 percent respectively.  They also collected pressure
data over various diurnal temperature cycles on a lawnmower fuel tank.  Over the 65-105F
cycle, the measured a pressure increase of about 2.5 psi. Even under an extreme cycle of 68-
121F, the measured increase in tank pressure was about 3.6 psi.
                                          5-21

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Final Regulatory Impact Analysis
       5.1.5.2 Limited Flow Orifice

       Another strategy for maintaining a design pressure is to use a limited flow orifice on the
vent.  In our testing, we are looked at three orifice sizes: 25, 75, and 1,000 microns in diameter.
Again, we performed tests over a 72-96F diurnal using a 17 gallon aluminum tank. To get these
exact orifice sizes, we ordered from a company that specializes in boring holes with a laser
device. These orifices were relatively inexpensive.  It should be noted that a smaller tank would
need a smaller orifice and a larger tank could use a larger orifice to build up the same pressure in
the tank.  The test results are presented in Table 5.1-15.  For all of the tests with the limited flow
orifices, no vent hose was attached.

         Table 5.1-15:  Diurnal Evaporative Emissions with Limited Flow Orifices
Orifice Diameter (microns)
baseline (open vent with hose)
1000
75
25
Peak Pressure [psi]
0.0
0.0
1.6
3.1
Evaporative HC [g/gallon/day]
1.40
1.47
1.16
0.24
       By limiting the flow of the vapor from the tank, emissions were reduced with some
pressure build up in the tank. However, because the vapor is flowing from the tank even at low
pressure, this strategy is less effective for reducing diurnal emissions than a pressure relief valve.
Generally, a higher peak pressure is necessary with the LFO for a given emission reduction.  In
addition, the limited flow orifice would have to be sized for worst case conditions to prevent the
tank from reaching too high of a pressure. A LFO sized for worst case conditions would be less
effective under typical conditions because the vapor flow out of the tank could be too low for the
LFO to create a restriction.  In comparison, a pressure relief valve would achieve higher percent
reductions under typical conditions than for worst case conditions because the valve would open
less often.

       5.1.5.3 Vacuum Relief Valve

       For some fuel tanks, pressure relief is not necessary. An example of this is portable
marine fuel tanks which are currently equipped with a manual sealing valve.  This valve can be
sealed by the operator during storage to prevent vapor from escaping. Although pressure will
build up during diurnal heating, the fuel tanks are designed to withstand this pressure. However,
the valve must be opened by the operator during engine operation so that a vacuum does not
form in the fuel tank as fuel is drawn to the engine. If this vacuum were to become too high, it
could cause the engine to stall by restricting fuel to the engine.

       The existing design requires that the operator close the valve whenever the engine is not
running for diurnal emissions to be controlled.  If an automatic vacuum relief valve were used,
                                           5-22

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                                             Feasibility of Evaporative Emission Control
then the operator would not need to operate the sealing mechanism. It would always control
diurnal emissions. At the same time, the vacuum relief valve would allow air to be drawn into
the fuel tank when the engine is operating to prevent a significant vacuum from being formed.

       One manufacturer's approach to this automatic valve design is to use a diaphragm valve
such as those used in automotive fuel systems.35 This inexpensive design would be able to seal
the tank under pressure, yet open at very low vacuums. This design (or other vacuum relief
valve designs) could be used in any nonroad application where the fuel system is able to
withstand pressure.

5.1.6 Selective Permeability Membrane

       Another approach we  investigated was fitting a molecular membrane in the vent line.
The theory was that the membrane would allow oxygen and nitrogen to pass through, but block
most longer-chain hydrocarbon molecules. We used a membrane fabricated using Teflon AF
which is an amorphous fluoropolymer. Because oxygen and nitrogen (and some smaller
hydrocarbons) can pass through the membrane, hydrocarbons can be trapped in the fuel tank.
However, the process for molecules passing through the membrane is slow, so it is important  to
size the membrane properly to prevent pressure build-up. This membrane could be placed in  the
vent line or directly in an opening in the top of the fuel tank.

       Similar membranes are already used for several applications. One manufacturer provides
membranes for a variety of uses such as oxygen or nitrogen enrichment of air or for separation of
hydrocarbons from air.36 One of these uses is to act as a vapor processor to prevent hydrocarbon
vapor from escaping from retail gasoline stations in California.37 Another membrane used for
similar applications allows hydrocarbons to permeate but blocks smaller gases. This membrane
is used in hydrocarbon recovery applications.38 In the above noted applications, the membranes
are typically used with a pump to provide a pressure drop across the membrane which causes
permeation through the membrane. Typically, adequate mixing is needed to maintain an
efficient diffusion rate.

       We tested an amorphous fluoropolymer membrane with a surface area of about 40 cm2 in
the vent line of both a 30 and a 17 gallon aluminum fuel tank over three temperature cycles. The
membrane was applied to a wire mesh in a cylindrical shape with the an outside diameter not
much larger than the vent hose. Hydrocarbon emissions and fuel tank pressure were measured.
Over these tests we consistently saw a pressure build up, even over a 24 hour test. To investigate
the impacts of surface area, we increased the surface area by using 3 filters in parallel (single
vent line to assembly).  Our test results suggest that the pressures associated with this technology
are comparable with the pressure relief valves needed to achieve the same reductions. However,
this technology may have the potential for meeting our standards if used in conjunction with a
pump to provide  a pressure differential across the filter without allowing pressure (and mixing)
to build up in the fuel tank. Our test results are presented in Table 5.1-16.
                                          5-23

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Final Regulatory Impact Analysis
      Table 5.1-16: Diurnal Venting Emissions with Selective Permeable Membranes
Tank Size
[gallons]
30


17


Venting
open
1 filter
3 filters
open
3 filters
72-96F
g/gal/day psi
1.50
0.24
0.39
1.40
0.45
0
2.9
2.2
0
2.1
78-90F
g/gal/day psi
0.85
0.14
-

0.30
0
1.5
-

1.2
81.6-86.4F
g/gal/day psi
0.47
0.19
-

-
0
0.6
-

-
5.1.7  Volume Compensating Air Bag

       Another concept for minimizing pressure in a sealed fuel tank is through the use of a
volume compensating air bag.39  The purpose of the bag is to fill up the vapor space in the fuel
tank above the fuel itself. By minimizing the vapor space, less air is available to mix with the
heated fuel and less fuel evaporates.  As vapor is generated in the small vapor space, air is forced
out of the air bag, which is vented to atmosphere.  Because the bag collapses as vapor is
generated, the volume of the vapor space grows and no pressure is generated.3 Once the fuel
tank cools as ambient temperature goes down, the resulting vacuum in the fuel tank will open the
bag back up.

       We tested a 6 gallon portable plastic fuel tank with a 1.5 gallon volume compensating
bag made out of Tedlar. Tedlar is a light, flexible, clear plastic which we use in our labs for
collecting exhaust emissions samples.  In our testing, the pressure relief valve never opened
because the volume compensating bag was able to hold the vapor pressure below 0.8 psi for each
of the three days.  This testing supports the theory that a volume compensating bag can be used
to minimize pressure in a fuel tank, which  in turn, reduces emissions when used in conjunction
with a pressure relief valve.

       We did see an emission rate of about 0.4 g/gal/day over the 3 day test. The emission rate
was fairly constant, even when the ambient temperature was cooling during the test.  This
suggests that the emissions measured were likely permeation through the tank. Other materials
may be more appropriate than Tedlar for the construction of these bags. The bags would have to
hold up in a fuel tank for years and resist permeation while at the same time be light and flexible.
One such material that may be appropriate would be a fluorosilicon fiber.
       3 The Ideal Gas Law states that pressure and volume are inversely related. By increasing the volume of the
vapor space, the pressure can be held constant.
                                          5-24

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                                             Feasibility of Evaporative Emission Control
5.1.8  Bladder Fuel Tank

       Probably the most effective technology for reducing evaporative emissions from fuel
tanks is through the use of a collapsible fuel bladder. In this concept, a non-permeable bladder
would be installed in the fuel tank to hold the fuel. As fuel is drawn from the bladder, the
vacuum created collapses the bladder. Therefore, there is no vapor space and no pressure build
up. Because the bladder would be sealed, there would be no vapors vented to the atmosphere.
In addition, because there is no vapor space, vapor is not displaced during refueling events. We
have received comments that bladder tanks would be cost prohibitive because its use would
increase tank costs by 30 to 100 percent depending on tank size. However, bladder fuel tanks
have positive safety implications as well and are already sold by at least one manufacturer to
meet market demand in niche applications. Information on this system is available in the
docket.40

       We tested a marine bladder fuel tank in our lab for both diurnal and permeation
emissions. Over the diurnal test procedure we saw an emission rate of 0.2 g/gal/day.  Because
the system was sealed, this measured emission rate was likely due to permeation through the
bladder and not due to diurnal losses. We later tested the bladder fuel tank for permeation
emissions at 29C and measured a permeation rate of 0.46 g/gal/day.  The bladder used in our
testing was constructed out of polyurethane. The manufacturer of this bladder tank is now
working with a lower permeability material known as THV.  THV is a fluoropolymer that can be
used to achieve more than a 95 percent reduction in permeation from current bladder fuel tanks
made  out of polyurethane.41 In addition, THV is resistant to ethanol.  Permeation rates for these
materials are presented in Appendix 5D.

5.1.9  Floating Fuel and Vapor Separator

       Another concept used in some stationary engine applications is a floating fuel and vapor
separator. Generally small, impermeable plastic balls are floated in the fuel tank. The purpose
of these balls is to provide a barrier between the surface of the fuel and the  vapor space.
However, this strategy does not appear to be viable for fuel tanks used in mobile sources.
Because of the motion of Small SI equipment and Marine  SI vessels, the  fuel sloshes and the
barrier would be continuously broken. Even small movements in the fuel could cause the balls
to rotate and transfer fuel to the vapor space.  In addition, the unique geometry of many fuel
tanks could case the balls to collect  in one area of the tank. However, we do not preclude the
possibility that some form of this approach could be made to work effectively in some mobile
source applications.
5.1.10  Liquid Vapor Trap

       One company has developed a
liquid vapor trap that it refers to as a
fuel vapor containment system (VCS).42
The VCS behaves similar to a liquid
trap used in sink drains in that trapped
Figure 5.1-3: Liquid Vapor Trap
II
fuel tank
L -^^
VCS
~il Ir
A

B

                                    vent
                                          5-25

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Final Regulatory Impact Analysis
liquid creates a barrier to gases. This trap would be placed in the vent line to limit fuel vapor
emitted from the fuel tank.  Figure 5.1-3 presents an illustration of the basic concept.

       When the temperature in the fuel tank increases, the vapor would expand in the fuel tank.
The fuel vapor would enter chamber A and force more of the liquid into chamber B.  This would
provide room for the vapor to expand without allowing vapor to escape through the vent. As the
fuel tank cools, the vapor would condense. This would cause the level of the liquid in chamber A
to rise while the level of the liquid in chamber B would drop. Some pressurization may occur in
the fuel tank with this system, but it would be much less than for a sealed fuel tank due to the
expansion chamber.  Any pressure or vacuum in the fuel system would be a function of the VCS
design and would be expected to be less than 0.5 psi. In addition, a pressure relief valve could
be added to the system to protect against any high pressure excursions.

       In the initial testing of the VCS, the manufacturer has used water as the liquid barrier.
However, they stated that ethylene-glycol or even oil could be used which would be more stable
liquids and would resist freezing.  Diurnal testing was performed on a 25  gallon fuel  tank
equipped with a roughly 3 gallon VCS unit.43 Testing was performed in a mini-SHED over the
EPA 72-96C diurnal cycle for two days.  The tank was filled to 50 percent capacity with 9 RVP
certification gasoline. The total weight loss was 1.1 grams on the first day and 2.6 grams on the
second day.  Using the higher of the two days, we get a diurnal emission rate of about 0.1
g/gal/day.  The peak pressure during this testing was approximately 0.5 psi.

5.2  Running Loss Emissions

       Running loss emissions are similar to diurnal emissions except that the fuel temperature
rise is due to heat from the engine or other heat producing components, such as hydraulic
systems, when the engine is running.  This section summarizes the data and rationale supporting
the running loss emission standard for Small SI equipment presented in the Executive Summary.

5.2.1 Baseline Emissions

       To investigate running loss emissions, we instrumented seven riding lawnmowers, three
walk-behind lawnmowers, two generators, and one pressure washer to measure the fuel
temperature during typical operation. Many of the temperature measurements were made by a
contractor.44 Of the  riding mowers, two had fuel tanks in front near the engine, three had fuel
tanks in rear away from engine (but near the hydraulic system), and two were "zero-turn"
mowers that had pairs of side saddle tanks that were relatively close to the rear mounted engine.
All of the riding mowers had plastic fuel tanks.  One of the walk-behind mowers had a metal
tank directly mounted to the block while the others had plastic tanks near the top/side of the
engine. Both generators had plastic tanks mounted above the engine while the pressure washer
had a metal tank mounted above the engine. All of the equipment vented through the fuel caps.
The pressure washer had a metal fuel tank mounted above the engine. The equipment was
operated in the field  until the fuel temperature stabilized. For lawnmowers, the fuel temperature
stabilized within 20 to 30 minutes while the larger equipment took up to an hour.
                                          5-26

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                                             Feasibility of Evaporative Emission Control
       By measuring the increase in fuel temperature during operation, we were able to make a
simple determination of the running loss emissions vented from the fuel tank. Other potential
running loss emissions would be from the carburetor, due to permeation increases due to heating
the fuel, or vibration-induced leaks in the fuel system. However, we believed that the majority
of the running loss emissions would be due to breathing losses associated with heating the fuel.
Table 5.2-1 presents the results of the temperature testing.

       We contracted with an independent testing laboratory to test fuel tanks from most of the
above pieces of equipment over the measured fuel temperature profiles.45 For three of the tests
on larger fuel tanks, we found that the measured emissions were inconsistent with theoretical
predictions.  An investigation of the test data suggested that the test had been ended too soon to
see the full effect of the heat build. Repeat tests were performed with a longer sample time.46
From this data we get the running loss emissions due to the breathing losses associated with the
heating of the fuel tank. New tanks were purchased for this testing that had not been previously
exposed to fuel so permeation emissions would not be included in the emission measurements.
Table 5.2-1 also presents the test results for the above equipment.

            Table 5.2-1: Fuel Temperature Measurements During Operation of
     Small SI Equipment and Hydrocarbons Measured Over This Temperature Profile
Equipment Type

Riding mower
front tank near engine
Riding mower
rear tank away from engine

Zero-turn riding mower
2 saddle tanks near engine
Walk-behind mower (plastic)

Walk-behind mower (metal)
Generator set

Pressure washer
Fuel Capacity
[gallons]
1.7
1.1
6.5
3.0
2.5
6.5x2
1.4x2
0.34
0.25
0.22
8.5
7.0
1.8
Min. Temp
C
19.5
15.7
24.3
26.6
27.0
20.5
21.9
23.3
28.7
28.7
20.6
25.8
19.0
Max. Temp
C
30.3
28.4
33.2
28.4
35.0
23.9
29.7
33.0
46.7
59.7
25.8
50.0
50.6
HC [g/hr]

1.4
1.0
7.8
0.7
3.2
3.4
2.5
0.3
1.2
8.1
1.8
69.3
20.3
       The California Air Resources Board performed running loss tests on several pieces of
Small SI equipment.47 This equipment included four lawnmowers (2 new and 2 old), one string
trimmer, two generators, two ATVs, and two forklifts. To measure running loss emissions, the
equipment were operated on California certification fuel in a SFtED and the exhaust was routed
                                          5-27

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Final Regulatory Impact Analysis
outside the SHED. Running loss emissions were determined by measuring the HC concentration
in the SHED. Therefore the measurements included all evaporative emissions during operation
including those from fuel heating, permeation, carburetor losses, and, for the two older
lawnmowers, liquid fuel leaks.  Although the ATVs and forklifts are not considered to be small
offroad engines, these data can be used as surrogates for equipment that were not tested. Table
5.2-2 presents this data.

                   Table 5.2-2: Results from ARE Running Loss Tests
Equipment Type
lawnmower
string trimmer
generator
ATV
forklift
Model Year*
2000
2001
1994
1989
1999
1995
2001
2001
2001
1995
1987
Running Loss [g/hr]
0.8
2.6
27.0
12.1
0.6
19.5
1.8
21.4
1.3
1.8
7.4
               the 2000 and 2001 equipment were new at the time of testing
5.2.2  Control Technology

       Running loss emissions can be controlled by sealing the fuel cap and routing vapors from
the fuel tank to the engine intake. In doing so, vapor generated heat from the engine will be
burned by the engine.  It may be necessary to use a valve or limited flow orifice in the purge line
to prevent fuel from entering the line in the case of the equipment turning over and to limit the
vapor to the engine during operation. Depending on the configuration of the fuel system and
purge line, a one way valve in the fuel cap may be desired to prevent a vacuum in the fuel tank
during engine operation. We anticipate that a system like this would eliminate running loss
venting emissions. However, higher temperatures during operation would increase permeation
somewhat. In  addition, the additional length of vapor line would increase permeation.
Considering these effects, we still believe that the system described here would result in more
than a 90 percent reduction in running loss emissions from Small SI equipment.

       A secondary benefit of running loss control for Small SI equipment has to do with
diffusion emissions. As discussed above, venting a fuel tank through a hose (rather than through
an open orifice) greatly reduces diffusion. In the system discussed above, all venting losses
would occur through the vapor hose to the engine intake rather than through open vents in the
                                          5-28

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                                             Feasibility of Evaporative Emission Control
fuel cap. Therefore, the diffusion effect should be largely eliminated.

       Another approach to reducing running loss emissions would be to insulate the fuel tank
or move it further from heat sources such as the engine or hydraulic system. With this approach,
the fuel cap vent would likely still be used, but diffusion could be controlled using a tortuous
vent path in the cap as described above.

       For marine fuel tanks we are not considering running loss emissions. For portable fuel
tanks and installed fuel tanks on larger vessels, we would not expect there to be significant
heating of the fuel tanks during engine operation due to the distance from the engine and the
cooling effect of operating the vessel in water.  For personal watercraft, the fuel tanks have a
sealed  system with pressure relief that should help contain running loss emissions. For other
installed fuel tanks, we would expect the diurnal emission control system to capture about half of
any running losses as well.

5.3 Fuel Tank Permeation

       The polymeric material (plastic)  of which many gasoline fuel tanks manufactured
generally has a chemical composition much like that of gasoline. As a result, constant exposure
of gasoline to these surfaces allows the material to continually  absorb fuel. Permeation is driven
by the  difference in the chemical potentials of gasoline or gasoline vapor on either side of the
material. The outer surfaces of these materials are exposed to ambient air,  so the gasoline
molecules permeate through these fuel-system components and are emitted directly  into the air.
Permeation emissions continue at a nearly constant rate, regardless of how much the vehicle or
equipment is used. Because of these effects, permeation-related emissions can therefore add up
to a large fraction of the total emissions from nonroad equipment.

       This section summarizes the data and rationale supporting the permeation emission
standard for Small SI and Marine SI fuel tanks presented in the Executive Summary.

5.3.1 Baseline Fuel Tank Technology  and Emissions

       Fuel tanks may be constructed in several ways.  Portable marine fuel tanks and some
small, higher production-volume, installed marine fuel tanks are generally blow-molded using
high-density polyethylene (HDPE). Larger, installed marine fuel tanks are generally either
rotationally-molded using cross-link polyethylene (XLPE) or are constructed out of welded
aluminum. Some boat builders even construct the fuel tanks out of fiberglass as part of the
vessel  construction.  Fuel tanks on Small SI equipment may be injection molded, blow molded or
rotationally molded. Blow-molded and injection-molded tanks are primarily made of HDPE, but
nylon is used as well in some applications. Rotationally molded fuel tanks are generally made
out of XLPE.

       Blow molding is widely used for the manufacture of Small SI, portable marine, and PWC
fuel tanks. Typically, blow molding is performed by creating a hollow tube, known as a parison,
by pushing high-density polyethylene (HDPE) through an extruder with a screw.  The parison is

                                          5-29

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Final Regulatory Impact Analysis
then pinched in a mold and inflated with an inert gas. In automotive applications, non-
permeable plastic fuel tanks are produced by blow molding a layer of ethylene vinyl alcohol
(EVOH) or nylon between two layers of polyethylene. This process is called coextrusion and
requires at least five layers: the barrier layer, adhesive layers on either side of the barrier layer,
and HDPE as the outside layers which make up most of the thickness of the fuel tank walls.
However, multi-layer construction requires additional extruder screws which significantly
increases the cost of the blow molding machine.

       Injection molding can be used with lower production volumes than blow molding due to
lower tooling costs.  In this method, a low viscosity polymer is forced into a thin mold to create
each side of the fuel tank. The two sides are then welded together.  In typical  fuel tank
construction, the sides are welded together by using a hot plate for localized melting and then
pressing the sides together.  The sides may also be connected using vibration or sonic welding.

       Rotational molding has two advantages over blow molding, which is widely used for
forming automotive parts. First, the tooling cost is an order of magnitude lower than for blow-
molding. Therefore, for small production volumes such as seen for marine applications,
rotational molding is more cost-effective. Manufacturers of rotationally molded plastic fuel
tanks have commented that they could not produce their tanks  with competitive pricing in any
other way.  The second advantage of rotational molding is that larger parts can generally be
molded on rotational molding machines than on blow-molding machines. Plastic marine fuel
tanks can exceed 120 gallons.

       Installed plastic marine fuel tanks are often produced in many shapes and sizes to fit the
needs of specific boat  designs. These fuel tanks tanks are generally rotationally-molded out of
cross-link polyethylene.  Cross-link polyethylene, which has a permeation rate comparable to
HDPE, is used in larger marine applications because of its ability to pass the U.S. Coast Guard
flame resistance requirements (33 CFR 183.590).  Rotational-molding is also used in some Small
SI applications where there are low production volumes of unique fuel tanks.  XLPE is used in
these fuel tanks as well because the fuel tank is often exposed  and must be able to withstand
impacts such as flying debris.

       5.3.1.1 Baseline permeation test data

       5.3.1.1.1 Marine fuel tanks

       To determine the baseline permeation emissions from marine fuel tanks, we have
collected permeation data on several plastic fuel tanks. Because gasoline does not permeate
through aluminum, we did not perform permeation testing on aluminum fuel tanks.

       We tested ten plastic fuel tanks that were either intended for marine  use or are of similar
construction.  This permeation testing was performed at 29C with gasoline. Prior to testing, the
fuel tanks were stored with gasoline in them for about 20 weeks to ensure stable permeation
rates. Table 5.3-1 presents the measured permeation rates for these fuel tanks in grams per
gallon of fuel tank capacity.  Where the internal surface area was either easily determined or

                                          5-30

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                                             Feasibility of Evaporative Emission Control
supplied by the manufacturer, we also calculated the permeation rate in terms of grams per
square meter of inside surface area.  The 31 gallon tank showed much lower permeation than the
other fuel tanks.  This was likely due to the thickness of the walls in this tank.  Even after
stabilization, permeation is a function of material thickness.  According to Pick's Law, if the
wall thickness of a fuel tank were double, the permeation rate would be halved.48

   Table 5.3-1:  Permeation Rates for Plastic Marine Fuel Tanks Tested by EPA at 29C
Tank Capacity
[gallons]
3.3
6.0
6.0
6.0
6.6
6.6
6.0
23
31
Permeation
[g/gal/day] [g/m2/day]
0.96
0.61
1.18
0.75
0.83
0.77
0.60
0.64
0.44
12.7
6.8
13.1
8.4
9.1
8.4
8.3
8.1
5.5
Construction
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
cross-link
cross-link
cross-link
Application
portable marine
portable marine
portable marine
portable marine
portable marine
portable marine
marine test tank
installed marine
installed marine
       The Coast Guard tested three rotationally-molded, cross-link polyethylene marine fuel
tanks at 40C (104F) for 30 days.49 The results are presented in Table 5.3-2. Because
permeation emissions are a function of surface area and wall thickness, there was some variation
in the permeation rates from the three tanks on a g/gal/day basis. These results are not directly
comparable to the EPA testing because of the difference in test temperature. However, we can
adjust the permeation rates for temperature using Arrhenius' relationship50 combined with
empirical data collected on permeation rates for materials used in fuel tank constructions
(described below).  These adjusted permeation rates are shown in Table 5.3-2 and are consistent
with the EPA test data.

         Table 5.3-2:  Permeation Rates for Cross-Link Marine Fuel Tanks at 40C
Tank Capacity
[gallons]
12
18
18
Measured Permeation
Loss [g/gal/day]
1.48
1.39
1.12
Average Wall
Thickness [mm]
5.3
5.6
6.9
Adjusted to 29C
[g/gal/day]
0.71
0.67
0.54
       5.3.1.1.2  Small SI equipment fuel tanks

       The California Air Resources Board (ARE) investigated permeation rates lawn & garden
equipment fuel tanks. The ARE data is compiled in several data reports on their web site and are
                                          5-31

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Final Regulatory Impact Analysis
included in our docket.51'52'53'54'55 Table 5.3-3 presents a summary of this data which was
collected using the ARB Test Method 513.56 Where multiple tests were run on a given tank or
tank type, the average results are presented.  Although the temperature in the ARB testing is
cycled from 18 - 41C rather than held at a constant temperature, the average temperature is
29C which is similar to the EPA testing.  Therefore,  the permeation results would likely be
similar if the data were collected at the average temperature of 29C used in the EPA testing.
Variation  in permeation rates on a gram per square meter basis is likely due to differences in the
wall thicknesses.  Note that surface area measurements were not available for all of the fuel
tanks.  Smaller fuel tanks would be expected to have  higher emissions on a gram per gallon basis
due to the increased surface area to volume ratio.  However, lower permeation rates were
observed for the fuel tanks less than  1 quart, potentially due to relatively thicker walls or due to a
difference in material used for these  applications.
                                           5-32

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                            Feasibility of Evaporative Emission Control
   Table 5.3-3: Permeation Rates for Plastic Lawn and
Garden Fuel Tanks Tested by ARE Over a 18-41C Diurnal
Tank Capacity
[gallons]
0.06
0.08
0.09
0.09
0.10
0.12
0.15
0.16
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.29
0.38
0.38
0.38
0.38
0.50
0.50
0.55
0.74
1.4
1.7
1.8
3.9
5.0
5.0
5.0
7.5
Permeation Loss
[g/gal/day]
0.20
0.26
0.12
0.19
0.28
0.53
0.42
0.29
1.32
0.73
0.67
0.74
0.86
0.68
1.06
1.24
0.99
0.67
0.66
0.62
1.39
1.26
1.27
0.27
1.30
0.92
0.08
1.39
1.04
1.24
1.82
1.72
1.14
1.47
3.28
3.20
2.75
3.82
2.07
Permeation Loss
[g/m2/day]
5.39
6.67

5.88

9.01
7.32
4.79
11.56
10.65
9.75
10.75
12.54
9.91
9.24
10.84
8.68
9.80
9.65
9.07
12.17
11.03
15.00

10.66
9.18

12.69
8.53


7.81

6.19
4.84


8.80
2.86
                         5-3

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Final Regulatory Impact Analysis
       Some handheld equipment, primarily chainsaws, use structurally-integrated fuel tanks
where the tank is molded as part of the body of the equipment.  In these applications the frames
(and tanks) are typically molded out of nylon for strength.  We tested structurally-integrated fuel
tanks from four handheld equipment manufacturers at 29C on both gasoline and s  10 percent
ethanol blend.  The test results suggest that these fuel tanks are capable of meeting  the standards
using their current materials. In the cases where the permeation rates were higher than the
standards, it was observed that the fuel cap seals had large  exposed surface areas on the O-rings,
which were not made of low permeation materials. Emissions could likely be reduced
significantly from these tanks with improved seal designs.  Table 5.3-4a presents the results of
this testing.  Note that permeation emissions are 20 to 70 percent higher on E10 than on gasoline
for these fuel tanks.

     Table 5.3-4a: Permeation Rates for Handheld Fuel Tanks Tested by EPA at 29C
Tank ID
Rl
R2
R3
Bl
B2
B3
B4
Wl
W2
W3
Gl
G2
G3
Application
clearing saw
(0.24 gallons)
hedge clipper
(0.05 gallons)

chainsaw
(0.06 gallons)
chainsaw
(0.06 gallons)
Material
nylon 6
nylon 6, 33% glass

nylon 6, 30% glass
nylon 6, 30% glass
Test Fuel
gasoline
E10
E10
gasoline
E10
E10
E10
gasoline
E10
E10
gasoline
E10
E10
Permeation Loss
[g/m2/day]
0.34
0.42
0.48
0.62
1.01
1.12
0.93
1.45
2.18
2.46
1.30
1.41
2.14
       The handheld industry also tested a number of fuel tanks for their products.57 In this
testing, they investigated the effect of fuel type and gasket material on the permeation results.
These test results suggested that permeation can be reduced significantly by using a low
permeation material, such as FKM, for the seal on the fuel cap. In addition, data on aged tanks
suggested that NBR o-rings may deteriorate in-use such that the permeation rate (or vapor leak
rate) through the seal increases greatly.  This test data is presented in Table 5.3-4b.

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                                             Feasibility of Evaporative Emission Control
       Table 5.3-4b: Permeation Rates for Handheld Fuel Tanks Tested by Industry
Tank
Capacity
350cc
260cc
773cc
400cc
1538cc
1538cc
530cc
400cc
Tank Material
nylon 6, 30% glass
nylon 6, 30% glass
nylon 6, 30% glass
nylon 6, 30% glass
nylon 6, 33% glass
nylon 6, 30% glass
nylon 6, 30% glass
HOPE
O-ring
Material
NBR
NBR
Aged NBR*
New NBR*
NBR
NBR
FKM
NBR
NBR
FKM
NBR
NBR (gasket)
Test
Temp.
28C
28C
40C
40C
40C
40C
40C
40C
Test Fuel
CE10
CE10
CE10
CE10
gasoline
CE10
CE10
CE10
gasoline
gasoline
Permeation Loss
[g/m2/day]
1.00
0.64
45.2
0.92
1.31
0.64
3.58
2.60
1.10
0.40
1.11
1.42
0.37
1.55
17.5
       * these units were used in the field prior to testing
       5.3.1.1.3  Portable fuel tanks

       The California Air Resources Board (ARE) investigated permeation rates from portable
fuel containers. Although this testing was not on Small SI or marine fuel tanks, the fuel tanks
tested are of similar construction.58'59 The ARB data is compiled in several data reports on their
web site and is included in our docket. Table 5.3-5 presents a summary of this data which was
collected using the ARB Test Method 513.60 Due to the increasing surface to volume ratio with
decreasing fuel tank sizes, data presented in terms of grams per gallon for smaller tanks would be
expected to be higher for the same grams per surface area permeation rate.  Although the
temperature in the ARB testing is cycled from 18 - 41C rather than held at a constant
temperature, the results would likely be similar if the data were collected at the average
temperature of 29C which is used in the EPA testing.
                                          5-35

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Final Regulatory Impact Analysis
                   Table 5.3-5:  Permeation Rates for HDPE Portable
                 Fuel Containers Tested by ARE Over a 18-41C Diurnal
Tank Capacity
[gallons]
1.0
1.0
1.0
1.0
1.0
1.0
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
2.1
2.1
2.1
2.1
2.5
2.5
5.0
5.0
5.0
5.0
5.0
5.0
5.0
6.6
Permeation Loss
[g/gal/day]
1.63
1.63
1.51
0.80
0.75
0.75
0.50
0.49
0.51
0.52
0.51
0.51
1.51
1.52
1.88
1.95
1.91
1.78
1.46
1.09
0.89
0.62
0.99
1.39
1.46
1.41
1.47
1.09
       5.3.1.2 Effect of temperature on permeation rate

       It is well known that the rate of permeation is a function of temperature.  For most
materials, permeability increases by about a factor of 2 for every 10C increase in temperature.61
To determine this relationship for nonroad fuel tanks, we performed permeation testing on nine
HDPE Small  SI fuel tanks at both 29C and 36C (85F and 96F).  This sample set included
both baseline and surface treated fuel tanks. On average (excluding the outlier), the temperature
effect was equivalent to nearly a factor of 2 increase in permeation per 10C increase in
temperature.  The one outlier likely resulted from measurement error due to the very low
permeation levels (0.5 grams lost over 2 weeks). Table 5.3-6 presents the test results.

                                         5-36

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                                           Feasibility of Evaporative Emission Control
    Table 5.3-6: Effect of Temperature on Permeation from HOPE Small SI Fuel Tanks
Tank
A
B
C
D
E
F
H
I
J
Treatment
untreated


sulfonated


fluorinated


29C [g/m2/day]
11.5
11.4
11.2
2.48
2.73
2.24
0.56
0.62
0.22
36C [g/m2/day]
17.1
16.6
17.0
4.10
3.98
3.42
0.75
0.68
0.31
Increase per 10C
92%
86%
97%
127%
85%
100%
60%
17%
80%
      Published data collected on HDPE samples at four temperatures62'63 suggest that the
permeation of gasoline through HDPE increases by about 80 percent for every 10C increase in
temperature.  This relationship is presented in Figure 5.3-1, and the numeric data can be found in
Appendix 5D.

               Figure 5.3-1:  Effect of Temperature on HDPE Permeation
      450
         0
           0
10       20       30       40
               degrees Celsius
50
60
70
      Another study was performed on the permeation from complete automotive fuel
systems.64 These fuel systems, which included fuel tanks, hoses, and other components, were
tested at both 29C and 40C on three fuel types (gasoline, ethanol blend, and MTBE blend).
                                        5-37

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Final Regulatory Impact Analysis
The effect of temperature on permeation did not appear to be significantly affected by fuel type.
Table 5.3-7 presents this data for ten automotive fuel systems tested on gasoline.  This data
showed more than a factor of 2 increase in permeation per 10C increase in temperature.

     Table 5.3-7: Effect of Temperature on Permeation from Automotive Fuel Systems
Fuel System
2001 Toyota Tacoma
2000 Honda Odyssey
1999 Toy ota Corolla
1997 Chrysler Town & Country
1995 Ford Ranger
1993 Chevrolet Caprice Classic
1991 Honda Accord LX
1989 Ford Taurus GL
1985 Nissan Sentra
1978 Olds Cutlass Supreme


Fuel Tank
Metal
Plastic (enhanced
evap)
Metal
Plastic (enhanced
evap)
HOPE
Fluorinated HOPE
Metal
Metal
Metal
Metal
29C
[mg/hr]
9
21
10
23
309
95
40
24
53
57


40C
[mg/hr]
20
55
24
52
677
255
110
52
148
122


Increase
per 10C
101%
136%
124%
110%
102%
143%
148%
100%
152%
99%


       5.3.1.3 Units for reporting the permeation rate (g/gal/day vs. g/m2/day)

       Much of the permeation data presented in this chapter is in units of grams of
hydrocarbons lost in a day divided by the capacity of the fuel tank (g/gal/day).  For diurnal
emissions, these units are used because the vapor generation is a function of fuel tank volume.
For permeation emissions, we considered using these units because the capacity of the fuel tank
is generally readily available; either identified on the fuel tank or readily measured. However,
although volume is generally used to characterize fuel tank emission rates, permeation is actually
a function of surface area. Because the surface to volume ratio of a fuel tank changes with
capacity and geometry of the tank, two similar shaped tanks of different volumes or two different
shaped tanks of the same volume could have different g/gal/day permeation rates even if they
were made of the same material and used the same emission control technology.  For this reason,
the final standards are based on units of grams per square meter of inside surface  area
(g/m2/day).

       This  chapter presents permeation data for a large number of Small SI, marine, and other
fuel tanks. For many of these fuel tanks, we had information on both the volume and inside
surface area. Figure 5.3-2 presents the relationship between fuel tank volume in gallons and
inside surface area in square meters.  As a fuel tank becomes smaller, its surface to volume ratio
increases.  This relationship can be seen better in the chart to the right which presents only data
for fuel tanks less than 1 gallon.  A hyperbolic curve is fit through the data in Figure 5.3-2 to
represent this relationship.  This is seen better in the right-side chart which presents only smaller
tank sizes. In addition to fuel tank volume, the surface to volume ratio  is affected by geometry
                                          5-38

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                                              Feasibility of Evaporative Emission Control
of the fuel tank. A long flat-fuel tank would have a higher surface to volume than a cube or
spherical design. Larger plastic fuel tanks, used primarily in marine vessels, tend to have
somewhat high surface to volume ratios for this reason.

        Figure 5.3-2: Relationship Between Tank Volume and Inside Surface Area
      0.0
          0      10     20      30
                 volume [gallons]
40
                                                   0.20
           0.00
0.0             0.5            1.0
       volume [gallons]
       5.3.1.4 Effect of fuel tank fill level on permeation

       Permeation is driven by the chemical potential of the fuel or vapor in contact with the
plastic.  In a fuel tank, the vapor is essentially at equilibrium with the fuel in a fuel tank.
Therefore, the permeation rate is the same through the surfaces in contact with saturated vapor as
it is through the surfaces in contact with the liquid fuel. Because the permeation rate of saturated
vapor and liquid fuel are the same, the fill level of the fuel tank during a permeation test does not
affect the measured results.
       The fact that liquid fuel and saturated fuel vapor result
in the same permeation rates is supported by published
literature.65'66'67'68 In two of these studies, permeation was
measured for material samples using the cup method
illustrated in Figure 5.3-3.  In these tests, no significant
difference was seen between the permeation rates for material
samples exposed to liquid fuel or to fuel vapor.  To test for
permeation with fuel vapor, the cup was inverted so that the
fuel was on the bottom and the sample was taken off the top.
Table 5.3-8 presents the data from these two reports. In both
cases, the material being tested was a fluoroelastomer.
                                                            Figure 5.3-3: Cup Method
                                          5-39

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Final Regulatory Impact Analysis
 Table 5.3-8: Permeation Measured in Cup Method with Fuel Versus Vapor Fuel Exposure
Paper
SAE 200 1-0 1-1999
SAE 2000-0 1-1096
Fuel
CE10
CE10
CM15
Temperature
40C
23C
40C
23 C
40C
Liquid Fuel Exposure
30.5 g/m2/day
0.3 g/test
2.6 g/test
3.1 g/test
9.5 g/test
Fuel Vapor Exposure
29.5 g/m2/day
0.3 g/test
2.5 g/test
2.9 g/test
8.5 g/test
       One commenter presented test data suggesting that fill level may affect permeation
emissions.69  They tested four HDPE jugs, two filled to 40 percent and two filled to 100 percent
with gasoline and saw a 15 percent difference in the average permeation results for the two fill
levels (1.3 g/gal/day for 40 percent fill and 1.5 g/gal/day for 100 percent fill). Although this
small measured difference was likely due to test variability, we performed our own testing to
study the effect of fill level.  For this testing, we used two 6-gallon FfDPE portable marine fuel
tanks.  The fuel tanks were soaked with gasoline for 12 weeks to ensure a stabilized permeation
rate. Each tank was tested at both 50 percent and 90 percent fill. No significant difference in
permeation rate was observed for either tank. Table 5.3-9 presents the results in terms of
g/gal/day at 29C.

                Table 5.3-9: Effect of Fuel Tank Fill Level on Permeation
                    for Two Portable Marine Fuel Tanks [g/gal/day]

Tank 1
Tank 2
50% fill
1.16
0.77
90% fill
1.21
0.78
       Another study showed mixed results.  Four automotive fuel systems (including fuel tank,
hose, and other components) were tested for permeation with the fuel tanks filled with Fuel C to
both 20 percent and 100 percent of capacity.70 Prior to the testing, the fuel tanks were soaked
with fuel at the specified fill levels until a stable permeation rate was achieved. It was not clear
what fraction of the permeation came from the fuel tanks compared to other fuel system
components or how the fuel level affected the exposure of the other components.  In this study,
two of the fuel systems saw no significant change in permeation as a result of a change in fill
level.  These two fuel system were on older vehicles, one with an untreated and one with a
fluorinated HDPE fuel tank. Two other fuel systems, using fuel tanks that meet automotive
enhanced evaporative emission requirements, showed significant reductions in fuel system
permeation (32 percent and 49 percent) when tested with the fuel tank filled to only 20 percent
capacity. The study presented no rationale for this effect; however, it should be noted that these
were very  low permeation systems and measurement error would presumably be larger. These
data are presented in Table 5.3-10. In addition, it is possible that the change in fill level affected
whether or not there was fuel in the hoses. As discussed later in this chapter, the vapor
                                         5-40

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                                             Feasibility of Evaporative Emission Control
concentration in fuel hoses may be significantly lower than saturated when exposed only to
vapor due to diffusion constraints.

               Table 5.3-10: Effect of Fuel Tank Fill Level on Permeation
                   for Four Automotive Fuel Systems at 29C [g/hour]

Rig 2
Rig 4
Rig 5
Rig 6
Description of Fuel Tank
enhanced evap system
enhanced evap system
HDPE fuel tank
fluorinated HDPE fuel tank
20% fill
0.013
0.021
0.350
0.095
80% fill
0.019
0.041
0.349
0.094
       The California Air Resources Board also performed testing on three pairs of portable fuel
tanks.71 All of the fuel tanks were identical 1 gallon tanks made out of HDPE. Each pair was
filled to a different level with California certification fuel (30 percent, 50 percent and 70 percent
fill). The fuel tanks were then sealed and subjected to five days of the California diurnal test
(65-105T) and weight loss was measured daily. Over the five days of testing, the tanks with
lower fill levels actually saw significantly higher permeation than the other tanks. Looking at
the last day of testing, which represents some conditioning of the fuel tanks by the fuel resulting
in more stabilized permeation rates, the permeation rates are similar regardless of the fill level.
This data, which is presented in Table 5.3-11, suggests that the fuel vapor in the tanks permeated
at the same rate as (or higher than) the liquid fuel.

               Table 5.3-11: Effect of Fuel Tank Fill Level on Permeation
                     for Three Pairs  of Portable Fuel Tanks [g/day]
Tank
30a
3 Ob
50a
5 Ob
70a
70b
Fill Level
30%
50%
70%
5 -Day Permeation
1.79
1.57
1.53
1.03
1.26
1.08
Last Day Permeation
1.87
1.91
1.91
1.43
1.85
1.43
       5.3.1.5 Effect of background concentration on permeation

       As discussed above, permeation is driven by the difference in chemical potential between
the inside and outside of the tank. If the concentration of vapor outside the fuel tank were large
enough, it could reduce the permeation rate of fuel through the tank. One commenter presented
test data suggesting that, at very low concentrations of vapor in the boat around the fuel tank,
that the permeation rate would be significantly reduced.72 This test data was based on two three
hour tests on 5 gallon HDPE bottles at 35C. They measured 0.57 g/hr with a background
                                          5-41

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Final Regulatory Impact Analysis
concentration of 26 ppm and 0.36 g/hr with a background of 212 ppm.  No repeat tests were run.
It is not clear why the above results were measured. Compared to the concentration of the fuel
vapor in the tank, this difference between 212 and 26 ppm is minuscule (about three orders of
magnitude difference from saturated vapor). It is more likely that this effect was due to test
variation.

       To investigate this potential effect on permeation emissions further, we performed our
own testing. First, we measured the concentration of fuel vapor around the fuel tank on a
summer day in a runabout with the tank installed in the hull.  This concentration was 1400 ppm.
We then tested two different fuel tanks for permeation with different background concentrations.
The background concentration was maintained by controlling the bleed of fresh air through the
test container or SHED.  Each test ran for about two weeks and the permeation rates were
determined using the weight loss method. Prior to the testing, the tanks were soaked until a
stable permeation rate was achieved, then new fuel was added to the tank just prior to beginning
the test. The fuel tank was soaked until the fuel temperature stabilized at 29C before the
beginning weight was measured.  The results, which are presented in Table 5.3-12, showed no
significant difference in permeation as a function of background concentrations of hydrocarbon
vapor.

            Table 5.3-12: Effect of Background Concentration on Permeation
Fuel Tank
6 gallon HOPE
23 gallon cross-link PE
Background [ppmC]
30
1500
30
150
1350
Permeation [g/gal/day]
0.77
0.78
0.64
0.67
0.66
5.3.2  Fuel Tank Permeation Reduction Technologies

       There are several strategies that can be used to reduce permeation from plastic fuel tanks.
This section presents data collected on five permeation control strategies:  sulfonation,
fluorination, non-continuous barrier platelets, coextruded continuous barrier, and alternative
materials.

       5.3.2.1 Sulfonation

       Sulfonation is a process where the surface of the fuel tank is treated to minimize
permeation. The sulfonation process uses sulfur trioxide is used to create the barrier by reacting
with the exposed polyethylene to form sulfonic acid groups  on the surface. Current practices for
sulfonation are to place fuel tanks on a small assembly line and expose the inner surfaces to
sulfur trioxide, then rinse with a neutralizing agent. However, sulfonation can also be performed
off-line.  Either of these processes can be used to reduce gasoline permeation by more than 90
                                          5-42

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                                              Feasibility of Evaporative Emission Control
percent from new tanks.73

       We tested several sulfonated marine fuel tanks at 29C for permeation. This testing
included both HDPE blow-molded fuel tanks and cross-link polyethylene rotationally-molded
tanks.  Both gasoline and alcohol fuel blends were investigated.  In some cases, the fuel tanks
were exposed to durability testing as described in Section 5.6.2.  The fuel tanks were stored with
fuel in them (soaked) for preconditioning, then they were drained and then filled with fresh fuel
prior to each permeation test.  The purpose of the soak periods was to ensure that the fuel
permeation rate had stabilized and the purpose of the pressure cycles and slosh testing was to
evaluate the durability of the barrier treatment.

       We also collected data from ARB and other sources on the effectiveness of sulfonation
for reducing permeation emissions from plastic fuel tanks. Most of this research has been
performed on blow-molded HDPE fuel tanks. As shown in these data, it is important that the
resin formulation be matched to the sulfonation process. The following discussions look at
sufonation results on HDPE and on cross-link polyethylene separately.

       HDPE fuel tanks

       We tested several HDPE fuel tanks that were  sulfonated on the internal surfaces.  These
included three 6-gallon and one 3.3 gallon portable marine fuel tanks and three all-terrain vehicle
(ATV) fuel tanks. These fuel tanks were sent to a sulfonater for barrier treatment. Multiple fuel
tanks were used so that they could be tested on certification gasoline , E10 (10 percent ethanol),
and M15 (15 percent methanol).  The test results, presented in Table 5.3-13, showed more than a
90 percent reduction in permeation emissions from baseline.  However, the two fuel tanks that
were subjected to slosh testing saw emission levels above the standard.  This may have been a
material compatibility issue as discussed below. The test results are consistent with similar data
collected by the California Air Resources Board.
                                          5-43

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Final Regulatory Impact Analysis
      Table 5.3-13: EPA Permeation Data on Sulfonated HDPE Fuel Tanks at 29C
Treatment
Fuel
Soak Period
g/gal/day
g/m2/day
6 gallon portable marine fuel tanks
baseline
sulfonated
sulfonated
sulfonated
sulfonated
gasoline
gasoline
gasoline, sloshed
E10
M15
15 weeks
16 weeks
12 weeks
24 weeks
24 weeks
0.77
0.04
0.39
0.14
0.08
8.53
0.45
4.30
1.58
0.84
4 gallon ATV fuel tanks
sulfonated
sulfonated
sulfonated
gasoline
E10
M15
20 weeks
24 weeks
24 weeks
0.13
0.06
0.08
1.05
0.45
0.64
3.3 gallon portable fuel tank
baseline
sulfonated
sulfonated
E10
E10
E10, sloshed
14 weeks
14 weeks
38 weeks
0.96
0.06
0.16
12.7
0.83
2.09
       We performed slosh testing on the 6 and 3.3 gallon portable marine fuel tanks with E10
fuel. This slosh testing included 1 million cycles consistent with the durability test procedure.
After the slosh testing, the permeation rates were measured to be 2.0 and 4.3 g/m2/day for the 3.3
and 6 gallon fuel tanks, respectively. As discussed below, we believe that the impact of the
durability testing on the effectiveness of sulfonation can be minimized if the sulfonation process
and material properties are matched properly. However, this data supports the need for the
durability testing requirements.

       The California Air Resources Board (ARE) collected test data on permeation rates from
sulfonated portable fuel containers using California certification fuel.74  The results show that
sulfonation can be used to achieve significant reductions in permeation from plastic fuel
containers. This data was collected  using a diurnal cycle from 18-41C which is roughly
equivalent to steady-state permeation testing at 29C. The average emission rate for the 32
sulfonated fuel tanks is 0.35 g/gal/day; however, there was a wide range in variation in the
effectiveness of the sulfonation process for these fuel tanks.  Some of the data outliers were
actually higher than baseline emissions.  This was likely due to leaks in the fuel tank which
would result in large emission increases due to pressure built up with temperature variation over
the diurnal cycle. Removing these five outliers, the average permeation rate is 0.17 g/gal/day
with a minimum of 0.01 g/gal/day and a maximum of 0.64 g/gal/day. This data suggests that
more than a 90 percent reduction in  permeation from HDPE fuel tanks is possible through
sulfonation.  This data is presented in Table 5.3-14.
                                          5-44

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                                              Feasibility of Evaporative Emission Control
Plastic































Table 5.3-14: Permeation Rates for Sulfonated
Fuel Containers Tested by ARE Over a 18-41C Diurnal
Tank Capacity
[gallons]
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
5
5
5
5
5
5
5
Permeation Loss
[g/gal/day]
0.05
0.05
0.05
0.06
0.06
0.06
0.08
0.12
0.14
1.23
1.47
1.87
0.02
0.02
0.48
0.54
1.21
0.03
0.08
0.32
0.38
0.42
0.52
0.64
0.80
0.01
0.04
0.05
0.06
0.11
0.13
0.15
































       Variation can occur in the effectiveness of this surface treatment if the sulfonation
process is not properly matched to the plastic and additives used in the fuel tank material.  For
instance, if the sulfonater does not know what UV inhibitors or plasticizers are used, they cannot
maximize the effectiveness of their process. Earlier data collected by ARB showed consistently
high emissions from sulfonated fuel tanks; however, ARB and the treatment manufacturers agree
that this was due to inexperience with treating fuel tanks and that these issues have since been

                                           5-45

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Final Regulatory Impact Analysis
largely resolved.75

       ARB also investigated the effect of fuel slosh on the durability of sulfonated surfaces.
Three half-gallon fuel tanks used on Small SI equipment were sulfonated and tested for
permeation before and after being sloshed with fuel in them 1.2 million times.76'77  These fuel
tanks were blow-molded HDPE tanks used in a number of Small SI applications including
pressure washers, generators, snowblowers, and tillers.  The results of this testing show that an
85 percent reduction in permeation was achieved on average even after the slosh testing was
performed. Table 5.3-15 presents these results which were recorded in units of g/m2/day.  The
baseline level for Set #1 is an approximation based on testing of similar fuel tanks, while the
baseline level for Set #2 is based on testing of those tanks.

       The sulfonater was not aware of the materials used in the fuel tanks sulfonated for the
slosh testing.  After the tests were performed, the sulfonater was able to get some information on
the chemical make up of the fuel tanks and how it might affect the  sulfonation process. For
example, the UV inhibitor used in some of the fuel tanks is known  as HALS. HALS also has the
effect of reducing the effectiveness of the sulfonation process. Two other UV inhibitors, known
as carbon black and adsorber UV, are also used in similar fuel tank applications.  These UV
inhibitors cost about the same  as HALS, but have the benefit of not interfering with the
sulfonation process. The sulfonater claimed that if HALS were not used in the fuel tanks,  a 97
percent reduction in permeation would have been seen.78 To confirm this, one manufacturer
tested a sulfonated tank similar to those in Set #2 except that carbon black, rather than HALS,
was used as the UV inhibitor.  This fuel tank showed a permeation rate of 0.88 g/m2/day at
40C79 which was less than half of what the CARB testing showed on their constant temperature
test at 40C.80 A list of resins  and additives that are compatible with the sulfonation process is
included  in the docket.81'82
                                          5-46

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                                             Feasibility of Evaporative Emission Control
                Table 5.3-15: Permeation Rates for Sulfonated Fuel Tanks
                   with Slosh Testing by ARE Over a 18-41C Diurnal
Technology
Configuration
Set #1 Approximate
Baseline
Set #1 Sulfonated

Set#l Sulfonated &
Sloshed

Set #2 Average Baseline
Set #2 Sulfonated

Set #2 Sulfonated &
Sloshed

Units
g/m2/day
g/m2/day
%
reduction
g/m2/day
%
reduction
g/m2/day
g/m2/day
%
reduction
g/m2/day
%
reduction
Tankl
10.4
0.73
93%

1.04
90%

12.1
1.57
87%

2.09
83%

Tank 2
10.4
0.82
92%

1.17
89%

12.1
1.67
86%

2.16
82%

Tank3
10.4
1.78
83%

2.49
76%

12.1
1.29
89%

1.70
86%

Average
10.4
1.11
89%

1.57
85%

12.1
1.51
88%

1.98
84%

       About a year and a half after the California ARE tests on the Set #2 fuel tanks, we
performed permeation tests on these fuel tanks. During the intervening period, the fuel tanks
remained sealed with California certification fuel in them. We drained the fuel tanks and filled
them with fresh California certification fuel.  We then measured the permeation rate at 29C.
Because this is roughly the average temperature of the California variable temperature test,
similar permeation rates would be expected.  The untreated fuel tanks showed slightly lower
permeation over the constant temperature test.  This difference was likely due to the difference in
the temperature used for the testing. However, the Sulfonated fuel tanks showed an increase in
permeation. This increase in permeation appears to be the result of the 1.5 year additional fuel
soak.  After this long soak, the average permeation reduction changed from 84 to 78 percent.
Table 5.3-13 presents this comparison.
                                          5-47

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Final Regulatory Impact Analysis
     Table 5.3-16: Permeation Rates [g/m2/day] for Sulfonated Fuel Tanks Tested by
    ARE and EPA on CA Certification Gasoline with a 11A Year Fuel Soak Differential
Technology
Configuration
Baseline, CARB testing
Baseline, EPA testing
after 1.5 year additional
fuel soak
Sulfonated, CARB
testing
Sulfonated, EPA testing
after 1.5 year additional
fuel soak
Temperatu
re
18-4FC
29C
% change
18-4FC
29C
%
reduction
Tankl
12.1
11.5
-5%
2.09
2.48
78%
Tank 2
12.1
11.4
-6%
2.16
2.73
76%
Tank3
12.1
11.2
-7%
1.70
2.24
80%
Average
12.1
11.4
-6%
1.98
2.5
78%
       After the above testing, we drained the fuel tanks and filled them with certification
gasoline splash-blended with 10 percent ethanol (E10).  We then soaked the fuel tanks for 20
weeks to precondition them on this fuel. Following the preconditioning, we tested these fuel
tanks for permeation at 29C (85F).  Table 5.3-17 presents these emission results compared to
the emission results for three baseline tanks (untreated) that were subject to the same
preconditioning. Percent reductions are presented based on the difference between the
sulfonated fuel tanks and the average results of the three untreated fuel tanks.

      Table 5.3-17: Permeation Rates for Sulfonated Fuel Tanks on E10 Fuel at 29C
Technology
Configuration
Baseline (untreated)
Sulfonated

Units
g/m2/day
g/m2/day
%
reduction
Tankl
13.9
3.91
72%

Tank 2
13.7
4.22
70%

Tank3
14.4
2.92
79%

Average
14.0
3.69
74%

       An in-use durability testing program was also completed for sulfonated HDPE fuel tanks
and bottles.83 The fuel tank had a 25 gallon capacity and was removed from a station wagon that
had been in use in southern California for five years (35,000 miles). The fuel tank was made of
FIDPE with carbon black used as an additive.  After five years, the sulfonation level measured on
the surface of the plastic fuel tank did not change.  Tests before and after the aging both showed
a 92 percent reduction in gasoline permeation due to the sulfonation barrier compared to the
permeation rate of a new untreated tank. Testing was also done on 1 gallon bottles made of
FIDPE with 3 percent carbon black. These bottles were shown to retain over a 99 percent barrier
                                          5-48

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                                              Feasibility of Evaporative Emission Control
after five years. This study also looked at other properties such as yield strength and mechanical
fatigue and saw no significant deterioration.

       One study looked at the effect of alcohol in the fuel on permeation rates from sulfonated
fuel tanks.84 In this study, the fuel tanks were tested with both gasoline and various methanol
blends.  No significant increase in permeation due to methanol in the fuel was observed.

       XLPE fuel tanks

       We tested eight sulfonated cross-link polyethylene (XLPE) fuel tanks for permeation
emissions.  These tanks were produced by marine fuel tank manufacturers specifically for this
testing.  The fuel tanks were then treated by a sulfonater. For the first four tanks tested, the fuel
tanks were molded using the resin formulation and processes currently used by the fuel tank
manufacturers.  When the sulfonation was applied, we observed that the barrier was soft and
could be scraped off easily. When tested, the barrier on these fuel tanks was not as effective as
had been seen on HDPE fuel tanks.

       Because the barrier could  be scratched off, the sulfonater ascertained that the sulfonation
had poor surface penetration and the darkness of the barrier suggested heavy oxidation.  For the
next batch of four test tanks, the sulfonater worked with the material supplier and roto-molder
and attempted to develop a formulation that may be more compatible with sulfonation. They
decided to use the same material,  but bake it in the oven longer to remove more  oxygen from the
surface of the fuel tank.  Four bake times were used to produce the four 6-gallon test tanks: 11,
12, 14, and 16 minutes.  It was observed that the sulfonation barrier could not easily be scratched
off these fuel tanks. We tested the four sulfonated on E10 (10 percent ethanol) using the same
procedures as for the HDPE tanks discussed above.  The test results did not show a significant
improvement.

        Another approach may be to mold an inner liner  of HDPE inside a XLPE shell.  These
materials readily bond with each other and sulfonation has been demonstrated for HDPE. This
construction, which is currently used in chemical storage applications, is performed in the oven
through the use of a "drop box" in the mold containing the HDPE. This drop-box is opened part
way through the oven cycle allowing for a HDPE layer to be molded on the inside of the fuel
tank.

       5.3.2.2 Fluorination

       Another barrier treatment  process is known as fluorination.  The fluorination process
causes a chemical reaction where exposed hydrogen atoms are replaced by larger fluorine atoms
which form a barrier on the surface of the fuel tank.  In this process, fuel tanks are generally
processed post production by stacking them in a steel container. The container is then voided of
air and flooded with fluorine gas.   By pulling a vacuum in the container, the fluorine gas is
forced into every crevice in the fuel tanks. As a result of this process, both the inside and outside
surfaces of the fuel tank would be treated.  As an alternative, fuel tanks can be fluorinated on-
line by exposing the inside surface of the fuel tank to fluorine during the blow molding process.

                                          5-49

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Final Regulatory Impact Analysis
However, this method may not prove as effective as off-line fluorination which treats the inside
and outside surfaces.

       We tested several fluorinated marine fuel tanks at 29C for permeation. This testing
included both HDPE blow-molded fuel tanks and cross-link polyethylene rotationally-molded
tanks.  Both gasoline and alcohol fuel blends were investigated. In some cases, the fuel tanks
were exposed to durability testing as described in Section 5.6.2. The fuel tanks were stored with
fuel in them (soaked) for preconditioning, then they were drained and then filled with fresh fuel
prior to each permeation test.  The purpose of the soak periods was to ensure that the fuel
permeation rate had stabilized and the purpose of the pressure cycles and slosh testing was to
evaluate the durability of the barrier treatment.

       We also collected data from ARB and other sources on the effectiveness of fluorination
for reducing permeation emissions from plastic fuel tanks. Most of this research has been
performed on blow-molded HDPE fuel tanks.  However, we believe that fluorination can also be
applied effectively for injection-molded HDPE tanks as well.  The following discussion looks at
each material separately as well as rotationally-molded cross-link polyethylene.

       Blow-molded HDPE fuel tanks

       We tested one fluorinated HDPE fuel tank which we bought off the shelf and sent to a
fluorinater for barrier treatment.  The fuel tank type used was a 6-gallon portable marine fuel
tank.  The fuel tank was soaked for 20 weeks with certification gasoline prior to testing. We
measured a permeation rate of 0.05 g/gal/day (0.56 g/m2/day) which represents more than a 95
percent reduction from baseline. We then began soaking this fuel tank on E10, subjected it to
the pressure and slosh testing, and retested the fuel tank. The post durability testing result
showed a permeation rate of 0.6 g/gal/day (6.8 g/m2/day).  As discussed below, we believe that
the impact of the durability testing on the effectiveness of fluorination on can be minimized if
the fluorination process and material properties are matched properly. In addition, this fuel tank
was treated to a significantly lower level of fluorination than is now available. However, this
data supports the need for the durability testing requirements.

       The California Air Resources Board (ARB) collected test data on permeation rates from
fluorinated fuel containers using California certification fuel.85'86 The results show that
fluorination can be used to achieve significant reductions in permeation from plastic fuel
containers.  This data was collected using a diurnal cycle from 18-41C which is roughly
equivalent to  steady-state permeation testing at 30C.  For the highest level of fluorination, the
average permeation rate was 0.04 g/gal/day which represents a 95 percent reduction from
baseline. Earlier data collected by ARB showed consistently high emissions from  fluorinated
fuel tanks; however, ARB and the treatment manufacturers agree that this was due to
inexperience with treating fuel tanks and that these issues have since been largely resolved.87
The ARB data is presented in Table 5.3-18.
                                           5-50

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                                              Feasibility of Evaporative Emission Control
                     Table 5.3-18:  Permeation Rates for Fluorinated
             Plastic Fuel Containers Tested by ARE Over a 18-41C Diurnal
Barrier Treatment*
Level 4

(average =0.09 g/gal/day)


Level 5
(average =0.07 g/gal/day)














SPAL
(average =0.04 g/gal/day)
Tank Capacity
[gallons]
1
1
1
5
5
5
1
1
1
1
1
1
1
1
1
2.5
2.5
2.5
2.5
2.5
5
5
5
5
5
5
Permeation Loss
[g/gal/day]
0.05
0.05
0.06
0.11
0.11
0.15
0.03
0.04
0.05
0.05
0.07
0.08
0.11
0.11
0.12
0.04
0.04
0.05
0.07
0.07
0.05
0.10
0.11
0.04
0.04
0.04
        * designations used in ARB report; shown in order of increasing treatment
       All of the data on fluorinated fuel tanks presented above were based on fuel tanks
fluorinated by the same company.  Available data from another company that fluorinates fuel
tanks shows a 98 percent reduction in gasoline permeation through a HDPE fuel tank due to
fluorination.88

       ARB investigated the effect of fuel slosh on the durability of fluorinated surfaces.  Two
sets of three fluorinated fuel tanks were tested for permeation before and after being sloshed with
fuel in them 1.2 million times.89'90  These fuel tanks were 0.5 gallon, blow-molded HDPE tanks
used in a number of Small SI applications including pressure washers, generators, snowblowers,
and tillers.  The results of this testing show that an 80 percent reduction in permeation was
achieved on average even after the slosh testing was performed for Set #1. However, this  data
                                          5-51

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Final Regulatory Impact Analysis
also showed a 99 percent reduction for Set #2.  This shows the value of matching the barrier
treatment process to the fuel tank material.  Table 5.3-19a presents these results which were
recorded in units of g/m2/day.  The baseline level for Set #1 is an approximation based on testing
of similar fuel tanks, while the baseline for Set #2 is based on testing of those tanks.

               Table 5.3-19a: Permeation Rates for Fluorinated Fuel Tanks
                   with Slosh Testing by ARE Over a 18-41C Diurnal
Technology
Configuration
Set #1 Approximate
Baseline
Set #1 Fluorinated

Set #1 Fluorinated &
Sloshed

Set #2 Approximate
Baseline
Set #2 Fluorinated

Set #2 Fluorinated &
Sloshed

Units
g/m2/day
g/m2/day
%
reduction
g/m2/day
%
reduction
g/m2/day
g/m2/day
%
reduction
g/m2/day
%
reduction
Tankl
10.4
1.17
89%

2.38
77%

12.1
0.03
>99%

0.07
99%

Tank 2
10.4
1.58
85%

2.86
73%

12.1
0.00
>99%

0.11
99%

Tank3
10.4
0.47
96%

1.13
89%

12.1
0.00
>99%

0.05
>99%

Average
10.4
1.07
90%

2.12
80%

12.1
0.01
>99%

0.08
99%

       About a year and a half after the California ARB tests on the Set #2 fuel tanks, we
performed permeation tests on these fuel tanks.  During the intervening period, the fuel tanks
remained sealed with California certification fuel in them. We drained the fuel tanks and filled
them with fresh California certification fuel. We then measured the permeation rate at 29C.
Because this is roughly the average temperature of the California variable temperature test,
similar permeation rates would be expected. The untreated fuel tanks showed slightly lower
permeation over the constant temperature test.  This difference was likely due to the difference in
the temperature used for the testing. However, the fluorinated fuel tanks showed an increase in
permeation. This increase in permeation appears to be the result of the 1.5 year additional fuel
soak.  Even after this long fuel soak, the fluorination achieves more than a 95 percent reduction
in permeation. Table 5.3-19b presents this comparison.
                                          5-52

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                                              Feasibility of Evaporative Emission Control
    Table 5.3-19b: Permeation Rates [g/m2/day] for Fluorinated Fuel Tanks Tested by
    ARE and EPA on CA Certification Gasoline with a 11A Year Fuel Soak Differential
Technology
Configuration
Baseline, CARB testing
Baseline, EPA testing
after 1.5 year additional
fuel soak
Fluorinated, CARB
testing
Fluorinated, EPA testing
after 1.5 year additional
fuel soak
Temperature
18-4FC
29C
% change
18-4FC
29C
% reduction
Tankl
12.1
11.5
-5%
0.07
0.56
95%
Tank 2
12.1
11.4
-6%
0.11
0.62
95%
Tank3
12.1
11.2
-7%
0.05
0.22
98%
Average
12.1
11.4
-6%
0.08
0.47
96%
       After the above testing, we drained the fuel tanks and filled them with certification
gasoline splash-blended with 10 percent ethanol (E10).  We then soaked the fuel tanks for 20
weeks to precondition them on this fuel. Following the preconditioning, we tested these fuel
tanks for permeation at 29C (85F).  Table 5.3-21 presents these emission results compared to
the emission results for three baseline tanks (untreated) that were subject to the same
preconditioning. Percent reductions are presented based on the difference between the
fluorinated fuel tanks and the average results of the three untreated fuel tanks. The slight
increase in permeation on the E10 fuel was similar for the baseline and fluorinated fuel tanks and
still resulted in permeation rates well below the standard.

      Table 5.3-20: Permeation Rates for Fluorinated Fuel Tanks on E10 Fuel at 29C
Technology
Configuration
Baseline (untreated)
Fluorinated
Units
g/m2/day
g/m2/day
% reduction
Tankl
13.9
0.43
97%
Tank 2
13.7
0.62
96%
Tank3
14.4
0.62
96%
Average
14.0
0.56
96%
       The handheld industry also tested a number of fluorinated fuel tanks for their products.91
This testing included three fuel types and two test temperatures.  These test results suggest that
fluorination may be used to significantly reduce permeation from handheld fuel tanks. Higher
permeation rates were observed in CE10 than gasoline; however, it is not clear whether these
impacts were due to increased permeation through the gaskets or through the tank. As shown
earlier in Table 5.3-4b, the use of low permeation gasket materials can significantly improve
permeation rates, especially on fuel CE10. This test data is presented in  Table 5.3-21.
                                          5-53

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Final Regulatory Impact Analysis
       Table 5.3-21: Permeation Rates for Handheld Fuel Tanks Tested by Industry
Tank Capacity
695

420

400*
252


Gasket Material
NBR

NBR

NBR
FKM
NBR


Test Temp.
28C

28C

40C
40C


Test Fuel
CE10

CE10

gasoline
CE10
gasoline
CE10
E10
Permeation Loss
[g/m2/day]
2.01
2.88
1.46
1.32
0.56
0.64
2.94
0.84
1.95
1.40
       * A similar, untreated, tank was measured to have a permeation rate of 17.5 g/m2/day.
       Another study also looked at the effect of alcohol in the fuel on permeation rates from
fluorinated fuel tanks.92 In this study, the fuel tanks were tested with both gasoline and various
methanol blends. No significant increase in permeation due to methanol in the fuel was
observed.

       Under their rule for small offroad equipment, California may issue executive orders to
manufacturers with low emission products. As of August, 2006, ARB has issued 5 executive
orders for low permeation fuel tanks.93  Under these executive orders, three fluorination
approaches have been approved. The California fuel tank permeation standard is 1.5 g/m2/day
tested at 40C on California certification fuel. Table 5.3-22 presents the test results for the fuel
tanks with ARB executive orders. Note that the reported emissions are the average of five test
samples.

      Table 5.3-22: ARB Fuel Tank Executive Orders for Small Offroad Equipment
EO#
C-U-05-015
C-U-06-019
C-U-06-006
Test Fuel
Phase II
Phase II
Phase II
g/m2/day
1.10
0.30
0.38
       One automobile manufacturer used fluorination to reduce permeation on HDPE fuel
tanks to meet the LEV I vehicle standards. This manufacturer used similar or more stringent
requirements for fuel soak, durability, and testing than finalized today.  At 40C, this
                                          5-54

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                                              Feasibility of Evaporative Emission Control
manufacturer stated that they measured 0.15-0.2 g/day for fluorinated tanks compared to over 10
g/day for untreated HDPE fuel tanks.94

       Injection-molded HOPE fuel tanks

       The issue has been raised by manufacturers that HDPE intended for injection-molding
has a somewhat different composition than HDPE used for blow-molding. To address this
concern, testing has been performed on fluorinated, injection-molded fuel tanks as well.95 These
fuel tanks were tested using California's TP-901 test procedures which preconditioning steps
including fuel soak, slosh testing, and pressure-vacuum cycling. California Phase II gasoline
was used for this testing.

       Three similar fuel tanks were tested also over the Federal test procedure.96 Under this
testing, E10 fuel was used. Weight loss tests were performed before and after the durability tests
in 40 CFR 1501.515.97  These durability tests included slosh testing, pressure vacuum cycling,
and UV exposure.  Results from this testing are presented in Table 5.3-23. The permeation was
significantly higher when tested on E10 fuel, especially when accounting for differences in test
temperature. In addition, permeation increased somewhat after the durability testing. However,
the measured permeation rates were well below the fuel tank permeation standard on E10 after
the durability testing.

 Table 5.3-23:  Permeation Rates for Fluorinated, Injection-Molded Fuel Tanks [g/mVday]
Test Procedure
California TP-901
Federal Baseline
After Durability Testing
Test
Temperature
40C
28C
28C
Tankl
0.28
0.32
0.30
Tank 2
0.26
0.47
0.92
Tank 3
0.27
0.42
0.57
Average
0.27
0.41
0.60
       XLPE fuel tanks

       We tested several fluorinated cross-link polyethylene (XLPE) fuel tanks for permeation
emissions. The first tank was a 6 gallon test tank produced by a marine fuel tank manufacturer
specifically for this testing.  The remaining fuel tanks were purchased on the open market. The
fuel tanks were then treated by a fluorinater. We tested the first tank on certification gasoline.
After a 20 week soak, we observed a permeation rate of 0.11 g/gal/day (1.52 g/m2/day), which
represented more than an 80 percent reduction in permeation.

       The remainder of the fluorinated tanks were tested on E10 (10 percent ethanol) using the
same procedures as for the HDPE tanks discussed above.  These fuel tanks were treated at a level
equivalent to what the fluorinater uses for automotive applications.  All of the fuel tanks were
treated both on the inside and outside.  The test results, presented in Table 5.3-24, showed
emission reductions of about 40 percent on average. Emission results from the sloshed fuel
                                          5-55

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Final Regulatory Impact Analysis
tanks were not significantly different than from the tanks that were not sloshed.

  Table 5.3-24:  EPA Permeation Data on Fluorinated Cross-Link Fuel Tanks at 29C on
                                          E10
Fuel Tank
1




2



3


Capacity
12 gallons




12 gallons



12 gallons


Soak Period
29 weeks




29 weeks



29 weeks


g/gal/day
0.27
0.39
0.32
0.36
0.38
0.39
0.34
0.42
0.32
0.28
0.22
0.22
g/m2/day
4.1
5.9
4.9
5.4
5.8
5.7
5.0
6.2
4.6
3.4
2.6
2.8
slosh test?
no
no
no
no
no
yes
no
no
no
yes
no
no
       5.3.2.3 Barrier Platelets

       Another approach to creating a permeation barrier in a fuel tank is to blend a low
permeable resin in with the HDPE and extrude it with a single screw.  The trade name typically
used for this permeation control strategy is Selar.  The low permeability resin, typically nylon
or EVOH, creates non-continuous platelets in the HDPE fuel tank which reduce permeation by
creating long, tortuous pathways that the hydrocarbon molecules must navigate to pass through
the fuel tank walls. Although the barrier is not continuous, this strategy can still achieve greater
than a 90 percent reduction in permeation of gasoline.  EVOH has much higher permeation
resistance to alcohol than nylon; therefore, it would be the preferred material to use for meeting
our standard which is based on testing with a 10 percent ethanol fuel.

       We tested  several portable gas cans and marine tanks  molded with low permeation non-
continuous barrier platelets 29C.  Six of fuel tanks tested were constructed using nylon as the
barrier material. The remainder of the fuel tanks were constructed using ethylene vinyl alcohol
(EVOH) as the barrier material. The advantage of EVOH is that it has much better resistance to
alcohol than nylon. Five of the nylon based fuel tanks were tested on  certification gasoline. The
sixth tank was tested on E10 (10 percent ethanol) to evaluate the effectiveness of this material
with alcohol blended fuel.  The fuel tanks with the EVOH barrier were all tested on E10.

       Testing was performed after the fuel tanks had been filled with fuel and stored at room
temperature. The purpose of the soak period was to ensure that the fuel permeation rate had
stabilized. Although 20 weeks was generally accepted as an acceptable period, we soaked the
tanks with gasoline for 22 weeks and the tanks with E10 for 37 weeks. The fuel tanks were
                                          5-56

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                                              Feasibility of Evaporative Emission Control
drained and then filled with fresh fuel prior to the permeation tests. Because the barrier platelets
are integrated in the tank wall material, it did not seem likely that pressure or slosh testing would
significantly affect the performance of this technology.

       Table 5.3-25 presents the results of the permeation testing on the fuel tanks with barrier
platelets. These test results show more than an 80 percent reduction for the nylon barrier tested
on gasoline. However, the nylon barrier does not perform as well when a fuel with a 10 percent
ethanol blend is used.  Testing on a pair of 2 gallon tanks with nylon barrier showed 80 percent
percent higher emissions when tested on E10 than on gasoline. We also tested fuel tanks that
used EVOH barrier platelets.  EVOH has significantly better resistance to permeation on E10
fuel than nylon (see Appendix 5D for material properties). For the fuel tanks blended with 6
percent EVOH, we observed an average permeation rate of about 1.4 g/m2/day on E10 fuel
which meets our permeation standard.

               Table 5.3-25:  Permeation Rates for Plastic Fuel Containers
                       with Barrier Platelets Tested by EPA at 29C
Percent
Selar*
Tank Capacity
[gallons]
Test Fuel
Nylon barrier platelets
unknown* *
unknown* *
4%
4%
4%
4%
2
2
5
5.3
6.6
6.6
gasoline
E10
gasoline
gasoline
gasoline
gasoline
EVOH barrier platelets
2%
4%
4%
6%
6%
6.6
6.6
6.6
6.6
6.6
E10
E10
E10
E10
E10
Fuel Soak
[weeks]

40
40
22
22
22
22

37
37
37
37
37
g/gal/day
g/m2/day

0.54
0.99
0.35
0.11
0.15
0.14
3.7
6.8
4.1
1.2
1.6
1.5

0.23
0.14
0.15
0.08
0.09
3.0
1.9
2.0
1.4
1.4
       *trade name for barrier platelet technology used in test program
       ** designed to meet California permeation requirement
       Manufacturers raised the concern about whether or not a tank using barrier platelets
would have a stabilized permeation rate after 20 weeks. In other words, manufacturers were
concerned that this technology may pass the test, but have a much higher permeation rate in-use.
We tested one of the 4 percent and 6 percent EVOH tanks on E10 again after soaking for a total
of 104 weeks (2 years). The measured permeation rates were 2.0 and 1.4 g/m2/day for the 4
percent and 6 percent EVOH tanks, respectively, which represents no significant changes in
permeation from the 37 week tests. In contrast we measured the 4 percent nylon tanks again
after 61 weeks and measured a permeation rates of 2.8 and 2.7 g/m2/day which represented about
                                           5-57

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Final Regulatory Impact Analysis
an 80-90 percent increase in permeation compared to the 22 week tests.

       The California Air Resources Board (ARE) collected test data on permeation rates from
portable fuel containers molded with low permeation non-continuous barrier platelets using
California certification fuel. These fuel tanks all used nylon as the barrier resin. The results
show that this technology can be used to achieve significant reductions in permeation from
plastic fuel containers.  This data was collected using a diurnal cycle from 18-41C which is
roughly equivalent to steady-state permeation testing at 30C.  Because the data is reported in
g/gal/day, we only include the data on fuel tanks here that are compatible in size with marine
fuel tanks.  This test data showed that more than a 90 percent reduction in permeation is
achievable through the use of nylon barrier platelets. However, all of this testing was performed
on California certification fuel which does not include ethanol.

               Table 5.3-26: Permeation Rates for Plastic Fuel Containers
              with Barrier Platelets Tested by ARB Over a 18-41C Diurnal
Percent Selar*
4%

(average =0.12 g/gal/day)



6%

(average =0.09 g/gal/day)




807
/O

(average =0.07 g/gal/day)
Tank Capacity
[gallons]
5
5
5
5
5
6
6
5
5
5
5
5
5
6
6
5
5
6
6
Permeation Loss
[g/gal/day]
0.08
0.09
0.13
0.16
0.17
0.08
0.10
0.07
0.07
0.07
0.08
0.12
0.17
0.06
0.07
0.08
0.10
0.05
0.06
       *trade name for barrier platelet technology used in test program
             Dupont, who manufacturers Selar, has performed testing on HDPE with higher
blends of EVOH (known as Selar RB). Table 5.3-27 presents permeation rates for HDPE and
three Selar RB blends when tested at 60C on xylene.98 Xylene is a component of gasoline and
gives a rough indication of the permeation rates on gasoline.  This report also shows a reduction
of 99 percent on naptha and 98 percent on toluene for 8 percent Selar RB.
                                          5-58

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                                             Feasibility of Evaporative Emission Control
             Table 5.3-27:  Xylene Permeation Results for Selar RB at 60C
Composition
100% HOPE
10%RB215/HDPE
10%RB300/HDPE
15%RB421/HDPE
Permeation, g mm/m2/day
285
0.4
3.5
0.8
% Reduction
_
99.9%
98.8%
99.7%
       5.3.2.4 Alternative Materials

       Permeation can also be reduced from fuel tanks by constructing them out of a lower
permeation material than HDPE. Examples of alternative materials are metal, various grades of
plastic, and new fiberglass construction.

       5.3.2.4.1 Metal

       Gasoline does not permeation through metal. Therefore, the only permeation from a
metal fuel tank would be through rubber gaskets or O-rings that may be used to seal connections
on the fuel tank. Examples would be the gasket or O-ring in a fuel cap or a bolted-on component
such as a sender unit for a marine tank. Presumably, the exposed surface area of the gaskets
would be small enough that a metal fuel tank would be well below our permeation standard.
One issue with metal fuel tanks, however, is fuel leakage due to corrosion.  A study sponsored
by the Coast Guard in 1994 showed that aluminum (and even stainless steel) fuel tanks are prone
to failure, both in salt water and fresh water applications., due to corrosion." Fuel leakages
would not only be an environmental issue, but could be a safety issue as well. Aluminum fuel
tank manufacturers have stated that corroding fuel tanks are typically due to improper
installation.

       5.3.2.4.2 A Iternative Plastics

       There are grades of plastics other than HDPE that could be molded into fuel tanks.  One
material that has been considered by manufacturers is nylon; however, although nylon has
excellent permeation resistance on gasoline, it has poor chemical resistance to alcohol-blended
fuels. As shown in Appendix 5D, nylon could be used to achieve more than a 95 percent percent
reduction in permeation compared to HDPE for gasoline. However, for a 10 percent ethanol
blend, this reduction would significantly less depending on the grade of nylon. For a 15  percent
methanol blend, the permeation would actually be several times higher through nylon than
HDPE.

       Some handheld equipment, primarily chainsaws, use structurally-integrated fuel tanks
where the tank is molded as part of the body of the equipment. In these applications, the frames
(and tanks) are typically molded out of nylon for strength. We tested structurally-integrated fuel
tanks from four handheld equipment manufacturers at 29C on both gasoline and a 10 percent
ethanol blend. The test results suggest that permeation emissions are 20 to 70 percent higher on

                                          5-59

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Final Regulatory Impact Analysis
E10 than on gasoline for these fuel tanks. Note these fuel tanks are capable of meeting the
standards using their current materials.  In the cases where the permeation rates were higher than
these standards, it was observed that the fuel cap seals had large exposed surface areas on the O-
rings, which were not made of low permeation materials.  Emissions could likely be reduced
significantly from these tanks with improved seal designs.  Table 5.3-28 presents the results of
this testing.

  Table 5.3-28: Permeation Rates for Nylon Handheld Fuel Tanks Tested by EPA at 29C
Tank ID
Rl
R2
R3
Bl
B2
B3
B4
Wl
W2
W3
Gl
G2
G3
Application
clearing saw

hedge clipper


chainsaw

chainsaw

Material
nylon 6

nylon 6, 33% glass


nylon 6, 30% glass

nylon 6, 30% glass

Test Fuel
gasoline
E10
E10
gasoline
E10
E10
E10
gasoline
E10
E10
gasoline
E10
E10
Permeation Loss
[g/m2/day]
0.34
0.42
0.48
0.62
1.01
1.12
0.93
1.45
2.18
2.46
1.30
1.41
2.14
       Other materials which have excellent permeation resistance even with alcohol-blended
fuels are acetal copolymers and thermoplastic polyesters.  These polymers can be used to form
fuel tanks in the blow-molding, rotational-molding, and injection-molding processes.  An
example of an acetal copolymer is known as Celcon which has excellent chemical resistance to
fuel and has been shown to be durable based on exposure to automotive fuels for 5000 hours at
high temperatures.100  As shown in Appendix 5D, Celcon would result in more than a 99 percent
reduction in permeation compared to HDPE for gasoline.  On a 10 percent ethanol blend, the use
of Celcon would result in more than a 95 percent reduction in permeation. Two thermoplastic
polyesters, known as Celanex and Vandar, are also being considered for fuel tank construction
and are being evaluated for permeation resistance by the manufacturer. Celcon has a more
crystalline structure than Vandar resulting in lower permeation but less impact resistance.

       We tested a 1-liter blow-molded Vandar fuel tank and three rotationally-molded 3-liter
fuel tanks made of impact toughened Celcon for permeation at 29C on E10 fuel. Prior to the
permeation testing, the fuel containers were soaked in E10 for more than 20 weeks. These test
results are included in Table 5.3-29 below. For the Celcon tank tests, higher emissions were
observed in the second week than the first week. This behavior was seen in repeat tests and was
                                          5-60

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                                             Feasibility of Evaporative Emission Control
likely due to deterioration of the epoxy seal used in this testing.  Therefore, the actual emission
rates of the material are likely lower than presented below. More detailed data on this testing is
available in the docket.101

      Table 5.3-29: Permeation Results Acetal Copolymer Fuel Tanks at 29C on E10
Material Name
Vandar VI
Impact CIO
Resistant
Cll
Celcon C13
Material Type
thermoplastic polyester
modified
acetal copolymer

g/gal/day
1.7
0.13
0.09
0.10

g/m2/day
5.6
0.75
0.53
0.59

       Fuel tank manufacturers have expressed some concern that the acetal copolymer is not as
tough as cross-link polyethylene.  Thermoplastic polyesters have better impact resistance, but
higher permeation. The impact toughened fuel tanks mentioned above were in response to these
concerns.  Also, the rotational molding process must be better controlled to use these materials in
comparison to XLPE. The temperature profile must be tightly controlled to uses Celcon, or
formaldehyde gases may form. The moisture level of Vandar must be kept low prior to molding.

       Acetal copolymers are also used today to produce many fuel resistant automotive
components such as low permeation fuel caps. This construction has been used for many years
in automotive applications and now acetal copolymers are being used to manufacture low
permeation fuel caps for nonroad equipment as well.

       Another low permeation thermoplastic that can be used in the manufacture of fuel tanks
is a polyester/polycarbonate alloy.  One example is marketed under the trade name of Xenoy
6620. This engineered plastic is impact modified and is intended for the injection molding
process. The polyester provides good chemical resistance and the polycarbonate provides the
impact resistance. Permeation testing was performed on a fuel tank made of Xenoy 6620
following the California test procedures.  At 40C on California Phase II CERT fuel, the
measured permeation rate was 0.26 g/m2/day.102  The manufacturer of this material also has a
version that is modified slightly so that it can be used in the blow-molding process.

       5.3.2.4.3  Low Permeation Fiberglass

       One manufacturer has developed a low permeation fiberglass fuel tank construction.103
The composite tanks are fabricated using a glass fiber reinforced closed cell urethane composite
sheet as substrate and assembled with structural urethane adhesive as a fastening medium. These
fuel tanks may be hand constructed, or for larger volume production, they may be  molded at
lower cost. Once fully assembled with necessary fuel fittings the tank is coated with fiberglass
reinforced resin,  sufficient for H-24 ABYC (American Boat and Yacht Council) and 33 CFR
183.510 standards for fuel systems mechanical strength requirements. A final gel coat finish may
                                          5-61

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Final Regulatory Impact Analysis
was applied for aesthetics.

       Permeation control is achieved by incorporating fillers into a resin system and coating the
assembled tank interior and exterior.  This filler is made up of nanocomposites (very small
particles of treated volcanic ash)4 which are dispersed into a carrier matrix. This construction
creates a tortuous pathway for hydrocarbon migration through the walls of the fuel tank. We
tested a 14 gallon fuel tank provided by this manufacturer and measured a permeation rate of
0.97 g/m2/day on E10 fuel at 29C. Other advantages of this technology are improved strength
and flame resistance compared to plastic fuel tanks.

       5.3.2.5 Multi-Layer Construction

       Fuel tanks may also be constructed out of multiple layers of materials. In this way the
low cost and structural advantages of traditional materials can be utilized in conjunction with
higher grade materials which can provide effective permeation resistance. Today, fuel tanks are
made in many ways including  higher volume blow-molding, lower volume injection molding,
and very low volume rotational-molding.  The discussion below presents data on several multi-
layer fuel constructions.

       5.3.2.5.1 Blow-Molded Coextruded Barrier

       Coextruded barrier technology has been long established for blow-molded automotive
fuel tanks.  Data from one automobile manufacturer showed permeation rates of 0.01-0.03 g/day
for coextruded fuel tanks at 40C on EPA certification fuel. They are using this technology to
meet LEV II vehicle standards. For comparison, this manufacturer reported permeation rates of
more than 10 g/day for standard HDPE fuel tanks.104

       Another study looks at the permeation rates, using ARB test procedures, through multi-
layer fuel tanks.105 The fuel tanks in this study were 6 layer coextruded plastic tanks with EVOH
as the barrier layer (3 percent of wall thickness).  The outer layers were HDPE and two adhesive
layers were needed to bond the EVOH to  the polyethylene.  The sixth layer was made of
recycled polyethylene. The two test fuels were a  10 percent ethanol blend (CE10) and a 15
percent methanol blend (CM15). See Table 5.3-30.

  Table 5.3-30:  Permeation  Results for a Coextruded Fuel Tank Over a 18-41C  Diurnal
Composition
100% HDPE (approximate)
3% EVOH, 10% ethanol (CE10)
3% EVOH, 15% methanol (CM15)
Permeation, g/day
6-8
0.2
0.3
% Reduction
97%
96%
       4 Chemically modified montmorillonite for nanocomposite formulation

                                          5-62

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                                             Feasibility of Evaporative Emission Control
       The California Air Resources Board tested two sets of three 5-gallon portable fuel
containers.106 Each set was manufactured by a different company, but all of the fuel tanks were
blow-molded with a coextruded barrier layer. Testing was performed over the California 18-
41 C temperature cycle with California Phase II gasoline. Testing was performed with and
without the spouts removed. The test data presented in Table 5.3-31 was after 174 days of fuel
soak with the spouts removed and the openings welded shut.  California reported the test results
in grams per gallon. Table 5.3-31 also presents approximate g/m2/day values based on the
relationship between tank capacity and inside surface area used in the NONROAD2005
emissions model.
       Table 5.3-31: ARB Permeation Results for a Coextruded Portable Fuel Tanks
Fuel Tank
Bl
B2
B3
Average
Ml
M2
M3
Average
Permeation, g/gal/day
0.01
0.01
0.01
0.01
0.01
0.02
0.02
0.02
Approximate Rate
0.09
0.11
0.11
0.10
0.14
0.21
0.18
0.17
in g/m2/day


       The handheld industry also tested a number of fuel tanks for their products that had been
coextruded with an EVOH barier.107 Even with NBR gaskets on the fuel caps, these tanks had
permeation rates well below the new standards. This test data is presented in Table 5.3-32.

       Table 5.3-32: Permeation Rates  for Handheld Fuel Tanks Tested by Industry
Tank Capacity
1840
470
Gasket Material
NBR
NBR
Test Temp.
28C
28C
Test Fuel
CE10
CE10
Permeation Loss
[g/m2/day]
0.23
0.26
0.75
0.54
       Another approach has recently been developed in which a multi-layer fuel tank can be
blow-molded with only two layers.108 In this construction, a barrier layer of a polyarylamide
known as Ixef MXD6 is used on the inside of a HDPE fuel tank. Ixef has permeation properties
similar to EVOH.  Test results showed a permeation rate of 0.8 g-mm/m2/day at 60C on CE10
for a test film of Ixef. Unlike EVOH, Ixef can be exposed directly to the fuel which removes the
need for an inner layer of HDPE. In addition, a tie material can be blended into the HDPE which
will allow the polyarylamide to bond directly to the HDPE rather than using an adhesive layer.
                                          5-63

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Final Regulatory Impact Analysis
       Permeation emissions were measured on five 2.5 liter fuel tanks at 28C using fuel
CE10.109 During the preconditioning of these fuel tanks, the pressure-vacuum, slosh, and UV-
exposure durability tests were performed.  All of the testing was performed using stock fuel caps
and gaskets. One of the fuel tanks showed considerably higher emissions than the others.  This
higher emitting tank was found to have an issue with the interface between the tank and the fuel
cap.  In general, the permeation rates were well below the tank permeation standard. These test
results are presented in Table 5.3-33.

       We also tested three test bottles and three fuel tanks made using this construction for
permeation emissions.  The test bottles were about 1.3 liters in volume and used a fluoropolymer
gasket under the caps. The fuel tanks were similar to those described above. Each of the test
bottles and tanks was filled with E10 and soaked for more than 20 weeks. Prior to the two week
weight loss test, fresh fuel was added to each bottle/tank.  As shown in Table 5.3-33, the
measured permeation results were well below the new tank permeation standard.

        Table 5.3-33: Permeation Results Ixef Barrier Test Bottles at 29C on E10
Tank
tank 1
tank 2
tankS
tank 4
tank5a
tank 6
tank 7
tankS
bottle lb
bottle 2b
bottle 3b
Conditions
28 C,
Fuel CE10



29C,
Fuel E10

29C,
Fuel E10

Preconditioning
fuel soak, slosh,
pre ssure -vacuum,
and UV exposure


fuel soak


fuel soak


g/gal/day
0.11
0.14
0.19
0.13
0.34
0.04
0.19
0.04
0.05/0.02
0.14/0.02
0.07/0.02
g/m2/day
0.67
0.87
1.17
0.80
2.07
0.36
1.80
0.36
0.26/0.12
0.72/0.12
0.39/0.12
       3 interface issue reported with cap
       b repeated test with epoxy seal on fuel cap
       Tanks 6-8 and bottles 1-3 were tested by EPA using screw on fuel caps with gaskets. For
the test bottles, gaskets were cut at EPA from FKM rubber. It was thought that the permeation
results were affected by the seal at the fuel cap.  Therefore, the tests were rerun 6 months later
using epoxy as a secondary seal at the fuel cap.  As a result, much lower permeation rates were
measured for all three test bottles.  For the fuel tanks, the stock fuel caps and gaskets were used.
One of the tanks had significantly higher permeation emissions than the other two tanks. This
difference may have been a seal issue at the fuel cap.

       5.3.2.5.2 Rotational Molded Dual-layer Construction

       As discussed above, an inner layer can be molded into the inside of a rotationally molded
                                          5-64

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                                             Feasibility of Evaporative Emission Control
fuel tank through the use of a drop-box that opens after the XLPE tank begins to form.  Through
this method, a XLPE fuel tank could be molded with a low permeation inner barrier. With this
construction, it may be possible to reduce the amount of XLPE used depending on the structural
characteristics of the inner liner material. For instance, acetal copolymer can be rotationally
molded and could be used as the inner liner. This way, the permeation characteristics of an
acetal copolymer could be achieved through an inner liner while still retaining the toughness of
XLPE . One issue would be that acetal copolymers do not readily adhere to XLPE.  Therefore
fitting designs would need to account for this.

       Another material that could be used in a multi-layer approach is nylon which comes in
many grades. Typical nylon grades used in Small SI fuel tank constructions may not perform
well in marine applications because of the hygroscopic nature of these nylons. In other words,
typical nylon adsorbs water which can make it brittle. In addition, E10  fuel permeates through
nylon much more readily than gasoline.

       One manufacturer is working with a nylon known as Rilsan polyamide 11 (PA 11) in
constructing low permeation multi-layer rotational-molded fuel  tanks.110 Rilsan polyamide 11
has two advantages to traditional nylons in that it is not hygroscopic and it is more resistive to
alcohol fuels. One manufacturer has manufactured fuel tanks using the PA11 as an  inner liner in
a polyethylene shell. The manufacturer using this approach reports a permeation rate of about 3
g-mm/m2/day on fuel CE10 at 28C compared to about 30 g-mm/m2/day for XLPE.  In addition,
the nylon used in multi-layer constructions is formulated with a polyethylene graft that causes it
to adhere well to XLPE.  This prevents the layers from separating in use.

       We tested two 10 gallon multi-layer rotational molded fuel tanks at 29C with E10 fuel
after a 35 week  soak with two fuel changes during that period.111 One of the tanks was molded
with an outer shell of medium-density polyethylene while the other was molded with an outer
shell of cross-link polyethylene.  The long soak period was due  to test equipment problems and
the fuel was changed with each test  attempt. However, it presents valuable data on the longer
term effectiveness of this technology.  This test data is presented in Table 5.3-34. The
manufacturer reported that this tank design passed testing on the Coast Guard burn,  pressure,
shock, and impulse test requirements.112'113'114'115  In addition, a tank of this construction was
tested and passed the tank durability tests for snowmobiles specified in  SAE J288.116 These tests
include cold (-40C) and hot temperature (60C) immersion and drop tests.

       Typically, multi-layer rotational-molded fuel tanks are constructed with the use of a drop
box which adds the inner-layer material into the mold after the first material sets. Other
approaches are to use a meltable bag containing the inner-layer  material or even to pull the mold
from the oven to add the inner-layer material. However, one manufacturer, that participated in
the SBREFA process, has stated that they have developed a method to mold the inner liner
without the use  of a drop box or other approach that lengthens molding  cycle time.  This fuel
tank manufacturer is selling fuel tanks using this construction for use in Small SI equipment and
is selling mono-layer XLPE rotational-molded tanks for use in boats.
                                          5-65

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Final Regulatory Impact Analysis
         Table 5.3-34: Permeation Results PA 11/PE Fuel Tanks at 29C on E10
Tank
1
2
Outer Shell
MDPE
XLPE
g/gal/day
0.05
0.06
g/m2/day
0.71
0.79
       Under their rule for small offroad equipment, California may issue executive orders to
manufacturers with low emission products. As of August, 2006, ARB has issued 5 executive
orders for low permeation fuel tanks.117 Under these executive orders, two basic multi-layer
rotomolded (XLPE and nylon) approaches have been approved.  The California fuel tank
permeation standard is 1.5 g/m2/day tested at 40C on California certification fuel.  However,
most of the testing was performed on fuel CE10 which is a significantly more aggressive fuel for
permeation.  Table 5.3-35 presents the test results for rotational-molded fuel tanks with ARB
executive orders. Note that the reported emissions are the average of 3-5 test samples.

      Table 5.3-35: ARB Fuel Tank Executive Orders for Small Offroad Equipment
EO#
C-U-05-005
C-U-06-014
Test Fuel
CE10
Phase II
CE10
CE10
CE10
g/m2/day
0.81
0.18
0.10
0.00
0.09
       There is another approach to dual-layer rotomolded fuel tanks under development that
uses a "single shot" approach to molding.118 In this method a material known as polybutylene
terephthalate cyclic oligimor (CBT) is combined with the XLPE in the mold. Because of the
different melt rates and viscosities of the two materials, during the mold process, the CBT
polymerizes into a thermoplastic known as polybutylene terephthalate (PBT) to form a barrier
layer on the inside of the fuel tank.  Adhesion between the PBT and XLPE comes from
mechanical bonding between the two layers. This material can be used without lengthening the
cycle time for rotational molding, and it does not require forced cooling.119 Initial testing shows
a permeation rate of <1 g/m2/day when tested with fuel CE10 at 40C for a sample with a 3.9 mm
total wall thickness.120  This wall thickness for this testing was composed of 0.9mm CBT and
3.0mm XLPE. PBT itself has a permeation rate on CE10 at 40C  of less than 0.05 g-mm/m2/day.

       5.3.2.5.3 Injection-Molded Dual-Layer Construction

       To add a barrier layer in the injection molding process, a thin sheet of the barrier material
may be placed inside the mold prior to injection of the poleythylene. The polyethylene, which
generally has a much lower melting point than the barrier material, bonds with the barrier
material to create a shell with an  inner liner.
                                         5-66

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                                              Feasibility of Evaporative Emission Control
       5.3.2.5.4 ThermoformedMulti-Layer Construction

       As an alternative, multiple layers can be created through thermoforming.121 In this
process, sheet material is heated then drawn into two vacuum dies.  The two halves are then
fused while the plastic is still molten to form the fuel tank. Before the halves are fused together,
it is possible to add components inside of the fuel tank. Low permeation fuel tanks can be
constructed using this process by using multi-layer sheet material. This multi-layer sheet can be
extruded using similar materials to multi-layer blow-molded fuel tank designs.  A typical barrier
construction would include a thin EVOH barrier, adhesion layers on both sides, a layer of HDPE
regrind, and HDPE layers on the outside surfaces.

       This process has low capital costs compared to blow-molding  and should be cost
competitive with injection molding and rotational-molding. Manufacturers have indicated that
this construction could be coated with an intumescent material which  would help it pass the
Coast Guard fire test. This coating could be applied directly to the multi-layer plastic sheets
while they are still hot after extrusion.  Once the plastic cools, it could be applied using flame
ionization or electric arcing to increase the surface are of the plastic for adhesion.

       EPA tested two, 5.6 gallon, thermoformed fuel tanks for permeation.  These fuel tanks
were constructed as described above with a thin EVOH barrier and were soaked with E10 for 27
weeks prior to testing. Due to test variability, testing was repeated at  35  and 44 weeks (fresh
fuel was added prior to each weight loss test).  From day to day, a constant weight loss was not
always observed, and weight gains were occasionally seen. This variability  in measured weight
loss was likely due to the very low permeation rates combined with the effect of atmospheric
conditions on measured weight. The highest variations in weight loss were observed when
storms passed through suggesting that the changes in barometric pressure and relative humidity
were affecting the buoyancy of the fuel tanks (discussed in more detail in Section 5.6.2.3). In
the third round of testing (after 44 weeks), barometric pressure and humidity were measured and
deemed to be relatively stable.  In addition, a smaller tank with sand in it (rather than fuel) was
measured simultaneously as a control to give some indication of the buoyancy effect.  A small
weight loss was measured for the control tank, suggesting that the measured test results may
slightly overstate the permeation for the thermoformed fuel tanks. Table 5.3-36 presents the test
results for each of the three tests.
                                           5-67

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Final Regulatory Impact Analysis
 Table 5.3-36: Permeation Results Multilayer Thermoformed Fuel Tanks at 29C on E10
Soak (weeks)
27
35
44
Average
Tank
#16
#21
#16
#21
#16
#21
#16
#21
g/gal/day
0.01
0.01
0.01
0.01
0.01
0.00
0.01
0.01
g/m2/day
0.15
0.05
0.07
0.09
0.11
0.04
0.11
0.06
       5.3.2.5.5 Epoxy Barrier Coating

       Another approach that has shown promising results is to coat a plastic fuel tank with a
low permeation epoxy barrier coating. Early attempts at coating a plastic fuel tank resulted in
coatings that eventually wear off due to the difficulty of bonding some materials to HDPE and
XLPE. However, because fluorination increases the surface energy of the plastic, a low level of
fluorination can be used to make it possible to apply an epoxy coating, even to XLPE.  Because
this approach is applied to the fuel tank post-molding, it can be used for any plastic fuel tank,
regardless of the production molding method.

       We performed permeation testing on six 12 gallon rotationally-molded XLPE fuel tanks
with a thin, low-permeation epoxy coating. This coating was a two-part epoxy that was sprayed
onto the tank and thermally cured in 45 minutes. Prior to the permeation measurements, the fuel
tanks were soaked with E10 fuel at about 25C for 15 weeks.  The tanks were then drained and
fresh E10 was added prior to the 29C constant temperature permeation test. Inspection of the
externally coated fuel tanks  showed that the epoxy was unevenly applied and that some bare
spots existed. This was reflected in the unsatisfactory permeation results. A more careful
coating would be expected to result in similar results as the internal coatings.  One of the
externally coated fuel tanks was over-coated with a 1-part epoxy that was cured with a 45 second
UV exposure. This tank was soaked for an additional  6 weeks prior to retesting.  These test
results, which are presented in Table  5.3-37, show that this technology can be used to reduce
permeation emissions by more than 90 percent.
                                          5-68

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                                             Feasibility of Evaporative Emission Control
 Table 5.3-37: EPA Permeation Data on Epoxy Coated XLPE Fuel Tanks at 29C on E10
Fuel Tank Set
1


2


3

Coating
Inside
Thermocured

Outside
Thermocured*

Outside
UV cured
Soak Period
15 weeks


15 weeks


additional
6 weeks
g/gal/day
0.04
0.001
0.07
0.13
0.23
0.23
0.03

g/m2/day
0.6
0.02
1.0
1.9
3.3
3.3
0.4

slosh test?
no
no
yes
no
no
yes
no

       * inspection showed uneven application of the coating which affected permeation results
       Since the above testing was performed, the fluorinater and the epoxy manufacturer who
developed this approach have performed more testing on their UV cured, 1-part epoxy. The
testing was performed on epoxy coated HDPE bottles and 2 gallon fuel tanks using the
California ARB test procedure of 40C with California certification fuel.122 At 29C, we would
expect the permeation rate to be about half of these levels due to the relationship between
permeation and temperature discussed above in Section 5.3.1.2.  The results for this testing were
reported to be 0.3 g/m2/day on average for both the bottles and tanks on gasoline. The bottles
had a permeation rate of 0.5 g/m2/day on gasohol (ethanol blend). This technology resulted in
better than 95 percent reductions in permeation. Table 5.3-38 presents the test results after a 9
week fuel soak at 40C.
Table 5.3-38:  Permeation Data: Epoxy Coated HDPE Fuel Tanks at 40C on CA Cert Fuel
Fuel Tank
1
2
3
4
g/gal/day
0.04
0.02
0.02
0.08
g/m2/day
0.25
0.09
0.11
0.49
       Roto-molders of marine fuel tanks generally use cross-link polyethylene.  The advantage
of XLPE is that its cross-link structure causes it to behave like thermoset which helps the fuel
tanks pass the Coast Guard fire test (33 CFR 183.590) by holding their shape longer under
exposure to fire.  If a flame retardant were included in the epoxy coating, a less expensive
material, such as FIDPE could be used to make fuel tanks that are subject to the flame test
requirement. The manufacturers who have developed the above approach for permeation have
developed an additive that provides an intumescent coating to allow the fuel tanks to be
produced at a lower cost. Testing on the Coast Guard burn test showed that an FIDPE fuel tank
would fail around after being exposed to a flame for about 1.5 minutes (the standard is 2.5
                                          5-69

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Final Regulatory Impact Analysis
minutes). With the intumescent coating, the fuel tank passed the flame test and survived more
than 5 minutes.123

5.4  Fuel/Vapor Hose Permeation

       The polymeric materials (plastic or rubber) used in the construction of gasoline fuel and
vapor hoses generally have chemical compositions much like that of gasoline. As a result,
constant exposure of gasoline to these surfaces allows the material to continually absorb fuel.
Permeation is driven by the difference in the chemical potentials of gasoline or gasoline vapor on
either side of the material. The outer surfaces of these materials are exposed to ambient air, so
the gasoline molecules permeate through these fuel-system components and are emitted directly
into the air. Permeation emissions continue at a nearly constant rate,  regardless of how much the
vehicle or equipment is used. Because of these effects, permeation-related emissions can
therefore add up to a large fraction of the total evaporative emissions.

       This section summarizes the data and rationale supporting the permeation emission
standard for fuel lines presented in the Executive Summary.

5.4.1  Baseline Hose Technology and Emissions

       5.4.1.1 Marine Fuel Hose Subject to 33 CFR part 183

       The majority of marine fuel hoses are constructed primarily of nitrile rubber with a
chloroprene cover for abrasion and flame resistance. Hoses are designed to meet the Coast
Guard requirements in 33 CFR part 183 which reference SAE J1527.124 Fuel hose for boats with
gasoline engines (excluding outboards) must meet the Class 1,  Type A requirements which
specify a maximum permeation rate of 100 g/m2/day at 23C on ASTM Reference Fuel C125 (50
percent toluene, 50 percent iso-octane). Class  1 refers to hose that is used where liquid fuel is
normally continuously in the hose. Type A refers to hose that will pass a 2V2 minute flame
resistance test.

       On a fuel containing an alcohol blend, permeation would likely be higher from these fuel
hoses.  In fact, the SAE J1527 standard also requires Class  1 hose to meet a permeation rate of
300 g/m2/day on fuel CM15 (15 percent methanol). Although ethanol is generally less
aggressive than methanol, ethanol in the fuel would still be expected to increase the permeation
rate significantly through most fuel hoses.  Based on the data presented in Appendix 5D,
permeation through nitrile rubber is about 50 percent higher when tested on Fuel CE10 (10
percent ethanol) compared to testing on Fuel C.

       Fuel fill neck hoses are subject to a less stringent permeation standard under the Coast
Guard specifications because they are not normally continuously in contact with fuel (Class 2).
This relaxed standard is 300 g/m2/day on Fuel C and 600 g/m2/day on Fuel CM15 at 23C.
Where marine fuel hose is typically extruded,  fill neck hose is generally constructed by wrapped
layers on a mandrill. Fill neck hose is constructed with  a larger inner diameter (1.5-2") to
accommodate higher fuel rates and with thicker, more heavily reinforced walls, to prevent

                                          5-70

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                                             Feasibility of Evaporative Emission Control
buckling and pinching.

       Marine fuel hose is typically designed to be somewhat lower than the SAE J1527
requirements.  Confidential data by one manufacturer supplying baseline marine fuel hose
suggested that their fuel feed hose is about 25 percent lower than the Class 1, Type A
requirement on Fuel C and about 35 percent lower on Fuel CM15. In their comments on the
2002 proposal for marine evaporative emission control, Lawrence industries stated that the
majority of their fill neck hose permeates in the range of 150 to 180 g/m2/day which is about half
of the 300 g/m2/day  requirement required by the Coast Guard.126

       We  collected test data on marine hose permeation through contracts with outside
laboratories.127'128'129'130'131 Data was also available on a fuel feed hose testing funded by the
marine industry.132  All of the hose were prepared by soaking with liquid fuel for long enough
periods to stabilize the permeation rate.  This data is  presented in Table 5.4-1. Note that this data
shows somewhat lower permeation than was reported by manufacturers based on their own
testing.  Especially in the case of the fuel feed hose, this may be a function of the hose
construction. This hose was purchased by the contractor without any knowledge of the hose
construction. Therefore, it is not known if this is a representative sample of a baseline hose
construction or if it contains some sort of barrier material.

        Table 5.4-1: Permeation Rates for Baseline SAE J1527 Marine Fuel Hose
Hose Type
fuel feed hose
vent hose
fill neck hose
fill neck hose
fill neck hose
I.D.
3/8"
5/8"
1.5"
1.5"
1.5"
Fuel Type*
E10
Fuel CE10
E10
FuelC
FuelC
Fuel CE10
FuelC
E10
Fuel CE10
g/m2/day
43
88
37
95
98
109
87
164
123
123
274
Test Temperature
23 C
28 C
22-36 C
temperature cycle
23 C
23 C
       * E10 refers to gasoline with 10 percent ethanol
       Although fuel hose used in personal watercraft is subject to 33 CFR part 183, personal
watercraft manufacturers do not use hose specified in SAE J1527. Fuel hose specifications are
contained in a separate recommended practice under SAE J2046.133 Under this practice, the
permeation requirement is 300 g/m2/day with testing performed in accordance with SAE J1527.
                                          5-71

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Final Regulatory Impact Analysis
       5.4.1.2 Other Marine Fuel Hose

       Fuel hose used with outboard engines is not subject to 33 CFR part 183. This hose
includes the fuel line from the portable fuel tank to the engine and fuel hose on the engine itself
and is generally either constructed out of nitrile rubber with an abrasion resistant cover similar to
hose used in recreational vehicle applications or is constructed out of polyvinyl chloride (PVC).
One manufacturer of marine hose for use in outboard marine engines supplied permeation data
on five hose constructions tested at 23C.134 This data is presented in Table 5.4-2 for Fuel C,
Fuel CE10, and Fuel CM15 (15 percent methanol). As shown by this data, hose permeation rates
can increase dramatically when tested on fuel blended with alcohol.  Fuel lines connected to a
portable fuel tank are also generally fitted with a primer bulb which is also typically constructed
from nitrile rubber.

         Table 5.4-2: Permeation Rates for Baseline Fuel Hose [g/m2/day at 23C1
Fuel Hose
C-464-D11
C-530-D2-CE
ECO/CPE
J30R7
CMC ESI 763
FuelC
195
5
228
426
141
Fuel CE10
420
183
402
279
290
Fuel CM 15
590
546
565
433
314
gasoline*
66
4
53
27
43
E10
192
74
131
126
103
       * cited as Marathon 92

       5.4.1.3 Small SI Equipment Hose

       Fuel hoses produced for use in Small SI equipment are generally extruded nitrile rubber
with a cover for abrasion resistance. This hose is often equivalent to SAE J30 R7 hose which as
a permeation requirement of 550 g/m2/day at 23C135 on ASTM Fuel C (50 percent toluene, 50
percent iso-octane).  On a fuel containing an alcohol blend, permeation would likely be much
higher for these fuel hoses. R7 hose is made primarily of nitrile rubber (NBR).  Based on the
data presented in Appendix 5D, permeation through NBR is 50 percent higher when tested on
Fuel CE10 (10 percent ethanol) compared to testing on Fuel C.

       One manufacturer performed a study of several hose samples and various fuel types.136
Permeation testing was performed using the methodology in SAE J30. These hose samples
included SAE J30 R7, R8, and R9 hose.  The R7 hose samples were constructed with an
acrylonitrile inner tube with a chlorosulfonated polyethylene cover layer.  The R8 hose  samples
were constructed using a epichlorohydrin ethyleneoxide copolymer. The R9 hose used  a
fluoroelastomer barrier for the inner tube with an outer tube made of chlorosulfonated
polyethylene compound reinforced with a polyester braid. Over the two week tests, the study
showed a peak permeation rate after 4-6 days for R7 and R8 hose and a peak permeation rate
after 10-12 days for the lower permeating R9 hose.  Table 5.4-3 below presents  the two week
averages for each of the hose samples and test fuels.  In this study, the hose manufacturers were
not identified, but the hose samples were each given a letter designation.
                                          5-72

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                                            Feasibility of Evaporative Emission Control
        Table 5.4-3: Permeation Rates for SAE J 30 Fuel Hose [g/m2/day at 23C1
Fuel Hose
SAE J30 R7 "mfr. D"
SAE J30 R7 "mfr. E"
SAE J30 R8 "mfr. B"
SAE J30 R8 "mfr. F"
SAE J30 R9 "mfr. A"
SAE J30 R9 "mfr. C"
FuelC
450
330
152
130
2
2
Fuel CE10
508
501
385
355
11
6
Fuel CE15
541
433
337
308
10
4
Fuel CM 15
587
707
620
545
73
55
       Handheld equipment typically use smaller diameter hose made of a single material with
no cover. This fuel hose may either be extruded straight run hose or may be more complex
injection-molded designs.  To determine baseline permeation emission rates from hose on
handheld equipment, testing was performed by industry using a modified SAE J30 weight loss
procedure.137 In this modified procedure, E10 fuel was used and the testing followed a 30 day
fuel soak intended to stabilize the permeation rate. Further testing was later performed by
industry on similar fuel lines exposed to E10 and to CE10.138 This testing showed much higher
permeation on CE10 than on E10 for these hose samples. Table 5.4-4 presents the test results.

          Table 5.4-4:  Handheld Product Fuel Line Permeation Test Data [23"C1
Hose ID
90014
90015
90016
S3
S4
HI
H2
Bl*
B2*
SI
S2
C*
Bl*
B2*
E*
p*
A*
Construction
extruded








molded


extruded

molded


Test Fuel
E10








E10


CE10

CE10


Material
NBR








NBR
NBR/PVC
NBR/PVC
NBR

NBR
NBR/PVC
NBR/PVC
g/m2/day
198
192
168
165
171
360
455
205
224
198
386
270
742
662
1148
736
975
        average of 5 measurements
                                         5-73

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Final Regulatory Impact Analysis
       5.4.1.4 Fuel Effects on Hose Permeation

       As shown in the data above, adding ethanol or methanol to the test fuel significantly
affects the permeation rate through fuel hoses. Because the SAE guidelines typically specify
Fuel C for testing, most of the hose data available in the literature is on Fuel C or some blend of
Fuel C and ethanol or methanol.

       One study looked at the effect of fuel composition on the permeation of several materials
used in baseline hose constructions.139 This data suggests that Fuel C is a more aggressive fuel
with respect to permeation than gasoline. In addition, this data shows that permeation for these
materials is very low with diesel fuel. Table 5.4-5 presents the data from this  study. Appendix
5D includes a table spelling out the acronyms for the hose materials in this table.

  Table 5.4-5:  Permeation Rates by Fuel and Fuel and Hose Material [g/m2/day at 21C]
Material
CFM
CO
ECO
ETER
39%ACNNBR
CSM
CR
FuelC
nil
150
190
230
300
490
640
CE10
35
270
390
400
420
575
690
CM10
nil
255
310
360
360
665
740
Indolene*
0.1
10
55
65
110
210
320
IE10
20
80
180
205
200
240
340
IM10
nil
125
150
165
200
300
385
Diesel
3
2
5
10
15
nil
10
  "Indolene" refers to a fuel meeting the EPA specifications for certification gasoline
       This difference in permeation between Fuel C and gasoline is likely due to the higher
aromatic content of Fuel C than of certification gasoline.  A second study compared three
common fuel system materials on Fuel C and certification gasoline.140 Fuel C is made up of 50
percent toluene and 50 percent isooctane.  As a result, it is half aromatics and half aliphatics. In
this study, the certification gasoline was observed to be 29 percent aromatics, 67 percent
aliphatics, and 4 percent olefms. The test results were indicative of the effect of aromatics on
permeation. Table 5.4-6 presents the permeation rate reported in g-mm/m2/day for three sample
materials:  a low permeation fluoroelastomer (FKM), two medium permeation epichlorohydrins
(ECO) and two high permeation nitrile rubbers (NBR).  This testing, which was performed at
24C, gives a good comparison of the effect of gasoline versus Fuel C on permeation.
                                          5-74

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                                              Feasibility of Evaporative Emission Control
    Table 5.4-6:  Fuel C Versus Gasoline Permeation by Hose Material  [g-mm/mVday]
Material
FKM-1
ECO-1
ECO-3
NBR-1
NBR-2
FuelC
3.3
180
282
570
705
Indolene*
1.2
33
45
255
510
% difference
-64%
-82%
-84%
-55%
-28%
  "Indolene" refers to a fuel meeting the EPA specifications for certification gasoline
       5.4.1.5 Vent Hose Permeation

       Permeation occurs not only through hose walls that are in contact with liquid gasoline,
but also through surfaces exposed to fuel vapor.  In the event that the fuel vapor represents a
saturated mix of air and fuel, we would expect permeation to be the same as that for exposure to
liquid fuel. In a fuel tank, the walls of the tank are readily exposed to saturated vapor as
discussed earlier in Section 5.3.1.4. In a fuel system hose not continuously exposed to liquid
fuel, the vapor concentration may be significantly lower than saturation for several reasons.
Clearly, if a hose is open to atmosphere, such as vent hose, there would be a gradient through the
hose ranging from saturated vapor in the fuel tank to fresh air outside of the fuel system. In
addition, if the tank is venting and drawing in air due to diurnal (or other) temperature changes,
then the fuel hose will regularly be exposed to varying vapor concentrations.

       To investigate permeation rates for vent hose exposed to gasoline vapor, we contracted
with an outside laboratory to measure the permeation of fuel through marine hoses under various
venting configurations.141'142  The marine hose used in this testing met the USCG requirements
for SD/I vessels in specified in 33 CFR part 183 and SAE Recommended Practice J1527. Each
section of hose was connected to a metal fuel reservoir and exposed to liquid fuel for 8 weeks at
40C to stabilize the permeation rate. The test fuel was EPA certification gasoline blended with
10 percent ethanol (E10) Each section of hose was then soaked for an  additional 2 weeks at
40C in the planned test configuration. After the soak, fresh fuel was added to the  reservoirs and
permeation was measured in a mini-SFIED.  Hose sections were tested at constant temperature in
three configurations.

       One section of hose was tested exposed to liquid fuel.  Two sections of hose (1.5 and 5/8"
ID.) were tested with one end connected to the fuel  reservoir and the other opened to
atmosphere through a fitting  in the SFIED.  This configuration was intended to simulate vent
hose at constant temperature.  A third configuration  was also tested where three sections of hose
were configured as vent hose and tested over a 22.2-35.6C one day diurnal sequence. This test
was intended to simulate vent hose in a fuel system exposed to fuel tank breathing  caused by
temperature variation. The data in this testing, shown in Table 5.4-7, suggest that permeation
rates for vent lines are much  lower than for hose that is regularly exposed to liquid fuel.  This
result is likely due to a fuel concentration gradient in the hose which is largely due to one end
                                          5-75

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Final Regulatory Impact Analysis
being exposed to fresh air.

          Table 5.4-7: Effect of Venting on Hose Permeation with E10 [g/m2/dayl
I.D.
inches
1.5
0.625
0.625
0.625
0.625
Length
feet
1
3
3
3
3
Temperature
28C (84F) constant
22-3 6C (72-96F) diurnal
Liquid Exposure
123*
37
-
Vented to Atmosphere
3.3
5.8
4.3
4.5
4.9
       * taken from Table 5.4-1 on a similar hose for comparison
       The marine industry also funded permeation testing on vent hose exposed only to fuel
vapor and air.143 The vent line hose was preconditioned by attaching the hose to a 55 gallon steel
drum containing commercial gasoline containing 10 percent ethanol and setting the drum outside
during the summer. A carbon canister was attached to the end of the hose to simulate a vent line
with diurnal emission control. Permeation was measured after 90, 120, 150, and 180 days of
preconditioning. Because of the large size of the test rig, weight loss testing could not be
performed. Instead, a sleeve was fitted over the hose and nitrogen was flowed through the sleeve
to a carbon trap.  The change in the weight of the carbon trap was then measured to determine
the permeation rate. As with the fill neck testing, the hose was configured to run vertically from
the top of the fuel reservoir (55 gallon drum). Repeat testing was performed on this hose and
both values for each hose are presented in Table 5.4-8. The permeation rates for this testing
were lower than for similar hose exposed to liquid fuel. Fuel vapor stratification may have been
caused by a number of factors including breathing of fresh air into the tank during ambient
cooling periods, gravity, and a limiting diffusion rate.

       Table 5.4-8: Industry Test Data on Marine Vent Hose Exposed to Fuel Vapor
Hose manufacturer
#1
#2
Permeation [g/m2/day]
2.7,2.2
2.7,2.8
8.9,8.5
5.7,6.6
2.2,2.0
2.5,2.2
2.5,2.6
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                                              Feasibility of Evaporative Emission Control
       5.4.1.6 Vapor Hose Permeation

       Even in a vapor hose that is sealed at one end, stratification may occur for a fuel system
due to gravity. An example of vapor hose would be fuel fill neck hose with a sealed cap.
Because fuel vapor is heavier than air, even a large diameter hose may see stratification of fuel
vapor concentration if it reaches high enough above the surface of the liquid fuel.  The
stratification of vapor molecules happens slowly but would likely be observed under static
conditions. Another cause of low vapor concentration in fuel system hose may occur due to the
properties of diffusion discussed above in Section 5.1.3.  If the hose diameter is small compared
to its length, diffusion of vapor into the hose may be the rate limiting step rather than the
permeation rate through the hose.  In other words, the fuel vapor may enter the hose much slower
than rate at which it could permeate through the hose.  This effect could be combined with the
other effects discussed above to cause lower permeation for fuel hose exposed to vapor rather
than liquid fuel.

       The marine industry funded permeation testing on fill neck exposed only to fuel vapor.144
For the fill neck hose, a three foot  section of hose was attached to the top of a five gallon metal
fuel reservoir and configured vertically.  The fuel reservoir was filled half-way with gasoline
containing 10 percent ethanol.  Approximately every 30 days, this hose/reservoir assembly was
weighed for five days in a row. After the fifth day, the fuel in the reservoir was replaced with
fresh fuel. Testing was performed at 23C. The only liquid fuel exposure was a weekly
inversion of the assembly for about 1 minute. No attempt was made to simulate fuel slosh that
would be likely be seen in a boat in the water.  Also the hose was configured straight up and
down rather than in a more representative configuration as seen on a boat that would include
more horizontal orientation for most of the length of the hose. Repeat testing was performed on
the hose.145 During this repeat testing, permeation was also measured for the same fill neck hose
exposed to liquid fuel.

       Four of the fill neck hose constructions were specified as meeting the A2 designation in
SAE J1527. The other two fill neck hose samples were not identified except that they are made
by a hose manufacturer that is known to offer fill neck hose with and without a fluoroelastomer
barrier.  Table 5.4-9 presents the test results which show much lower permeation rates for fill
neck hose exposed vapor rather than liquid fuel.  Because the end of the hose was not exposed to
atmosphere, and because the hose was situated well above the surface of the liquid fuel in a
vertical fashion, stratification may have occurred in the hose largely due to gravity. This
stratification would be expected to lower the vapor concentration in the hose and therefore lower
permeation.
                                          5-77

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Final Regulatory Impact Analysis
       Table 5.4-9: Industry Permeation Data on Marine Fill Neck Hose [g/mVday]
Hose manufacturer
#1
#2
Vapor Exposure
4.8,4.8
4.5,4.4
4.7,4.8
4.7,4.7
1.3, 1.1
0.6,6.9
Liquid Exposure
129
114
113
121
5.6
8.5
       The marine industry testing was all performed on static test rigs with vertically oriented
hose. No consideration was given to how sloshing the test configuration, as would be seen in a
boat in the water, would have affected the results. For in-use equipment, especially boats in the
water, the fuel is sloshed regularly due to operation or waves.  This sloshing may mix up the
vapor in the tank and hose.  The industry test program also did not consider how a different hose
configuration (i.e. more horizontally oriented) would have affected the results. Fill neck hose in
boats often runs nearly horizontal from the tank to the edge of the boat, then runs more vertically
near the fill port.
                                               Figure 5.4-1: Hose Test Configurations
                                                              Liquid
                                                             Horizontal
                                                                                   Vertical
       We contracted with an outside test lab to
investigate the effects of fuel slosh and hose
configuration on permeation through marine fill
neck hose.146 All of the testing was performed
on 3 foot sections of 1.5" ID. marine fill neck
hose.  Testing was performed in each of the
three configurations shown in Figure 5.4-1. For
each fuel vapor exposure test, the hose was first
preconditioned by subjecting it to liquid fuel for
5 weeks followed by fuel vapor for an
additional 5 weeks. For the liquid fuel exposure
tests, the hose was soaked with liquid fuel for
10 weeks. Fuel soaking was performed at 40C.

       A total of eleven tests were run.  For each configuration, testing was performed on three
fuels: Fuel C, CE10, and E10. The liquid fuel exposure tests were performed in the static
position, while the fuel vapor exposure tests were performed with the fuel tanks on a slosh table.
Sloshing was performed at 15 cycles per minute with a deviation of+7 to -7 from level to
simulate movement that might be seen on a boat. An additional two tests were performed to
measure permeation through vapor hose in the vertical and horizontal positions without sloshing.
Permeation was measured similar to the industry testing using weight loss measurements of the
entire test rigs at 23 C.

       The test results from this testing are presented in Table 5.4-10.  It was observed that
permeation was much lower for vapor fuel exposure than for liquid fuel exposure. Fuel
                                          5-78

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                                              Feasibility of Evaporative Emission Control
permeation was significantly higher for the horizontal hose configuration than for the vertical
hose configuration.  This suggests that a large amount vapor stratification was occurring for the
vertical hose, while some fuel vapor was collecting in the horizontal hose. The fuel sloshing
applied in this testing doubled the permeation through the horizontal hose. Regardless of fuel
slosh, no measurable permeation was observed through the vertically oriented hose.  Permeation
emissions were observed to be about twice as high on fuel CE10 than on Fuel C or E10.

               Table 5.4-10: Effect of Hose Configuration, Vapor Exposure,
               and Test Fuel on Marine Fill Neck Hose Permeation at 23C
Hose Configuration
horizontal
vertical
Vapor Exposure
stationary
sloshed
sloshed
sloshed
stationary
sloshed
sloshed
sloshed
liquid soak
Test Fuel
CE10
CE10
E10
FuelC
CE10
CE10
E10
FuelC
CE10
E10
FuelC
Permeation |g/m2/day]
4.6
9.1
4.6
9.1
0.0
0.0
0.0
0.0
273.7
123.2
123.2
       In another study, the effects of liquid fuel versus vapor were studied in which the vapor
hose was not open to atmosphere.147 The fuel hose used for this testing was purchased over the
counter and was labeled as SAE J30 R7.  Further investigation of the hose revealed that this
particular grade is made of lower permeation materials than typical Small SI hose constructions.
It was constructed of NBR with a relatively high ACN blend (39 percent) and an ECO cover was
used. This construction was originally intended to allow the hose to be painted with a lacquer-
based paint, then dried in an oven. Although this is a somewhat atypical hose construction, the
test results  should still reflect the effects of liquid versus vapor on permeation.

       In this testing, all of the fuel hose was preconditioned by soaking in liquid fuel for 5
weeks at about 40C. This soak was then repeated, except that half of the hose sections were
then exposed only to fuel vapor resulting from attaching the hose to the top of a metal fuel
reservoir. Three fuels were used; California certification gasoline (CARB II), EPA certification
gasoline (gasoline), and EPA gasoline blended with 10 percent ethanol (E10). After the soak
period, the  fuel was refreshed and weight loss testing was performed at 23C. Table 5.4-11
presents the test results.  Note that each data point in this table is the average of three hose
samples.  In this testing, the end of the hose was plugged and the hose was configured
horizontally. The lower permeation rates for vapor exposure were likely the result a low vapor
concentration in the hose. This low vapor concentration may have been caused because the
diffusion into the long narrow hose may have been the rate limiting effect rather than the
                                          5-79

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Final Regulatory Impact Analysis
permeation rate through the hose.

     Table 5.4-11: Fuel Hose Permeation with Vapor vs. Liquid Exposure [g/m2/day]
Test Fuel
CARBII
Gasoline
E10
Liquid Exposure
35.8
44.5
80.3
Vapor Exposure
0.3
0.1
0.7
5.4.2  Hose Permeation Reduction Technologies

       Materials used in current automotive fuel lines are two to three orders of magnitude less
permeable than nitrile hoses.148 In automotive applications, multilayer plastic tubing, made of
fluoropolymers is generally used. An added benefit of these low permeability lines is that some
fluoropolymers can be made to conduct electricity and therefore can prevent the buildup of static
charges.149 Although this technology can achieve more than an order of magnitude lower
permeation than barrier hoses, it is relatively inflexible and may need to be molded in specific
shapes for each Small SI application. For marine applications, this tubing would not likely meet
the Coast Guard or AB YC  durability specifications for fuel and vent hose.

       Thermoplastic fuel  lines for automotive applications are generally built to SAE J2260
specifications.150 Category 1 fuel lines under this specification have permeation rates of less than
25 g/m2/day at 60C on CM15 fuel (15 percent methanol). One thermoplastic used in
automotive fuel line construction is polyvinylidene fluoride (PVDF). Based on the data
presented in Appendix 5D, a PDVF fuel line with a typical wall thickness (1 mm) would have a
permeation rate of 0.2 g/m2/day at 23C on CM15 fuel. However, manufacturers involved in the
boat building industry have commented that this fuel line would not be flexible enough to use in
their applications because they require flexible rubber hose to fit tight radii and to resist
vibration.  They also commented that the hose they use must pass the Coast Guard flame
resistance requirements.151452

       Recreational vehicle manufacturers are required to use hose that meets a permeation
standard of 15  g/m2/day at  23C on gasoline blended with 10 percent ethanol (E10). Low
permeation hose constructions that have been identified for these applications could also be used
in Small SI equipment.  We believe that the same barrier materials that will be used for
recreational vehicle hose can also be used for marine hose constructions. Marine hose
constructions generally meet the Coast Guard flame resistance requirements either through the
use of a flame-resistant cover,  or by increasing the wall thickness. Therefore, the addition of an
inner permeation barrier would not be expected to affect the flame resistance of the hose.
Several low permeation hose constructions are discussed below.  Even though most of this data
is on hoses not designed for marine applications, the barrier technology can be used in marine
hose.
                                          5-80

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                                             Feasibility of Evaporative Emission Control
       We are requiring that fuel and vapor hose meet our standards on E10 fuel for two
reasons. First, ethanol is commonly a component of in-use fuels. Second, for many materials
used in hose constructions, permeation would likely be much higher for fuel containing ethanol.
For instance, a typical barrier material used in barrier hose constructions is FKM. Based on the
data presented in Appendix 5D for FKM, the permeation rate is 3-5 times higher on Fuel CE10
than Fuel C. Therefore, a hose meeting 15 g/m2/day at 23C on Fuel C may actually permeate at
a level of 40-50 g/m2/day on fuel with a 10 percent ethanol blend.

       There are lower permeation fuel hoses available today that are manufactured for
automotive applications. These hoses are generally used either as vapor hoses or as short
sections of fuel line to provide flexibility and absorb vibration. One example of such a hose153 is
labeled by General Motors as "construction 6" which is a multilayer hose with an inner layer of a
fluoroplastic known as THV sandwiched in inner and outer layers of a rubber known as ECO.5
A hose of this construction would have less than 8 g/m2/day at 40C when tested on CE10.

       Permeation data on several low permeation hose designs were provided to EPA by an
automotive fuel hose  manufacturer.154 This hose, which is as flexible as non-barrier hose, was
designed for automotive applications and is available today.  Table  5.4-12 presents permeation
data on three hose designs that use THV 800 as the barrier layer.  The difference in the three
designs is the material used on the inner layer of the hose.  This material does not significantly
affect permeation emissions through the hose but can affect leakage at the plug during testing (or
connector in use) and fuel that passes out of the end of the hose which is known as wicking. The
permeation testing was performed using the ARB 18-41C diurnal cycle using a fuel with a 10
percent ethanol blend (E10).

  Table 5.4-12: Hose Permeation Rates with THV 800 Barrier over ARB Cycle (g/m2/day)
Hose Name
CADBAR9610
CADBAR9710
CADBAR9510
Inner Layer
THV
NBR
FKM
Permeation
0.16
0.17
0.16
Wicking
0.00
0.29
0.01
Leaking
0.02
0.01
0.00
Total
0.18
0.47
0.18
       The data presented above shows that there is hose available that can easily meet the hose
permeation standard on CE10 fuel. Although hose using THV 800 is available, it is produced for
automobiles that must meet the tighter evaporative emission requirements in the Tier 2
standards. Hose produced in mass quantities today uses THV 500. This hose is less expensive
and could be used to meet the hose permeation requirements.  Table 5.4-13 presents information
comparing hose using THV 500 with the hose described above using THV 800  as a barrier
layer.155 In addition, this data shows that permeation rates more than double when tested on
CE10 versus Fuel C.
       5 THV = tetrafluoroethylene hexafluoropropylene, ECO = epichlorohydrin/ethylene oxide

                                          5-81

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Final Regulatory Impact Analysis
 Table 5.4-13: Comparison of Hose Permeation Rates with THV 500 and 800 (g/m2/day)*
Hose Inner
Diameter, mm
6
8
10
THV 500
FuelC
0.5
0.5
0.5
Fuel CE10
1.4
1.4
1.5
THV 800
FuelC
0.2
0.3
0.2
Fuel CE10
0.5
0.5
0.5
        Calculated using data from Thwing Albert materials testing (may overstate permeation)
       We contracted with an independent testing laboratory to test several samples of SAE J30
R9 hose and a sample each of automotive vent line and fill neck hose for
permeation.156'157'158'159'160'161 The fuel and vapor hoses had a six mm inner diameter. The test lab
used the SAE J30 test procedures for R9 hose with both Fuel C and Fuel CE10.  Most of the R9
fuel hose was supplied by recreational vehicle manufacturers who also supplied information on
the materials used in the construction of the hose as well.  We purchased one sample of the R9
hose (which was labeled as such) from a local auto parts store without knowing its construction.
Two additional R9 hoses were tested by a fuel hose manufacturer on fuel CE10 after a four week
soak.162 The SAE permeation specification for R9 hose is 15 g/m2/day at 23 C on Fuel C.  The
R9 hose tested all met this limit, even on ethanol blend fuels which typically result in higher
permeation.  The automotive vent line showed similar results, but the automotive fill neck
showed much lower permeation. Table 5.4-14 presents the test data on the above hose samples.
                                          5-82

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                                            Feasibility of Evaporative Emission Control
      Table 5.4-14: Test Results on Commercially Available Hose Samples (g/m2/day)
Hose Sample
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
SAE J30 R9
Automotive vent line
Automotive fill neck
Construction
FKM/ECO
FKM/ECO
FKM/NBR/CM
FKM/ECO
FKM/ECO
PVC/EEC
FKM barrier
fluorine/hydrin
unknown
FKM barrier
FKM barrier
unknown
unknown
FuelC
-
-
-
-
-
-
-
-
10.1
-
-
10.9
0.33
Fuel CE10
7.6
2.1
4.2
10.9
5.2
11.6
6.6
9.0
12.1
4.2
6.7
9.0
0.49
       Another hose construction that can be used to meet the marine hose permeation standards
is known as F200 which uses Teflon as a barrier layer.  Teflon has a permeation rate of 0.03-
0.05 g-mm/m2/day on 15 percent methanol fuel. F200 hose is used today to meet SAE J30 Rl 1
and R12 requirements for automotive applications.  Table 5.4-15 presents data on permeation
rates for several F200 constructions.163
                      Table 5.4-15: F200 Typical Fuel Permeation
Film Thickness [mils]
2
2
2
2
2
1
1
Hose Diameter [in.]
0.375
0.275
0.275
0.470
0.625
0.625
1.5
Fuel
TF-2
TF-2
M25
CE10
CE10
CE10
CE10
g/m2/day @23C
~
~
0.5
~
~
~
1.5
g/m2/day @40C
0.7
1
4
3
3
4
~
       Low permeability hoses produced today are generally constructed with a barrier material
                                         5-83

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Final Regulatory Impact Analysis
layer. There are hoses used in some marine applications with a thermoplastic layer (either nylon
or EVOH) between two rubber layers to control permeation. Because the thermoplastic layer is
very thin, on the order of 0.1 to 0.2 mm, the rubber hose retains its flexibility.  Through contract
with two independent labs, we tested three samples of marine barrier hose that were available
prior to our 2002 proposal for marine permeation emissions. This hose included two 3/8"
samples and one 5/8" sample which all used nylon as the permeation barrier.  These hose
constructions are used in some sterndrive and inboard applications.  Table 5.4-16 presents the
permeation test results at 23C.164'165'166'167'168'169

     Table 5.4-16:  Test Results on Available Barrier Marine Hose Samples (g/m2/day)
Hose Description
3/8" marine barrier fuel hose
5/8" marine barrier fuel hose
Lab 1
FuelC
0.80
~
Fuel CE10
5.2
11.6
3.4
Lab 2*
FuelC
0.36
0.76
       * average of three tests

       Similar testing was performed by the marine industry on commercially available low
permeation marine hose.170 In this testing, the 3/8" ID. fuel hose samples were connected to
metal fuel reservoirs and soaked with gasoline containing 10 percent ethanol at 23 C for 180
days. The weight of the container/hose assembly was measured for five days in a row
approximately every 30 days. The fuel was replaced with fresh fuel after each series of weight
measurements. The test report did not specify details on the hose constructions. However, based
on the manufacturer part numbers, several of the hoses in this test program were determined to
use a nylon barrier layer.  One of the hoses included was a baseline rubber construction meeting
Coast Guard requirements for SD/I fuel hose.  Repeat testing was performed on the hose.171
During this repeat testing, permeation was also measured for the same hose exposed to fuel
CE10. Although the permeation rate was generally higher on fuel CE10, the barrier hose
permeation rates were still well below the standard. Table 5.4-17 presents the results of this
testing.

    Table 5.4-17: Permeation Results for Commercially Available Marine Barrier Hose
             Tested at 23C with Gasoline Containing 10% Ethanol (g/mVday)
Hose Construction
SAE J1527 Al constructions with nylon barrier
not reported
Gasoline with 10% Ethanol
6.2,5.2
5.6,5.1
4.4,3.8
4.4,3.2
0.4,0.1
CE10
6.1
6.7
10.0
12.1
0.0
                                          5-84

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                                             Feasibility of Evaporative Emission Control
       After the 2002 proposal for marine permeation emissions, two marine hose manufacturers
developed hose samples using the F200 hose construction.  In addition, other hose manufacturers
supplied samples of barrier hose using the F200 hose construction and using THV800 as a
barrier layer.  These manufacturers stated that they could make marine hose using the same
barrier construction. We contracted to have these hose samples permeation tested on fuel CE10
at 23C following a four week soak.172 These test results are presented in Table 5.4-18.

    Table 5.4-18:  Permeation Test Results on New Marine Barrier Hose Constructions
Application
marine fill neck
marine fuel hose
fuel hose
fuel hose
Barrier Material
Teflon (F200)
Teflon (F200)
Teflon (F200)
THV800
I.D. [inches]
P/2
3/8
1/4
1/4
g/m2/day
0.2
5.0
3.8
5.1
       Currently, the Coast Guard requires that fuel pumps on engines be located on or near the
engine to minimize the length of high pressure fuel lines on the vessel. However, at least one
manufacturer sells boats with the high pressure fuel pump in the fuel tank.  They received a
waiver from the Coast Guard by using fuel lines that use either a glass fiber or stainless steel
braid cover and quick connect end fittings that are designed to withstand very high pressures
(much higher than would be seen on a boat).173 This particular fuel line construction also uses
Teflon as a barrier layer. Table 5.4-19 presents permeation test data on this hose.174

              Table 5.4-19: Permeation Test Data on Reinforced Fuel Hose
Application
Marine
Outdoor Power
Equipment
I.D. [inches]
0.31
0.25
0.19
0.31
0.25
0.19
Temperature
23C
60C
Fuel
CE10
CM15
g/m2/day
0.05
0.08
0.05
0.52
0.93
1.08
       Primer bulbs are typically injection-molded out of nitrile rubber.  Fuel lines for some
handheld equipment are manufactured in a similar manner. Low permeation primer bulbs and
fuel lines could be manufactured using a similar process by molding them from a
fluoroelastomer such as FKM. Fluoroelastomers, such as FKM, have similar physical properties
as nitrile rubber but are much more fuel-resistant.  If the primer bulb or fuel line were molded
out of a FKM with a sufficient flurorine concentration, the permeation rate would be less than
fuel line permeation standard.  Alternatively, primer bulbs could be manufactured to meet the
standards by molding a fluoroelastomer  inner liner with a nitrile shell to reduce costs. Other
                                          5-85

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Final Regulatory Impact Analysis
materials may be applicable as well (see tables of material properties in Appendix 5D).

       One manufacturer has developed a low-permeation primer bulb replacement that meets
the hose permeation standard.175476  This design uses a rigid, low permeation housing in the
shape of a traditional primer bulb. However, it uses a simple piston displacement pump inside to
take the place of soft elastomer squeeze type bulb.  It is designed to have similar dimensions to
existing primer bulbs and to be easily retrofitted into current applications.

       Under their rule for small offroad equipment, California may issue executive orders to
manufacturers with low emission products. As of August, 2006, ARB has issued 24 executive
orders for low permeation fuel lines.177 The California fuel line permeation standard is 15
g/m2/day tested at 40C on California certification fuel. However, many of the manufacturers
tested their products on CE10 fuel which results in  significantly higher permeation rates. Some
manufacturers even tested at 60C.  In all cases, the test results were below the 15 g/m2/day
standard, even under the more challenging test conditions.  Table 5.4-20 presents the test results
for the fuel lines with ARB executive orders. Note that the reported emissions are the average of
5-6 test samples.
                                          5-86

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                                            Feasibility of Evaporative Emission Control
      Table 5.4-20: ARB Fuel Hose Executive Orders for Small Offroad Equipment
EO#
C-U-06-016
C-U-06-001
G-05-016
G-05-017
G-05-019
C-U-05-004
C-U-05-010
G-05-019*
G-05-015a
C-U-05-001
C-U-06-001*
C-U-06-001*
C-U-06-020
C-U-05-014
C-U-06-021
C-U-06-002
C-U-06-011
C-U-05-011
C-U-06-017
C-U-05-013
C-U-05-006
C-U-05-012
C-U-05-003
G-05-018
C-U-05-009
C-U-06-010
C-U-05-002
ID. [mm]
4.8
6.0
6.4
6.4
6.4
6.4
6.4
6.4
7.9
8.0
6.0
6.0
4.5
6.4
6.4
6.4
6.4
2.0
3.5
4.0
4.0
4.0
4.5
4.8
4.8
4.8
6.4
Test Fuel
CE10
CE10
CE10
CE10
CE10
CE10
CE10
CE10
CE10
CE10
CM15
FuelC
Indolene
Indolene
Indolene
Indolene
Indolene
Phase II
Phase II
Phase II
Phase II
Phase II
Phase II
Phase II
Phase II
Phase II
Phase II
Temperature
40
40
40
40
40
40
40
60
60
60
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
g/m2/day
3.75
1.42
4.62
5.97
0.02
12.3
10.6
0.26
11.1
8.22
3.77
0.78
3.20
8.20
7.40
5.00
12.7
4.63
10.8
1.22
10.3
7.33
12.3
0.87
3.94
4.69
3.76
       * fuel tube
5.4.3  Low Temperature Hose Materials

       In some applications, molded fuel hoses are used rather than simple extruded fuel hose.
These fuel hoses are typically molded out of nitrile rubber (NBR) or a fluoroelastomer such as
FKM.  FKM is essentially rubber impregnated with fluorine which results in good fuel
permeation resistance.  Manufacturers of handheld equipment that may be used in very cold
weather have stated that they must use nitrile rubber because the FKM material may become
brittle at very low temperatures.178 Examples  of such equipment are ice augers and chainsaws.
                                         5-87

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Final Regulatory Impact Analysis
       Industry has not raised an issue with the capability of using extruded multi-layer hose in
cold temperature applications. This type of hose construction has been demonstrated for low
temperature use in automobiles and snowmobiles.  Extruded fuel hose meeting SAE and ASTM
standards is available today which meets a widespread set of safety and durability requirements.
Industry has stated that for some applications, such as chainsaws, that extruded fuel hose will not
work. In these applications, injection molding is used to manufacture complex fuel hose
geometries designed to account for high vibration of the equipment.  This vibration generally
results in different motion patterns for the carburetor and fuel tank resulting in variable distances
between the two.

       Industry presented information on FKM fuel lines that became brittle and cracked at very
low temperatures.179'180 However, this information was was based on an FKM compound without
a low temperature additive package.  There are a wide range of FKM products available on the
market.  Many of these fluoroelastomers are designed for use at low temperatures.181'182 For
instance, low temperature o-rings are common in automotive applications.183'184'185 Low
temperature grade FKM products are available with a glass transition temperature as low as -
40C and a brittleness point as low as -60C.186 However, low temperature grade FKM products
typically cost several times as much as FKM products intended for less severe temperatures. In
addition, these materials have not been demonstrated for use in molded fuel lines for handheld
applications.

       A lower cost option may be to blend a standard fluorosilicone such  as FVMQ with a
standard grade FKM.  The fluorosilicone brings very low temperature characteristics to the
blend. However, the permeation resistance is not nearly as good as for FKM products. The
blended product would be intended to create a balance between cost, permeation, and low
temperature properties.187 This product is currently used in automotive o-rings. However, it is
not clear if this material could be molded into fuel lines that would meet the appropriate design
criteria for handheld applications.

       A new material, called F-TPV, has been developed that is a dynamically vulcanized
combination of fluorothermoplastic resin and fluoroelastomer compound.188 The mix of the two
materials can be varied to trade-off permeation resistance with material hardness.  This material
has been shown to have a permeation rate ranging from 3 to 30 g-mm/m2/day on fuel CE10 at
60C. Rubber hose molded out of even the softest version of this material would be expected to
be capable of achieving a permeation rate well below the standard.  In addition, the impact
brittleness temperature is below -50C for the full range of material blends  discussed above.
Finally, the cost of this material is much lower than for low-temperature FKM products. Further
development efforts would be necessary to determine the suitability  of this material for fuel lines
on handheld equipment.

       Table 5.4-4, above, presents permeation data on several samples of NBR fuel lines used
on handheld equipment today. The permeation rates from these fuel lines range from 165 to 455
g/m2/day with E10 fuel at 23 C.  Later discussions with industry revealed that the NBR hose
with the lower permeation rates had higher acrylonitrile (ACN) contents. Although high ACN
rubber cannot achieve the same low permeation rates as FKM or F-TPV, some permeation

                                          5-88

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                                              Feasibility of Evaporative Emission Control
reductions could still be achieved with this material.

5.5  Other Evaporative Emissions

5.5.1  Other Venting Losses

       Hot soak emissions occur after the engine is turned off, especially during the resulting
temperature rise. The primary source of hot soak emissions is the evaporation of the fuel left in
the carburetor bowl.  Other sources can include increased permeation and evaporation of fuel
from plastic or rubber fuel lines in the engine compartment.

       Refueling emissions occur when the fuel vapors are forced out when the tank is filled
with liquid fuel.  At a given temperature, refueling emissions are proportional to the volume of
the fuel dispensed into the tank. Every gallon of fuel put into the tank forces out one-gallon of
the mixture of air and fuel vapors. Thus, refueling emissions are highest when the tank is near
empty.  Refueling emissions are also affected by the temperature of the fuel vapors and
dispensed fuel.  At low dispensed fuel temperatures, the fuel vapor content of the vapor space
that is replaced is lower than it is at higher temperatures because of the cooling effect on the
vapor in the fuel tank.

       In automotive applications, the carbon canister is sized not only to capture diurnal
emissions, but refueling, hot soak, and running loss emissions as well. With an engine purge, the
canister would effectively capture running loss emissions and hot soak emissions because the
canister would presumably be nearly empty after a short period of operation.  For the canister to
be effective at collecting refueling emissions, it would need to be purged before the refueling
event.  However, even without a purged canister, refueling emissions could be minimized by
matching the geometry of the fuel fill opening to the fuel pump nozzle.  By minimizing the open
space in the fuel fill opening around the nozzle, less air will be entrained which will minimize
vapor generation during the refueling event.  This will not help control the expulsion of vapor
that is displaced by liquid fuel.

5.5.2  Refueling Spitback/Spillage

       Installed fuel systems on boats  are typically open vented. The exception to this is PWC
which have sealed  fuel  tanks with pressure relief valves, largely to prevent spillage of fuel during
operation. For larger boats, fuel spillage during operation is less of an issue; however, it is
common for fuel to be lost to the environment during refueling or shortly thereafter.189'190 There
are several mechanisms that lead to fuel loss due to a refueling event. These mechanisms
include restrictions in the fill neck, fuel flowing out the vent line, and expansion of fuel in the
tank.

       The American Boat and Yacht Council (AB YC) has a voluntary refueling standard
designed to help prevent fuel from backing up the fill neck during a refueling event.191  This test
requires that no fuel back up the fill neck when a fuel tank in a boat is filled from 25 to 75
percent full at a fill rate of 9 gallons per minute.  This test is apparently designed to make sure

                                          5-89

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Final Regulatory Impact Analysis
that the fill neck does not have a restriction that may cause fuel to back up the fill neck during
refueling. To prevent fill from backing up the fill neck, fill necks are typically made of large
diameter hose which is reinforced to prevent kinking.  In addition, the fuel fill opening is
typically positioned higher than the vent line. This test does not consider fuel overflow that may
occur from filling a marine tank to 100 percent full. In addition, the full rate may be too low to
require a design that would work in typical in-use situations. One survey on 19 marinas saw a
range of 8 to 25 gallons per minute for gasoline fill nozzles with an average of 14 gallons per
minute.192

       The most common refueling spillage today is overflow out the vent line.  Typically the
vent line is the path of least resistance for fuel overflow. Boats typically do not have a
mechanism that prevents fuel tanks from filling all the way to the top.  In fact, the fill and vent
hose are attached to the top of the fuel tank and are often filled with fuel in addition to the tank.
Because the vent hose exits the boat lower than the fill neck opening, the tank can be filled until
fuel begins to exit through the vent hose. In addition, fuel may expand in the fuel tank when
cool fuel is pumped into the fuel tank on a warm day.  This expansion can cause additional fuel
overflow out the vent line.

       A number of devices have been produced to help control fuel spillage during refueling.
These devices include liquid/vapor separators, combination deck fills and vents, and fuel flow
monitoring systems. A study was performed by Boat US Foundation to evaluate the
effectiveness of several of these systems which  are currently available on the market.193  The
results of this study are discussed below.

       Liquid/vapor separators are valves that are installed in the fuel line. The typical design is
for the valve to contain a ball that rises when liquid fuel reaches it which closes the vent to liquid
fuel. As the tank fills, fuel backs up the fill neck, allowing the automatic shut-off on the nozzle
to stop the fuel flow. The study found that these systems typically worked best at lower fuel fill
rates and that the larger units were more effective. The effectiveness of the larger units was
probably because they essentially included a reservoir, allowing extra room for fuel expansion.
For the smaller units, the testing consistently showed fuel backing up the fill neck too quickly for
the automatic shut-off valve to engage and fuel  spit back out of the deck fill.

       In a vented deck fill design, the vent line is routed back to the top of the fill neck. The
intent is that the fuel surging out of the vent line would return to the fill neck and back to the
tank.  The study found that the combination vented deck fills significantly reduced
spitback/spillage, but still needed to be used with some caution.  One issue was that even when
the fuel came back up and shut off the nozzle, pressure in the fuel tank would cause fuel to
continue to rise in the line and spill onto the deck. Another manufacturer has a similar device
except that a clear section of tubing that redirects the fuel overflow from the vent line to the fill
neck. The operator only attaches this tubing during refueling. Because the tubing is clear, the
operator can see when the fuel is coming out of the vent and can manually slow down  or stop the
fuel flow.

       Fuel flow monitoring systems are designed to keep track of fuel usage by measuring fuel

                                          5-90

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                                              Feasibility of Evaporative Emission Control
flowing to the engine. The study did not present definitive results for the use of flow meters to
accurately refuel the tank without overfill.

       Where a carbon canister is used in the vent line for diurnal vapor control, it is important
to include a device to prevent liquid fuel from entering the canister. This device could take the
form of a floating ball valve, limited flow orifice, or other liquid/vapor separation mechanism.
In addition, this device  could be positioned in such a way as to prevent the tank from filling all
the way to the top. For instance, the vent fitting could reach down into the fuel tank. Leaving a
vapor space in the fuel tank gives room for fuel in the tank to expand.

       In automotive applications, carbon canisters have been used for many years in vehicles
that also meet fuel spit-back standards set by EPA. In typical automotive fuel systems, the fuel
shut-off on the nozzle is tripped before the fuel comes back out the fill neck. It is common to
have a narrow tube parallel to the fill neck reach into the fuel tank at the desired peak fill level of
the tank. The narrow tube connects to the fill neck near the top where the small hole on the
nozzle would be.  When fuel splashes on this  small hole, the vacuum draw is broken and the
shut-off device is triggered. Fuel travels up the narrow tube more quickly than up the fill neck
and triggers the nozzle shut-off well before fuel spit-back can occur.

       At least one company is developing a  similar design for use in boats. Testing has been
performed on one system by an independent laboratory that also performs ABYC and Coast
Guard tests for the marine industry. During the testing, a fuel tank was filled 30,000 times, using
this fuel system configuration, without any  spillage.194 Also, this fuel system configuration
creates a vapor space in the top of the tank which allows fuel to expand during heating, thereby
preventing fuel spillage due to expansion of the fuel in the tank.195 This system has since been
modified to be adaptable to any fuel tank with a fuel sending unit based on the standard SAE 5-
hole pattern.  The updated system was tested using a similar methodology as in the Boat US
study discussed above and underwent 25,000  refueling events at 15 gallons per minute without
experiencing  any spills.196  Pictures and video of this system are included in the docket.

5.6  Evaporative Emission Test  Procedures

       This section discusses test procedures  for measuring fuel line permeation, fuel tank
permeation, and diurnal emissions.

5.6.1 Fuel line Permeation Testing

       Fuel line permeation must be measured at a temperature of 23  2C using the weight
loss method specified in SAE J30197 and SAE J1527.198  In this method, one end of a specified
length of hose is connected to a metal reservoir while the other end is plugged. Test fuel is then
added to the reservoir at a volume high enough to ensure that the hose is filled with fuel. Once
care has been taken to ensure that no air bubbles are trapped in the fuel line, the reservoir is
sealed and the entire system is weighed. Permeation is determined by weighing the system every
24 hours and  noting the weight loss.  After  each weighing, the fuel is mixed by inverting the
assembly, then returning it to its original position.

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Final Regulatory Impact Analysis
       We are including two modifications to SAE J30 that are consistent with our current
requirements for recreational vehicles and highway motorcycles. First, the test fuel must be
ASTM Fuel  C199 (50 percent toluene, 50 percent iso-octane) blended with 10 percent ethanol.6
This fuel is known as CE10 and is commonly used in industry standards and test procedures such
as in SAE recommended practices (including SAE J1527).  Section 5.4, and Appendix 5D
presents permeation data for several hose constructions and materials used in hose constructions
on fuels with and without ethanol. As shown in this data, adding ethanol to the test fuel
significantly increases permeation. Standard recommended practice for hose testing uses Fuel C,
or some blend of Fuel C and either ethanol or methanol. This test fuel is generally more
aggressive than standard gasoline. Although hoses are not generally exposed to Fuel C in use,
the level of the standard was based on testing using Fuel C and Fuel C blends.  In addition, most
of the test data on low permeation hose presented in this Chapter is based on fuel CE10.  For
these reasons, we believe that it is appropriate to allow Fuel CE10 for hose testing.

       The second modification is that the hose must be preconditioned by filling the hose with
fuel and soaking long enough to ensure that the permeation rate has stabilized.  We are using a
soak period of 8 weeks at 23  5C. If a longer time period is necessary to achieve a stabilized
permeation rate for a  given hose design, we expect the manufacturer to use a longer soak period
(and/or higher temperature) consistent with good engineering judgement.  For instance, thick-
walled marine fuel hose may take longer to reach a stable permeation rate than thinner-walled
hose used in Small SI applications. In addition, we are clarifying that the weight loss
measurement period should be two weeks.

       Alternatively, for purposes of submission of data at certification, permeation could be
measured using alternative equipment and procedures that provide equivalent results. One
alternative approaches that we anticipate manufacturers may use are the recirculation technique
described in SAE J1737.200  To use other alternative methods, such as enclosure-type testing such
as in 40 CFR part 86, manufacturers have to apply to us and demonstrate equivalence. In
enclosure testing, manufacturers would need to show how they would account for the ethanol
fraction of the permeate.

       Recommended practice for automotive fuel tubing is defined in SAE J2260.201  The
permeation requirements in this standard are  one to two orders of magnitude lower than those
defined for marine hoses. These permeation  requirements are based on the same fuels as the
revised SAE J 1527, but at a much higher temperature (60C).  At 60C, permeation rates for a
given material may be 16 times as high or higher than at 23 C based on the rule of thumb that
permeation doubles for every 10C increase in temperature.  SAE J2260 refers to the permeation
test procedures in SAE J1737.202

       The procedures in SAE J1737 were designed to measure the low permeation rates needed
in automotive applications to meet EPA evaporative emission requirements. There was concern
that the weight loss measurement, such as used in SAE J1527, was not sensitive enough to
       6 An exception to this is that fuel IE10 may be used for cold-weather fuel lines.

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                                              Feasibility of Evaporative Emission Control
measure these low permeation rates. In addition, this procedure requires exposing the material to
be tested for hundreds of hours, depending on the material and fuel, to reach a steady-state
permeation rate. In this procedure, fuel is heated to 60C and circulated through a tube running
through a glass  test cell. Nitrogen around the tube in this test cell is used to carry the permeate
to activated charcoal canisters.  The canisters are weighed to determine their capture.  Because
the canister is much lighter than the reservoir/hose in the SAE J1527 configuration, a much more
accurate measurement of the permeation loss can be made.

       Some manufacturers of low permeability product are finding that as their emission rates
decrease, they need more refined test procedures to accurately measure permeation.  These
manufacturers are finding that the weight of the charcoal canisters are much higher than the
permeate being measured.  As an alternative to the gravimetric approach used in the above two
procedures, even very low permeation emissions can be measured by a flame ionization detector
and a SHED. As discussed earlier, SHED testing is generally used to measure evaporative
emissions from whole automobile systems as well.

5.6.2 Fuel Tank Permeation Testing

       We are applying similar fuel tank permeation test procedures to Small SI equipment and
Marine SI vessels as we currently use for recreational vehicles.  This testing includes
preconditioning, durability testing,  and permeation measurement.  The differences in the test
procedure compared to recreational vehicles are minor and are intended to simplify the testing.
For instance, the durability testing is performed during the preconditioning soak period prior to
the weight loss  testing rather than testing the tank twice; once before durability testing, and once
after.  Figure 5.6-2 provides flow charts for this testing (2) compared to the recreational vehicle
test (1) which includes the calculation of a deterioration factor.
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Final Regulatory Impact Analysis
        Figure 5.6-2:  Flow Chart of Fuel Tank Permeation Test with and without a
                          Deterioration Factor (DF) Determination
         1: Full Test Procedure
        with DF* Determination
            2: Short Test without
              DF Determination
                   baseline
                permeation test run
                   ElOfuel
                   28 + 2 C
               Durability Testing


                Pressure Cvclina
            !  10,000 x-0.5 to 2.0 psi
                  UV Exposure
                    24W/m2
                 Slosh Testina
                 1 million cycles
                   ElOfuel
Durability Testing

Pressure Cvclina
1 0,000 x -0.5 to 2.0





UV Exposure
24W/m

Slosh Testina
1 million cycles
ElOfuel
psi 





                    final
                permeation test run
                   ElOfuel
                   282C
                use final permeation
                  test result for
                  certification
                                                          use final permeation
                                                            test result for
                                                             certification
* The deterioration factor (DF) is the difference
between the baseline and final permeation test
runs in the full test procedure. In future tests, the
first 3 steps would be performed,  then a DF could
be applied to determine the final test result.

** The length of  "soak" during durability testing
may be included in the fuel soak period provided
that fuel remains in the tank.  Soak periods can be
shortened to 10 weeks if performed at 43 5 C
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                                              Feasibility of Evaporative Emission Control
       For the purpose of this testing, "fuel tank" includes the fuel cap and other components
directly mounted to the tank that become part of the barrier for the fuel and vapor. During
testing, fittings and openings in the fuel tank intended for hose connections (or petcock) is sealed
with an impermeable plug.  An opening containing a fuel petcock could also be plugged with an
impermeable fitting because this is an opening to the fuel hose which will be required to meet
permeation standards. In many installed marine fuel tanks, the fuel cap is not directly mounted
on the fuel tank.  Instead, the fuel cap is usually linked to the fuel tank by a fill neck hose.  In
this case, the fill neck opening in the fuel tank may be sealed with an impermeable plug during
permeation testing.

       5.6.2.1 Durability Testing

       Prior to the weight loss test, the fuel tank must be preconditioned to ensure that the
hydrocarbon permeation rate has stabilized. Under this step, the fuel tank must be filled with a
10 percent ethanol blend (E10), sealed, and soaked for 20 weeks at a temperature of 28  C  5
C. Once the permeation rate has stabilized, the fuel tank is drained and refilled with E10,
sealed, and tested for a baseline permeation rate. The permeation rate from the fuel tank is
determined by measuring the weight difference the fuel tank before and after soaking at a
temperature of 28 C  2 C over a period of at least 20 weeks.  The soak periods could be
shortened to 10 weeks if performed at 43 C  5 C. The durability testing described below may
be performed during the soak period. During the slosh testing, a lower tank fill level, consistent
with the slosh test, is acceptable.

       To determine a permeation emission deterioration factor, we established three durability
tests: slosh testing, pressure-vacuum cycling, and  ultra-violet (UV) light exposure.  The purpose
of these deterioration tests is to help ensure that the technology is durable and the measured
emissions are representative of in-use permeation rates. For slosh testing, the fuel tank is filled
to 40 percent capacity with E10 fuel and rocked for 1 million cycles.  The pressure-vacuum
testing contains 10,000 cycles from -0.5 to 2.0 psi.  The slosh testing is designed to assess
treatment durability as discussed above.  These tests are designed to assess  surface
microcracking concerns.  These two durability tests are based on a draft recommended SAE
practice.203 The third durability test is intended to  assess potential impacts of UV sunlight (0.2
|im - 0.4 |im) on the durability of the surface treatment. In this test, the tank must be exposed to
a UV light of at least 0.40 W-hr/m2 /min on the tank surface for 15 hours  per day for 30 days.
Alternatively, it can be exposed to direct natural sunlight for an equivalent period  of time in
exposure hours.

       The order of the durability tests is optional. However, we require that the fuel tank be
soaked to ensure that the permeation rate is stabilized just prior to the weight loss test. If the
slosh test is run last, the length of the slosh test may be considered as part of this soak period.
Where possible, the deterioration tests may  be run concurrently.  For example, the fuel tank
could be exposed to UV light during the slosh test.  In addition, if a durability test can clearly be
shown to not be appropriate for a given product, manufacturers may petition to have this test
waived.  Only fuel tanks using surface barrier treatments or barriers consisting of post-
processing coatings are subject to the slosh  and pressure-vacuum tests. In addition, a fuel tank

                                           5-95

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Final Regulatory Impact Analysis
that is only used in vehicles where an outer shell prevents the tank from being exposed to
sunlight may not be subject UV testing.

       After the durability testing, once the permeation rate has stabilized, the fuel tank is
drained and refilled with fresh fuel, sealed, and tested for a final permeation rate. The final
permeation rate from the fuel tank is determined using the same measurement method as for the
baseline permeation rate.  The final permeation rate is used for the emission rate from this fuel
tank. The difference  between the baseline and final permeation rates could be used to determine
a deterioration factor for use on subsequent testing of similar fuel tanks.

       5.6.2.2 Test Fuel

       As discussed in Chapter 3, about much of the fuel sold in the U.S. contains ethanol and
this percentage is expected to increase dramatically in 2012 and later.  The fuel tank permeation
test fuel is E10, which is a blend of 90 percent certification gasoline (as specified in 40 CFR
1065.210) blended with 10 percent ethanol for permeation testing of fuel tanks.  As an
alternative, we would allow testing  on ASTM Fuel C blended with 10 percent ethanol (Fuel
CE10). Fuel CE10 is commonly used in industry standards and test procedures such as in SAE
recommended practices.

              5.6.2.2.1 Effect of ethanol on fuel tank permeation

       Most plastic nonroad fuel tanks today are made out of high-density polyethylene (HDPE)
or cross-link polyethylene (XLPE).  For Small SI and Marine SI markets, plastic is much more
widely used than metal for fuel tank constructions. For HDPE, E10 fuel has little effect on
permeation emissions and may even result in slightly lower emissions according to one study.204
We tested three 0.5 gallon Small SI fuel  tanks for permeation using both certification gasoline
and E10 and found a  slight increase in permeation due to ethanol. ARB also tested several Small
SI fuel tanks on both  gasoline and ethanol  blends 205'206>207>208 ancj saw a small increase in
permeation. Permeation data was collected on two XLPE marine fuel tanks on E10.  The
measured permeation rates were within the range of data from other XLPE marine fuel tanks
tested on gasoline presented earlier in Table 5.3-1. This data is presented in Table 5.6-1.
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                                              Feasibility of Evaporative Emission Control
           Table 5.6-1: Effect of Ethanol on Permeation for HDPE Fuel Tanks
Material
HDPE
HDPE


HDPE





XLPE

Test Equipment
material sample
Small SI fuel
tanks
(EPA Testing)
Small SI fuel
tanks
(ARE Testing)



marine tanks
(EPA testing)
Tank
gallons
NA
0.5
0.5
0.5
0.25
0.25
0.25
0.25
0.25
0.5
3.9
12
12
Test
Temp(s)
40C
29C


18-41T





29C

gasoline
[g/m2/day]
90a
11.5
11.4
11.2
11.6
10.7
12.5
9.9
9.2
12.7
4.8
__b

E10
[g/m2/day]
69a
13.9
13.7
14.4
13.6
11.6
11.4
10.3
10.3
14.8
5.0
7.5
8.5
Increase in
Permeation
-23%
21%
21%
28%
18%
7%
-9%
4%
12%
17%
4%
minimal

3 ASTM Fuel C was used as gasoline (50% toluene, 50% isooctane). Units are per mm of thickness
b See Table 5.3-1 for data on similar tanks tested on gasoline.
       Although E10 does not have a large effect on permeation through polyethylene, it does
have a large effect on most other materials used in fuel systems, especially those designed for
low permeation.  This is supported by the data presented in Appendix 5D of permeation rates for
several fuel system materials on fuel C, CE10, and CIS. In addition, ethanol is commonly
blended into fuels in-use and alcohol fuels may be used more in the future in an effort to use
alternative energy sources. Therefore, we are requiring El0 as a test fuel to ensure that the
permeation standard will be met on in-use fuels.

       One study found that permeation from automotive fuel systems increased significantly
when gasoline containing ethanol was used compared to gasoline without ethanol.209  In this
case the ethanol fuel was specifically blended to achieve two weight percent  oxygen.  This test
fuel represents California reformulated fuel and contains 5.7 percent by volume ethanol.  Table
5.6-2  presents the test results at 29C. The average increase in permeation due to using E5.7 was
60 percent. Presumably, this effect would have been higher on E10. Because most of the fuel
tanks  are metal, the effect is largely due to fuel hose/tubing permeation.
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Final Regulatory Impact Analysis
       Table 5.6-2: Effect of Ethanol on Permeation from Automotive Fuel Systems
Fuel System
2001 Toyota Tacoma
2000 Honda Odyssey
1999 Toyota Corolla
1997 Chrysler Town & Country
1995 Ford Ranger
1993 Chevrolet Caprice Classic
1991 Honda Accord LX
1989 Ford Taurus GL
1985 Nissan Sentra
1978 Olds Cutlass Supreme
Fuel Tank
Metal
Plastic (enhanced evap)
Metal
Plastic (enhanced evap)
HOPE
Fluorinated HOPE
Metal
Metal
Metal
Metal
Gasoline
10
19
11
40
348
94
39
28
73
73
E5.7
32
53
57
66
342
137
100
73
177
139
Increase
220%
179%
418%
65%
-2%
46%
156%
161%
142%
90%
       One significant finding with the above study was that switching from one fuel to another
affects the permeation rate within a few weeks.  Although operating on gasoline with ethanol
changes the fuel tank material in such a way that permeation increases, this effect is reversible
when gasoline is used in the fuel tank for a long enough period of time. This study found that
the permeation rate at 40C typically approached a stabilized level within 1 to 2 weeks of
switching from one fuel to another.

       To investigate the potential effects of fuel switching, we tested two pairs of 6.6 gallon
portable marine fuel tanks. These fuel tanks used the barrier platelet technology discussed
above. The first pair used nylon as a barrier material which is highly sensitive to ethanol while
the second pair used EVOH which is much less sensitive to ethanol. All four tanks were soaked
on E10 fuel, then the fuel was drained and replaced for testing. For each pair, one tank was
tested on EPA certification gasoline and the other was tested on E10 fuel (10 percent ethanol, 90
percent gasoline). We continued the test for more than six weeks to observe the effects of fuel
switching on the permeation rates. The results suggest that switching to gasoline significantly
reduces the permeation rate for the nylon barrier tanks, but has no significant effect on the fuel
tanks using EVOH as a barrier. Note that the nylon tanks had permeation rates near the
standards when soaked and tested on gasoline, but have much higher permeation rates when
tested on E10. This data is presented in Figure 5.6-1.  The R-squared values for linear fits to the
data are also presented. The fuel tank with a nylon barrier that experienced fuel switching had a
lower R-squared value than the other fuel tanks.
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                                             Feasibility of Evaporative Emission Control
  Figure 5.6-1: Effect of Fuel Switching on Permeation from Barrier Platelet Fuel Tanks
                    Nylon, Gasoline
                    Nylon, E10
                    EVOH, Gasoline
                    EVOH, E10
       Fuel tank permeation data on both gasoline and E10 fuel are presented earlier in this
chapter for nylon handheld tanks, fluorinated and sulfonated Small SI tanks, portable tanks with
non-continuous nylon barrier platelets, and rotationally molded tanks with a nylon inner barrier.
This data is repeated here in Table 5.6-3 to better focus on the effect of ethanol on fuel tank
permeation. As shown by this data and the previous discussion, ethanol in the test fuel tends to
increase permeation.  However, the effect of ethanol on permeation appears to be highly variable
depending on the materials or surface treatments used in constructing the fuel tank.
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Final Regulatory Impact Analysis
        Table 5.6-3: Permeation Rates on Gasoline and E10 for Barrier Fuel Tanks
Permeation Control
nylon 6
nylon 6, 33% glass
nylon 6, 30% glass
nylon 6, 30% glass
fluorination
sulfonation
non-continuous nylon platelets
Rotomolded with PA1 1 liner*
Capacity
[gallons]
0.24
0.05
0.06
0.06
0.5
0.5
2.0
1mm barrier
thickness
Gasoline
[g/m2/day]
0.34
0.62
1.45
1.30
0.56
0.62
0.22
2.5
2.7
2.2
3.7
0.17
0.24
0.12
E10
[g/m2/day]
0.42
0.48
1.01
1.12
0.93
2.2
2.5
1.4
2.1
0.43
0.62
0.62
3.9
4.2
2.9
6.8
0.91
0.72
0.78
0.81
% Increase
32%
65%
60%
37%
19%
49%
84%
350%
  based on testing for California (California Phase II gasoline and fuel CE10)
              5.6.2.2.2 Effect ofCElO versus E10 on fuel tank permeation

       As discussed above, we will allow the use of fuel CE10 as an alternative to E10 for fuel
tank permeation testing.  The primary fuel, E10 is representative of in-use fuel and is consistent
with the certification fuel used for recreational vehicles.  However, fuel CE10 is widely used by
industry for materials testing.  Data presented earlier in this chapter suggests that permeation is
generally significantly higher on fuel CE10 for fuel hoses. We were therefore interested in the
effect of fuel CE10 versus E10 on fuel tank permeation.  We tested several fuel tanks and found
that permeation was only slightly higher on CE10 than E10 for most of the fuel tanks tested.

       To study the effects of CE10 versus E10 on permeation, we used fuel tanks that had been
previously tested on fuel E10. All of these tanks were drained and refueled with fresh test fuel.
Most of the tanks were filled with fuel CE10; however, with some exceptions, one of each tank
type was filled with fresh E10 for comparison. These fuel tanks were then preconditioned by
soaking them for 12 weeks with the new test fuel. Note that all of the test tanks had been
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                                             Feasibility of Evaporative Emission Control
soaking with E10 fuel for more than a year (and in some cases multiple years) prior to beginning
this preconditioning soak. Following the soak period, each tank was drained, refilled with fresh
fuel, and sealed. Permeation was measured over two weeks at 29C. The fuel tanks were
weighed on each weekday during this period.

       Table 5.6-4 presents the results of this testing. In most cases, emissions were only
slightly higher on CE10 than E10.  The exceptions were the nylon 6 and the acetal copolymer
fuel tanks which showed much higher permeation on CE10. However, the permeation rates for
these fuel tanks were still below the standard when tested on fuel  CE10. The fuel tank with a
continuous EVOH barrier was well below the standard on fuel CE10. No comparison was made
to E10 results for this technology.

       Table 5.6-4: Permeation Rates on Gasoline and E10 for Barrier Fuel Tanks
Permeation Control
nylon 6
HOPE
fluorination
sulfonation
non-continuous platelets (4% nylon)
non-continuous platelets (2% EVOH)
non-continuous platelets (4% EVOH)
non-continuous platelets (6% EVOH)
continuous EVOH barrier
acetal copolymer
Capacity
[gallons]
0.24
0.5
0.5
0.5
6.6
6.6
6.6
6.6
5.6
0.8
E10
[g/m2/day]
0.69
12.5
0.41
3.1
4.5
3.0*
2.2
1.3
~
0.25
CE10
[g/m2/day]
1.4
1.2
13.3
13.5
0.49
0.52
4.2
2.9
5.3
3.3
2.3
1.4
0.05
0.01
0.55
0.65
% Increase
90%
7%
21%
16%
16%
10%
6%
6%
NA
140%
 based on previous testing (presented earlier in this chapter)
       5.6.2.3 Reference Tank

       In cases where the permeation of a fuel tank is low, and the sample tank is properly
sealed, the effect of air buoyancy can have a significant effect the measured weight loss.  Air
buoyancy refers to the effect on air density on the perceived weight of an object.  As air density
                                         5-101

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Final Regulatory Impact Analysis
increases, it will provide an upward thrust on the fuel tank and create the appearance of a lighter
tank.  Air density can be determined by measuring relative humidity, air temperature, and air
pressure.210

       One testing laboratory presented data to EPA on their experience with variability in
weight loss measurements when performing permeation testing on portable fuel tanks.211 They
found that the variation was due to air buoyancy effects.  By applying correction factors for air
buoyancy, they were able to greatly remove the variation in the test data. A technical brief on
the calculations they used is available in the docket.212

       A more direct approach to accounting for the effects of air buoyancy is to use a reference
fuel tank. In this approach, an identical fuel tank to that being tested for permeation is tested
without fuel in it and used as a reference fuel tank. Dry sand can be added to this tank to make
up the difference in mass associated with the test tank being full of fuel. The reference tank is
then sealed so that the buoyancy effect on the reference tank is the same as the test tank. The
measured weight loss of the test tank can then be corrected by any measured changes in weight
in the reference tank. The California Air Resources Board uses this approach for measuring
portable fuel tank emissions, and they refer to the reference tank as a "trip blank."213

       5.6.2.4 Engineering Design-Based Certification

       A metal fuel tank automatically meets the design criteria for a design-based certification
as a low-permeation fuel tank, subject to the restrictions on fuel caps and seals described below.
There is also a body of existing test data showing that co-extruded fuel tanks from automotive
applications have permeation rates that are well below the new standard.  We are allowing
design-based certification for co-extruded high-density polyethylene fuel tanks with a continuous
ethylene vinyl alcohol (EVOH) barrier layer. The EVOH barrier layer is required to be at least 2
percent of the wall thickness of the fuel tank. In addition, the ethylene content of the EVOH can
be no higher than 40 mole percent.

       To address the permeability of the gaskets, and seals used on metal and co-extruded
tanks, the design criteria include a specification that  seals (e.g. gaskets and o-rings) not made of
low-permeation materials must have a total exposed  surface area less than 0.25 percent of the
total inside surface area of the fuel tank. For example, consider a four gallon fuel tank with an
inside surface area of 0.40 square meters. The total exposed surface area of these seals on the
fuel tank, in this example, must be smaller than 1000 mm2 (= 0.25%/100 x 0.40m2 x 1,000,000
mm2/m2). This is consistent with the  proposed rule and the current requirements for recreational
vehicles, but allows for larger seals for larger tanks.  In addition, if a non-metal fuel cap is
directly mounted to the fuel tank, the surface area of the fuel cap (determined by the
cross-sectional  area of the fill opening) may not exceed 3.0 percent of the total inside surface
area of the fuel tank.

       A metal or co-extruded fuel tank with a fuel cap and seals that meet these design criteria
would be expected to reliably pass the standard.  However, we believe it is not appropriate to
assign an emission level to fuel tanks using a design-based certification option that will allow

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                                              Feasibility of Evaporative Emission Control
them to generate emission credits. Given the uncertainty of emission rates from the seals and
gaskets, we will not consider these tanks to be any more effective than other fuel tanks meeting
emission standards.

       In the case where the fuel cap is directly mounted on the fuel tank, we consider the cap
and associated seals to be part of the fuel tank. As discussed above, we allow the fuel cap to be
tested either mounted on the fuel tank,  or individually.  As an alternative to testing the fuel cap,
the manufacturer may opt to use a default permeation rate of 30 g/m2/day. To be eligible for this
default rate,  the seal on the fuel cap must be made of a low-permeation material,  such as a
fluoroelastomer. The surface area associated with this default value is the cross sectional area of
the opening that is sealed by the fuel cap. If this default value were used, the fuel fill would be
sealed with a non-permeable plug during the tank permeation test, and the default permeation
rate would be factored into the final result.
       For the purposes of this provision, we consider low-permeation materials to be those that
haves a permeation rate not more than 10 g-mm/m2/day at 23 C on CE10 fuel as tested under the
procedures specified in SAE J2659.214

5.6.3  Diurnal Emission Testing

       The test procedure for diurnal emissions is to place the fuel tank in a SHED7, vary the
temperature over a prescribed profile, and measure the hydrocarbons escaping from the fuel tank.
The final result is reported in grams per gallon where the grams are the mass of hydrocarbons
escaping from the fuel tank over 24 hours and the gallons are the nominal fuel tank capacity.
The test procedure is based on the automotive evaporative emission test described in 40 CFR
part 86, subpart B, with modifications specific to marine applications.

       5.6.3.1 Temperature Profile

       For installed marine fuel tanks, we believe that the fuel temperature profile observed in
the tank has a lower variation in temperature due to the inherent insulation provided by the boat
hull. Data discussed earlier in this chapter, and presented in Appendix 5A, suggest that the fuel
temperature in an installed marine tank sees a change in temperature less than that of ambient
air. Based on this data, the fuel temperature change in boats stored on trailers would be expected
to be about half of ambient.  For boats stored in the water, the fuel temperature change would be
expected to be about 20 percent of ambient. Based on discussions with industry, we use a boat
length as a surrogate for determining if a boat is a trailer boat. We consider a boat that is at or
below 8.5 feet in width and below 26 feet in length as a trailer boat and larger boats as being
primarily stored in the water.

       To account for the differences between ambient and fuel temperature, we established a
       7 Sealed Housing for Emission Determination

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Final Regulatory Impact Analysis
test temperature profile of 78-90F (25.6-32.2C) for marine fuel tanks installed in boats less
than 26 feet in length and at or below 8.5 feet in width. For larger boats, we established a test
temperature profile of 81.6-86.4F (27.6-30.2C). These test temperature profiles are based on
fuel rather than ambient temperature. Figure 5.6-3 presents the three temperature profiles over
24 hours. Numerical values are presented in Appendix 5E.

                       Figure 5.6-3:  Diurnal Temperature Profiles
                                                            portable (air temp)
                                                            installed <26ft (fuel temp)
                                                            installed >26ft (fuel temp)
                                   8           12           16

                                      Elapsed Time [hours]
20
24
       The automotive diurnal test procedure includes a three day temperature cycle. The
purpose of this test length is to ensure that the carbon canister can hold at least three days of
diurnal emissions without vapor breaking-through the canister. For vessels using carbon
canisters as an evaporative emission control strategy, we established a multiple day cycle here as
well so that the passive purging can be observed.  In the automotive test, the canister is loaded,
then purged during an engine test prior to the first day of testing. Because we are anticipating
canisters on marine applications to be passively purged we are using a different approach.  Prior
to the first day of testing, the canister is loaded to full working capacity, then run over the
diurnal test temperature cycle to allow one day of passive purging.  The test result is then based
on the highest recorded value in the following three days.

       For fuel systems using a sealed system (or sealed-system with pressure relief), we do not
believe that a three day test is necessary. Prior to the first day of testing, the fuel is stabilized at
the initial test temperature.  Following this stabilization, the SHED is purged and a single diurnal
temperature cycle run.  Because this technology does not depend on purging or storage capacity
of a canister, multiple days of testing should not be necessary. Therefore, we established a one-
day test for the following technologies:  sealed system without pressure relief, sealed system with
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                                              Feasibility of Evaporative Emission Control
a pressure relief valve, sealed bladder fuel tanks, sealed fuel tanks with a volume compensating
air bag.

       5.6.3.2 Test Fuel

       Consistent with the automotive test procedures, the test must take place using
certification gasoline with a vapor pressure of 9.0 RVP. We do not require ethanol to be blended
into the test fuel. Although ethanol has a significant effect on permeation, it would not be
expected to affect diurnal emissions except in that it may affect fuel vapor pressure.

       Diurnal emissions are not only a function of temperature and fuel volatility, but of the
size of the vapor space in the fuel tank as well.  Consistent with the automotive procedures, the
fill  level at the start of the test must be 40 percent of the nominal capacity of the fuel tank.
Nominal capacity of the fuel tank is defined as the volume of fuel, specified by the manufacturer,
to which the fuel tank can be filled when sitting in its intended position. The vapor space that
normally occurs in a fuel tank,  even when "full," is not considered in the nominal capacity of the
fuel tank.

       5.6.3.3 Tank Configuration

       Installed marine fuel  tanks are typically equipped with a vent line. As shown above, this
vent line can impact the  emissions determined over the test procedure because it largely restricts
diffusion losses. Therefore,  open vent marine fuel tanks that are designed with a connection for
a vent line must be equipped with a one meter fuel line to more accurately reflect real world
emissions.  This should only be necessary for baseline configurations.

       The majority of marine fuel tanks are made of plastic. Even plastic fuel tanks  designed to
meet our standards are expected to have some amount of permeation. However, over  the length
of the diurnal test, if it were performed on a new tank that had not been previously exposed to
fuel, the effect of permeation on the test results should be insignificant. For fuel tanks that have
reached their stabilized permeation rate (such as testing on in-use tanks), we believe that it is
appropriate to correct for permeation. In such a case, the permeation rate could be measured
from the fuel tank and subtracted from the final diurnal test result. The fuel tank permeation rate
has to be stabilized on the 9 RVP test fuel used for the diurnal test and measured either over the
diurnal temperature cycle or at a constant temperature (28  2C). This test measurement is
made just prior (within 24 hours) to the diurnal emission test to ensure that the permeation rate
does not change prior to the diurnal test. In addition, the test fuel needs to remain in the fuel
tank between the permeation and diurnal tests to ensure a stable permeation rate. The fuel tank
could be emptied to change test fuels and test set ups; however, this period will not be allowed to
exceed one hour.  As an alternative to stabilizing the permeation rate prior to testing, the
permeation could be measured immediately before and after the diurnal test, and the lower
permeation rate used to correct the diurnal test results.  In this case, the test fuel is  not removed
after the diurnal test, and the second permeation test begins within 8 hours of the end of the
diurnal test.
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Final Regulatory Impact Analysis
       5.6.3.4 Carbon Canister Engineering Design

       Design-based certification may be used as an option to performing the above test. For
vessels using a carbon canister to control diurnal emissions, it is important to ensure that the
canister design is sufficient to achieve the standards. The following discussion outlines the
requirements that are necessary to ensure adequate canister design. These design parameters and
their associated test procedures are largely based on our understanding of current industry
practices for marine grade carbon.215

       5.6.3.4.1 Carbon canister capacity

       In a passive purge system, the storage capacity of the carbon canister must be properly
matched to the fuel system. Ideally, the canister is large enough to take full advantage of the
passive purge caused by cooling  of the fuel tank.  By creating more open sites in the canister,
greater vapor collection is possible during the next heating event.  If a canister is undersized,
then the vessel would not likely meet the standards. On the other hand, after a certain point,
increasing the size of the canister offers little additional emission control. Once the system
reaches a stabilized purge/load condition, the emission reduction potential is based on the
portion of the canister that purges and loads rather than the full volume of the  canister.

       The storage capacity of a  carbon canister is based both on the volume of the canister and
the working capacity of the carbon.  Butane working capacity (BWC) is a measure of the vapor
storage capacity of the carbon and is expressed in units of mass of butane per unit of volume.
The BWC of the carbon must be  at least 9 g/dL based on the test procedures specified in ASTM
D5228-92.216  Under this test procedure, butane vapor is fed through a carbon sample at a
specified rate, until the mass of the carbon sample reaches equilibrium.  The butane is then
purged off with dry air. BWC  of the carbon sample is calculated from the difference in the
measured mass of the carbon sample before and after the purge.

       Using the ASTM test procedure, the BWC represents the full saturated capacity of the
canister and not the amount of vapor that the canister will hold before breakthrough occurs.
Under the EPA automotive test procedure in 40 CFR 86.134-96, the canister capacity is based on
the amount of butane loaded in the canister until 2 grams of breakthrough is measured.
However, the ASTM procedure gives a repeatable measure that is currently used by industry.
The design standard of 9 g/dL is based on this test procedure and therefore accounts for the
differences in the ASTM and existing EPA automotive procedure.

       Based on the data presented earlier in this  chapter, we are requiring that the volume of
the carbon canister must be a minimum of 0.04 liters of carbon per gallon of fuel tank capacity
for fuel tanks installed in trailerable boats (<26 feet in length and <8.5 feet in width).  For larger
boats, the fuel temperature may be less affected by diurnal temperature swings for two reasons.
First, these fuel tanks are in larger vessels which are more likely to be stored in the water and
therefore, subject to smaller temperature fluctuations. Second, these fuel tanks are generally
larger and have larger thermal inertia in the fuel which may lead to lower temperature
fluctuation.  Therefore, for fuel tanks installed on non-trailerable boats (>26 feet in length or

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                                              Feasibility of Evaporative Emission Control
>8.5 feet in width), the design minimum volume is 0.016 liters of carbon every gallon per gallon
of fuel tank capacity.

       5.6.3.4.2 Carbon humidity resistance

       In a marine environment, the carbon may be exposed to more humid air, on average, than
in land-based applications such as cars and trucks. Traditional carbons used in automotive
applications can adsorb water, thereby closing sites off to hydrocarbons. With active purge and
carbon heating during refueling vapor collection, the water vapor is easily purged off the carbon.
Under this rule, we are basing the design specification on a passive purge canister design and are
not requiring onboard refueling vapor recovery.  Therefore, we believe that the carbon should be
resistant to moisture in the air.  In the in-use program discussed above, marine grade carbon was
used that was developed specifically for high humidity applications.217

        Design-based certification requirements for humidity resistance are based on the
specifications of the humidity-resistant carbon used in the in-use demonstration program.  This
carbon meets a moisture adsorption capacity maximum of 0.5 grams of water per gram of carbon
at 90 percent relative humidity and a temperature of 255C.  This limit is based on a test
procedure where dried carbon is exposed to water vapor and the pressure in the sample chamber
is controlled to achieve the correct partial pressure of the water to achieve the desired relative
humidity. The adsorption of water in the carbon is calculated based on the reduction in pressure
in the sample chamber. More detail on this test procedure is available in the docket.218

       5.6.3.4.3 Carbon durability

       Another issue that has been raised with regard to canister use in marine applications is
the durability of the canister under the shocks that can be observed on a marine vessel.
Automotive applications see shocks and vibration as well and the carbon is protected by packing
it under pressure in the canister.  To address the concern of carbon durability,  however, we are
including a carbon strength requirement. This strength requirement is consistent with the
specifications for the carbon used in the in-use test program described above, which was
designed to have a higher hardness value and lower dust attrition rates than typical automotive
carbons.

       The industry procedure for carbon pellet strength is to determine the average pellet size
in a sample of carbon before and after a pan hardness test. Pellet size is determined by
separating the carbon by size using sieves. The pan hardness test involves shaking the carbon in
a pan with steel balls over a fixed period of time.  The pellet strength is determined by taking the
ratio of the average pellet size of the carbon before and after the pan and ball attrition test. Pellet
strength must be at least 85 percent. The test procedure is ASTM D3802-79219 with two
variations. First, as discussed above,  hardness is defined as the ratio  of mean particle diameter
before and after the attrition test.  Second, the attrition test uses twenty 1/2M steel balls and ten 3A"
steel balls rather than fifteen of each as specified in ASTM D3802-79.  These  variations on the
ASTM procedure reflect common industry practice for pelletized carbons in contrast to the
original test procedure which were intended for granular carbons.220

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Final Regulatory Impact Analysis
       5.6.3.4.4 Canister design

       The design of the canister itself is important in building an effective and durable carbon
canister system.  The canister should be made of a material that is compatible with the
application.  For instance, the material should be fuel resistant and durable. Where a flame test
is required by the Coast Guard, the material should be able to pass this test on its own or with a
protective cover.  In addition, the canister material must have good structural integrity at
temperatures that it would be exposed to in a boat. If the material changes in dimension at
temperature, that flexing may loosen the carbon packing, allowing the carbon to move and
eventually deteriorate.  The canister should be installed in the boat in such a way that undue
stress is not placed on the canister. It should also be properly constructed so that there are no
leaks in the canister.

       The canister must be packed in such a way that the carbon does not move inside the
canister in-use. If the carbon were able to move, it would eventually break down under
vibration. Over time the carbon could deteriorate into dust which could eventually escape from
the canister.  This is not an issue with a carbon canister that uses a properly designed and
installed volume compensator. The basic  design of a volume compensator is that compression is
held on the carbon bed with a spring.  A mesh or foam cover is used on the volume compensator
that will allow air to pass through, but will hold the  carbon pellets in place.

       The carbon should be packed into the canister in such a way that there is a consistent size
of carbon pellets throughout the canister.  If the carbon settles in the storage hopper, it would be
possible for some canisters to be filled largely with the smallest diameter carbon pellets  (or dust)
which would increase the pressure restriction of the canister.  Also, if the carbon is not packed
properly when placed into the canister, it could later settle leading to a volume reduction of the
carbon that is too large  for the volume compensator to address.

       The carbon canister design must allow for a  proper flow path of vapor and air through the
carbon bed.  In current carbon canister designs, an air gap is typically installed upstream of the
carbon bed.  Flow directors may be molded into this air gap.  The  purpose of the air gap is to
allow the vapor or purge air to disperse and flow through the entire carbon bed. Even with a
small air gap, the vapor will  disperse because it will attempt to follow the path of least resistance
through the canister.  Without the  air gap,  the flow could be predominately in the center of the
carbon (or wherever the intake hose connection is located). In addition, to prevent flow
restriction, the carbon granules must have a minimum mean diameter of 3.1 mm based on the
procedures in ASTM D2862.221

       The geometry of a carbon canister can affect the effectiveness of the control system. For
instance, a long, narrow canister will have higher efficiency than a short wide canister.  This is
because some breakthrough can occur if the pathway is too short for the flow of vapor. Based on
one study, the effectiveness of the carbon  canister increases notably until a length to diameter
ratio of about 3.5 is achieved.222 At higher ratios, less of an impact on efficiency was observed.
At too high of a length to diameter ratio, significant back pressure may occur in the system.
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                                              Feasibility of Evaporative Emission Control
       5.6.3.4.5 Integration with Fuel System

       It is important that a carbon canister system be appropriately integrated into the fuel
system. For instance, the canister must be positioned in the vent line, and potentially a liquid
separation valve added, to ensure that liquid fuel does not reach the canister during refueling.
We also expect the fuel system design to minimize spit-back out of the fill neck during refueling.
A design that caused fuel to stream out the fill neck during refueling, even with a fuel nozzle
shut-off mechanism, is not acceptable.

5.7  Impacts on Noise, Energy, and Safety

       The Clean Air Act requires EPA to consider potential impacts on noise, energy, and
safety when establishing the feasibility of new emission standards for marine vessels.

5.7.1  Noise

       In this case, we do not expect evaporative emission controls to have any impact on noise
from Small SI equipment or marine vessels because noise from the affected parts of the fuel
system is insignificant.

5.7.2  Energy

       We anticipate that the evaporative emission standards will have a positive impact on
energy. By capturing or preventing the loss of fuel through evaporation, we estimate that the
lifetime average fuel savings will be about 1.4 gallons for an average piece of Small SI
equipment and 28 gallons for an average boat. This translates to a fuel savings of about 45
million gallons for Small SI equipment and 26 million gallons for Marine SI vessels in 2030
when most of the affected equipment used in the U.S. is expected to have evaporative emission
control.

5.7.3  Safety

       As part of the development of this rule, EPA performed a technical study on the safety of
emission control technology for  Small SI equipment and Marine SI vessels.223 The conclusions
of this study are presented below.  Although the study focuses on equipment with engines less
than 37 kilowatts, the conclusions drawn for marine apply to boats with larger engines as well as
ABYC, USCG,  UL, and SAE requirements do not distinguish between engine sizes.

       EPA has reviewed the fuel hose and fuel tank characteristics for NHH and HH equipment
and evaluated control technology which could be used to reduce evaporative emissions from
these two subcategories. This technology is capable of achieving reductions in fuel tank and fuel
hose permeation without an adverse incremental impact on safety. For fuel hoses and fuel tanks,
the applicable consensus standards, manufacturer specific test procedures and EPA requirements
are sufficient  to ensure that there will be no increase in the types of fuel leaks that lead to fire
and burn risk  in use. Instead, these standards will reduce vapor emissions both during operation

                                          5-109

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Final Regulatory Impact Analysis
and in storage. That reduction, coupled with some expected equipment redesign, is expected to
lead to reductions in the risk of fire or burn without affecting component durability.

       We also conducted a design and process Failure Mode and Effects Analyses (FMEA)
comparing current Phase 2 and Phase 3 compliant engines and equipment to evaluate
incremental changes in risk probability as a way of evaluating the incremental risk of upgrading
Phase 2 engines to meet Phase 3 emission standards.224 This is an engineering analysis tool to
help engineers and other professional staff on the FMEA team to identify and manage risk. In a
FMEA, potential failure modes, causes of failure, and failure effects are identified and a
resulting risk probability is calculated from these results.  This risk probability is used by the
FMEA team to rank problems for potential  action to reduce or eliminate the causal factors.
Identifying these causal factors is important because they are the elements that a manufacturer
can consider reducing the adverse effects that might result from  a particular failure mode.
       Our FEMA evaluated permeation and running loss controls on nonhandheld engines.  We
found that these controls do not increase the probability of fire and burn risk from those expected
with current fuel systems, but could in fact lead to directionally improved systems from a safety
perspective. Finally, the running loss control program for nonhandheld equipment will lead to
changes that are expected to reduce risk of fire during in-use operation.  Moving fuel tanks away
from heat sources, improving cap designs to limit leakage on tip over, and requiring a tethered
cap will all help to eliminate conditions which lead to in-use problems related to fuel leaks and
spillage.  Therefore, we believe that the application of emission control technology to reduce
evaporative emissions from these fuel hoses and fuel tanks will not lead to an increase in
incremental risk of fires or burns and in some cases is likely to at least directionally reduce such
risks.

       EPA has reviewed the fuel hose and fuel tank characteristics for marine vessels and
evaluated control technology which could be used to reduce evaporative emissions from boats.
With regard to fuel hoses, fuel tanks, and diurnal controls, there are rigorous USCG, ABYC, UL,
and SAE standards which manufacturers will continue to  meet for fuel system components.  All
of these standards are designed to address the in-use performance of fuel systems, with the goal
of eliminating fuel leaks.  The low permeation fuel hoses  and tanks needed to meet the Phase 3
requirements need to pass these standards and every indication is that they will pass.

       Furthermore, the EPA permeation certification requirements related to emissions
durability will add an additional layer of assurance. Low permeation fuel hoses are used safely
today in many marine vessels.  Low permeation fuel tanks and diurnal emission controls have
been demonstrated in various applications for many years without an increase in safety risk.
Furthermore, a properly designed fuel system with fuel tank and fuel hose permeation  controls
and diurnal emission controls will reduce the fuel vapor in the boat, thereby reducing the
opportunities for fuel related fires. In addition,  using improved low permeation materials
coupled with designs meeting USCG and ABYC requirements should reduce the risk of fuel
leaks into the vessel. EPA believes that the application of emission control technologies on
marine engines and vessels for meeting the evaporative emissions standards will not lead to an

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                                              Feasibility of Evaporative Emission Control
increase in incremental risk of fires or burns, and in many cases may incrementally decrease
safely risks in certain situations.
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Final Regulatory Impact Analysis
APPENDIX 5A:  Diurnal Temperature Traces
         Figure 5A-1:  Temperature Trace for Personal Watercraft on Trailer
    O)
    0)
    o
    2
    0)
    Q.
    0)
        12:OOAM   12:OOAM   12:OOAM   12:OOAM    12:OOAM   12:OOAM   12:OOAM   12:OOAM
                Figure 5A-2:  Temperature Trace for Jet Boat on Trailer
      95.00
      90.00
      85.00
      80.00
    O)
    0)
      75.00
    I
    0)
    Q.


    0)
      70.00
65.00
60.00
      55.00
      50.00
      45.00
        12:OOAM  12:OOAM  12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM 12:OOAM  12:OOAM  12:OOAM
                                         5-112

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                                       Feasibility of Evaporative Emission Control
         Figure 5A-3: Temperature Trace for Runabout on Trailer
105.00
  12:00 AM
            12:OOPM   12:00 AM
                                 12:OOPM    12:00 AM
                                                     12:OOPM    12:00 AM
                                                                         12:00 PM
          Figure 5A-4: Temperature Trace for Jet Boat on Trailer
    ::OOAM    12:OOPM
                       12:00 AM   12:OOPM   12:00 AM   12:OOPM   12:00 AM   12:OOPM
                                   5-113

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Final Regulatory Impact Analysis
                 Figure 5A-5: Temperature Trace for Runabout in Water
 a
  2
  o>
  a.
  E
  a>
                                  Fuel Temp
                                  Ambient Temp
                                  Water Temp
    12:OOAM   12:OOAM   12:OOAM    12:OOAM   12:OOAM   12:OOAM    12:OOAM
12:00 AM
                 Figure 5A-6:  Temperature Trace of Deckboat in Water
                                       Fuel Temp
                                       Ambient Temp
                                       Water Temp
     12:OOAM   12:OOAM   12:OOAM  12:OOAM   12:OOAM  12:OOAM   12:OOAM  12:OOAM   12:OOAM
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                                       Feasibility of Evaporative Emission Control
APPENDIX 5B: Emission Results for Small SI Equipment Fuel Tanks
Showing Effect of Venting on Diffusion

5B.1 Diffusion Effects from Variable Temperature Diurnal Testing

      Figure 5B-1: Diurnal/Diffusion Test Results for BM Metal Fuel Tank (2 Labs)
190
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-^ 10 w ^ c
P o o o o c
O o O O O C
Temperature [deg C]
                                    5-115

-------
Final Regulatory Impact Analysis
           Figure 5B.1-2: Diurnal/Diffusion Test Results for BP Plastic Fuel Tank
8 0
7 0
6 0
5 0
(A
E
2 4 n
a
o
I 30
9 n
1 0
0 0 i

^^" ^^S^^ ^.
/ ^^-L
^^ ^
4f To m n o TQ ti ir

*  *  M o a i TI e a u
^/ - Stock Cap
//* -^4^ Hose Vent


^i-^-*-^^*^~^
0 3 6 9 12 15 18
Test Hours
4n n
*^*^ 35 0
30 0
o"
"""  	 ~^-\ 2.
9Q o 
e =
-ii~,\/m-it 150 J"
ap vent ' j-u jj
Vent 10.0 1"
a)
5 0

0 0
21 24
           Figure 5B.1-3: Diurnal/Diffusion Test Results for HP Plastic Fuel Tank
  re
  O)
  O
                                                                            48.0
                                                                            40.0
                                                                            32.0
                                                                            24.0
                                                                            16.0
                                                                             8.0
                        O

                         O)
                         0)
                                                                                  
                                                                                  Q.

                                                                                  E
                                                                             0.0
                                 9       12      15

                                     Test Hours
18
21
24
                                         5-116

-------
                                 Feasibility of Evaporative Emission Control
Figure 5B.1-4: Diurnal/Diffusion Test Results for TP Plastic Fuel Tank






E
2
S
0
X





1 . D
1 4
1 9

1 n
0 8

0 6

n 4
n 9
n n f
(



/^ ^V
y1^ ^^^
/
-^



A /^*^
si^
~*^*_
3 3 6 9 12 1
Test Hours


	 Temperature
^^ Stock Cap Vent
 ^  noss vsm
^^^^
^  ~_






18 21 2


35 0
30 0

oc n
i
20 0
L
15 0

10 0
5 0
On
4





O)
0)
2,
D
(0
Q)
Q.
0)
1-


                              5-117

-------
Final Regulatory Impact Analysis
5B.2 Isothermal Results for Small SI Equipment Fuel Tanks Showing Effect of Venting on
Diffusion
         Figure 5B.2-1: Isothermal Diffusion Test Results for BM Metal Fuel Tank
7 nn
6.00


't/j'
EA nn
ss
11 "} nn
o 3-
I
? nn
1 nn
n nn 
c

M'
jm
/_
" mT~

^ 	 Temp (cap)
_/ ^ Temp (hose)
f \ i
/ -m- Stock Cap Vent
^ ^- Hose Vent
M
* ^ Jr-^*^^*^^^
V ^^^r^^
^z^^^^
 -zzsL.
D 3 6 9 12 15 18 21 2
Test Hours
T^ n
OO.U
30 0


^O.U Q
O)
a)
20.0 ^.

15.0 ^
5
0)
m n Q.
> IU.U ^
03
cn I-
o.O
n n
4
          Figure 5B.2-2: Isothermal Diffusion Test Results for BP Plastic Fuel Tank
7 nn -,
6 00
5 on
"t/T
E4 nn
SS
1  ' "} nn
o d-uu
X
p nn
1 nn
0.00 i
(
J9
J*/
^
#^
#
*>
<*
*
<*
J*

*
	 Temp (mod cap)
Temp (cap)
	 Temp (hose)
-- Stock Cap Vent
-m- Stock Cap Vent
* Hose Vent
S
* i   -^==1 t=B=l=l=l=!
r   M^T^* - * ^
J 3 6 9 12 15 18 21 2
Test Hours
35.0
*n n
-1 -1 f0 ro c
en o en o en c
CD CD CD CD CD C
Temperature [deg C]
i 0.0
4
                                       5-118

-------
                                   Feasibility of Evaporative Emission Control
Figure 5B.2-3:  Isothermal Diffusion Test Results for HP Plastic Fuel Tank
n /}E> -,
0 30
n 9*^
"to1
En n
SS
1  ' n 15
o -1b
I
Om

n nn i




^^^
m^^^^^
^L9*^
^Z^^
*./
^^
^Temperature
-m- Stock Cap Vent
-*^- Hose Vent

0 3 6 9 12 15 18 21 2
Test Hours
35.0
30.0
, 25' 0
O)
0)
on n w
p en o y, c
CD CD o CD C
Temperature [c
Figure 5B.2-4: Isothermal Diffusion Test Results for TP Plastic Fuel Tank
0 35 oc n
0.30
n OEi
En pn
SS
- 015
o U-I!D
X
n m

Onn j


^ 	 ^^^^^^ ^^^^^^^^0
^^^^^^" ^^^^^^ ^^^^^^
MMMMMMMMMMMM^1*"111**^^^*^^^^^*
j^3
^^^
*^^
-^A^1
J*

Temp (cap)
	 Temp (hose)
^^ Stock Cap Vent
^- Hose Vent
.uu  	 1 	 1 	 1 	 1 	 1 	 1 	 1 	
0 3 6 9 12 15 18 21 2
Test Hours
OO.VJ
30.0
25.0 JJ
1 0)
a)
-^
p en o y, c
CD CD o CD C
Temperature [c
                               5-119

-------
Final Regulatory Impact Analysis
APPENDIX 5C: Diurnal Emission Results: Canister and Passive-Purge
Diurnal Emissions for a 30
50.00
45.00 H
40.00
.g 35.00
t/>
w 30.00
5
^ 25.00
' 20.00
0
Q.
J 15.00
UJ
10.00
5.00
0.00
C
Fuel Tank with 2.1 L Can
Gallon Marine
ister, 72-96F



Baseline Emission Level











i
) 5 10 15





 
	 *4 *
* Diurnal Emissions
QMonday Outliers

20 25
















30
Test Days
                                        5-120

-------
                                              Feasibility of Evaporative Emission Control
APPENDIX 5D: Material Properties of Common Fuel System Materials

       This appendix presents data on permeation rates for a wide range of materials that can be
used in fuel tanks and hoses. The data also includes effects of temperature and fuel type on
permeation. Because the data was collected from several sources, there is not complete data on
each of the materials tested in terms of temperature and test fuel.  Table D-l gives an overview
of the fuel systems materials included in the data set. Tables D-2 through D-3 present
permeation rates using Fuel C, a 10 percent ethanol blend (CE10), and a 15 percent methanol
blend (CE15) for the test temperatures of 23, 40, 50, and 60C.

      	Table 5D-1:  Fuel System Materials	
        Material Name
        ACN NBR
        Carilon
        Celcon
        CFM
        CO
        CR
        CSM
        E14659
        E14944
        ECO
        ETER
        ETFE
        EVOH
        FEE
        FEP
        FKM
        FPA
        FVMQ
        GFLT
        HOPE
        HOPE
        HNBR
        LDPE
        NBR
        Nylon 12
        PBT
        PFA
        Polyacetal
        PTFE
        PVDF
        THV
Composition
acrylonitrile
aliphatic poly-ketone thermoplastic
acetal copolymer
fluoroelastomer
epichlorohydrin homopolymer
polychloroprene polymer
chlorosulfonated polyethylene
fluoropolymer film
fluoropolymer film
epichlorohydrin-ethylene oxide copolymer
epichlorohydrin-ethylene oxide terpolymer
ethylenetetrafluoroethylene, fluoroplastic
ethylene vinyl alcohol, thermoplastic
fluorothermoplastic
fluorothermoplastic
fluorocarbon elastomer
copolymer of tetrafluoroethylene and perfluoroalkoxy monomer
fluorovinyl methal silicone rubber (flourosilicone)
fluoroelastomer
high-density polyethylene
high density polyethylene
hydrogenated acrylonitrile-butadiene rubber
low density polyethylene
acrylonitrile-butadiene rubber
thermoplastic
polybutylene terephthalate, thermoplastic
fluorothermoplastic
thermoplastic
polytetrafluoroethylene, fluoroplastic
polyvinylidene fluoride, fluorothermoplastic
tetrafluoroethylene, hexafluoropropylene, vinyledene fluoride
                                          5-121

-------
Final Regulatory Impact Analysis
 Table 5D-2: Fuel System Material Permeation Rates at 23C by Fuel Type
                                                                         225,226,227,228,229,230
Material Name
HOPE
Nylon 12, rigid
EVOH
Polyacetal
PBT
PVDF
NBR (33% ACN)
HNBR (44%ACN)
FVMQ
FKM Viton A200 (66%F)
FKM Viton B70 (66%F)
FKM Viton GLT (65 %F)
FKM Viton B200 (68%F)
FKM Viton GF (70%F)
FKM Viton GFLT (67%F)
FKM -2 120
FKM - 5830
Teflon FEP 1000L
Teflon PTFE
Teflon PFA 1000LP
Tefzel ETFE 1000LZ
Nylon 12 (GM grade)
Nitrile
Silicone Rubber
Fluorosilicone
FKM
FE 5620Q (65.9% fluorine)
FE 5840Q (70.2% fluorine)
PTFE
ETFE
PFA
THV500
FuelC
g-mm/m2/day
35
0.2
-
-
-
-
669
230
455
0.80
0.80
2.60
0.70
0.70
1.80
8
1.1
0.03
-
0.18
0.03
6.0
130
-
-
-
-
-
0.05
0.02
0.01
0.03
Fuel CE10
g-mm/m2/day
_
-
-
-
-
-
1028
553
584
7.5
6.7
14
4.1
1.1
6.5
-
-
0.03
-
0.03
0.05
24
635
-
-
16
7
4
-
-
-
-
CM15
g-mm/m2/day
35
64
10
3.1
0.4
0.2
1188
828
635
36
32
60
12
3.0
14
44
8
0.03
0.05
0.13
0.20
83
1150
6500
635
-
-
-
0.08*
0.04*
0.05*
0.3
       * tested on CM20.
                                          5-122

-------
                                      Feasibility of Evaporative Emission Control
Table 5D-3: Fuel System Material Permeation Rates at 40C by Fuel Type
                                                                    231,232
Material Name
Carilon
EVOH-F101
EVOH-XEP380
HOPE
LDPE
Nylon 12 (L2 10 IF)
Nylon 12 (L2140)
Celcon
Fortran PPSSKX-3 82
Celcon Acetal M90
Celanex PBT 3300 (30% GR)
Nylon 6
Dyneon El 465 9
Dyneon El 4944
ETFE Aflon COP
m-ETFE
ETFE Aflon LM730 AP
FKM-70 16286
GFLT 19797
Nitrile
FKM
FE 5620Q (65.9% fluorine)
FE 5840Q (70.2% fluorine)
THV-310X
THV-500
THV-610X
FuelC
g-mm/m2/day
0.06
<0.0001
<0.0001
90
420
2.0
1.8
0.38
-
-
-
-
0.25
0.14
0.24
0.27
0.41
11
13
-
-
-
-
-
0.31
-
Fuel CE10
g-mm/m2/day
1.5
0.013
-
69
350
28
44
2.7
0.12
0.35
3
26
-
-
0.67
-
0.79
35
38
1540
86
40
12
-
-
-
CM15
g-mm/m2/day
13
3.5
5.3
71
330
250
-
-
-
-
-
-
2.1
1.7
1.8
1.6
2.6
-
-
3500
120
180
45
5.0
3.0
2.1
 Table 5D-4: Fuel System Material Permeation Rates at 50C by Fuel Type
                                                                     233
Material Name
Carilon
HOPE
Nylon 12(L2140)
Celcon
ETFE Afcon COP
FKM-70 16286
GFLT 19797
FuelC
g-mm/m2/day
0.2
190
4.9
0.76
-
25
28
Fuel CE10
g-mm/m2/day
3.6
150
83
5.8
1.7
79
77
CM15
g-mm/m2/day
_
-
-
-
-
-
-
                                  5-123

-------
Final Regulatory Impact Analysis
   Table 5D-5: Fuel System Material Permeation Rates at 60C by Fuel Type 234-235-236-237
Material Name
Carilon
HOPE
Nylon 12 (L2140)
Celcon
ETFE Afcon COP
FKM-70 16286
GFLT 19797
polyeurethane (bladder)
THV-200
THV-310X
THV-510ESD
THV-500
THV-500 G
THV-610X
ETFE 6235 G
THV-800
FEP
FuelC
g-mm/m2/day
0.55
310
9.5
1.7
-
56
60
285
-
-
6.1
-
4.1
2.4
1.1
1.0
0.2
Fuel CE10
g-mm/m2/day
7.5
230
140
11
3.8
170
130
460
54
-
18
11
10
5.4
3.0
2.9
0.4
CM15
g-mm/m2/day
_

-
-
-
-
-
-
-
38
35
20
22
9.0
6.5
6.0
1.1
                                        5-124

-------
                                        Feasibility of Evaporative Emission Control
APPENDIX 5E: Diurnal Test Temperature Traces




           Table 5E-1: Temperature vs. Time Sequence for Diurnal Testing
Test
Time*
[minutes]
0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
900
960
1020
1080
1140
1200
1260
1320
1380
1440
Portable Fuel Tanks
SHED Air Temperature
Fahrenheit
72.0
72.5
75.5
80.3
85.2
89.4
93.1
95.1
95.8
96.0
95.5
94.1
91.7
88.6
85.5
82.8
80.9
79.0
77.2
75.8
74.7
73.9
73.3
72.6
72.0
Celsius
22.2
22.5
24.2
26.8
29.6
31.9
33.9
35.1
35.4
35.6
35.3
34.5
33.2
31.4
29.7
28.2
27.2
26.1
25.1
24.3
23.7
23.3
22.9
22.6
22.2
Installed Fuel Tanks
Trailerable Boat
Fuel Temperature
Fahrenheit
78.0
78.3
79.8
82.2
84.6
86.7
88.6
89.6
89.9
90.0
89.8
89.1
87.9
86.3
84.8
83.4
82.5
81.5
80.6
79.9
79.4
79.0
78.7
78.3
78.0
Celsius
25.6
25.7
26.5
27.9
29.2
30.4
31.4
32.0
32.2
32.2
32.1
31.7
31.0
30.2
29.3
28.6
28.0
27.5
27.0
26.6
26.3
26.1
25.9
25.7
25.6
Installed Fuel Tanks
Nontrailerable boat
Fuel Temperature
Fahrenheit
81.6
81.7
82.3
83.3
84.2
85.1
85.8
86.2
86.4
86.4
86.3
86.0
85.5
84.9
84.3
83.8
83.4
83.0
82.6
82.4
82.1
82.0
81.9
81.7
81.6
Celsius
27.6
27.6
27.9
28.5
29.0
29.5
29.9
30.1
30.2
30.2
30.2
30.0
29.7
29.4
29.1
28.8
28.5
28.3
28.1
28.0
27.9
27.8
27.7
27.6
27.6
* Repeat as necessary
                                    5-125

-------
Final Regulatory Impact Analysis
Chapter 5 References
1.  Reddy, S., "Prediction of Fuel Vapor Generation From a Vehicle Fuel Tank as a Function of Fuel RVP and
Temperature," SAE Paper 892089, 1989, Docket Identification EPA-HQ-OAR-2004-0008-0169.

2.  Gushing, T., "Fuel Tank Hydrocarbon Emission Testing," prepared by Sterling Performance for the U.S. EPA,
Report #040107, September 30, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0137.

3.  Gushing, T., "Fuel Tank Hydrocarbon Emission Testing," prepared by Sterling Performance for the U.S. EPA,
Report #040137, November 3, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0138.

4.  "Evaporative Emissions from Offroad Equipment," California Air Resources Board, June 22, 2001, Docket
Identification EPA-HQ-OAR-2004-0008-0051.

5.  "Docket No. A-2000-02; Notice or Proposed Rulemaking for the Control of Emissions from Spark-Ignition
Marine Vessels and Highway Motorcycles; 40 C.F.R. Parts 86, 90, 1045, 1051, and 1068," Comments from the
National Marine Manufacturers Association, Docket Identification EPA-HQ-OAR-2004-0008-0211.

6.  "Before the United States Environmental Protection Agency, Comments by Brunswick Corporation, Notice of
Proposed Rulemaking, Part 1045  Control of Emissions from Spark-Ignition Marine Vessels," Comments from
Brunswick Corporation, Docket Identification EPA-HQ-OAR-2004-0008-0192.

7. "Diurnal Emissions Testing of Walk-Behind  Mowers Configured with Fuel Tank Pressure Relief Valves
(September 2002)," California Air Resources Board, September 17, 2002, Docket Identification EPA-HQ-OAR-
2004-0008-0052.

8. "Aboveground Storage Tanks (AST); Enhanced Vapor Recovery Regulation," California Air Resources Board,
August 16, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0413.

9. Email from Pamela Gupta,  California Air Resources Board, to Mike Samulski, U.S. EPA, "Aboveground Storage
Tanks (ASTs) Field Study Presentation," September 6, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0420.

10. Samulski, M., "Characterization and Control of Evaporative Emissions from Fuel Tanks in Nonroad
Equipment," SAE Paper 2006-32-0094, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0424.

11. Beverley, K., Clint, I, Fletcher, P., "Evaporation Rates of Pure Liquids Measured Using a Gravimetric
Technique," Phys. Chem. Chem. Phys., 1999, 1, 149-153, Received July 9, 1998,  Accepted October 13, 1998,
Docket Identification EPA-HQ-OAR-2004-0008-0103.

12. Batterman, S., Yu, Y., Jia, C., Godwin, C., "Non-methane Hydrocarbon Emissions from Vehicle Fuel Caps,"
Atmospheric Environment 39 (2005), Received May 27, 2004, Accepted December 1, 2004, Docket Identification
EPA-HQ-OAR-2004-0008-0102.

13. Sterling Performance, "USEPA Fuel Tank Hydrocarbon Emission Testing," prepared for the U.S. EPA, Report
Number 040195, January 26, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0139.

14. "24 hr EPA Diurnal MicroSHED of Lawn Mower Gas Tanks," Testing Services Group, Reports L504835-1.1,
Prepared for U.S. EPA, April 20,  2005, Docket Identification EPA-HQ-OAR-2004-0008-0140.

15. "24 hr EPA Diurnal Micro SHED of Lawn Mower Gas Tanks," Testing Services Group, Reports L504835-1.2,
Prepared for U.S. EPA, April 20,  2005, Docket Identification EPA-HQ-OAR-2004-0008-0141.
                                               5-126

-------
                                                    Feasibility of Evaporative Emission Control
16.  "24 hr EPA Diurnal MicroSHED of Lawn Mower Gas Tanks," Testing Services Group, Reports L504835-1.3,
Prepared for U.S. EPA, April 20, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0142.

17.  "24 hr EPA Isothermal MicroSHED of Lawn Mower Gas Tanks," Testing Services Group, Reports L504835-
2.1, Prepared for U.S. EPA, April 20, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0143.

18.  "24 hr EPA Isothermal MicroSHED of Lawn Mower Gas Tanks," Testing Services Group, Reports L504835-
2.2, Prepared for U.S. EPA, April 20, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0144.

19.  "24 hr EPA Isothermal MicroSHED of Lawn Mower Gas Tanks," Testing Services Group, Reports L504835-
2.3, Prepared for U.S. EPA, April 20, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0145.

20.  Haskew, H., Cadman, W., "Evaporative Emissions Under Real Time Conditions," SAE Paper 891121, 1989,
Docket Identification EPA-HQ-OAR-2004-0008-0168.

21.  Haskew, H., Cadman, W., Liberty, T., "The Development of a Real-Time Evaporative Emissions Test," SAE
Paper 901110, 1990, Docket Identification EPA-HQ-OAR-2004-0008-0170.

22.  Tschantz, M., "Activated Carbon for Use in Marine Evaporative Control Applications," Presented by
MeadWestvaco Corporation at the 2004 International Boatbuilders Exposition, October 25, 2004, Docket
IdentificationEPA-HQ-OAR-2004-0008-0040.

23.  Internal MeadWestvaco memorandum from M. Tschantz to C. Pierson, "Preliminary 3 mm SeaGuard
Specifications," August 31, 2005, Docket IdentificationEPA-HQ-OAR-2004-0008-0136.

24.  "A Picture Book Concerning the NMMA 2005 Summer Test Program: Carbon Canisters for Marine Diurnal
Control," Harold Haskew & Associates, Inc., July 12, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0127.

25.  Dr. Michael Tschantz, "Summer Test Program Carbon Analysis," presented by Meadwestvaco Corporation at
the 2005 International Boatbuilders Exhibition and Conference, October 20, 2005, Docket Identification EPA-HQ-
OAR-2004-0008-0290.

26.  Andreatta, D., Heydinger, G., Bixel, R., Park, I, Jorgensen, S., "Evaluation of the Ignition Hazard Posed by
Onboard Refueling Vapor Recovery Canisters," SAE Paper 2001-01-0731, 2001, Docket Identification EPA-HQ-
OAR-2004-0008-0494.

27. Giacomazzi, R., "The Evolution of Automotive Fuel Tanks," Presented at the International Boat Builders'
Exposition and Conference, October 11, 2007.

28. Engineered Composite Solutions, "Products; Carbon Canisters," retrieved from
www.engineeredcompositesolutions.com/Products.htm on April 24, 2008.

29. "Diurnal Testing of Off-Road Equipment Retrofitted with Carbon Canister Evaporative Emission Control
Systems (March 2003)," California Air Resources Board, March 25, 2003, Docket Identification EPA-HQ-OAR-
2004-0008-0053.

30.  Haskew, H., Cadman, W., Liberty, T., "The Development of a Real-Time Evaporative Emissions Test," SAE
Paper 901110, 1990, Docket Identification EPA-HQ-OAR-2004-0008-0170.

31.  Email from Reid Clontz, MeadWestvaco, to Mike Samulski, U.S. EPA, "Temperature and Ethanol Questions,"
July 7, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0423.

32.  American Boat and Yacht Council, "H-24 Gasoline Fuel Systems," 2005, Docket Identification EPA-HQ-OAR-
2004-0008-0429.

                                               5-127

-------
Final Regulatory Impact Analysis
33. Sutherland, S., Hayes, I, "Analysis of the 2007 California Survey of Outboard and Sailboat Owners Regarding
Use of Portable Outboard Marine Fuel Tanks," Prepared for the California Air Resources Board by the Institute for
Social Research at California State University, Sacramento, March 2007.

34. "Diurnal Emissions Testing of Walk-Behind Mowers Configured with Fuel Tank Pressure Relief Valves
(September 2002)," California Air Resources Board, September 17, 2002, Docket Identification EPA-HQ-OAR-
2004-0008-0052.

35. Letter from Bill Scott, Country Industries Technologies, to Mike Samulski U.S. EPA, regarding a gas tank vent
design, July 20, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0287.

36. Compact Membrane Systems, Inc., www.compactmembrane.com, Docket Identification EPA-HQ-O AR-2004-
0008-0100.

37. Koch, W., "Developing Technology for Enhanced Vapor Recovery: Part 1  - Vent Processors," Petroleum
Equipment & Technology, February/March 2001, Docket Identification EPA-HQ-OAR-2004-0008-0099.

38. Membrane Technology & Research, Inc., www.mtrinc.com, Docket Identification EPA-HQ-OAR-2004-0008-
0101.

39. "New Evaporative Control System for Gasoline Tanks," Memorandum from Chuck Moulis, EPA to Glenn
Passavant, Nonroad Center Director, EPA, March 1, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0261.

40. Letter from Kevin Madison, Top Dog Systems, to Mike Samulski, U.S. EPA, regarding the Top Dog vaporless
fuel system, April 23, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0258.

41. Facsimile from Bob Hazekamp,  Top Dog Systems to Mike Samulski, U.S.  EPA, "Permeation of Polyurethane
versus THV Materials @ 60C," January  14, 2002, Docket A-2000-01, Docket Identification EPA-HQ-O AR-2004-
0008-0435.

42. Emails from Steve Vaitses, Seacurefill to Mike Samulski, U.S. EPA, "VCS diagrams 1-4 attachments," and
"VCS attachments 5-7," April 27, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0395.

43. Testing Services Group, "Marine Fuel Tank Vapor Trap Diurnal Emissions Testing; 48 hr EPA (custom)
Diurnal," TSG Report No. L605816-1.2, July 14, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0445.

44. Fox, J., "Fuel Temperature Measurements on Small Equipment," Fox Automotive, August 2004, Docket
Identification EPA-HQ-OAR-2004-0008-0181.

45. Gushing, T., "Fuel Tank Hydrocarbon Emission Testing," prepared by Sterling Performance for the U.S. EPA,
Report #040107, September 30, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0137.

46. Gushing, T., "Fuel Tank Hydrocarbon Emission Testing," prepared by Sterling Performance for the U.S. EPA,
Report #040137, November 3, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0138.

47. Wong, W., "Addition of Evaporative Emissions for Small Off-Road Engines," California Air Resources Board
OFFROAD Model Change Technical Memo, Revised April 21, 2003, Docket OAR-2004-0008, Document OAR-
2004-0008-0006.

48. Tuckner, P., Baker, J., "Fuel Permeation Testing using Gravimetric Methods," SAE Paper 2000-01-1096, 2000,
Docket Identification EPA-HQ-O AR-2004-0008-0160.

49. Allen, S.J., "Fuel Tank Permeability Test Procedure Development; Final Report," U.S. Coast Guard, December
1986, Docket Identification EPA-HQ-OAR-2004-0008-0231.

                                               5-128

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                                                    Feasibility of Evaporative Emission Control
50. Nulman, M, Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.

51.  "Permeation Rates of Small Off Road Engine High-Density Polyethylene Fuel Tanks (April 2001 Testing), June
8, 2001, California Air Resources Board, Docket Identification EPA-HQ-OAR-2004-0008-0146.

52.  "Permeation Rates of Small Off Road Engine High-Density Polyethylene Fuel Tanks (February 2001 Testing),
June 8, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0147.

53.  "Permeation Rates of High-Density Polyethylene Fuel Tanks  (June 2001), June 12, 2001, California Air
Resources Board, Docket Identification EPA-HQ-OAR-2004-0008-0148

54.  "Permeation Rates of High-Density Polyethylene Fuel Tanks  (May 2001), June 11, 2001, California Air
Resources Board, Docket Identification EPA-HQ-OAR-2004-0008-0149.

55. "Average Permeation Rates of High-Density Polyethylene Off-Road Equipment Fuel Tanks Using a Surface
Area Approach,  (March 2002)," March 15, 2002, California Air Resources Board, Docket Identification EPA-HQ-
OAR-2004-0008-0256.

56.  "Test Method 513; Determination of Permeation for Spill-Proof Systems," California Air Resources Board,
Adopted July 6, 2000, Docket Identification EPA-HQ-OAR-2004-0008-0150.

57.  "OPEIHHPC Comments on EPA Proposed Phase 3 Rule for  HH Fuel Tank Permeation," Outdoor Power
Equipment Institute," Presentation to EPA, February 5, 2008.

58.  www.arb.ca.gov/msprog/spillcon/reg.htm, Updated March 26, 2001, Copy of linked data reports  available in
Docket, Docket Identification EPA-HQ-OAR-2004-0008-0186.

59.  Email from Jim Watson, California Air Resources Board, to Phil Carlson, U.S. EPA, "Early Container Data,"
August 29, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0200.

60.  "Test Method 513; Determination of Permeation for Spill-Proof Systems," California Air Resources Board,
Adopted July 6, 2000, Docket Identification EPA-HQ-OAR-2004-0008-0150.

61.  Lockhart, M., Nulman, M., Rossi,  G., "Estimating Real Time  Diurnal Permeation from Constant Temperature
Measurements,"  SAE Paper 2001-01-0730, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0161.

62.  Hopf, G., Ries, H., Gray, E., "Development of Multilayer Thermoplastic Fuel Lines with Improved Barrier
Properties," SAE Paper 940165, 1994,  Docket Identification EPA-HQ-OAR-2004-0008-0174.

63.  Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.

64. Haskew, H.,  McClement, D., "Fuel Permeation from Automotive Systems; Final Report," prepared for the
California Air Resources Board and the Coordinating Research Council, CRC Project No. E-65, September 2004,
Docket Identification EPA-HQ-OAR-2004-0008-0151.

65.  Tuckner, P., Baker, J., "Fuel Permeation Testing using Gravimetric Methods," SAE Paper 2000-01-1096, 2000,
Docket Identification EPA-HQ-OAR-2004-0008-0160.

66.  Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.
                                                5-129

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Final Regulatory Impact Analysis
67. Stevens, M, Demorest, R., "Fuel Permeation Analysis Method Correction," SAE Paper 1999-01-0376, 1999,
Docket Identification EPA-HQ-OAR-2004-0008-0157.

68. Lockhart, M., Nulman, M., Rossi, G., "Estimating Real Time Diurnal Permeation from Constant Temperature
Measurements," SAE Paper 2001-01-0730, Docket Identification EPA-HQ-OAR-2004-0008-0161.

69. Testimony of and Presentation, H. Haskew, President, Harold Haskew & Associates, MI, October 7, 2002,
Docket Identification EPA-HQ-OAR-2004-0008-0202.

70. Haskew, H., McClement, D., "Fuel Permeation from Automotive Systems; Final Report," prepared for the
California Air Resources Board and the Coordinating Research Council, CRC Project No. E-65, September 2004,
Docket Identification EPA-HQ-OAR-2004-0008-0151.

71. Email from Jim Watson, California Air Resources Board, to Mike Samulski, U.S. EPA, "Vapor Loss for
Variable Volume Containers.xls," October 26, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0291.

72. Email from Harold Haskew,  Harold Haskew & Associates, to Mike Samulski, U.S. EPA, "High-low permeation
data," April 9, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0238.

73. Kathios, D., Ziff, R., Petrulis, A., Bonczyk, J., "Permeation of Gasoline and Gasoline-alcohol Fuel Blends
Through High-Density Polyethylene Fuel Tanks with Different Barrier Technologies," SAE Paper 920164, 1992,
Docket Identification EPA-HQ-OAR-2004-0008-0172.

74. www.arb.ca.gov/msprog/spillcon/reg.htm, Updated March 26, 2001, Copy of linked data reports available in the
Docket, Docket Identification EPA-HQ-OAR-2004-0008-0186.

75. Email from Jim Watson, California Air Resources Board, to Phil Carlson, U.S. EPA, "Early Container Data,"
August 29, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0200.

76. "Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine Fuel Tanks,"
California Air Resources Board,  June 21, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0152.

77. "Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine Fuel Tanks,"
California Air Resources Board,  March 7, 2003, Docket Identification EPA-HQ-OAR-2004-0008-0153.

78. Conversation between Mike  Samulski, U.S. EPA and Tom Schmoyer, Sulfo Technologies, June 17, 2002.

79. "Sulfo Data", E-mail from Tom Schmoyer, Sulfotechnologies to Mike Samulski, U.S. EPA, March 17, 2003,
Docket Identification EPA-HQ-OAR-2004-0008-0223.

80. "ADDENDUM TO: Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine
Fuel Tanks," California Air Resources Board, March 27, 2003, Docket Identification EPA-HQ-OAR-2004-0008-
0154.

81. "Resin and Additives - SOS  Compatible," Email from Tom Schmoyer, Sulfo Technologies to Mike Samulski
and Glenn Passavant, U.S. EPA,  June 19, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0215.

82. Email from Jim Watson, California Air Resources Board, to Mike Samulski, U.S. EPA, "Attachment to Resin
List,"  August 30, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0234.

83. Walles, B., Nulford, L., "Five Year Durability Tests of Plastic Gas Tanks and Bottles with Sulfonation Barrier,"
Coalition Technologies, LTD,  for Society of Plastics Industry, January 15, 1992, Docket Identification EPA-HQ-
OAR-2004-0008-0233.
                                                5-130

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                                                    Feasibility of Evaporative Emission Control
84. Kathios, D., Ziff, R., "Permeation of Gasoline and Gasoline-Alcohol Fuel Blends Through High-Density
Polyethylene Fuel Tanks with Different Barrier Technologies," SAE Paper 920164, 1992, Docket Identification
EPA-HQ-OAR-2004-0008-0172.

85. www.arb.ca.gov/msprog/spillcon/reg.htm, Updated March 26, 2001, Copy of linked data reports available in
Docket, Docket Identification EPA-HQ-OAR-2004-0008-0186.

86. "Permeation Rates of Blitz Fluorinated High Density Polyethylene Portable Fuel Containers," California Air
Resources Board, April 5, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0155.

87. Email from Jim Watson, California Air Resources Board, to Phil Carlson, U.S. EPA, "Early Container Data,"
August 29, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0200.

88. www.pensteel.co.uk/light/smp/fluorination.htm. A copy of this site, as downloaded on August 13, 2004, is
available in Docket, Docket Identification EPA-HQ-OAR-2004-0008-0214.

89. "Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine Fuel Tanks,"
California Air Resources Board, June 21, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0152.

90. "Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine Fuel Tanks,"
California Air Resources Board, March 7, 2003, Docket Identification EPA-HQ-OAR-2004-0008-0153.

91. "OPEIHHPC Comments on EPA Proposed Phase 3 Rule for HH Fuel Tank Permeation," Outdoor Power
Equipment Institute," Presentation to EPA, February 5, 2008.

92. Kathios, D., Ziff, R., "Permeation of Gasoline and Gasoline-Alcohol Fuel Blends Through High-Density
Polyethylene Fuel Tanks with Different Barrier Technologies," SAE Paper 920164, 1992, Docket Identification
EPA-HQ-OAR-2004-0008-0172.

93. "SORE Component EO Summary," email from Jim Watson, California Air Resources Board, to Mike Samulski,
U.S. EPA, August 18, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0405.

94. "Fluorination Information," e-mail from Doug McGregor, BMW, to Mike Samulski, US EPA, August 8, 2003,
Docket Identification EPA-HQ-OAR-2004-0008-0259.

95. "Final Report: Permeation Testing of Injection Molded Walk Behind Mower (WBM) Fuel Tanks using
California's TP-901 Procedures," Automotive Testing Laboratories, Inc., August 30, 2005, Docket Identification
EPA-HQ-OAR-2004-0008-0182.

96. "Baseline Test Results: Permeation Testing of Injection Molded Walk Behind Mower (WBM) Fuel Tanks using
Federal Test Procedures," Automotive Testing Laboratories, Inc., August 30, 2005, Docket Identification EPA-HQ-
OAR-2004-0008-0183.

97. "Final Results: Permeation Testing of Injection Molded Walk Behind Mower (WBM) Fuel Tanks using Federal
Test Procedures," Automotive Testing Laboratories, Inc., July 28, 2006, Docket Identification EPA-HQ-OAR-2004-
0008-0419.

98. "Selar RB Technical Information," Faxed from David Zang, Dupont, to Mike Samulski, U.S. EPA on May 14,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0221.

99. Lyn, K., "A Study on Problems with Aluminum Fuel Tanks in Recreational Boats," Underwriters Laboratories
Inc., sponsored by USCG, 1994, Docket Identification EPA-HQ-OAR-2004-0008-0098.
                                                5-131

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Final Regulatory Impact Analysis
100. E-mail from Alan Dubin, Ticona, to Mike Samulski, U.S. EPA, "Fuel Permeation Chart and Aggressive Fuels
Brochure," July 31, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0196.

101. Samulski, M., "Permeation Emission Testing on Three Roto-Molded Acetal Copolymer Fuel Tanks," Memo to
Docket OAR-2004-0008, October 25, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0443.

102. E-mail from Jim Watson, California ARB to Mike Samulski, U.S. EPA, "fuel tank specs.xls," March 6, 2006,
Docket Identification EPA-HQ-OAR-2004-0008-0357.

103. Chambers, J., "Marine Fuel Containment... A Permanent Solution," Presentation by Engineered Composite
Structures Inc. at the 2004 International Boatbuilders Exposition, October 25, 2004, Docket Identification EPA-HQ-
OAR-2004-0008-0037.

104. "Fluorination Information," e-mail from Doug McGregor, BMW, to Mike Samulski, US EPA, August 8, 2003,
Docket Identification EPA-HQ-OAR-2004-0008-0259.

105. Fead, E., Vengadam, R., Rossi, G., Olejnik, A., Thorn, J., "Speciation of Evaporative Emissions from Plastic
Fuel Tanks," SAE Paper 981376, 1998, Docket Identification EPA-HQ-OAR-2004-0008-0175.

106. Email from Dennis Goodenow, California Air Resources Board, to Mike Samulski, U.S. EPA, "Coextruded
PFC Data, September 11, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0436.

107. "OPEIHHPC Comments on EPA Proposed Phase 3 Rule for HH Fuel Tank Permeation," Outdoor Power
Equipment Institute," Presentation to EPA, February 5, 2008.

108. Solvay Advanced Polymers, "Solvay Advanced Polymers Unveils Modified Ixef Polyarylamide Barrier
Material for Automotive Fuel Systems," Press Release, March 2, 200, Docket Identification EPA-HQ-OAR-2004-
0008-0539.

109. "Test Report: EPA CCD-05-14 Fuel Tank Permeation Testing," Testing Services Group, TSG Report Numbers
L706619-1.1, 2.1, 3.1, and4.1A, October 19, 2007, Docket Identification EPA-HQ-OAR-2004-0008-XXXX.

110. O'Brien, Partridge, Clay, "New Materials and Multi-Layer Rotomolding Technology for Higher Barrier
Performance Rotomolded Tanks," Atofina Chemicals, Inc., Presented at the Topcon Rotational Molding by Design
Conference, June 6-8, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0044.

111. Samulski, M., "Permeation Emission Testing of Two Multi-Layer Roto-Molded Fuel Tanks," Memo to Docket
OAR-2004-0008, August 31, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0132.

112. Partridge, R., "Petro-SealTM for Ultra-Low Permeation," Arkema Inc., Presentation at 2004  International
Boatbuilders Exposition, October 25, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0038.

113. "Test Report 16514-1A: NMMA/USCG Tests of Prototype Fuel Tank for Atofina Chemicals, Inc.," IMANNA
Laboratory, July 16, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0416.

114. "Test Report 16544-1A: NMMA/USCG Tests of Prototype Fuel Tank for Atofina Chemicals, Inc.," IMANNA
Laboratory, July 16, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0417.

115. "Test Report 17474-1: NMMA/USCG Tests of 40 Gallon Prototype Fuel Tank for Arkema, Inc.," IMANNA
Laboratory, October 12, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0418.

116. "Final Report, Fuel Tank Testing, Procedure Number: SAE J288 DEC 02, Sections 4.2, 4.3," MGA Research
Corporation,  October 19, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0406.
                                               5-132

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                                                    Feasibility of Evaporative Emission Control
117.  "SORE Component EO Summary," email from Jim Watson, California Air Resources Board, to Mike
Samulski, U.S. EPA, August 18, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0405.

118.  Faler, Gary, "Cyclics CBT Resin for Dual Layer Applications in Rotomolding," Cyclics Corporation, August
2006, Docket Identification EPA-HQ-OAR-2004-0008-0415.

119.  Faler, Gary, ""Cyclics CBT Resin for Rotomolding," Cyclics Corporation, Presented at ARMO 2006
Convention & Exposition, September, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0414.

120.Graham, B., Cook, D., "Measurement of Fuel Barrier Properties of Rotational Molded Materials," Article from
ANTEC 2006 Rotational Molding Division, May 12, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0404.

121.  Fish, D., "Advanced Polymer Concepts," Presentation at the 2004 International Boatbuilders Exposition,
October 25, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0039.

122.  Bauman, B., "Advances in Plastic Fuel Tanks," Presentation by Fluoro-Seal International at the 2004
International Boatbuilders Exposition, October 25, 2004, Docket Identification EPA-HQ-OAR-2004-0008-0036.

123.  Bauman, B., "Advances in Plastic Fuel Tanks," Presentation by Fluoro-Seal International at the 2004
International Boatbuilders Exposition, October 25, 2004, Docket Identification EPA-HQ-OAR-2000-0008,
Document OAR-2004-0008-0036.

124.  SAE Surface Vehicle Standard, "Marine Fuel Hoses," Society of Automotive Engineers J 1527, Issued 1985-
12, Revised 1993-02, Docket Identification EPA-HQ-OAR-2004-0008-0177.

125.  American Society for Testing and Materials, "Standard Test Method for Rubber Property-Effects of Liquids,"
ASTM D 471-06, November 2006, Docket Identification EPA-HQ-OAR-2004-0008-0511.

126.  "Public Hearing on Proposed Evaporative Emission Standards for New Marine Vessels that Use Spark-Ignition
Engines," Held on Monday, October 7, 2002 at the U.S. Environmental Protection Agency, Office of Transportation
and Air Quality, in Ann Arbor, Michigan, De Scribe Reporting, Inc., Docket Identification EPA-HQ-OAR-2004-
0008-0265.

127.  "Test Report: 24  hr MicroShed Test on 3 Standard Fuel Hoses," Testing Services Group, TSG Report Number
L201672-2.5, July 29,  2002, Docket Identification EPA-HQ-OAR-2004-0008-0227.

128.  Akron Rubber Development Laboratory, "Test Report PN# 50107" Prepared for the U.S. EPA, December 13,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0184.

129.  Akron Rubber Development Laboratory, "Test Report PN# 50108" Prepared for the U.S. EPA, December 13,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0185.

130.  "Test Report: Marine Fuel Hose Testing; 6-hour/28C Constant Temperature MicroSHED after a cumulative
13-week soakinIE-10 Test Fuel at40C," Testing Services Group, TSG Report Number L404396-1.1A, January 20,
2005, Docket Identification EPA-HQ-OAR-2004-0008-0407.

131. "Test Report: Permeation by Weight Loss," Testing Services Group, TSG Report Number L505371-6.1, May
15, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0409.

132.  Harold Haskew, "NMMA/EPA Meeting," Harold Haskew & Associates, Inc, presented at NMMA/EPA
meeting on January 24, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0359.

133.  SAE Vehicle Recommended Practice, "Personal Watercraft Fuel Systems,"  Society of Automotive Engineers J
2046, Issued January 19, 1993, Docket Identification EPA-HQ-OAR-2004-0008-0179.

                                               5-133

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Final Regulatory Impact Analysis
134. Memorandum from Mike Samulski to Docket A-2000-02, "Hose Permeation Data from Saint-Gobain
Performance Plastics," October 17, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0210.

135. SAE Recommended Practice J30, "Fuel and Oil Hoses,"June 1998, Docket Identification EPA-HQ-OAR-
2004-0008-0176.

136. Baltz, G., "Effects of Alcohol Extended Fuels on the Rate of Fuel Hose Permeation," SAE Paper 880709,
Presented at the International Congress and Exposition February 29-March 4, 1988, Docket Identification EPA-HQ-
OAR-2004-0008-0167.

137. "OPEI Fuel Line Permeation Results," Walbro Engine Management, April 12,  2006, Docket Identification
EPA-HQ-OAR-2004-0008-0440.

138. "HHPC Evaluation of EPA Proposed Phase 3 Rule for Fuel Line Permeation," Outdoor Power Equipment
Institute, presentation to EPA, February 5, 2008.

139. Horvath, I, "Optimizing Permeation Resistance and Low Temperature Flexibility in Heat Resistant NBR Fuel
Hose," SAE Paper 790661, presented at the Passenger Car Meeting, June 11-15, 1979, Docket Identification EPA-
HQ-OAR-2004-0008-0166.

140. MacLachlan, I, "Automotive Fuel Permeation Resistance - A Comparison of Elastomeric Materials," SAE
Paper 790657, presented at the Passenger Car Meeting, June 11-15, 1979, Docket Identification EPA-HQ-OAR-
2004-0008-0165.

141. Testing Services Group, "Marine Fuel Hose MicroSHED Testing;  6-hour/28C Constant Temperature
MicroSHED after a cumulative 13-week soak in IE-10 Test Fuel at 40," TSG Report No. L404396-1.1A, January
24, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0407.

142. Testing Services Group, "Marine Fuel Hose MicroSHED Testing;  24-hourEPA MicroSHED after a cumulative
2-week soak in IE-10 Test Fuel at 40," TSG Report No. L404396-2.1A, January 24, 2005, Docket Identification
EPA-HQ-OAR-2004-0008-0408.

143. Harold Haskew, "Marine Fuel System Hose Permeation Testing: 2nd Progress Report," Harold Haskew &
Associates, Inc., testing performed at Sterling Performance Testing Laboratory, October 3, 2005, Docket
IdentificationEPA-HQ-OAR-2004-0008-0358.

144. Harold Haskew, "Marine Fuel System Hose Permeation Testing: 2nd Progress Report," Harold Haskew &
Associates, Inc., testing performed at Sterling Performance Testing Laboratory, October 3, 2005, Docket
IdentificationEPA-HQ-OAR-2004-0008-0358.

145. Harold Haskew, "NMMA/EPA Meeting," Harold Haskew & Associates, Inc, presented at NMMA/EPA
meeting on January 24, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0359.

146. "Test Report: Permeation by Weight Loss," Testing Services Group, TSG Report Number L505371-6.1, May
15, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0409.

147. Sterling Performance, "U.S.E.P.A. Fuel Line Permeation 050085; Version 1.0," August 13, 2005, Docket
IdentificationEPA-HQ-OAR-2004-0008-0428.

148. Denbow, R., Browning, L., Coleman, D., "Report Submitted for WA 2-9, Evaluation of the Costs and
Capabilities of Vehicle Evaporative Emission Control Technologies," ICF, ARCADIS Geraghty & Miller, March
22, 1999, Docket Identification EPA-HQ-OAR-2004-0008-0194.
                                               5-134

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                                                   Feasibility of Evaporative Emission Control
149.  Denbow, R., Browning, L., Coleman, D., "Report Submitted for WA 2-9, Evaluation of the Costs and
Capabilities of Vehicle Evaporative Emission Control Technologies," ICF, ARCADIS Geraghty & Miller, March
22, 1999, Docket Identification EPA-HQ-OAR-2004-0008-0194.

150. SAE Recommended Practice J2260, "Nonmetallic Fuel System Tubing with One or More Layers," 1996,
Docket Identification EPA-HQ-OAR-2004-0008-0180.

151.  33CFR183.558

152.  SAE Surface Vehicle Standard, "Marine Fuel Hoses," Society of Automotive Engineers J 1527, Issued 1985-
12, Revised 1993-02, Docket Identification EPA-HQ-OAR-2004-0008-0177.

153.  "Visit to Dyneon on June 12, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-01, June
17, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0208.

154.  "Meeting with Avon on June 27, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-01,
August 6, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0207.

155.  "Meeting with Avon on June 27, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-01,
August 6, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0207.

156.  Akron Rubber Development Laboratory, "Test Report; PN# 49503," Prepared for the U.S. EPA, September 3,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0187.

157.  Akron Rubber Development Laboratory, "Test Report PN# 50107" Prepared for the U.S. EPA, December 13,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0184.

158.  Akron Rubber Development Laboratory, "Test Report PN# 50108" Prepared for the U.S. EPA, December 13,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0185.

159.  Akron Rubber Development Laboratory, "Test Report PN# 53609" Prepared for American Honda Motor
Company, September 26, 2003, Docket Identification EPA-HQ-OAR-2004-0008-0189.

160.  Akron Rubber Development Laboratory, "Test Report PN# 53630" Prepared for the U.S. EPA, September 26,
2003, Docket Identification EPA-HQ-OAR-2004-0008-0190.

161.  Akron Rubber Development Laboratory, "Test Report PN# 53908" Prepared for the U.S. EPA, October 20,
2003, Docket Identification EPA-HQ-OAR-2004-0008-0191.

162.  Email from Mike Fauble, Avon Automotive to Mike Frederick Jr., Avon Automotive, "SAE J30 Test Results,"
April 26, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0394.

163.  Fuller, R., "Unique Low Permeation Elastomeric Laminates  for Fuel Hose; F200 Technology used in
Automotive Fuel Hose," Hearing Testimony for Dupont-Dow Elastomers on NPRM, October 7, 2002, Docket
Identification EPA-HQ-OAR-2004-0008-0197.

164.  "Test Report: 24 hr MicroSHED Test of Fuel Line Assemblies After 8 Week Soak in Fuel C," Testing Services
Group, TSG Report Number L201672-3.1, June 25, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0229.

165.  "Test Report: EPA MicroSHED Test on Fuel Line Assemblies 24-Hour EPA MicroSHED Test with Multipoint
@ 8-Weeks," Testing Services Group, TSG Report Number L201672-2.3, June 17, 2002, Docket Identification
EPA-HQ-OAR-2004-0008-0228.

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Final Regulatory Impact Analysis
166.  "Test Report: EPA MicroSHED Test on Fuel Line Assemblies 24-Hour EPA MicroSHED Re-Test of Part
#01672-11," Testing Services Group, TSG Report Number L201672-3.1R, July 8, 2002, Docket Identification EPA-
HQ-OAR-2004-0008-0230.

167.  Akron Rubber Development Laboratory, "Test Report PN# 50107" Prepared for the U.S. EPA, December 13,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0184.

168.  Akron Rubber Development Laboratory, "Test Report PN# 50108" Prepared for the U.S. EPA, December 13,
2002, Docket Identification EPA-HQ-OAR-2004-0008-0185

169.  Akron Rubber Development Laboratory, "Test Report PN# 52318" Prepared for the U.S. EPA, July 24,2003,
Docket Identification EPA-HQ-OAR-2004-0008-0188.

170. Harold Haskew, "Marine Fuel System Hose Permeation Testing: 2nd Progress Report," Harold Haskew &
Associates, Inc., testing performed at Sterling Performance Testing Laboratory, October 3, 2005, Docket
IdentificationEPA-HQ-OAR-2004-0008-0358.

171.  Harold Haskew, "NMMA/EPA Meeting," Harold Haskew & Associates, Inc, presented at NMMA/EPA
meeting on January 24, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0359.

172.  Akron Rubber Development Laboratory, "Test Report PN# 52318" Prepared for the U.S. EPA, July 24,2003,
Docket Identification EPA-HQ-OAR-2004-0008-0188.

173.  "Meeting with DuPont and Teleflex on December 10, 2002," memorandum from Mike Samulski, U.S. EPA to
Docket A-2000-02, December 10, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0260.

174.  "Low perm marine fuel hose," e-mail from Rob Bentley, Teleflex to Alan Stout U.S. EPA, July 16, 2003,
Docket Identification EPA-HQ-OAR-2004-0008-0225.

175. Engineered Composite Solutions, "Press Release: Feb 2008 ECS develops low permeation primer bulb,"
retrieved from http://www.engineeredcompositesolutions.com/press_releases.htm on April 24, 2008.

176. BluSkies Marine Products, "Primer Bulb; A White Paper," retrieved from www.bluskies.us on June 25, 2008.

177.  "SORE Component EO Summary,"  email from Jim Watson, California Air Resources Board, to Mike
Samulski, U.S. EPA, August 18, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0405.

178.  Letter from William Guerry, Kelly Drye Collier Shannon, to Glenn Passavant, U.S. EPA, and Susan Bathalon,
U.S. Consumer Product Safety Commission, "EPA Proposal, Phase III, Small Engine Regulations - Fuel Lines for
Cold Weather Handheld Products," January 25, 2007, Docket Identification EPA-HQ-OAR-2004-0008-0524.

179.  Outdoor Power Equipment Institute, "Fuel Hose Design in Relation to the Design and Operation of Handheld
Power Equipment," Presentation to EPA,  June 21, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0399.

180.  Outdoor Power Equipment Institute, "Comparison of NBR and FPM (Viton) Performance on Hand Held
Equipment," Presentation to EPA, Docket Identification EPA-HQ-OAR-2004-0008-0441.

181.  "Alpha List of OEM Approvals," http://www.precixinc.com/oemlist.html, downloaded August 15,  2006,
Docket Identification EPA-HQ-OAR-2004-0008-0411.

182. "Viton: Volume Swell of Viton Fluoroelastomers in Fuel C / Ethanol Blends," DuPont Performance
Elastomers, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0510.
                                               5-136

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                                                    Feasibility of Evaporative Emission Control
183. "FKM / Genuine Viton," http://www.o-ring.info/en/datasheets/fkm-genuine-viton/, downloaded August 15,
2006, Docket Identification EPA-HQ-OAR-2004-0008-0410.

184. Hatano, M, Otsuka, M, Ogata, C., Suetsugu, N, Amemiya, T., Kudo, M., "Development of New FKM O-
Rings with Superior Fuel-Oil Resistance and Low-Temperature Properties," SAE Paper 2005-01-1743, 2005, Docket
Identification EPA-HQ-OAR-2004-0008-043 3.

185. Yamaguchi, Y., Shojima, D., Ogata, C., Oya, K., Kawasaki, K., Kudo, M., "Development of the New FKM O-
Ring for a Cooling Device," 2005-01-1753, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0434.

186. "Technical Information; Dyneon Fluorelastomer LTFE 6400X," 3M, Issued February, 2003, Docket
Identification EPA-HQ-OAR-2004-0008-0521.

187. "Relative Permeation of Elastomers," Precix, downloaded from www.precixinc.com on February 14, 2007,
Docket Identification EPA-HQ-OAR-2004-0008-0525.

188. Balzer, J., "F-TPV: A New Horizon for TPE Technology," Presented by Daikin America to U.S. EPA on
February 14, 2007, Docket Identification EPA-HQ-OAR-2004-0008-0522.

189. Letter from Trevor J. Richards, President Spring Cove Marina, "Fuel Spills While Filling Pleasure Craft
Tanks," April 23, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0383.

190. Letter from Van DePiero,  City of Pittsburg, California to Steve Burkholder, Enviro Fill, April 19, 2006, Docket
IdentificationEPA-HQ-OAR-2004-0008-0384.

191. American Boat and Yacht Council, "H-24 Gasoline Fuel Systems," 2005, Docket Identification EPA-HQ-
OAR-2004-0008-0429.

192. Email from Steve Burkholder, Enviro-Fill, to Mike Samulski and Alan Stout, U.S. EPA, "Overfill Prevention
System Developments," July 25, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0447.

193. Boat U.S. Foundation, "Foundation Findings #40; Spill? What Spill?; Products to Keep Fuel Where it
Belongs-In Your Tank," www.boatus.com/foundation/Findings/fmdings40, March 2005, Docket Identification
EPA-HQ-OAR-2004-0008-0431.

194. Letter from Steve Burkholder, Enviro-Fill, to Mike Samulski, U.S. EPA, March 1, 2006, Docket Identification
EPA-HQ-OAR-2004-0008-0430.

195. Letter from Steve Burkholder, Enviro-Fill, to Mike Samulski, U.S. EPA, January  13, 2006, Docket
Identifications? A-HQ-OAR-2004-0008-0446.

196. Email from Steve Burkholder, Enviro-Fill, to Mike Samulski and Alan Stout, U.S. EPA, "Overfill Prevention
System Developments," July 25, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0447.

197. SAE Recommended Practice J30,  "Fuel and Oil Hoses," June 1998, Docket Identification EPA-HQ-OAR-
2004-0008-0176.

198. SAE Surface Vehicle Standard, "Marine Fuel Hoses," Society of Automotive Engineers J 1527, Issued 1985-
12, Revised 2007-01.

199. American Society for Testing and Materials, "Standard Test Method for Rubber Property-Effects of Liquids,"
ASTM D 471-06, November 2006, Docket Identification EPA-HQ-OAR-2004-0008-0511.
                                                5-137

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Final Regulatory Impact Analysis
200. SAE Recommended Practice J1737, "Test Procedure to Determine the Hydrocarbon Losses from Fuel Tubes,
Hoses, Fittings, and Fuel Line Assemblies by Recirculation,"1997, Docket Identification EPA-HQ-OAR-2004-0008-
0178.

201. SAE Surface Vehicle Standard, "Nonmetallic Fuel System Tubing with One or More Layers," Society of
Automotive Engineers J 2260, Issued 1996-11, Docket Identification EPA-HQ-OAR-2004-0008-0180.

202. SAE Surface Vehicle Recommended Practice, "Test Procedure to Determine the Hydrocarbon Losses from
Fuel Tubes, Hoses, Fittings, and Fuel Line Assemblies by Recirculation," Society of Automotive Engineers J 1737,
Issued 1997-08, Docket Identification EPA-HQ-OAR-2004-0008-0178.

203. Draft SAE Information Report J1769, "Test Protocol for Evaluation of Long Term Permeation Barrier
Durability on Non-Metallic Fuel Tanks," Docket Identification EPA-HQ-OAR-2004-0008-0195.

204. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.

205. "Permeation Rates of Small Off Road Engine High-Density Polyethylene Fuel Tanks (April 2001 Testing),
June 8, 2001, California Air Resources Board, Docket Identification EPA-HQ-OAR-2004-0008-0146.

206. "Permeation Rates of High-Density Polyethylene Fuel Tanks (June 2001), June  12, 2001, California Air
Resources Board, Docket Identification EPA-HQ-OAR-2004-0008-0148

207. "Permeation Rates of High-Density Polyethylene Fuel Tanks (May 2001), June  11, 2001, California Air
Resources Board, Docket Identification EPA-HQ-OAR-2004-0008-0149.

208. "Average Permeation Rates of High-Density Polyethylene Off-Road Equipment Fuel Tanks Using a Surface
Area Approach, (March 2002)," March 15, 2002, California Air Resources Board, Docket Identification EPA-HQ-
OAR-2004-0008-0256.

209. Haskew, H., McClement, D., "Fuel Permeation from Automotive Systems; Final Report," prepared for the
California Air Resources Board and the Coordinating Research Council, CRC Project No. E-65, September 2004,
Docket Identification EPA-HQ-OAR-2004-0008-0151.

210. Dickson, A., Goyet, C., "Handbook of Methods forthe Analysis of the Various  Parameters of the Carbon
Dioxide  System in Sea Water; Version 2," Prepared for the U.S. Department of Energy, SOP21 "Applying air
buoyancy corrections," September 29, 1997, Docket Identification EPA-HQ-OAR-2004-0008-0135.

211. Testing Services Group, "CARD TM-513: Portable Fuel Container Permeation Testing," Presented to U.S.
EPA on  August 18, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0133.

212. Testing Services Group, "Technical Brief: Buoyancy Correction for Mass Measurement of Fuel Containers,"
TB 50819-1, August 19, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0134.

213. California Air Resources Board, "TP-502: Test Procedure for Determining Diurnal Emissions from Portable
Fuel Containers," proposed July 22, 2005, Docket Identification EPA-HQ-OAR-2004-0008-0300.

214. "Test Method to Measure Fluid Permeation of Polymeric Materials by Speciation," SAE Surface Vehicle
Standard J2659, Issued December 2003, Docket Identification EPA-HQ-OAR-2004-0008-0512.

215. Internal MeadWestvaco memorandum from M. Tschantz to C. Pierson, "Preliminary 3 mm SeaGuard
Specifications," August 31, 2005,  Docket Identifications?A-HQ-OAR-2004-0008-0136.
                                                5-138

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                                                   Feasibility of Evaporative Emission Control
216.  "Standard Test Method for Determination of Butane Working Capacity of Activated Carbon," ASTM
International, Designation D5228-92 (Reapproved 2005), Docket Identification EPA-HQ-OAR-2004-0008-0347.

217.  Tschantz, M, "Activated Carbon for Use in Marine Evaporative Control Applications," Presented by
MeadWestvaco Corporation at the 2004 International Boatbuilders Exposition, October 25, 2004, Docket
IdentificationEPA-HQ-OAR-2004-0008-0040.

218.  "Carbon Specs," email fromM. Tschantz , MeadWestvaco to M. Samulski, U.S. EPA, November 18, 2005,
Docket Identification EPA-HQ-OAR-2004-0008-0421.

219.  "Standard Test Method for Ball-Pan Hardness of Activated Carbon," ASTM International, Designation D3802-
79 (Reapproved 2005), Docket Identification EPA-HQ-OAR-2004-0008-0348.

220.  "SOP 0960-610 vs. ASTM 3802," email from Mike Tschantz, MeadWestvaco to Mike Samulski, U.S. EPA,
January 13, 2006, Docket Identification EPA-HQ-OAR-2004-0008-0412.

221.  " Standard Test Method for Particle Size Distribution of Granular Activated Carbon," ASTM International,
Designation D2862-97 (Reapproved 2004).

222.  Williams, R., Clontz, R., "Impact and Control of Canister Bleed Emissions," SAE Paper 2001-01-0733, 2001,
Docket Identification EPA-HQ-OAR-2004-0008-0432.

223.  "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.

224.  "EPA Technical Study on the Safety of Emission Controls for Nonroad Spark-Ignition Engines < 50
Horsepower," U.S. Environmental Protection Agency, EPA420-R-06-006, March 2006, Docket Identification EPA-
HQ-OAR-2004-0008-0329.

225.  Hopf, G., Ries, H., Gray, E., "Development of Multilayer Thermoplastic Fuel Lines with Improved Barrier
Properties," SAE Paper 940165, 1994, Docket Identification EPA-HQ-OAR-2004-0008-0174.

226.  Stahl, W., Stevens, R., "Fuel-Alcohol Permeation Rates of Fluoroelastomers, Fluoroplastics, and Other Fuel
Resistant Materials,"  SAE Paper 920163, 1992, Docket Identification EPA-HQ-OAR-2004-0008-0171.

227.  "Visit to Dyneon on June 12, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-01, June
17, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0208.

228.  Goldsberry, D., "Fuel Hose Permeation of Fluoropolymers," SAE Paper  930992, 1993, Docket Identification
EPA-HQ-OAR-2004-0008-0173.

229. Tuckner, P., Baker, J., "Fuel Permeation Testing Using Gravimetric Methods," SAE Paper 20001-01-1096,
2000, Docket Identification EPA-HQ-OAR-2004-0008-0160.

230.  Fuller, R., "Unique Low Permeation Elastomeric Laminates for Fuel Hose; F200 Technology used in
Automotive Fuel Hose," Hearing Testimony for Dupont-Dow Elastomers on NPRM, October 7, 2002, Docket
Identification EPA-HQ-OAR-2004-0008-0197.

231.  Nulman, M., Olejnik,  A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.
                                               5-139

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Final Regulatory Impact Analysis
232. Duchesne, D., Hull, D., Molnar, A., "THV Fluorothermoplastics in Automotive Fuel Management Systems,"
SAE Paper 1999-01-0379, 1999, Docket Identification EPA-HQ-OAR-2004-0008-0159.

233. Nulman, M, Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.

234. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of Polymeric
Materials," SAE Paper 2001-01-1999, 2001, Docket Identification EPA-HQ-OAR-2004-0008-0162.

235. "Visit to Dyneon on June 12, 2002," Memorandum from Mike Samulski, U.S. EPA to Docket A-2000-01, June
17, 2002, Docket Identification EPA-HQ-OAR-2004-0008-0208.

236. Facsimile from Bob Hazekamp, Top Dog Systems, to Mike Samulski, U.S. EPA, "Permeation of Polyurethane
versus THV Materials @ 60C," January 14, 2002, Docket A-2000-01, Docket Identification EPA-HQ-OAR-2004-
0008-0435.

237. Duchesne, D., Hull, D., Molnar, A., "THV Fluorothermoplastics in Automotive Fuel Management Systems,"
SAE Paper 1999-01-0379, 1999, Docket Identification EPA-HQ-OAR-2004-0008-0159.
                                               5-140

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                                                                       Costs of Control
                     CHAPTER 6: Costs of Control

       This chapter describes our approach to estimating the cost of complying with the new
emission standards. We start with a general description of the approach  used to estimate costs,
then describe the technology changes we expect and assign costs to them.  We also present an
analysis of the estimated aggregate cost to society.

6.1 Methodology

       We developed the costs for individual technologies using estimates from ICF
Incorporated1, conversations with manufacturers, and other information  as cited below.  The
technology characterization reflects our current best judgment based on  EPA's technology
demonstrations, engineering analysis, information from manufacturers, and the published
literature.

       Costs of control include variable costs (for incremental hardware costs, assembly costs,
and associated markups) and fixed costs (for tooling, R&D, and certification).  Variable costs are
marked up at a rate of 29 percent to account for the engine or equipment/vessel manufacturers'
overhead and profit.2  For technologies sold by a supplier to the engine manufacturers, an
additional 29 percent  markup is included for the supplier's  overhead and profit. Labor estimates
are marked up by 100 percent to reflect fringe and overhead charges including management,
supervision, general and administrative expenses, etc.  All  costs are in 2005 dollars.

       The analysis presents an estimate of per-unit costs that will occur in the first year(s) of
new emission standards and the corresponding long-term costs.  Long-term costs decrease due to
two principal factors.  First, fixed costs are assessed for five years, after which they are fully
amortized and are then no longer part of the cost calculation. Second, manufacturers are
expected to learn over time to produce the engines with the new technologies or aftertreatment at
a lower cost. Consistent with analyses from other programs, we reduce  estimated variable costs
by 20 percent beginning with the sixth year of production.3 The small spark ignited engine
industry and the marine industry have different reasons for the learning.

       Learning for the Small  SI industry is expected to occur in the catalyst muffler designs. It
will likely occur for two reasons:  1) over time the number of different muffler catalyst designs
may be reduced thereby decreasing substrate costs due to larger ordering volumes. 2) heat shield
manufacturing may become automated and/or designs more uniform. Learning will not occur for
other technologies such as electronic fuel  injection systems for they currently exist on some
Small SI equipment and motorized vehicles such as scooters .

       In the marine industry,  manufacturers are less likely to put in the extra R&D effort for
low-cost manufacturing of engine families of relatively low sales volumes.  Learning will occur
in two basic ways.  As manufacturers produce more units, they will make improvements in
production methods to improve efficiency. The second way learning occurs is materials learning
where manufacturers  reduce scrap. Scrap includes units that are produced but rejected due to

                                          6-1

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Final Regulatory Impact Analysis
inadequate quality and material scrap left over from the manufacturing process. As production
starts, assemblers and production engineers will then be expected to find significant
improvements in fine-tuning the designs and production processes.

       We believe it is appropriate to apply this learning factor here for the marine industries,
given that they are facing new emission regulations, some for the first time, and it is reasonable
to expect learning to occur with the experience of producing and improving emission-control
technologies. Manufacturers do not have significant experience with most of the emissions
controls that are anticipated for meeting the standards.

       Many of the engine technologies available to Marine SI and Small SI engine
manufacturers to control emissions also have the potential to significantly improve engine
performance. This is clear from the improvements in automotive technologies.  As cars have
continually improved emission controls, they have also greatly improved fuel economy,
reliability, power, and  a reduced reliance on regular maintenance.  Similarly, the fuel economy
improvements associated with converting from two-stroke to four-stroke engines is well
understood.  We  attempt to quantify these expected improvements for each type of engine below.

       Even though the analysis does not reflect all the possible technology variations and
options that are available to engine manufacturers, we believe the projections presented here
provide a cost estimate representative of the different approaches manufacturers may ultimately
take. We expect manufacturers in many cases to find and develop approaches to achieve the
emission standards at a lower cost than we describe in this analysis.

6.2  Exhaust Emission Control Costs  for Small  SI Engines

       This section presents our cost estimates for meeting  the new exhaust emission standards
for Small land-based spark-ignition (Small SI) engines. EPA has relied upon model year 2008
certification data for this analysis to characterize the  current Class I and Class II market and the
technology mix needed to comply with the Phase 3 standards. EPA chose not include data from
Chinese manufacturers in this analysis because we have no  information on actual sales of their
engines in the United States.  Manufacturers do submit sales estimates to EPA at the time of
certification.  However, the sales estimates provided  by Chinese manufacturers would suggest
that sales of Small SI nonhandheld engines have doubled over the last few years. Based on
discussions with  nonhandheld engine manufacturers that have been certifying with EPA for over
ten years now, we do not believe this is the case and it is our understanding that sales of
nonhandheld engines from Chinese manufacturers are relatively small at this time. Therefore,
we believe it is appropriate to not include certification data  from Chinese manufacturers in our
analysis.

       In  1995, EPA finalized the first regulations for reducing emissions from small spark
ignited (SI) engines <19kW.  Small spark ignited engine designs include side valve and overhead
valve engine configurations designated in two groups by engine displacement.  Class I engines
are <225cc and Class II engines are >225cc and less than 19kW.  The Phase 2 regulations for
these engines were set with the expectation that Class I side valve engines would be converted to

                                           6-2

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                                                                        Costs of Control
overhead valve design.  Certification data from 2008 shows that engine manufacturers have been
able to achieve Phase 2 certification with the continued use of side valve engines in some cases.
A summary of the 2008 technology market mix is presented in Table 6.2-1.

       For the final Phase 3 standards, the EPA 2008 certification database was referenced. It
was found that the majority of Class I engines were in need of some emission reduction and
therefore it is estimated that these engines would use catalysts and the related engine design
improvements required to use catalysts safely.  For Class II engines, the 2008 certification
database revealed some engine families meet the Phase 3 emission levels and therefore
technologies are not required on all engine families. For those engine families needing  emission
reduction technology, different technologies were assigned depending on whether the engine was
a one cylinder or a multiple cylinder engine. A number of one cylinder engine families were
estimated to use catalysts. For two or more cylinders, the largest engine family per engine
manufacturer needing emission reduction technology was assigned closed loop electronic fuel
injection.  The remainder were assigned  catalysts with the appropriate muffler setup. The
expected technology market mix is presented in Table 6.2-2.

                        Table 6.2-1: 2008 Technology Market Mix

sv
OHV
w/ Catalyst
w/ Other (EFI and/or watercooled)
Class I
66%
34%
0.003%
0
Class II
2%
98%
0.4%
1%
         Table 6.2-2:  Technology Market Mix Expectations for Phase 3 Engines
     HC+NOx Emission Standards: 38% Reduction Class I, 34% Reduction Class II*
Exhaust Standard Implementation Date
SV
OHV
w/ Catalyst
w/ Other (EFI and/or watercooled)
2012
Class I
66%
34%
95%
0
2011
Class II
2%
98%
50%
6.6%
       *EPA 2008 certification data

   The following sections describe the technologies and related variable and fixed costs
followed by an analysis of aggregate costs.  The costs are based on a report from ICF
International entitled "Small SI engine Technologies and Costs."4 Variable costs to the
manufacturers vary with the engine size and the emission technologies considered.
                                           6-3

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Final Regulatory Impact Analysis
Manufacturers prices of all components were estimated from various sources including
information from engine and catalyst manufacturers and previous work performed by ICF
International on spark ignited engine technology.  All hardware costs to the engine
manufacturers are subject to a 29 percent mark-up.  This includes manufacturer overhead, profit,
dealer overhead and profit. A separate supplier markup of 29 percent is also applied to items
typically purchased from a suppliers such as fuel injection and catalysts.  A 5 percent warranty
mark-up is added to hardware cost of specific technologies including electronics, to represent an
overhead charge covering warranty claims associated with new parts.

       Fixed costs to the manufacturer include the cost of researching, developing and testing a
new technology. The cost of retooling the assembly line for the production of new parts as well
as engine certification including durability testing are also fixed costs.  Design and
development fixed costs per month are listed in Table 6.2-3. Tooling and specific R&D costs are
listed in the following sections. Fixed costs for certification are listed in Section 6.2.3.

                       Table 6.2-3: Design  and Development Costs
                       for use in Fixed Cost Estimates per Month 5

Hours
Rates
Costs
Design Costs Per Month
Engineer
160
$64.41
TOTAL Design Costs Per Month
$10,306
$10,306
Development Costs Per Month
Engineer
Technicians
Dynamometer Test
Time
160
320
20 tests
$64.41
$41.87
$250 ea
TOTAL Development Costs Per Month
$10,306
$13,398
$5,000
$28,704
6.2.1 Class I

       Class I engines currently emitting at or below the Phase 2 emission standard of 16.1
g/kWh will need to reduce their engine out HC+NOx emissions by 30-50 percent to comply with
the Phase 3  emission standard of 10 g/kWh with an appropriate margin. A number of Class I
side valve (SV) engines have been redesigned for the Phase 1 and Phase 2 rulemakings, however
SV and overhead valve (OHV)  engines will need a different approach to meet these emission
standards. One technology to reduce emissions to the Phase 3 levels is a three way catalyst with
appropriate precious metal loading for minimal CO conversion.  EPA work has shown that
catalysts can function effectively through a dynamometer aging of 125 hours with a catalyst
conversion of about the same amount at high hours as low hours6. The amount of conversion is
                                           6-4

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                                                                       Costs of Control
only constrained by 1) the size of the catalyst to fit in the existing, or slightly larger, muffler, 2)
residence time of the exhaust gas along with 3) muffler surface and exhaust gas temperature
issues with respect to the amount of CO converted within a catalyst. EPA's work has been
shown to convert HC+NOx within a range of 3.8-6.7 g/kW-h (median approx 5.7g/kW-h) on
OHV engines and 3.8-10.3 g/kW-h on SV engines (median of 6.8 g/kW-h).

      EPA's 2005 Phase 2 certification database lists OHV and SV engine HC+NOx emission
levels at low hours, a deterioration factor (df) and resultant certification levels.  Engine
manufacturers with most regulated experience were considered for these df ranges for we are
most familiar with the performance of these engines.  Engine families using credits to certify to
the emission standard with ABT were not included.

        Table 6.2-4: 2005 EPA Certification Database with Catalyst Assumptions7
Technology
Type/UL



SV/125
OHV/ 125
OHV/250
OHV/500
Engine Out
"zero
hours"
(Min-Max)

10-11
6-15
7-15
8-14
DF
(Min-Max)



1-1.24
1-1.356
1-1.136
1-1.161
Certification
Level
(Min-Max)


13-14
9-16
8-12
8-15
Catalyst
conversion
(median
from EPA
work)
6.8
5.7
5.7
5.7
Engine with Catalyst




6.2-7.2
3.3-10.3
2.3-6.3
2.3-9.3
       Table 6.2-4 is based on median HC+NOx catalyst conversion from EPA test work in the
Safety Study.8  The Safety Study also shows improvements in the cooling system design will
provide cooling to the engine and/or catalyst muffler system for reduced muffler skin
temperatures. Individual engine family applications will vary and engine  improvements may be
required for durable and effective catalyst operation.

       6.2.1.1  Engine Improvements for Class I

       Improvements in engine combustion efficiency and engine cooling will assure the engine
systems support catalyst durability. Engine improvements for durable catalyst operation include
changes that are fixed costs and variable costs. Improvements in engine systems resulting in
fixed costs potentially include the following: 1) improved combustion chamber design for
optimized combustion, 2) improved piston design for reduced crevice volumes and reduced HC
emissions, 3) improved machining and casting tolerances for all combustion chamber
components, 4) improved cylinder head fin design for improved cooling, and 5) improved
carburetion for fuel delivery and system durability. Some engines would also benefit greatly
from 6) improved flywheel design in order to provide additional  cooling to the engine and
muffler system. Clearly not all engines need these upgrades and many will implement few or
                                          6-5

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Final Regulatory Impact Analysis
none.

   Fixed costs per engine family for engine improvements are estimated at four months of design
work (one engineer) and six months of development work (one engineer, one technician and
dynamometer test time) along with tooling costs for the cylinder head, piston, connecting rod,
camshaft, carburetor, flywheel and setup changes. Tooling costs are estimated to be the same
across engine useful life categories with the exception of Class 1125 hour SV engines which
contains some engine families that are sold in much larger volumes and therefore would have
more tools to be modified.  These fixed costs are presented in Table 6.2-5.

             Table 6.2-5: Fixed Costs for Engine Improvements for Class I9
Engine Class
Useful life (his)
Valving
Class I
125
SV
125,250,500
OHV
R&D
Design (4 months)
Development (6 months)
TOTAL R&D per Engine Line
41,225
172,225
213,450
41,225
172,225
213,450
TOOLING COSTS
Cylinder Head
Piston
Connecting Rod
Camshaft
Carburetor
Flywheel
Setup Changes
TOTAL TOOLING per Engine Line
TOTAL FIXED
50,000
50,000
30,000
16,000
120,000
70,000
150,000
486,000
$699,450
25,000
25,000
15,000
8,000
60,000
35,000
75,000
243,000
$456,450
       Variable cost items were identified from EPA field aging of engines from several engine
manufacturers. EPA performed several lawnmower in-use test programs in 2003 to 2005.
Several of the SV and OHV engines were equipped with catalysts. The process revealed that
potentially several engine design characteristics needed improvement in some cases in order for
catalysts to be successfully applied in-use. Items included: 1) fuel filter to screen out impurities
(assure do not encounter a stuck float and thereby excessive fuel flowed through the engine
                                          6-6

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                                                                        Costs of Control
coating the catalyst and rendering it inactive.), 2) incorporation of an intake gasket to assure
leaks do not develop in the intake system thereby resulting in hot engine operation and a number
of engine operational issues, 3) engine shroud screen over fan (avoid debris collecting in the
engine fan), and 4) improved engine cooling system for SV engines to assure the engine's piston
and combustion chamber walls stay in contact so oil does not seep past the rings and into the
combustion chamber (see Chapter 4) thereby potentially poisoning the catalyst.  Lastly, the
incorporation of improved induction coils will reduce the opportunity for spark plug wire
failures and misfire events.  Table 6.2-6 lists the variable costs for engine improvements for
Class I engines certified to various useful lives. Clearly not all  engines need these upgrades to
succeed and many will implement few or none.
            Table 6.2-6:  Variable Costs for Engine Improvements for Class I
                                                                           10
Engine Improvement
Fuel Filter Screens (80% of engine sales)
cost/engine: 0.02
Improved Intake Gaskets (75% of engine sales for
Class I 125 hour useful life)
cost/engine: 0.03
Screen over cooling fan (16% of 125 hr Class I)
cost/engine: 0.45
Larger Induction Coils (all)
Engine Manufacturer Cost
TOTAL w/Markup
29% OEM
Learning Curve w/ 29% Markup
(0.8*Total w/Markup)* 1.29
UL 125
SV
0.02
0.02
0.07
0.10
0.21
0.27
0.22
UL 125
OHV
0.02
~
0.07
0.10
0.19
0.24
0.19
UL250
0.02
~
~
0.10
0.12
0.15
0.12
UL500
~
~
~
0.10
0.10
0.13
0.10
       6.2.1.2 Catalysts for Class I

       The following paragraphs describe details on catalysts substrates, washcoat and precious
metal, and muffler shielding for Class I engines.  Although commonly in use today, spark
arresters are discussed in the context of the overall design.

       Based on catalyst/muffler development and emission testing by EPA (2004-2005), an
engine which has an HC+NOx exhaust ratio of 60/40 is best suited for the use of a catalyst in
Small SI engines for the catalyst can be designed for minimal CO oxidation and related heat
generation. This ratio can be found on OHV engines for they have efficient combustion
chambers.  SV engines require slightly larger catalysts due to their less efficient combustion
chambers and less than optimum HC/NOx ratios.  In addition, SV engines are more likely to
                                           6-7

-------
Final Regulatory Impact Analysis
have oil seep past the piston rings due into the exhaust to cylinder distortion.  A longer catalyst,
or the use of a pipe catalyst prior to the brick catalyst, allows it to survive for the full useful life
for the catalyst is poisoned from the front of the catalyst to the back.  According to the EPA
Phase 2 certification database, Class I SV engine families are certified to the 125 hour useful life
and therefore the cost analysis includes two different catalyst costs for the 125 hour useful life.

       The engines certified to the 250 and 500 useful life categories are all of OHV engine
design.  As with the 125 hour category, catalyst substrate sizes are calculated as a  percentage of
the engine displacement. The certification database was queried for this engine displacement
data and the displacements are sales weighted, as seen in Table 6.2-7.  Catalyst volumes range
from 18 percent of the engine displacement for the 125 OHV useful life to 50 percent of the
engine displacement for the 500 hour useful life.  Larger catalysts are needed for longer useful
life periods in order to provide the emission conversion durability. Specific costs  for engines
within each useful life category  will differ.

       The substrate cost is based on an average cost of metallic and ceramic substrates as
presented in the ICF report11 due to the variety of Small SI equipment types and variety of
catalysts offered in the marketplace. This cost analysis estimates equal weighting of the substrate
types and therefore takes an average of the cost for both metallic and ceramic.

       Due to the concern of oil sulfur poisoning in Class I engines, EPA envisions  that a 5:1
ratio of Platinum/Rhodium precious metal would be used for these catalysts.  The cost of
precious metals was taken from a 3 year  average in price  from 2003-2005. Washcoat material is
expected to be a 30/70 percent mixture of cerium and alumina oxide, respectively.

       The design of the catalyst/muffler forms the basis for the degree of cooling needed at the
muffler and exhaust port.  EPA's solution for muffler surface and exhaust gas cooling included
three steps 1) forcing the cooling air from the engine fan/cylinder head region to the muffler can
be achieved through a slight redesign of  the engine's shroud, 2) a muffler shroud that is designed
to guide the cooling air around the entire muffler and exits at a specified location,  and lastly 3)
and if when needed an ejector is added to the muffler at the exhaust gas outlet so the exhaust gas
can be combined with ambient air before being accessible to the user.

       EPA's observation of a number of lawnmower engine designs revealed that the majority
of heat shields currently used on small engines need to be redesigned in order to allow the use of
air flow from the engine's fan to flow optimally around the muffler for cooling.  The portion of
engines that do have such systems and will not incur this cost were removed from the cost
analysis and ICF's estimates for this technology were adjusted.  EPA utilized the  2005
certification database to estimate sales and to calculate a percentage of engines that will be
estimated to redesign their muffler heat shield.  Table 6.2-7 contains the variable costs for
catalysts, heat shields and spark arresters.

-------
                                                                       Costs of Control
                    Table 6.2-7: Variable Catalyst Costs for Class I12
                            to Achieve the Phase 3 Standards
Useful Life
Engine Power (hp)
Engine Displacement (cc)
Catalyst Volume (cc)
Substrate Diameter (cm)
Substrate
Washcoat and Precious
Metal
Labor
Labor Overhead 40%
Supplier Markup 29%
Catalyst Manufacturer Price
Heat Shield*
Spark Arresters
Engine Manufacturer Cost
TOTAL w/Markup
29% OEM
UL125
SV
3.3
178
45
3.50
$1.97
$1.83
$1.40
$0.56
$1.67
$7.43
$0.50
$0.05
$7.98
$10.29
UL125
OHV
5.1
180
32
3.50
$1.53
$1.31
$1.40
$0.56
$1.39
$6.19
$0.29
$0.05
$6.53
$8.42
UL250
5.0
167
55
4.00
$2.32
$2.81
$1.40
$0.56
$2.06
$9.15
$0.18
$0.05
$9.38
$12.10
UL500
5.2
166
83
4.50
$3.22
$4.24
$1.40
$0.56
$2.73
$12.15
$0.14
$0.05
$12.34
$15.92
       * Based on EPA's work with small engine equipment from 2003-2005, it has been observed that
       some manufacturers have heat shielding that is sufficient or only needs slight modification.
       These sales volumes have been removed and the resultant price recalculated.
       The fixed costs related to catalyst development for Class I engine applications include
design (one engineer), of two months, and development (one engineer, one technician and
dynamometer time), for five months, of the muffler and heat shield.  The inside of the muffler is
to be redesigned to house the catalyst, provide supplemental air when needed, and provide
baffling for the exhaust flow in order to maximize heat dissipation from the exhaust flow.  The
muffler stamping will also need to be updated to account for the new design. A second critical
component of the catalyst/muffler system is the heat shield. The heat shield must be designed to
allow cooling air from the fan to flow around the muffler to maximize cooling of the muffler and
then exit at an optimum point. The muffler/heat shield system must be located at a
predetermined distance from the engine block in order to allow air to flow behind the muffler to
cool the backside.  Setup changes also are incurred with these modified stampings. The total
tooling per engine line is estimated at $240,000 for Class I engines of 125 hour useful life and
                                          6-9

-------
Final Regulatory Impact Analysis
$120,000 for Class I engines of other useful life periods. The difference is due to the additional
tooling for high volume SV engine families. Table 6.2-8 presents the fixed costs associated with
using catalysts on Class I engines.
                Table 6.2-8: Fixed Costs for Catalysts for Class I Engines
                                                                       13
Engine Class
Useful life (hrs)
Valving
Class I
125
SV
125, 250, 500
OHV
R&D
Design
(2 months)
Development (5 months)
TOTAL R&D per Engine Line
20,612
143,521
164,133
20,612
143,521
164,133
TOOLING COSTS
Modified Muffler Stamping
Heat Shield Stamping
Engine Shroud Modification
Setup Changes
TOTAL TOOLING per Engine Line
TOTAL FIXED COSTS
100,000
60,000
30,000
50,000
240,000
$404,133
50,000
30,000
15,000
25,000
120,000
$284,133
       A learning curve of 20 percent is applied to costs for catalyst technology starting in the
sixth year after the standard is implemented. This somewhat conservative since the learning
normally occurs at 20 percent with a doubling of production which would thus be in the third or
fourth year.  Optimized catalyst/muffler designs and manufacturing processes will likely be
developed as the industry becomes experienced in using mufflers with catalysts on Small SI
engines.  The muffler washcoat will still be unique per engine family per engine manufacturer
for engine out emissions will differ.  Table 6.2-9 presents the estimated learning curve impacts
on variable costs. The precious metal prices are determined in the marketplace and therefore
would not be affected by the learning curve.
                                           6-10

-------
                                                                       Costs of Control
            Table 6.2-9: Learning Curve Variable Catalyst Costs for Class I
                            to Achieve the Phase 3 Standards
Useful Life
Engine Power (hp)
Engine Displacement (cc)
Catalyst Volume (cc)
Substrate Diameter (cm)
Substrate
Washcoat and Precious
Metal
Labor
Labor Overhead
Supplier Markup 29%
Manufacture Price
Heat Shield
(adjusted % for eng w/
sufficient heat shield)
Flame/Spark Arrester
Hardware Cost to
Manufacturer
w/Markup
29% OEM
UL 125
-SV
3.3
178
45
3.50
$1.57
$1.83
$1.40
$0.56
$1.55
$6.92
$0.40
$0.05
$7.37
$9.50
UL 125
-OHV
5.1
180
32
3.50
$1.22
$1.31
$1.40
$0.56
$1.30
$5.80
$0.23
$0.05
$6.08
$7.84
UL250
5.0
167
55
4.00
$1.86
$2.81
$1.40
$0.56
$1.92
$8.55
$0.14
$0.05
$8.74
$11.28
UL500
5.2
166
83
4.50
$2.58
$4.24
$1.40
$0.56
$2.55
$11.32
$0.11
$0.05
$11.49
$14.82
       Table 6.2-10 contains the estimated total costs for Class I Phase 2 compliant engines to
meet the Phase 3 emission standards. Near term costs are those costs for the first five years.
Long term costs are those costs to which the learning curve has been applied.
                                          6-11

-------
Final Regulatory Impact Analysis
          Table 6.2-10: Class I Estimated Total Costs Per Engine (Variable) and
               Per Engine Family (Fixed) to Achieve the Phase 3 Standards
Useful Life
Engine Displacement (cc)
Catalyst Volume (cc)
Substrate Diameter (cm)
UL 125 -
SV
178
45
3.50
UL 125 -
OHV
180
32
3.50
UL250
167
55
4.00
UL500
166
83
4.50
Variable Costs - Near Term
Engine Improvements
Catalyst
Total Variable Cost (Near)
$0.27
$10.29
$10.56
$0.24
$8.36
$8.60
$0.15
$12.10
$12.25
$0.13
$15.92
$16.05
Variable Costs - Long Term (with Learning)
Engine Improvements
Catalyst
Total Variable Cost (Long)
$0.22
$9.50
$9.72
$0.19
$7.84
$8.04
$0.12
$11.28
$11.39
$0.10
$14.82
$14.92
Fixed Costs
Engine Improvements
Catalyst
Total Fixed Costs
$699,450
$404,133
$1,103,583
$456,450
$284,133
$740,583
$456,450
$284,133
$740,583
$456,450
$284,133
$740,583
6.2.2 Class II

       The Phase 3 HC+NOx emission standard for Class II is 8 g/k-Wh which is a 34 percent
emission reduction from the Phase 2 standards of 12.1 g/k-Wh. This standard is to be met at the
end of the regulatory useful life for each engine family.  The EPA Phase 2 certification database
shows that the majority of engines in this Class are of OHV design however, approximately 2
percent of the engines are still side valve engine technology.

       Class II side valve engines are currently certified to the Phase 2 standards with credits
from lower emitting OHV engines.  The EPA 2005 certification database shows the majority of
overhead valve engines currently certifying HC+NOx at a range of 7-11 g/kW-h and side valve
engines certifying in the range of 13-14 g/kW-h. Lowering of the emission standard will reduce
the number of emission credits available for side valves to certify and therefore, it is assumed
that the remaining side valve engines will be phased out and replaced with currently produced
overhead valve engines or continue to be certified using ABT credits from a limited number of
                                         6-12

-------
                                                                        Costs of Control
lower emitting engine families.

       Assuming a 2 g/kW-h compliance margin to 6 g/kW-h, emission reduction technologies
will need to be designed to reduce emissions 15-57 percent.  Table 6.2-11 illustrates potential
engine out emissions with emission reduction technologies applied to Phase 2 engines. OHV
engines are expected to potentially include some engine improvements and/or catalysts or
electronic fuel injection.

  Table 6.2-11:  2005 EPA Certification Database Summary With Catalyst Assumptions14
UL
OHV
250
500
1000
Engine Out
"zero hours"
(Min-Max)*
4.8-10.0
Median: 7.9
4.4-10.8
Median: 8.3
6.0-11.2
Median: 8.4
DF
(Min-Max)**
1-1.7
Median: 1.137
1-1.6
Median: 1.039
1-1.4
Median: 1.03
Certification
Level
(Min-Max)*
6.7-12.0
Median: 8.9
5.9-10.9
Median: 9.5
6.9-11.2
Median: 8.9
Catalyst
conversion
(non-EFI
engine)15
4.0
4.0
4.0
Engine with Catalyst
(Based on Median
values)
2.7-8.0
1.9-6.9
2.9-7.2
* Values of engines that meet the standard. 500 hr UL has a liquid cooled engine with catalyst that meets
a 2.6 g/kW-h HC+NOx and 1000 hr UL has the same that meets 1.8 g/kW-h HC+NOx.
**Some engines have catalysts and therefore claim a higher df
       Class II contains several liquid cooled engines. These engines likely have the ability to
be enleaned to more of a degree due to the additional cooling assistance and therefore may not
need a catalyst to meet the Phase 3 emission standards.

       6.2.2.1 Engine Improvements for Class II

       Engine improvements include improved engine design and larger induction coils as
shown in Tables 6.2-12 and 6.2-13. Improvements in engine design will allow for more efficient
combustion and a more favorable HC:NOx ratio for the use of a reducing catalyst. A larger
induction coil will reduce the opportunity for spark plug wire failure and misfire events. It is
estimated that 1000 hour engines currently have sufficient induction coils and will not need this
improvement.
                                          6-13

-------
Final Regulatory Impact Analysis
                            Table 6.2-12: Variable Costs for
                     Engine Improvements for Class II per Engine16

Larger Induction Coils
TOTAL
w/Markup 29% OEM
Learning w/29% OEM
(0.8*Total)*1.29
UL250
0.09
0.12
0.10
UL500
0.09
0.12
0.10
UL 1000
~
~
~
       Improved engine design includes machining and casting tolerances, improved
combustion chamber configuration, reduced crevice volumes, better cooling (improved fin
design on cylinder head and oil control), improved flywheel design and improved carburetion.
Better carburetor performance is needed to assure floats do not stick and better cooling so
engines operate at cooler temperatures.  Fixed costs include design (one engineer at 4 months),
development and tooling costs (one engineer, one technician and dynamometer time for 6
months) per engine family to achieve improved engine design. Projected fixed costs are
presented in Table 6.2-13. The fixed cost is estimated to be the same per engine family  and is
estimated at $456,450.
                                         6-14

-------
                                                                        Costs of Control
                              Table 6.2-13: Fixed Costs for
                  Engine Improvements for Class II per Engine Family17
Engine Class
Useful life (hrs)
Valving
Class II
250,500,1000
OHV
R&D
Design (4 months)
Development (6 months)
TOTAL R&D per Engine Line
41,225
172,225
213,450
TOOLING COSTS
Cylinder Head
Piston
Connecting Rod
Camshaft
Carburetor
Flywheel
Setup Changes
TOTAL TOOLING per Engine Line
TOTAL FIXED
25,000
25,000
15,000
8,000
60,000
35,000
75,000
$243,000
$456,450
       6.2.2.2 Catalysts for Class II

       Further emission reduction can be achieved through the use of catalysts. The catalyst
must be designed for durability throughout the engine's regulatory useful life.  A catalyst
efficiency of 25-45 percent is estimated for these engines.  The catalyst technology that would
be utilized would be similar to that used for Class I engines. The exceptions include:  1) Class II
engines would not use supplemental air because the HC and NOx ratios are more favorable in
Class II OHV engines due to their more efficient combustion chamber and larger displacement
and horsepower, and 2) the precious metals in the catalysts range from
platinum/palladium/rhodium for 250 and 500 hour Class II engines to to palladium/rhodium
(5:1) for 1000 hour regulatory useful life engines.

       Class II engine designs include engines 1 to 4 cylinders.  Engines with two or more
cylinders have specific issues to be considered in terms of safety with regard to engine exhaust
and catalyst use and this will be addressed towards the end of this section. The variable costs for
                                          6-15

-------
Final Regulatory Impact Analysis
catalysts of single cylinder engines are listed in Table 6.2-14. The catalyst substrate size is
calculated based on the engine displacement size.  To utilize one value per regulatory useful life
category for this analysis, the engine horsepower and displacements were sales weighted with
values from the 2005 EPA certification database information. Catalyst volumes range from 33
percent of the engine displacement for the 250 useful life to 50 percent of the engine
displacement for the 1000 hour useful life. Larger catalysts are needed for longer useful life
periods in order to provide the emission conversion durability.

       Catalyst substrate and heat shield variable costs will be decreased in the sixth year with a
learning curve of 20 percent.  This  somewhat conservative since the learning normally occurs at
20 percent with a doubling of production which would be in the third or fourth year. Optimized
catalyst/muffler designs and heat shield manufacturing processes will likely be developed as the
industry becomes experienced in application of the catalyst technology across their product line.
The muffler washcoat will likely still be unique per engine family per engine manufacturer and
therefore it is estimated there will likely not be a one size fits all catalyst/muffler design.  The
precious metal prices are determined in the marketplace and therefore are not discounted over
time.
                                           6-16

-------
                                                                        Costs of Control
      Table 6.2-14: Variable Catalyst Costs for Class II OHV Single Cylinder Engine
                   HC+NOx Emission Reduction to Phase 3 Standards

Useful Life
Engine Power (hp)
Engine Displacement (cc)
Catalyst Volume (cc)
Substrate Diameter (cm)
Substrate*
Washcoat and Precious Metal
Labor
Labor Overhead 40%
Supplier Markup 29%
Manufacture Price
Heat Shield
Spark Arrester
Hardware Cost to Manufacturer
w/Markup 29% OEM
Near Term Estimates
250
11.3
406
134
5.25
$4.78
$4.03
$1.40
$0.56
$3.12
$13.89
$4.23
$0.10
$18.22
$23.50
500
11.1
338
135
6.00
$4.81
$2.73
$1.40
$0.56
$2.75
$12.25
$3.96
$0.05
$16.26
$20.97
1000
9.5
329
165
7.00
$5.67
$4.10
$1.40
$0.56
$3.40
$15.13
$4.05
$0.05
$19.23
$24.80
Learning Curve Estimates
250
11.3
406
134
5.25
$3.82
$4.03
$1.40
$0.56
$2.84
$12.65
$3.38
$0.10
$16.14
$20.82
500
11.1
338
135
6.00
$3.84
$2.73
$1.40
$0.56
$2.47
$11.00
$3.17
$0.05
$14.23
$18.35
1000
9.5
329
165
7.00
$4.53
$4.10
$1.40
$0.56
$3.07
$13.66
$3.24
$0.05
$16.95
$21.87
              * 50/50- split of metallic vs ceramic substrates
       Fixed costs involve modification to the existing heat shield and cooling system.  If the
muffler is in close proximity to the engine fan then cost for a heat shield can also be included
because in some cases the heat shields will need to be improved in order to direct cooling air
from the engine's flywheel over the muffler for muffler cooling. These fixed costs are presented
in Table 6.2-15.
                                          6-17

-------
Final Regulatory Impact Analysis
            Table 6.2-15: Fixed Costs for Class II OHV Single Cylinder Engine
Engine Class
Useful life (hrs)
Valving
II
125, 250, 500
OHV
R&D
Design
(2 months)
Development (5 months)
TOTAL R&D per Engine Line
20,612
143,521
164,133
TOOLING COSTS
Modified Muffler Stamping
Heat Shield Stamping
Engine Shroud Modification
Setup Changes
TOTAL TOOLING per Engine Line
TOTAL FIXED COSTS
50,000
30,000
15,000
25,000
120,000
$284,133
Carbureted V-Twins

       Carbureted engines with more than one cylinder, ex: V-twins or more, have special
concerns when considering the use of catalyst application. Multi-cylinder engines may continue
to run if one cylinder misfires or does not fire at all. If this occurs, the results is raw unburned
fuel and air from one cylinder and hot exhaust gases from the other cylinder combining in the
muffler.  In a catalyst muffler, this condition will likely result in continuous backfire which
would create high temperatures within the muffler and potentially destroy the catalyst.  One
solution is to have separate catalyst mufflers for each cylinder.  The two cylinders in the V-twins
currently share one muffler. If two mufflers are used, then the individual mufflers would likely
need to be slightly larger. Each individual muffler would need to be 25-30 percent larger than
one half the volume of the original. Since the two cylinders in the V-twins currently share one
muffler one option for consideration would be to package the two catalysts in separate chambers
within one larger muffler.

       Costs for this new muffler design are listed in Tables 6.2-16 and 6.2-17. V-twin engines
from EPA's certification database were sales weighted for power and engine displacement per
regulatory useful life. ICF provided the estimates for existing muffler costs and new muffler
cost estimates.
             18
                                           6-18

-------
                                                                        Costs of Control
          Table 6.2-16: Variable Costs for Change to Two Mufflers for V-Twins
                                                                             19

Engine Power (hp)
Engine Displacement - Total (cc)
Per Cylinder Displacement (cc)
Current Muffler Cost
New Muffler Cost (includes 2)
Hardware Cost to Manufacturer
OEM Markup @ 29%
Total Component Costs
250 OHV
16.3
605
393
($20.24)
$26.31
$6.07
$1.76
$7.83
500 OHV
20.1
632
411
($23.13)
$30.07
$6.94
$2.01
$8.95
1000 OHV
17.1
627
408
($22.57)
$29.34
$6.77
$1.96
$8.73
       Fixed costs include modified muffler stamping, exhaust pipe changes and setup changes.
These costs are estimated at $100,000 per engine family. Special considerations were not
accounted for in the case where OEM's obtain their own muffler and assemble the muffler onto
the engine once the engine is received from the engine manufacturer. This analysis considers
that in most cases equipment manufacturers would buy their catalyst mufflers from the engine
manufacturer in order to avoid engine certification.

           Table 6.2-17:  Fixed Costs for Change to Two Mufflers for V-Twins2

Engine Power
Engine Displacement - Total (cc)
Per Cylinder Displacement
Modified Muffler Stamping
Exhaust Pipe Changes
Setup Changes
Total Tooling per Engine Line
250 OHV
16.3hp
605
393
$50,000
$25,000
$25,000
$100,000
500 OHV
20.1hp
632
411
$50,000
$25,000
$25,000
$100,000
1000 OHV
17.1hp
627
408
$50,000
$25,000
$25,000
$100,000
       In this analysis, catalyst sizes are related to the engine cylinder size and therefore since
cylinders of V-twin engines are smaller than one cylinder Class II engines, costs are recalculated
from Table 6.2-14. Note that one catalyst is used in each muffler for a total of two catalysts.
Tables 6.2-18 and 6.2-19 present the projected variable and fixed catalyst costs for Class II OHV
V-twin engines.
                                          6-19

-------
Final Regulatory Impact Analysis
         Table 6.2-18: Variable Catalyst Costs for Class II OHV V-Twin Engine,
                        Near Term and Learning Curve Effect

Useful Life
Engine Power (hp)
Engine Displacement per Cylinder
Catalyst Volume (cc)
Substrate Diameter (cm)
Substrate*
Washcoat and Precious Metal
Labor
Labor Overhead 40%
Supplier Markup 29%
Manufacture Price per Catalyst
Two Catalysts ($x2)
Heat Shield (2)
Spark Arrester (2)
Hardware Cost to Manufacturer
Markup
29% OEM
New Muffler Differential
TOTAL COST
Near Term Costs
250
16.3
303
100
5.00
$3.74
$3.00
$1.40
$0.56
$2.52
$11.22
$22.45
$8.53
$0.20
$31.18
$9.04
$7.83
$48.05
500
21.0
316
126
5.00
$4.55
$2.55
$1.40
$0.56
$2.63
$11.68
$23.36
$9.76
$0.10
$33.22
$9.63
$8.95
$51.80
1000
17.1
314
157
5.50
$5.44
$3.91
$1.40
$0.56
$3.28
$14.59
$29.18
$10.50
$0.10
$39.79
$11.54
$8.73
$60.06
Learning Curve Effect
250
16.3
303
100
5.00
$2.99
$3.00
$1.40
$0.56
$2.31
$10.26
$20.52
$6.82
$0.20
$27.54
$7.99
$6.26
$41.97
500
21.0
316
126
5.00
$3.64
$2.55
$1.40
$0.56
$2.36
$10.51
$21.02
$7.81
$O.10
$28.92
$8.39
$7.16
$44.76
1000
17.1
314
157
5.50
$4.35
$3.91
$1.40
$0.56
$2.96
$13.19
$26.37
$8.4
$0.1
$34.87
$10.11
$6.98
$51.97
             * 50/50- split of metallic vs ceramic substrates
                                        6-20

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                                                                         Costs of Control
                Table 6.2-19: Fixed Costs for Class II OHV V-Twin Engine
Useful Lives
250, 500, 1000
R&D COSTS
Design (2 months)
Development (5 months)
TOTAL R&D
$20,612
$143,521
$164,133
TOOLING COSTS
Heat Shield Stamping
Engine Shroud Modification
Setup Changes
New Muffler Design
Total Tooling per Engine Line
TOTAL FIXED COSTS
$50,000
$25,000
$25,000
$100,000
$200,000
$364,133
Electronic Fuel Injection

       Electronic fuel injection (EFI) is another solution for engines with two or more cylinders.
EFI will allow more equal fuel delivery between or among the engine cylinders.  In addition, it
enables better atomization and more efficient fuel delivery during load pickup.   If an engine
family is somewhat close to the Phase 3 standard currently then EFI may allow the engine to
meet the emission standards without a catalyst.  If a small catalyst is needed, EFI allows the
engine to be setup for cylinder monitoring and can be shut down if all cylinders are not operating
properly. Due to the anticipated higher cost for EFI compared to catalyst, EPA estimates that
each engine manufacturer will initially apply EFI to the engine family, of two or more cylinders,
with the highest sales volume.  Table 6.2-20 lists the estimated costs to apply electronic fuel
injection.  The cost tables include subtracting the existing carburetor.
                                          6-21

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Final Regulatory Impact Analysis
    Table 6.2-20:  Variable Costs for Electronic Fuel Injection - Open and Closed Loop
                  For Class II Engines and Applications with a Battery21

Injectors
Pressure Regulator
ECM/MAP Sensor
Throttle Body
Air Temperature Sensor
Fuel Pump
Oxygen Sensor
Wiring/Related Hardware
HARDWARE COST TO MANUFACTURE
OEM markup @ 29%
Warranty Markup @ 5%
Total Component Cost
Remove existing carburetor ($15) marked up 29%
EFI Technology Difference
Open Loop EFI
8.00
3.75
27.00
2.75
1.50
10.50
~
12.00
66.75
19.36
2.85
88.96
-19.35
$69.61
Closed Loop EFI
8.00
3.75
27.00
2.75
1.50
10.50
7.00
12.00
73.75
21.39
3.69
98.83
-19.35
$79.48
       Fixed costs for electronic fuel injection are listed in Table 6.2-21. Open loop fuel
injection requires more research and development time due to the fact that it does not use an
oxygen sensor to keep the air/fuel ratio in check. This analysis estimatess all engines using
electronic fuel injection will be developed as closed loop fuel injection systems.
                                          6-22

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                                                                        Costs of Control
      Table 6.2-21: Fixed Costs for Electronic Fuel Injection - Open and Closed Loop
                  For Class II Engines and Applications with a Battery

Design
Development
Modified Exhaust Manifold for O2 Sensor
Total Fixed Costs
Open Loop
$41,225
$229,633

$270,858
Closed Loop
$20,612
$57,408
$25,000
$103,020
       6.2.2.3 Equipment Costs

       The majority of Class I engines are sold as a unit and therefore the engine, fuel tank and
muffler are provided by the engine manufacturer to the equipment manufacturer. As shown in
EPA's Technical Study on the "Safety of Emission Controls for Nonroad Spark-Ignition Engines
<50 Horsepower", catalysts can be applied to Class I engines such that muffler temperatures are
equal to or less than those of the current Phase 2 product with minimal changes to the engine
package. Some engines may require larger mufflers to house a catalyst depending on current
muffler design. However the majority of equipment housing Class I engines are close coupled to
the engine with open access for air cooling and therefore it no equipment redesign costs are
applied to equipment manufacturers.

       The majority of Class II engines are not sold as a unit. The current industry practice
includes equipment manufacturers purchasing the muffler separate  from the engine.  Based on
conversations with industry it is believed that for several reasons this practice will change to the
dominant practice being the equipment manufacturer purchasing the muffler from the engine
manufacturer.  The offerings by the engine manufacturer will likely be influenced by the largest
customers and smaller equipment manufacturers will have a few set models from which to
choose. A limited amount of equipment redesign will be required on products.

       EPA's work with catalysts in mufflers of two one-cylinder Class II lawn tractor engines
has revealed that the current muffler on this equipment type has plenty of room to accommodate
the catalyst and internal baffling to promote cooling of the exhaust gases.  Smaller mufflers are
used in other applications in which engine noise is not of concern.  EPA did not work with these
mufflers and therefore, it is uncertain if the catalyzed muffler will work in these mufflers.  It is
possible that a larger muffler can may be required to accommodate the catalyst.

       Changes that will be required on Class II engines with catalysts includes a heat shield for
the muffler (counted in catalyst costs), necessary sheet metal to  direct cooling  from the engine
flywheel to the muffler and any equipment design changes to accommodate a different engine
envelope.

       Incorporating shrouding to direct the cooling air to and around the muffler is of most
                                          6-23

-------
Final Regulatory Impact Analysis
importance.  The shrouding added includes extending and rerouting some of the engine sheet
metal that is used to direct the air-flow out of the engine cylinder and blocking off the usual air
exit into the  engine compartment. The air is routed out the bottom of the chassis instead. In
EPA's Class II one cylinder engine testing, the "touch-guard" was boxed in by closing off it's
slots, closing off one end, and reducing the size of the opening on the opposite end.  The exhaust
exit was re-routed to a different location, and an ejector was added over the top of the exhaust.
The amount  of additional metal is fairly minimal and relatively thin-gage. The best examples are
the Kohler CV490 on one of the Craftsman tractors and the Kohler SV590 on the Cub Cadet.
Detailed photos of the SV590 installation can be found in EPA's Safety Study.22

      For equipment that use engines with catalysts and require heat shield or equipment
design changes, variable costs are estimated for the sheet metal and/or engine structure redesign
at $1.30 per  piece of equipment. Since a portion of engines are assigned to EFI, or will likely
not require additional heat shield or equipment modifications due to current equipment design, it
is estimated  that 60 percent of equipment will utilize increased sheet metal and/or engine
structure redesign.  This yields a sales weighted average of $0.78 per equipment. Fixed costs
for R&D for the added sheet metal design and/or engine restructure are estimated at $30,000 per
equipment model and tooling changes are also estimated at $45,000 per model. These estimates
are based on the estimates for developing and applying heat shields in the catalyst cost estimates
for Class II and can be seen in Table 6.2-22.

             Table 6.2-22: Average Equipment Costs Per Equipment Model

Heat Shield
Additional material for
equipment redesign or air
entrainment pathway
R&D
Tooling Changes
Variable Costs
-0- included in catalyst costs
1.30 per equipment
0.78 avg over all for 60% of
equipment
n/a
n/a
Fixed Costs
-0- included in catalyst costs
n/a
30,000
45,000
6.2.3  Compliance and Certification

       The certification and compliance costs include engine dynamometer aging as well as
emission testing pre- and post-aging. Certification and compliance costs are included in this
analysis as fixed costs.  After preliminary emission testing, engines are aged on the
dynamometer to the regulatory useful life. The aged engines are then emission tested.  The
engine's emission levels must be below the new standards. If not, then the engine family cannot
be certified unless the excesses are offset with other engine families within a manufacturers
product line and the manufacturer must be involved in the averaging, banking and trading
program.  Engine families will need to certify to the new emission standards using the updated
                                          6-24

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                                                                        Costs of Control
test procedure found in Chapter 4.

       The Phase 2 certification database was used as the basis for the number of engine
families to be certified to these standards. The 2005 Certification database contains a number of
engine manufacturers that have certified to the Phase 1 emission standards (1997) as well as a
large number of additional engine manufacturers that have certified to the Phase 2 standards
(2002).

       6.2.3.1 Measurement Protocol 1065 Compliance Costs

       New to the small engine industry are the 1065 protocols for gaseous emission
measurement.  These protocols are found in 40 CFR Part 1065. Depending on the analyzing
equipment used by the industry, the certification analyzers may have to be upgraded to the
estimated cost of $250,000.  It is possible that less costly upgrades on some analyzers will be
available. A CVS system can be assembled for $50,000 given manufacturer ingenuity.

       6.2.3.2 Certification Costs

       Certification costs include emission testing after a short engine break-in period and aging
on a dynamometer to the full useful life and then repeat emission testing.  Costs for
dynamometer aging of each Class and corresponding useful life are found in ICF's report "Small
SI Engine Technologies and Costs."23 The costs per dynamometer  aged engines are estimated in
Table 6.2-3. are based on test setup, data analysis, engine aging operation, dyno costs, scheduled
maintenance, prototype engine cost and fuel.

     Table 6.2-23: Dynamometer Aging Certification Costs Per Class and Useful Life
CLASS I
125
250
500
$9,532
$17,462
$33,353
CLASS II
250
500
1,000
$18,413
$34,658
$70,069
       The costs for the emission compliance tests are found in Tables 6.2-24 and 6.2-25 and
they are the same for each engine regardless of useful life category.  A total of two emission
tests after break-in and two at end of useful life are accounted for in this cost analysis. The
emission test costs are estimated at $2,012 each and are based on the costs for a private test
laboratory in 2005.24

                     Table 6.2-24:  Emission Testing Costs Per Class
CLASS I
all useful lives
$8,048
CLASS II
all useful lives
$8,048
                                          6-25

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Final Regulatory Impact Analysis
          Table 6.2-25:  Per Engine Family Emission Testing and Dynamometer
                         Aging Costs Per Class and Useful Life
CLASS I
125
250
500
$17,580
$25,510
$41,401
CLASS II
250
500
1,000
$26,461
$42,706
$78,117
6.2.4  LPG/CNG Engine Costs

       Engine manufacturers and equipment manufacturers certify engines to run on LPG.  The
number of engine families are obtained from EPA's 2008 Certification Database. Certification
costs found in Section 6.2.3.2 apply to these engines. Part 1065 compliance costs are not applied
since the engine manufacturers are the same as listed in the gasoline section (costs already
applied) and it is estimated that equipment manufacturers contract with a test lab due to the high
cost of maintaining an individual test lab.

       For engine certification, all engine families will be required to be tested for baseline
emissions, see Table 6.2-26.  Small volume engine manufacturers with a production of 10,000
engines or less can utilize an assigned deterioration factor and do not have to undergo
dynamometer aging or end of life emission testing.  Those listed under dynamometer aging in
Table 6.2-26 will need to age the engines and perform end of life emission testing. The number
of engine families listed under catalyst development will need emission reduction technology
such as catalysts.

              Table 6.2-26: Number of LPG Engine Families Per Class and
                    Useful Life Designation for Fixed Cost Analysis
CLASS I
UL
125
250
500
BaselineE
mission
Testing
~
~
2
Dynamo-meter
Aging + End of
Life Emission
Testing
~
~
2
Catalyst
Dev
~
~
1
CLASS II
UL
250
500
1000
Baseline
Emission
Testing
9
20
13
Dynamo-meter
Aging + End of
Life Emission
Testing
9
20
13
Catalyst
Dev
lcyl/2cyl
1
2
1
2
10
8
For Phase 3, companies with small volume production (<10,000) can use an assigned df.
                                          6-26

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                                                                        Costs of Control
       Table 6.2-27 lists the certification costs.
                         Table 6.2-27:  Certification Costs - LPG

Baseline Emission Testing
Dynamometer Aging
End of Life Emission Test
Total
Class I
$8,048
$66,706
$8,048
$82,802
Class II
$169,008
$1,769,774
$169,008
$2,107,790
       As mentioned above, the technology to reduce emissions to the Phase 3 levels is
catalysts.  Catalysts are currently being utilized on LPG engines as shown in EPA's 2008
Certification Database. Basic engine improvement design changes, accounted for in the gasoline
engine families, were not accounted for in these engines for they were already made in the base
engine before they were converted to run on LPG/CNG.  Costs that will be applied to these
engines are R&D for catalyst formulation and variable parts costs which will need to be
formulated for the exhaust makeup from these engines.  The majority of these engines are two
cylinder engines, however the concerns of the application of catalysts to these engine designs are
relieved in that some of the V-twin LPG engines are already certified with catalysts.  Costs for
catalyst system redesign for some of the existing engine families are included in order for these
families to meet the Phase 3 standards.  Table 6.2-28 lists the R&D and Tooling costs for
catalysts for LPG.  Table 6.2-29 contains the totals for fixed cost for each class given the total
number of engine families listed in Table 6.2-26.
                                          6-27

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Final Regulatory Impact Analysis
Table 6.2-28:  Fixed Costs for Class II OHV Single Cylinder Engine - LPG
Engine Class
Useful life (his)
Valving
II
125, 250, 500
OHV
R&D
Design
Development (5 months)
TOTAL R&D per Engine Line
$20,612
$143,521
$164,133
TOOLING COSTS
TOTAL TOOLING per Engine Line
TOTAL FIXED COSTS
0*
$164,133
       *LPG engines are modified from gasoline version engines. Tooling costs are not included for it
       is estimated that catalyst volume for these engines will be determined based on a percentage of
       engine displacement, as the gasoline version, and therefore the catalysts will fit into the same
       muffler space.

                        Table 6.2-29: Total Fixed Costs for LPG
                                 Engine Families  2005$

Catalyst R&D
Certification Cost
TOTAL
Class I
$492,399
$47,114
$539,413
Class II
$6,072,921
$1,146,438
$7,219,359
       Certification data on gaseous fueled engines show that the HC:NOx ratio is higher in
NOx than in HC which is opposite from gasoline engines.  Platinum will be used in the precious
metal mixture in order for the oxygen reduced from the NOx to be utilized to convert CO due to
the lack of HC. For Class I engines, the cost estimate presented in Table 6.2-7 is applicable
because it is calculated with a platinum/palladium/rhodium ratio of 5/0/1.  For Class II engines,
the 500 and 1000 hour catalyst cost estimates will be modified in order to include more platinum
and all useful life periods will have resized catalysts based on the sales weighted engine
displacement in the certification listing of LPG engines. Table 6.2-30 lists the variable catalyst
costs for Class II OHV Engines, 250 and 500 hour useful life engines (no 1000 hour UL engines
are listed in the LPG certification).  Two to three cylinder engines have higher displacement and
therefore costs are recalculated for those engine designs.
                                          6-28

-------
                                                                             Costs of Control
           Table 6.2-30: Variable Catalyst Costs for Class II OHV Engines - LPG
                    HC+NOx Emission Reduction to Phase 3 Standards

Useful Life
Engine Power (hp)
Engine Displacement (cc)
Engine/Catalyst
Catalyst Volume (cc)*** (per
cylinder)
Substrate Diameter
Substrate* (per cylinder)
Washcoat and Precious Metal
Labor
Labor Overhead 40%
Supplier Markup 29%
Manufacture Price (per catalyst)
Total Catalyst Cost
Heat Shield (2 for v-twin)
Spark Arrester (2 for v-twin)
Hardware Cost to Manufacturer
w/Markup 29% OEM
Add'l Muffler for V-twin
Total Catalyst Cost for LPG
engines
Total Catalyst Cost for Gasoline
Engines
Cost Difference
1 cylinder
250
13.8
415
33%
137
5.25
5.55
4.24
$1.40
$0.56
$3.41
$15.16
$15.16
$4.23
$0.10
$19.49
$25.14
-
$24.14
$23.50
$1.64
500
17.8
389
40%
156
6.00
8.91
4.82
$1.40
$0.56
$4.55
$20.24
$20.24
$4.26
$0.05
$24.55
$31.67
-
$31.67
$20.97
$10.70
1000**
-
-
-
-
-
-
-
-
-
-
-

-
-
-
-
-
-
-
-
2 cylinders
250
18.2
597
33%
197
5.00
3.70
2.96
$1.40
$0.56
$2.50
$11.12
$22.24
$5.90
$0.20
$28.34
$8.22
$7.83
$44.40
$48.05
-$3.66
500
19.2
743
40%
297
5.00
5.20
4.46
$1.40
$0.56
$3.37
$14.99
$30.00
$6.92
$0.10
$37.00
$10.73
$8.95
$56.68
$51.80
$4.87
1000
23
751
50%
376
5.50
6.34
8.86
$1.40
$0.56
$4.97
$22.14
$44.24
$7.32
$0.10
$51.69
$14.99
$8.73
$75.41
$60.06
$15.37
 * 50/50- split of metallic vs ceramic substrates
 ** No one cylinder LPG engines are certified to the 1000 hour useful life
*** these catalyst volumes were calculated from the engine disp in EPA's certification data for 2005
                                             6-29

-------
Final Regulatory Impact Analysis
       Calculations for the rulemaking have been completed using gasoline assumptions. To
account for the increase in costs due to some of the gasoline engines being used as LPG engines,
an increase in the total cost is added to the current gasoline engine variable cost total.
Table 6.2.-31 is an example of costs for 2012 in 2005$.

               Table 6.2-31: Change in Variable Cost in 2012, 2005$ - LPG

Total Engine
Sales
Estimate per
Useful Life
2012
%of
LPG/CNG
Engines in
Useful Life
per Class
#ofCyl
Number
of
Engines
with
change in
Cost
Estimate
Variable
Cost
Change in
2012
Total Change in
costs in 2012
2005$
Class I
125 OHV
250
500
2,953,419
905,005
623,431
0%
0%
0.63%
1
1
1
0
0
3574
0
0
0
0
0
0
Class II
250
500
1000
3,334,488
724,231
821,463
0.58%
1.94%
3.19%
1
2
1
2
2
14,500
10,469
12,918
90,630
18,700
$1.38
-$2.95
$9.25
$5.17
$15.59
2012 Total Increase
$20,027
-$30,923
$119,523
$ 468,553
$ 291,517
$868,698
* use the same technology as gasoline counterpart

       Table 6.2-32 contains the catalyst cost estimates for LPG engines including a learning
curve discount. This cost estimate is used in year six of the cost estimates.
                                          6-30

-------
                                                                            Costs of Control
  Table 6.2-32: Variable Catalyst Costs with Learning Curve for Class II OHV Engines
                LPG; HC+NOx Emission Reduction to Phase 3 Standards

Useful Life
Engine Power (hp)
Engine Displacement (cc)
Engine/Catalyst
Catalyst Volume (cc)*** (per
cylinder)
Substrate Diameter
Substrate* (per cylinder)
Washcoat and Precious Metal
Labor
Labor Overhead 40%
Supplier Markup 29%
Manufacture Price (per catalyst)
Total Catalyst Cost
Heat Shield (2 for v-twin)
Spark Arrester (2 for v-twin)
Hardware Cost to Manufacturer
w/Markup 29% OEM
Add'l Muffler for V-twin
Total Catalyst Cost for LPG
engines
Total Catalyst Cost for Gasoline
Engines
Cost Difference
1 cylinder
250
13.8
415
33%
137
5.25
4.44
4.24
$1.40
$0.56
$3.09
$13.73
$15.90
$3.38
$0.10
$17.21
$22.20
-
$22.20
$20.82
$1.38
500
17.8
389
40%
156
6.00
7.13
4.82
$1.40
$0.56
$4.03
$17.94
$24.88
$3.41
$0.05
$21.40
$27.61
-
$27.61
$18.35
$9.25
1000**
-
-
-
-
-
-
-
-
-
-
-

-
-
-
-
-
-
-
-
2 cylinders
250
18.2
597
33%
197
5.00
2.96
2.96
$1.40
$0.56
$2.29
$10.17
$20.33
$4.72
$0.20
$25.25
$7.32
$6.26
$38.84
$41.79
-$2.95
500
19.2
743
40%
297
5.00
4.16
4.46
$1.40
$0.56
$3.07
$13.65
$27.30
$5.54
$0.10
$32.93
$9.55
$7.16
$49.64
$44.47
$5.17
1000
23
751
50%
376
5.50
5.07
8.86
$1.40
$0.56
$4.61
$20.50
$41.00
$5.86
$0.10
$46.96
$13.62
$6.98
$67.56
$51.97
$15.59
 * 50/50- split of metallic vs ceramic substrates
 ** No one cylinder LPG engines are certified to the 1000 hour useful life
*** these catalyst volumes were calculated from the engine disp in EPA's certification data for 2005
                                            6-31

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Final Regulatory Impact Analysis
6.2.5  Small SI Aggregate Costs

       Costs presented in the previous sections are combined here to present streams of costs.
The first, Section 6.2.5.1, presents variable costs (recurring costs) for meeting the Phase 3
exhaust standards.  Section 6.2.5.2 presents a stream of fixed costs for meeting the Phase 3
exhaust standards.  Costs are based on assuming all engines are gasoline engines. Additional
costs for LPG engines are included at the end of this section.

       6.2.5.1 Variable Costs for Meeting Exhaust Standards

       Variable costs for Class I are summarized in Table 6.2-10 for engine improvements and
catalysts in near term and long term (with learning) costs.  Nearly all engines in Class I (96.9%
125 useful life (UL), 99.4% 250 UL and 72.65% 500 UL) are estimated to have both
technologies applied and therefore the costs are added according to useful life period and then
multiplied by the number of engines sold per useful life category, as will be discussed later.  The
resultant variable costs per engine is presented in Table 6.2-33.  Long term costs are six years
after the near term costs and include a 20 percent learning curve reduction for engine
improvement components, catalyst substrate and heat shield costs.

       Variable costs for Class II are a combination of engine improvements and catalyst or
engine improvements and electronic fuel injection (EFI), see Section 6.2.2.  Information on
engine designs and related certification emission results in the 2008 EPA Certification Database
were utilized to determine the percentage of technologies per useful life. A portion of the
engines, the largest multi-cylinder engine family per engine manufacturer needing emission
reduction, are assigned the use of electronic fuel injection. The remaining engine families are
assigned catalysts and related engine improvements.  Some engines would not to require any
costs. Long term costs (learning) are six years after the near term costs and include a 20 percent
learning curve reduction for engine improvement components, catalyst substrate and heat shield
costs.

              Table 6.2-32: Percentage Technologies Per Useful Life per Class II
Useful Life
250
500
1000
No changes

43.66%
59.84%
28.50%
2FI - Class II
V-twin
5.88%
5.62%
10.80%
V-twin
catalyst
0.61%
0.30%
18.24%
Catalvst-Sinale
Cylinder
49.85%
34.24%
42.46%
                                           6-32

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                                                                      Costs of Control
                  Table 6.2-33: Variable Costs Per Engine for Meeting
                        Exhaust Standards, Per Engine (2005$)
Useful Life (his)
125- SV
125 - OHV
250
500
1000
Class I
Near Term (20 12)
10.41
8.55
12.17
11.71
~
Long Term
(2017)*
9.43
7.80
11.33
10.87
~
Class II
Near Term (20 11)
~
~
16.8
11.93
30.07
Long Term
(2016)*
~
~
14.24
9.87
25.21
       *Long term includes learning reduction
       The total Small SI engine costs for the first 30 years (2008-2037) were estimated using
sales and growth estimates from the US EPA's NONROAD model. The percentage sales per
useful life category (Class I:  125, 250, 500, Class II: 250, 500, 1000) were calculated from the
manufacturer prescribed useful life period and yearly estimated sales per engine family in the
EPA 2008 Phase 2 certification database (confidential information).  The percentages in
Table 6.2-34 were applied to US EPA's NONROAD model sales estimates and the results are
presented in Table 6.2-35  Note that snowblowers are not included for they only have to comply
with the evaporative standards since they are exempted from the exhaust emission standards.

                            Table 6.2-34: Small SI Engines
                            Sale Percentages per Useful Life
Useful Life
125- SV
125 - OHV
250
500
1000
Class I
66%
23%
6%
5%

Class II


74%
11%
15%
                                         6-3

-------
Final Regulatory Impact Analysis
                    Table 6.2-35: Class I and Class II Projected Sales
                    per Useful Life Category (snowblowers excluded)
YEAR
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
CLASS 1
125
SV
6,139,695
6,250,204
6,360,351
6,474,907
6,584,353
6,698,636
6,810,588
6,921,857
7,031,516
7,144,731
7,256,744
7,370,110
7,482,752
7,594,978
7,706,370
7,818,799
7,931,065
8,043,780
8,157,416
8,270,846
8,383,989
8,497,471
8,610,967
8,724,583
8,838,143
8,951,587
9,064,949
9,178,412
9,291,898
9,405,435
125
OHV
2,112,583
2,150,608
2,188,508
2,227,925
2,265,584
2,304,907
2,343,428
2,381,714
2,419,446
2,458,402
2,496,944
2,535,952
2,574,710
2,613,326
2,651 ,654
2,690,339
2,728,969
2,767,752
2,806,853
2,845,883
2,884,814
2,923,861
2,962,913
3,002,007
3,041 ,082
3,080,116
3,119,122
3,158,163
3,197,212
3,236,279
250
OHV
565,168
575,340
585,479
596,025
606,099
616,619
626,924
637,167
647,261
657,683
667,994
678,429
688,798
699,129
709,382
719,732
730,066
740,442
750,902
761 ,343
771 ,758
782,204
792,652
803,110
813,564
824,006
834,442
844,886
855,333
865,784
500
OHV
489,249
498,055
506,832
515,961
524,682
533,789
542,710
551 ,577
560,315
569,337
578,263
587,296
596,272
605,215
614,091
623,051
631 ,997
640,978
650,034
659,072
668,088
677,131
686,175
695,229
704,278
713,318
722,352
731 ,393
740,436
749,484
CLASS II
250
OHV
3,375,298
3,436,078
3,497,169
3,560,736
3,621 ,924
3,685,741
3,747,698
3,809,238
3,870,775
3,933,230
3,995,499
4,058,405
4,120,822
4,183,226
4,245,149
4,307,507
4,369,904
4,432,728
4,495,615
4,558,320
4,620,946
4,683,749
4,746,567
4,809,474
4,872,290
4,935,044
4,997,777
5,060,568
5,123,362
5,186,178
500
OHV
485,273
494,012
502,795
511,934
520,731
529,906
538,814
547,662
556,509
565,488
574,441
583,485
592,459
601,431
610,333
619,299
628,270
637,302
646,344
655,359
664,363
673,392
682,423
691 ,468
700,499
709,521
718,540
727,568
736,596
745,627
1,000
OHV
687,306
699,683
712,123
725,067
737,527
750,522
763,138
775,669
788,200
800,917
813,597
826,406
839,116
851 ,824
864,433
877,131
889,837
902,629
915,435
928,203
940,956
953,744
966,536
979,345
992,137
1,004,915
1,017,689
1 ,030,475
1 ,043,262
1 ,056,053
       The Total Variable Costs were calculated using the sales information found in
Table 6.2-35 and applying the corresponding variable cost from Table 6.2-33. Results are
presented in Table 6.2-36. Engines used in snowblowers and handheld equipment will require
only evaporative control measures and these are presented in Section 6.5.
                                          6-34

-------
                                                                        Costs of Control
   Table 6.2-36: Variable Costs for Meeting Phase 3 Exhaust Emission Standards, 2005$
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
Class 1: Engine only
125
-
_
-
-
86,472,768
87,973,661
89,443,931
90,905,230
92,345,393
86,511,329
87,867,634
89,240,307
90,604,228
91,963,103
93,311,878
94,673,217
96,032,587
97,397,383
98,773,331
100,146,794
101,516,776
102,890,863
104,265,113
105,640,825
107,015,858
108,389,476
109,762,116
111,135,969
112,510,105
113,884,858
250
-
-
-
-
7,376,417
7,504,448
7,629,867
7,754,521
7,877,372
7,449,638
7,566,432
7,684,635
7,802,085
7,919,100
8,035,245
8,152,473
8,269,530
8,387,055
8,505,540
8,623,812
8,741 ,783
8,860,108
8,978,447
9,096,912
9,215,318
9,333,603
9,451 ,803
9,570,108
9,688,438
9,806,820
500
-
-
-
-
6,141,854
6,248,457
6,352,885
6,456,676
6,558,965
6,191,089
6,288,151
6,386,385
6,483,993
6,581 ,239
6,677,763
6,775,185
6,872,467
6,970,137
7,068,606
7,166,896
7,264,937
7,363,272
7,461,619
7,560,070
7,658,473
7,756,775
7,855,006
7,953,324
8,051 ,663
8,150,046
Class II: Engine & Equipment
250
-
-
-
59,835,023
60,863,232
61,935,618
62,976,746
64,010,872
55,130,893
56,020,430
56,907,330
57,803,283
58,692,279
59,581 ,099
60,463,047
61 ,351 ,207
62,239,924
63,134,711
64,030,407
64,923,505
65,815,481
66,709,969
67,604,683
68,500,650
69,395,337
70,289,133
71,182,631
72,076,956
72,971 ,320
73,865,999
500
-
-
-
6,105,598
6,210,517
6,319,944
6,426,181
6,531 ,704
5,493,685
5,582,326
5,670,704
5,759,984
5,848,571
5,937,140
6,025,024
6,113,527
6,202,086
6,291 ,250
6,380,504
6,469,500
6,558,384
6,647,518
6,736,674
6,825,955
6,915,109
7,004,174
7,093,210
7,182,327
7,271 ,449
7,360,602
1,000
-
-
-
21,799,867
22,174,477
22,565,182
22,944,499
23,321 ,265
19,873,736
20,194,399
20,514,111
20,837,087
21,157,554
21,477,959
21,795,886
22,116,052
22,436,419
22,758,975
23,081 ,857
23,403,804
23,725,346
24,047,793
24,370,323
24,693,303
25,015,822
25,338,020
25,660,111
25,982,500
26,304,902
26,627,419
       6.2.5.2 Fixed Costs

       Fixed costs for the small spark ignition engines include test cell modifications for 1065
compliance, emission certification of engine families as well as R&D and tooling expenditures
for engine design changes and equipment modifications. This section presents the aggregate
fixed costs for small spark ignition engines.

       The test procedure for small spark ignited engines for this rulemaking is governed by Part
1065 with regulation specific details in Part 1054. Evaluation of Part 1065 reveals that there are
some differences in calibration procedures with existing Part 90 and programming must be
changed to calculate via 1065.  As industry begins to apply 1065 requirements in its test cells
                                          6-35

-------
Final Regulatory Impact Analysis
there may be some other modifications that will be revealed.  To cover these costs, EPA is
allocating $600,000 per engine manufacturer for 1065 compliance. The number of engine
manufacturers is taken from the the certification database which lists 16 different engine
manufacturers of nonhandheld engines and 15 engine manufacturers of handheld engines.  The
certification database also lists a number of new offshore manufacturers.  These companies
typically certify through independent test laboratories within the United States and therefore
only encounter costs for these upgrades through increased service fees. For this cost analysis,
one additional manufacturer for nonhandheld and handheld is added to the certification database
totals to cover test labs.  Therefore, for nonhandheld engine manufacturers, a total of 17 test
facilities at 600,000 per test facility yields a total estimated cost of $10,200,000.  For the purpose
of this cost analysis, this cost is  spread evenly across all useful lives per class for a total of
1,700,000 for each.  Upgrades for test cells for handheld engines are calculated at $9,600,000.
Engine manufacturers are to begin using compliant test cells for new engine family certifications
beginning in 2013. This cost analysis estimates engine manufacturers will invest in their test
cells from 2008-2011.

                        Table 6.2-37: Fixed Costs for Compliance
                              with 1065, 2005$ (thousands)


TOTAL
CLASS I
125
1,700
250
1,700
500
1,700
CLASS II
250
1,700
500
1,700
1000
1,700
HANDHELD
9,600
Investment Per Year
2008
2009
2010
7011
425
425
425
475
425
425
425
475
425
425
425
475
425
425
425
475
425
425
425
475
425
425
425
475
2,400
2,400
2,400
7400
       Each engine family must certify each year to the emissions standards applicable in that
year.  This cost analysis assumes no carryover data, but that all engine families will undergo
durability aging and emission testing.  The number of engine families per Class and per useful
life category were taken from EPA's 2008 Certification Database. For Class I, the 2008 database
lists 66 engine families from traditionally regulated companies.  For Class II, the 2008 database
lists 121 engine families. The engine families are designated per useful life class by the claim in
the certification application. The estimates in Table 6.2-38 represent the number of engine
families per useful life designation used in this cost analysis to calculate fixed costs. Costs for
certifiers of LPG engines are covered in Section 6.2.4.
                                           6-36

-------
                                                                       Costs of Control
                   Table 6.2-38: Number of Engine Families Per Class
                      and Useful Life Designation for Certification
CLASS I
125
250
500
31
15
20
CLASS II
250
500
1000
39
18
64
       It should be noted that the certification database does contain certifications from a large
number of companies that have a short history of compliance and claim large sales numbers.
These companies were not used in this analysis for we are not yet convinced they are actually
selling in this country nor in the numbers they claim.  Engine families still certified to Phase 1
(either through credits, small engine family flexibilities or averaging) were also not included.
For Class II, there are a number of small volume engine families which have not yet been
certified to Phase 2 due to flexibilities in that rulemaking. Due to the low volume sales, these
engine families were estimated to be certified to the 250 hour useful life.   For Class I-A, engine
families are being moved to the <80cc category where they already meet the handheld emission
standard. Class I-B engines are traditionally low volume sales engine families; we believe that
they will likely be incorporated into the engine manufacturers ABT programs and certification of
these low volume sales engine families will be covered without engine improvement.

       The total engine exhaust emission certification costs are calculated by taking the number
of engine families from Table 6.2-38 and multiplying them  by the emission test and
dynamometer aging costs from Table 6.2-23. This analysis estimates that engine certification
costs are expended over two years prior to standard implementation as shown in Table 6.2-39.
The combined 1065 compliance and engine certification costs are presented in Table 6.2-40.

             Table 6.2-39: Engine Certification Costs to Exhaust Standards


2008
2009
2010
7011
CLASS I
125


272,490
777 490
250


191325
191375
500


455,411
455 411
CLASS II
250

635,064
635,064

500

811,414
811,414

1000

3,007,505
3,007,505

Handheld
$0




                         Table 6.2-40: Total Stream of Costs for
                        Engine Certification by Year, (thousands)


2008
2009
2010
7011
CLASS I
125
425
425
697
697
250
425
425
616
616
500
425
425
880
880
CLASS II
250
425
1,060
1,060
475
500
425
1,236
1,236
475
1000
425
3,432
3,432
475

Handheld
2,400
2,400
2,400
2400
                                          6-37

-------
Final Regulatory Impact Analysis
      Fixed costs for engine research and development and tooling changes to meet exhaust
emission standards are presented throughout sections 6.2.1 Class I and 6.2.2. Class II.  The fixed
costs include engine improvements, engine improvements with catalyst development or EFI
development and application. Class I engine families are assigned engine improvements and/or
engine improvements and catalyst development costs.  The number of engine families per Class
are from the 2008 EPA Certification Database.  Table 6.2-41 presents the number of engine
families estimated per technology package for Class I and Table 6.2-42 presents the number of
engine families estimated per technology for Class II.
Table 6.2-41: Estimated Number of Engine Families per Technology Package, Class I
Technology/Useful Life
- Engine Improvements (all)
- Catalysts
125
31
26
250
15
13
500
20
14
Table 6.2-42: Estimated Number of Engine Families per Technology Package, Class II
Technology/Useful Life
- Engine Improvements (all)
- One Cylinder Engine Catalyst
- Two or More Cylinders per Engine for Catalyst
- Electronic Fuel Injection on Two or More Cylinder Engines
250
39
16
7
4
500
18
4
3
3
1000
64
14
27
5
                      Table 6.2-43:  Total Fixed Costs (thousands)
                for Engines to Meet Phase 3 Exhaust Emission Standards

l&D
Pooling
TOTAL
CLASS I
125
SV
5,286
10,164
15,450
125
OHV
5,598
5,571
11,169
250
OHV
5,335
5,205
10,540
500
OHV
6,567
6,540
13,107
CLASS II
250
OHV
12,412
12,412
15,450
500
OHV
5,225
12,412
15,450
1000
OHV
20,780
12,412
15,450
                 Table 6.2-44: Total Fixed Costs Investment (thousands)
                for Engines to Meet Phase 3 Exhaust Emission Standards


2008
2009
2010
2011
CLASS 1
125-sv
1,322
1,322
6,404
6,404
125-ohv
1,400
1,400
4,185
4,185
250
1,334
1,334
3,936
3,936
500
1,642
1,642
4,912
4,912
CLASS 11
250
4,301
11,150
11,150

500
2,398
5,263
5,263

1000
7,419
18,498
18,498

                                         6-38

-------
                                                                        Costs of Control
       Total fixed costs for Small SI exhaust emissions are shown in Table 6.2-45.

                 Table 6.2-45:  Certification and Technology Fixed Costs
                      for Engines to Meet Phase 3 Exhaust Standards


2008
2009
2010
2011
Class 1
125
3,146
3,146
11,286
11.286
250
1,759
1,759
4,553
4.553
500
2,067
2,067
5,792
5.792
Class 11
250
4,562
12,046
12,046
425
500
2,167
5,843
5,843
425
1.000
7,352
21,438
21,438
425
Handheld
2,400
2,400
2,400
2.400
       Equipment companies using Class II engines are also estimated to incur fixed costs in
redesigning equipment models to incorporate Phase 3 Class II engines. The PSR database shows
there are 413 businesses using Class II engines.25 Assuming each business on average produces
two unique models requiring clearly different redesign yields a number of 826 redesigns.
Table 6.2-22 contains equipment costs per equipment model and Table 6.2-46 contains the total
equipment costs.

                      Table 6.2-46: Total Class II Equipment Cost

2009
2010
250
10325000
10325000
500
10325000
10325000
1000
10325000
10325000
       6.2.5.3 Operating Cost Savings

       The application of electronic fuel injection to an estimated 6.6% of the Class II engines is
expected to result in fuel savings. Fuel savings from the use of fuel injection on Class II engines
is estimated at 10 percent.  Kohler has been offering a fuel injected Class II engine for nearly 10
years and two articles (1996 OEM Off-Highway and 1998 Diesel Progress)26'27 claim 15-20
percent fuel savings over carbureted engines.  We elected to conservatively use a figure often
percent.  In calculating the fuel savings, we use a gasoline price of $1.81 per gallon without
taxes.28 Table 6.2-47 presents estimated fuel savings for Class II engines with electronic fuel
injection. The improvements and catalyst application to Class I engines are estimated to result in
no operating or fuel savings.  Fuel savings that are obtained from evaporative reduction
technologies are presented later in the evaporative portion of this chapter.
                                          6-39

-------
Final Regulatory Impact Analysis
                     Table 6.2-46: Fuel Savings from the Increased
                  Use of Electronic Fuel Injection on Class II Engines
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
7037
Gallons
0
0
0
3,916,719
7,074,990
10,071,145
11,966,500
13,835,431
15,252,178
16,221,164
16,966,562
17,576,831
18,104,416
18,532,855
18,916,185
19,267,974
19,607,579
19,935,933
20,259,628
20,579,305
20,896,206
21,210,286
21,521,549
21,830,758
22,138,949
22,446,266
22,752,947
23,059,059
23,363,883
23 667 468
Fuel Savings $
0
0
0
$7,104,929
$12,834,033
$18,269,057
$21,707,230
$25,097,472
$27,667,451
$29,425,191
$30,777,343
$31,884,371
$32,841,410
$33,618,599
$34,313,960
$34,952,106
$35,568,148
$36,163,782
$36,750,965
$37,330,860
$37,905,717
$38,475,459
$39,040,090
$39,600,995
$40,160,054
$40,717,527
$41,273,846
$41,829,132
$42,382,085
47 937 787
                                        6-40

-------
                                                                       Costs of Control
       6.2.5.4 Total Aggregate Costs

       The aggregate costs for meeting the exhaust emission standards are presented in
Table 6.2-47. Aggregate costs include variable costs and fixed costs for engine manufacturers
(technology, certification, 1065 compliance), equipment manufacturers and LPG engine families
and converters.  An average cost per engine is presented in Table 6.2-48 and the aggregate costs
with fuel savings is presented in Table 6.2-49.

                 Table 6.2-47: Total Aggregate for 30 year Cost Analysis
         for Exhaust Emission Standard Compliance without Fuel Savings,  2005$
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
Exhaust Only
CLASS I
7,012,721
7,012,721
21,671,947
21,671,947
99,991,039
101,726,567
103,426,684
105,116,426
106,781,731
100,152,057
101,722,217
103,311,327
104,890,306
106,463,442
108,024,886
109,600,875
111,174,585
112,754,576
114,347,477
115,937,502
117,523,496
119,114,243
120,705,179
122,297,808
123,889,649
125,479,854
127,068,925
128,659,401
130,250,205
131,841,723
CLASS II
15,393,779
71,614,262
71,614,262
93,177,678
93,481,939
95,129,055
96,728,158
98,316,508
85,010,277
86,381,917
87,749,492
89,131,026
90,501,833
91,872,369
93,232,307
94,601,825
95,972,201
97,351,938
98,733,075
100,110,208
101,485,609
102,864,885
104,244,509
105,626,063
107,005,647
108,383,854
109,761,603
111,140,627
112,519,710
113,899,279
1065
Certification
Upgrades
Handheld
2,400,OOC
2,400,OOC
2,400,OOC
2,400,OOC
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
       Table 6.2-48 presents a sales weighted average per-equipment cost estimate for engines

                                          6-41

-------
Final Regulatory Impact Analysis
meeting the Phase 3 exhaust standards. Note that the fixed costs are invested prior to the
implementation date for Class I and Class II engines and therefore the variable costs are what
remain in these years.  Near term costs for Class I are from 2012-2016 and for Class II are from
2011-2015. Long term costs include a learning curve deduction in manufacturing/production for
these engines in the 6th year and the Class I costs start in 2017 and Class II starts in 2016.

                  Table 6.2-48: Sales Weighted Average Per-Equipment
           Cost Estimates (Without Fuel Savings) for Exhaust Standards, 2005$
Short Term Costs
^years 1-5) per Class per
Useful Life
Near Term
Lone Term*
Class I
125
10.48
9.01
250
7.51
11.33
500
11.12
10.87
Class 11
250
17.70
15.02
500
13.66
10.76
1000
31.93
26.49
Handheld
(no Exhaust)
0.00
0.00
* Long term is with learning, if applicable

       The aggregate costs with fuel savings is presented in Table 6.2-49. Fuel savings are
available from Class II engines using electronic fuel injection and start in 2011 which is the first
year of standard implementation.
                                          6-42

-------
                                                                        Costs of Control
                 Table 6.2-49:  Total Aggregate for 30 year Cost Analysis
           for Exhaust Emission Standard Compliance with Fuel Savings, 2005$

2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
Class l
7,012,721
7,012,721
21,671,947
21,671,947
99,991,039
101,726,567
103,426,684
105,116,426
106,781,731
100,152,057
101,722,217
103,311,327
104,890,306
106,463,442
108,024,886
109,600,875
111,174,585
112,754,576
114,347,477
115,937,502
117,523,496
119,114,243
120,705,179
122,297,808
123,889,649
125,479,854
127,068,925
128,659,401
130,250,205
131.841.723
LJiass II
15,393,779
71,614,262
71,614,262
89,260,959
86,406,949
85,057,910
84,761,659
84,481,077
69,758,099
70,160,753
70,782,931
71,554,195
72,397,418
73,339,514
74,316,122
75,333,851
76,364,623
77,416,005
78,473,447
79,530,903
80,589,404
81,654,598
82,722,959
83,795,305
84,866,697
85,937,588
87,008,656
88,081,568
89,155,827
90.231.811
Handheld
2,400,00(
2,400,00(
2,400,00(
2,400,00(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
C
       At a 7 percent discount rate, over 30 years, the estimated annualized cost to
manufacturers for Small SI exhaust emission control, without fuel savings, is $182 million. The
corresponding estimated annualized fuel savings due to the use of electronic fuel injection on
Class II engines is $24 million. At a 3 percent discount rate, the estimated annualized cost to
manufacturers for Small SI exhaust emission control, without fuel savings, is $189 million. The
corresponding estimated annualized fuel savings due to the use of electronic fuel injection on
Class II engines is $27 million.
                                          6-43

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Final Regulatory Impact Analysis
6.3  Exhaust Emission Control Costs for Outboard and Personal Watercraft
Marine Engines

       This section presents our cost estimates for meeting the new exhaust emission standards
for outboard and personal watercraft marine engines.

       As of about a decade ago, outboard and personal watercraft (OB/PWC) engines were
primarily two-stroke carbureted engines. There were no emission control requirements.  Since
then, manufacturers have used two primary strategies to meet exhaust emission standards. The
first is two-stroke direct injection.  By injecting the fuel directly into the combustion chamber
after the exhaust port closes, the short-circuiting fuel losses with traditional two-strokes can be
largely eliminated.  The second approach is to convert to using four-stroke engines, either
carbureted or fuel-injected. One other approach that has been used by one PWC manufacturer
has been the use of a two-way catalyst in the exhaust of a two-stroke engine. Today, engine
sales are a mix of old and new technology. We anticipate that the standards will largely be met
by phasing out the old-technology engines and using technology already available in the
marketplace.

       Since California ARB has adopted standards similar to the new national standards,
manufacturers have already started with  design and testing efforts to meet our standards. To
reflect this in the cost analysis, we include no estimated costs for R&D to introduce the various
emission-control technologies.  This reflects the  expectation that manufacturers will not need to
conduct additional R&D for EPA's requirements, since they are introducing those technologies
for sale in California. As noted below, we are including estimated R&D expenditures as part a
compliance cost, because EPA's NTE standards  represent an incremental requirement beyond
what California ARB has adopted.

       For the purpose of this analysis, we divide outboards into five power categories and PWC
into three power categories. We present cost estimates of various  emission-control technologies
for each of these power categories.  Additional detail on the per-engine costs presented in this
section is available in the docket.29 Table 6.3-1 presents these power categories and the engine
size we use to represent each category.

                    Table 6.3-1: Engine Sizes Used for Cost Analysis

Outboard Engines




Personal
Watercraft
Engines
Power Range
0-25 hp
25-50 hp
50-100 hp
100-175 hp
>175 hp
50-100 hp
100-175 hp
>175 hp
Engine Power
9.9 hp
40 hp
75 hp
125 hp
225 hp
85 hp
130 hp
175 hp
Displacement
0.25 L
0.76 L
1.60 L
1.80L
3.00 L
1.65 L
1.85L
2.50 L
Cylinders
2
3
3
4
6
2
3
4
                                          6-44

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                                                                         Costs of Control
6.3.1  Two-Stroke Direct Injection

       Traditional outboards use carbureted two-stroke engine designs where the fuel and air are
mixed in the carburetor then pumped into the combustion chamber through the crankcase. The
piston itself acts to open and close the intake and exhaust ports. As a result, fuel may be lost out
the exhaust port. Better control of the fuel can be achieved using indirect injection in place of
the carburetor; however, this does not prevent short-circuiting losses. Indirect injection is
primarily used on the largest two-stroke engines. Direct-injection has been used by
manufacturers to reduce emissions from two-stroke outboards. By injecting the fuel directly into
the cylinder after the exhaust port is closed,  short-circuiting losses can be minimized.
Table 6.3-2 and 6.3-3 present incremental costs of applying direct injection to outboards and
PWC, respectively. For the largest power category, costs are presented incremental to indirect
injection. For the remaining categories, costs are presented incremental to carbureted engines.
For 135 hp PWC engine, incremental costs are presented for both IDI and carbureted engines
because baseline engines in this power category  use both approaches.

    Table 6.3-2:  OutboardProjected Incremental Costs for 2-Stroke Direct Injection


Hardware Cost to Manufacturer
carburetor(s)
fuel metering solenoids
IDI injectors
fuel distributer
pressure regulator
air compressor
air regulator
throttle body position sensor
intake manifold
fuel pump
electronic control module
air intake temperature sensor
manifold air pressure sensor
injection timing sensor/timing wheel
wiring/related hardware
Total Incremental Hardware Cost
Engine Manufacturer Markup
labor at $28/hour
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
9.9 hp
carb.

($28)
$36
~
~
~
$80
$15
$30
$5
$3
$85
$5
$10
$5
$20
$266

$13
$5
$82
$13
$380
40 hp
carb.

($114)
$60
~
~
~
$100
$15
$35
$5
$0
$90
$5
$10
$8
$30
$244

$15
$6
$77
$12
$354
75 hp
carb.

($135)
$66
~
~
~
$120
$17
$35
$9
($5)
$95
$5
$11
$9
$30
$257

$19
$8
$82
$13
$379
125 hp
carb.

($165)
$96
~
~
~
$140
$20
$40
$10
($6)
$100
$5
$11
$10
$50
$311

$22
$9
$99
$16
$456
225 hp
IDI

~
$156
($102)
($25)
($35)
$165
$22
$10
($5)
($35)
$0
$0
$0
$0
$0
$151

$14
$6
$49
$8
$228
                                           6-45

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Final Regulatory Impact Analysis
      Table 6.3-3: PWCProjected Incremental Costs for 2-Stroke Direct Injection


Hardware Cost to Manufacturer
carburetor(s)
fuel metering solenoids
IDI injectors
fuel distributer
pressure regulator
air compressor
air regulator
throttle body position sensor
intake manifold
fuel pump
electronic control module
air intake temperature sensor
manifold air pressure sensor
injection timing sensor/timing wheel
wiring/related hardware
Total Incremental Hardware Cost
Engine Manufacturer Markup
labor at $28/hour
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
85 hp
carb.

($114)
$44
~
~
~
$120
$17
$35
$9
($5)
$95
$5
$11
$9
$20
$246

$19
$8
$79
$12
$364
130 hp
carb.

($165)
$72
~
~
~
$140
$20
$40
$10
($6)
$100
$5
$11
$10
$30
$267

$22
$9
$86
$13
$398
130 hp
IDI

~
$72
($51)
($20)
($30)
$140
$20
$0
($10)
($30)
$0
$0
$0
$0
$0
$91

$12
$5
$31
$5
$144
175 hp
IDI

~
$104
($68)
($25)
($35)
$165
$22
$0
($5)
($35)
$0
$0
$0
$0
$0
$123

$12
$5
$41
$6
$186
                                         6-46

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                                                                       Costs of Control
6.3.2 Migration from Two-Stroke to Four-Stroke Engines

       The primary technology that manufacturers are using to meet exhaust emissions
standards has been to convert their product offering more to four-stroke engines.  Because four-
stroke engines are common in the market today, we do not include costs for research and
development or warranty. Rather, we anticipate that manufacturers will sell more of the four-
stroke engines and phase out the carbureted two-stroke designs as a result of the new standards.
Tables 6.3-4 and 6.3-5 below present a comparison between costs for two-stroke and four-stroke
outboard and PWC engines, respectively. These costs are based on prices for current product
offerings.

            Table 6.3-4: OutboardProjected Incremental Costs for 4-Stroke

2-stroke baseline technology
4-stroke control technology
2-stroke cost
4-stroke cost
Markup at 29%
Total Incremental Cost
9.9 hp
carb
carb
$900
$1,124
$65
$289
40 hp
carb
carb
$2,101
$2,633
$154
$686
75 hp
carb
carb
$3,076
$3,861
$228
$1,013
125 hp
carb
EFI
$4,195
$5,504
$380
$1,689
225 hp
DPI
EFI
$6,339
$7,761
$412
$1,834
              Table 6.3-5: PWCProjected Incremental Costs for 4-Stroke

2-stroke baseline technology
4-stroke control technology
2-stroke cost
4-stroke cost
Markup at 29%
Total Incremental Cost
85 hp
carb
EFI
$3,319
$4,350
$299
$1,330
130 hp
DPI
EFI
$4,578
$5,587
$293
$1,302
175 hp
DPI
EFI
$5,862
$7,207
$390
$1,735
                                          6-47

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Final Regulatory Impact Analysis
6.3.3  Four-Stroke Electronic Fuel Injection

       Manufacturers can gain better control of their fuel and air management through the use of
electronic fuel injection.  This is often used in larger OB/PWC engines today. For this analysis,
we consider the use of a port fuel-injection system, which refers to individual injectors located at
each intake port in the engine.  In addition to the injectors, this system includes a fuel rail,
pressure regulator, electronic control module, manifold air pressure and temperature sensors, a
high pressure fuel pump, a throttle assembly, a throttle position sensor, and a magnetic
crankshaft pickup for engine speed.  Tables 6.3-6 and 6.3-7 present the incremental costs of a
port fuel-injection  system compared to a carburetor-based fuel system for outboards and personal
watercraft, respectively.

          Table 6.3-6: OutboardProjected Incremental Costs for 4-Stroke EFI

Hardware Costs
carburetor(s)
injectors
fuel rail
pressure regulator
intake manifold
throttle body position sensor
fuel pump
electronic control module
air intake temperature sensor
manifold air pressure sensor
injection timing sensor
wiring/related hardware
Hardware Cost to Manufacturer
Engine Manufacturer Markup
labor at $28/hour
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
9.9 hp

($28)
$34
$40
$15
$5
$30
$13
$95
$5
$10
$5
$20
$244

$3
$1
$72
$12
$332
40 hp

($114)
$51
$55
$15
$5
$35
$10
$100
$5
$10
$8
$30
$210

$4
$2
$63
$11
$289
75 hp

($135)
$51
$65
$20
$6
$35
$10
$105
$5
$11
$9
$30
$212

$4
$2
$63
$11
$291
125 hp

($165)
$68
$70
$30
$10
$40
$14
$110
$5
$11
$10
$40
$243

$4
$2
$72
$12
$333
225 hp

($240)
$102
$80
$35
$15
$50
$17
$115
$5
$11
$10
$60
$260

$4
$2
$77
$13
$356
                                           6-48

-------
                                                         Costs of Control
Table 6.3-7: PWCProjected Incremental Costs for 4-Stroke EFI

Hardware Costs
carburetor(s)
injectors
fuel rail
pressure regulator
intake manifold
throttle body position sensor
fuel pump
electronic control module
air intake temperature sensor
manifold air pressure sensor
injection timing sensor
wiring/related hardware
Hardware Cost to Manufacturer
Engine Manufacturer Markup
labor at $28/hour
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
85 hp

($135)
$34
$65
$20
$6
$35
$10
$105
$5
$11
$9
$20
$185

$4
$2
$55
$9
$255
130 hp

($165)
$51
$70
$30
$10
$40
$14
$110
$5
$11
$10
$30
$216

$4
$2
$64
$11
$297
175 hp

($240)
$68
$80
$35
$15
$50
$17
$115
$5
$11
$10
$40
$206

$4
$2
$61
$10
$283
                            6-49

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Final Regulatory Impact Analysis
6.3.4  Catalysts

       We believe the OB/PWC exhaust emission standards can be achieved without the use of
catalysts.  At this time, three-way catalysts have not been demonstrated on OB/PWC engines.
However, one manufacturer has been using a two-way catalyst on PWCs with 2-stroke engines
for several years.  We include research and development costs for this technology because it is
not currently used in the marine industry, but is an alternative we assess in Chapter 11. Catalyst
sizes and formulations are based on the analysis discussed below for SD/I engines. Tables 6.3-8
and 6.3-9 present the incremental cost of adding catalysts to four-stroke, electronic fuel-injection
OB and PWC engines, respectively.

        Table 6.3-8: OutboardProjected Incremental Costs for Catalytic Control

Catalyst Unit Price
catalyst volume (L)
substrate diameter (cm)
substrate
ceria/alumina
Pt/Pd/Rd
can (18 gauge SS)
Total Material Cost
Labor
labor overhead at 40%
supplier markup at 29%
Manufacturer Price per Unit
Hardware Cost to Manufacturer
catalyst
exhaust manifold modifications
oxygen sensor
Total Incremental Hardware Cost
Engine Manufacturer Markup
labor at $28/hour
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
Fixed Cost to Manufacturer
research & development
tooling
units/year
years to recover
Fixed Cost/Unit
Total Incremental Cost
9.9 hp

0.09
4.5
$2
$1
$2
$0.4
$6
$14
$6
$8
$33

$33
$15
$25
$73

$1
$1
$22
$2
$99

$342,788
$75,000
5,000
5
$23
$122
40 hp

0.27
6.0
$4
$3
$7
$0.8
$15
$14
$6
$10
$45

$45
$17
$25
$87

$1
$1
$26
$2
$116

$352,938
$75,000
5,600
5
$21
$137
75 hp

0.56
8.5
$5
$6
$16
$1
$29
$14
$6
$14
$62

$62
$20
$25
$107

$1
$1
$32
$2
$143

$362,068
$75,000
6,400
5
$19
$162
125 hp

0.63
9.0
$6
$7
$18
$1
$32
$14
$6
$15
$67

$67
$25
$25
$117

$1
$1
$34
$3
$156

$372,980
$75,000
5,900
5
$21
$177
225 hp

1.05
10.0
$8
$12
$29
$2
$52
$14
$6
$21
$92

$92
$30
$25
$147

$1
$1
$43
$3
$195

$388,643
$75,000
4,700
5
$27
$222
                                          6-50

-------
                                                                       Costs of Control
          Table 6.3-9: PWCProjected Incremental Costs for Catalytic Control

Catalyst Unit Price
catalyst volume (L)
substrate diameter (cm)
substrate
ceria/alumina
Pt/Pd/Rd
can (18 gauge SS)
Total Material Cost
Labor
labor overhead at 40%
supplier markup at 29%
Manufacturer Price per Unit
Hardware Cost to Manufacturer
catalyst
exhaust manifold modifications
oxygen sensor
Total Incremental Hardware Cost
Engine Manufacturer Markup
labor at $28/hour
labor overhead at 40%
markup at 29%
warranty markup at 5%
Total Incremental Component Cost
Fixed Cost to Manufacturer
research & development
tooling
units/year
years to recover
Fixed Cost/Unit
Total Incremental Cost
85 hp

0.58
9.0
$5
$7
$16
$1
$30
$14
$6
$14
$63

$63
$35
$25
$123

$1
$1
$36
$3
$165

$363,502
$75,000
1,700
5
$71
$236
130 hp

0.65
9.0
$6
$7
$18
$1
$33
$14
$6
$15
$68

$68
$40
$25
$133

$1
$1
$39
$3
$177

$371,332
$75,000
5,300
5
$23
$200
175 hp

0.88
9.0
$7
$10
$25
$2
$44
$14
$6
$18
$82

$82
$45
$25
$152

$1
$1
$45
$4
$202

$381,016
$75,000
1,000
5
$126
$328
6.3.5  Certification and Compliance

       Outboard and PWC engines must already be certified to meet the current EPA HC+NOx
exhaust emission standards. We therefore do not anticipate any increase in clerical work
associated with these standards. In addition, manufacturers are likely to meet the new standards
by selling more of their lower-emission engines, which are certified today. However,
manufacturers may need to adjust engine calibrations to meet the new standard and collect
further data to demonstrate compliance with the not-to-exceed zone.  We therefore allow on
average two months of R&D for each engine family as part of the certification process.
Considering two engineers and three technicians and the corresponding testing costs for the two-
                                          6-51

-------
Final Regulatory Impact Analysis
month period, we estimate a total cost of $