6550-50-P

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 85, 86, and 1039

[EPA–HQ–OAR–2011–1032; FRL–9673-2]

RIN A2060–AR46

Heavy-Duty Highway Program: Revisions for Emergency Vehicles and SCR
Maintenance

AGENCY:  Environmental Protection Agency (EPA)

ACTION:  Notice of proposed rulemaking.

SUMMARY:  This proposal consists of three parts.  First, EPA is
proposing revisions to its heavy-duty diesel regulations that would
enable emergency vehicles, such as dedicated ambulances and fire trucks,
to perform their mission-critical life-saving work without risking that
abnormal conditions of the emission control system could lead to
decreased engine power, speed or torque.  The revisions would allow
manufacturers to request and EPA to approve modifications to emission
control systems on emergency vehicles so they do not interfere with the
vehicles’ missions.  Second, EPA is proposing to revise the
emission-related maintenance and scheduled maintenance intervals for all
motor vehicles and nonroad compression-ignition engines to specify
minimum maintenance intervals for replenishment of consumable chemical
reductant in connection with the use of selective catalytic reduction
technologies.  Third, EPA is proposing to offer short-term relief for
nonroad engines from performance inducements related to the emission
control system, for general purpose nonroad vehicles while operating in
temporary emergency service.  These actions are not expected to result
in any significant changes in regulatory burdens or costs.

DATES: Comments on all aspects of this proposal must be received on or
before July 27, 2012. See the SUPPLEMENTARY INFORMATION section on
“Public Participation” for more information about written comments.

Public Hearings: EPA will hold a public hearing on Wednesday, June 27,
2012 in Ann Arbor, Michigan. The hearing will start at 10 a.m. local
time and will continue until everyone has had a chance to speak.  For
more information about the public hearing, see “How Do I Participate
in the Public Hearing?” under the SUPPLEMENTARY INFORMATION section on
“Public Participation” below at Section VIII.B.

ADDRESSES: Submit your comments, identified by Docket ID No.
EPA-HQ-OAR-2011-1032, by one of the following methods:

 HYPERLINK "http://www.regulations.gov" www.regulations.gov : Follow the
on-line instructions for submitting comments.

Email:  HYPERLINK<EMAIL_ADDRESS><EMAIL_ADDRESS>

Fax:<PHONE_NUMBER>

Mail: Environmental Protection Agency, Air Docket, Mail-code 6102T, 1200
Pennsylvania Ave., NW, Washington, DC 20460.

Hand Delivery: EPA Docket Center (EPA/DC), EPA West, Room 3334, 1301
Constitution Ave., NW., Washington, DC, Attention Docket No.
EPA-HQ-OAR-2011-1032.  Such deliveries are only accepted during the
Docket’s normal hours of operation, and special arrangements should be
made for deliveries of boxed information.

Instructions:  Direct your comments to Docket ID No.
EPA-HQ-OAR-2011-1032.  For additional instructions on submitting written
comments, see the SUPPLEMENTARY INFORMATION section on “Public
Participation” below at Section VIII.A.

Docket: All documents in the docket are listed in the  HYPERLINK
"http://www.regulations.gov" www.regulations.gov  index.  Although
listed in the index, some information is not publicly available, e.g.,
confidential business information or other information whose disclosure
is restricted by statute.  Certain other material, such as copyrighted
material, will be publicly available only in hard copy in the docket.
Publicly available docket materials are available either electronically
in  HYPERLINK "http://www.regulations.gov" www.regulations.gov  or in
hard copy at the EPA Docket Center, EPA/DC, EPA West, Room 3334, 1301
Constitution Ave., NW, Washington, DC.  The Public Reading Room is open
from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal
holidays.  The telephone number for the Public Reading Room is (202)
566-1744, and the telephone number for the Air Docket is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: Lauren Steele, Environmental Protection
Agency, Office of Transportation and Air Quality, Assessment and
Standards Division, 2000 Traverwood Drive, Ann Arbor, Michigan 48105;
telephone number:<PHONE_NUMBER>; fax number:<PHONE_NUMBER>; email address:
steele.lauren (@epa.gov).

SUPPLEMENTARY INFORMATION:

Does this action apply to me?

This proposed action would affect you if you produce or import new
heavy-duty or nonroad diesel engines that are intended for use in
vehicles that serve the emergency response industry, including all types
of dedicated and purpose-built fire trucks and ambulances.  You may also
be affected by this action if you manufacture diesel engines that make
use of a consumable chemical reductant to comply with emissions
standards for nitrogen oxides. You may also be affected by this action
if you produce or import diesel engines for nonroad applications. The
following table gives some examples of entities that may be affected by
this proposed action.  Because these are only examples, you should
carefully examine the proposed and existing regulations in 40 CFR parts
85, 86 and 1039.  If you have questions regarding how or whether these
rules apply to you, you may call the person listed in the FOR FURTHER
INFORMATION CONTACT section above.

Category	NAICS Codesa	Examples of Potentially Regulated Entities

Industry	336111

336112

333618

336120	Engine and Truck Manufacturers

Industry	541514

811112

811198	Commercial Importers of Vehicles and Vehicle Components

Industry	811310	Engine Repair, Remanufacture, and Maintenance

Note:

a North American Industry Classification System (NAICS)

Table of Contents

  TOC \o "1-3" \n \h \z \u

 HYPERLINK \l "_Toc324942547" I. Overview

 HYPERLINK \l "_Toc324942548" A.	Emergency Vehicle Provisions

 HYPERLINK \l "_Toc324942549" B.	Diesel Exhaust Fluid Provisions

 HYPERLINK \l "_Toc324942550" C.	Nonroad Equipment Used Temporarily in
Emergency Service

 HYPERLINK \l "_Toc324942551" II. Statutory Authority and Regulatory
Background

 HYPERLINK \l "_Toc324942552" A.	Statutory Authority

 HYPERLINK \l "_Toc324942553" B.	Background: 2007 and 2010 NOX and PM
Standards

 HYPERLINK \l "_Toc324942554" (1) On-Highway Standards

 HYPERLINK \l "_Toc324942555" (2) Nonroad Standards

 HYPERLINK \l "_Toc324942556" III. Direct Final Rule

 HYPERLINK \l "_Toc324942557" IV. Emergency Vehicle Provisions

 HYPERLINK \l "_Toc324942558" A.	Background on Regulation of Emergency
Vehicles

 HYPERLINK \l "_Toc324942559" B.	Current Provisions for Other Emergency
Vehicles and Engines

 HYPERLINK \l "_Toc324942560" C.	Why is EPA Taking This Action?

 HYPERLINK \l "_Toc324942561" (1) How Does a DPF Work?

 HYPERLINK \l "_Toc324942562" (2) Why Are Emergency Vehicles Having
Problems with DPF Regeneration?

 HYPERLINK \l "_Toc324942563" (3) What Are the Concerns for Emergency
Vehicles Using SCR?

 HYPERLINK \l "_Toc324942564" D.	What Would Occur if EPA Took No Action?

 HYPERLINK \l "_Toc324942565" (1) The Industry Would Continue to Get
Smarter

 HYPERLINK \l "_Toc324942566" (2) The Fleet Would Continue to Migrate to
the 2010 Standards

 HYPERLINK \l "_Toc324942567" (3) Some Trucks Would Continue to
Experience Problems

 HYPERLINK \l "_Toc324942568" E.	Proposed Regulatory Action

 HYPERLINK \l "_Toc324942569" (1) Liberalized Regeneration Requests

 HYPERLINK \l "_Toc324942570" (2) Engine Recalibration

 HYPERLINK \l "_Toc324942571" (3) Backpressure Relief

 HYPERLINK \l "_Toc324942572" F.	What Engines and Vehicles Would be
Affected?

 HYPERLINK \l "_Toc324942573" (1) Newly Certified Engines and Vehicles

 HYPERLINK \l "_Toc324942574" (2) Certified Engines and Vehicles In-Use

 HYPERLINK \l "_Toc324942575" (3) Labeling Requirements

 HYPERLINK \l "_Toc324942576" (4) Other Regulatory Provisions

 HYPERLINK \l "_Toc324942577" V. Scheduled Maintenance and Maintenance
Interval for Replacement of Diesel Exhaust Fluid

 HYPERLINK \l "_Toc324942578" A.	Background

 HYPERLINK \l "_Toc324942579" B.	Proposed Regulatory Action

 HYPERLINK \l "_Toc324942580" (1) Scheduled Emission-Related Maintenance

 HYPERLINK \l "_Toc324942581" (2) Maintenance Intervals for On-Highway
Diesel Engines

 HYPERLINK \l "_Toc324942582" (3) Maintenance Intervals for Nonroad
Compression-Ignition Engines

 HYPERLINK \l "_Toc324942583" VI. Nonroad Engines in Temporary Emergency
Service

 HYPERLINK \l "_Toc324942584" A.	Use of Nonroad Engines in Emergency
Situations

 HYPERLINK \l "_Toc324942585" B.	Proposed Regulatory Action

 HYPERLINK \l "_Toc324942586" (1) General Requirements

 HYPERLINK \l "_Toc324942587" (2) Approval Criteria

 HYPERLINK \l "_Toc324942588" (3) Allowable Use of Emergency AECD’s

 HYPERLINK \l "_Toc324942589" VII. Economic, Environmental, and Health
Impacts of Proposed Rule

 HYPERLINK \l "_Toc324942590" A.	Economic Impacts

 HYPERLINK \l "_Toc324942591" (1) Economic Impacts of Emergency Vehicle
Proposal

 HYPERLINK \l "_Toc324942592" (2) Economic impacts of SCR Maintenance
Proposal

 HYPERLINK \l "_Toc324942593" (3) Economic Impacts for Nonroad Engines
Used in Emergency Situations

 HYPERLINK \l "_Toc324942594" B.	Environmental Impacts

 HYPERLINK \l "_Toc324942595" (1) Environmental Impacts of Emergency
Vehicle Proposal

 HYPERLINK \l "_Toc324942596" (2) Environmental Impacts of SCR
Maintenance Proposal

 HYPERLINK \l "_Toc324942597" (3) Environmental Impacts for Nonroad
Engines Used in Emergency Situations

 HYPERLINK \l "_Toc324942598" C.	Health Effects

 HYPERLINK \l "_Toc324942599" VIII. Public Participation

 HYPERLINK \l "_Toc324942600" A.	How Do I Submit Comments?

 HYPERLINK \l "_Toc324942601" B.	Will There Be a Public Hearing?

 HYPERLINK \l "_Toc324942602" IX. Statutory and Executive Order Reviews

 HYPERLINK \l "_Toc324942603" A.	Executive Order 12866: Regulatory
Planning and Review and Executive Order 13563: Improving Regulation and
Regulatory Review

 HYPERLINK \l "_Toc324942604" B.	Paperwork Reduction Act

 HYPERLINK \l "_Toc324942605" C.	Regulatory Flexibility Act

 HYPERLINK \l "_Toc324942606" D.	Unfunded Mandates Reform Act

 HYPERLINK \l "_Toc324942607" E.	Executive Order 13132: Federalism

 HYPERLINK \l "_Toc324942608" F.	Executive Order 13175: Consultation and
Coordination with Indian Tribal Governments

 HYPERLINK \l "_Toc324942609" G.	Executive Order 13045: Protection of
Children from Environmental Health and Safety Risks

 HYPERLINK \l "_Toc324942610" H.	Executive Order 13211: Energy Effects

 HYPERLINK \l "_Toc324942611" I.	National Technology Transfer
Advancement Act

 HYPERLINK \l "_Toc324942612" J.	Executive Order 12898: Federal Actions
to Address Environmental Justice in Minority Populations and Low-Income
Populations

Overview

Emergency Vehicle Provisions

EPA is proposing amendments to its heavy-duty diesel engine programs
that would specifically allow engine manufacturers to request to deploy
specific emission controls or settings for new and in-use engines that
are sold for use only in emergency vehicles.  EPA is proposing these
revisions to enable fire trucks and ambulances with heavy-duty diesel
engines to perform mission-critical life- and property-saving work
without risk of losing power, speed or torque due to abnormal conditions
of the emission control systems.

EPA’s current diesel engine requirements have spurred application of
emission controls systems such as diesel particulate filters (commonly
called soot filters or DPF’s) and other after-treatment systems on
most new diesel vehicles, including emergency vehicles. Some control
system designs and implementation strategies are more effective in other
segments of the fleet than in emergency vehicles, especially given some
emergency vehicles’ extreme duty cycles.  By this action, EPA intends
to help our nation’s emergency vehicles perform their missions; to
better ensure public safety and welfare and the protection of lives and
property.

Diesel Exhaust Fluid Provisions

EPA is proposing to amend its regulations for diesel engines to add
provisions specifying emission-related maintenance and scheduled
maintenance intervals for replenishment of consumable chemical reductant
in connection with engines and vehicles that use selective catalytic
reduction (SCR) technologies.  This would apply to the use of SCR with
model year (MY) 2011 and later light-duty vehicles and nonroad
compression ignition (NRCI) engines, and MY 2012 and later heavy-duty
vehicles and engines.

Most manufacturers of diesel engines and vehicles subject to our current
standards regulating oxides of nitrogen (NOX) have chosen to use a NOX
reduction technology known as selective catalytic reduction (SCR) in
order to meet these requirements.  SCR systems use a chemical reductant
that usually contains urea and is known as diesel exhaust fluid (DEF).
The DEF is injected into the exhaust gas and requires periodic
replenishment by refilling the DEF tank.

Given that SCR use is now common in the transportation sector and
replenishment of DEF is necessary for SCR to be effective, it is
appropriate to add DEF replenishment to the list of scheduled
emission-related maintenance published in the Code of Federal
Regulations (CFR), rather than rely on a case-by-case approval as is
specified in the current regulations. This action would improve the
clarity and transparency of EPA’s requirements for SCR systems.

Nonroad Equipment Used Temporarily in Emergency Service

EPA is proposing short-term relief from emission control system
performance inducements for any nonroad compression ignition engine
powered vehicles operating in temporary emergency service.  This relief
would address concerns about unusual circumstances where performance
inducements could hinder equipment performance in emergency conditions,
which are defined as conditions in which the functioning (or
malfunctioning) of emission controls poses a significant risk to human
life.  We are proposing provisions for a short-term emergency bypass of
the normal emission controls, including inducement strategies, which
could result in a loss of power of an engine; thus, allowing the
equipment to temporarily perform emergency-related work.  By this
action, EPA would help our nation’s nonroad equipment perform
temporary emergency service; to better ensure public safety and welfare
and the protection of lives.

Statutory Authority and Regulatory Background

Statutory Authority

Section 202(a)(1) of the Clean Air Act (CAA or the Act) directs EPA to
establish standards regulating the emission of any air pollutant from
any class or classes of new motor vehicles or new motor vehicle engines
that, in the Administrator’s judgment, causes or contributes to air
pollution which may reasonably be anticipated to endanger public health
or welfare.  Such standards apply for the useful life of the vehicles or
engines.  Section 202(a)(3) requires that EPA set standards applicable
to emissions of hydrocarbons, carbon monoxide, NOX and particulate
matter (PM) from heavy-duty trucks that reflect the greatest degree of
emission reduction achievable through the application of technology
which we determine will be available for the model year to which the
standards apply.  We are to give appropriate consideration to cost,
energy, and safety factors associated with the application of such
technology.  We may revise such technology-based standards, taking costs
into account, on the basis of information concerning the effects of air
pollution from heavy-duty vehicles or engines and other sources of
mobile source related pollutants on the public health and welfare.

Section 202(a)(4)(A) of the Act requires the Administrator to consider
risks to public health, welfare or safety in determining whether an
emission control device, system or element of design shall be used in a
new motor vehicle or new motor vehicle engine.  Under section
202(a)(4)(B), the Administrator shall consider available methods for
reducing risk to public health, welfare or safety associated with use of
such device, system or element of design, as well as the availability of
other devices, systems or elements of design which may be used to
conform to requirements prescribed by (this subchapter) without causing
or contributing to such unreasonable risk.

Section 206(a) of the Act requires EPA to test, or require to be tested
in such manner as it deems appropriate, motor vehicles or motor vehicle
engines submitted by a manufacturer to determine whether such vehicle or
engine conforms to the regulations promulgated under section 202.
Section 206(d) provides that EPA shall by regulation establish methods
and procedures for making tests under section 206.

Section 213 of the Act gives EPA the authority to establish emissions
standards for nonroad engines and vehicles (42 U.S.C. 7547).  Sections
213(a)(3) and (a)(4) authorize the Administrator to set standards and
require EPA to give appropriate consideration to cost, lead time, noise,
energy, and safety factors associated with the application of
technology. Section 213(a)(4) authorizes the Administrator to establish
standards to control emissions of pollutants (other than those covered
by section 213(a)(3)) which “may reasonably be anticipated to endanger
public health and welfare.” Section 213(d) requires the standards
under section 213 to be subject to sections 206-209 of the Act and to be
enforced in the same manner as standards prescribed under section 202 of
the Act.

Background: 2007 and 2010 NOX and PM Standards

On-Highway Standards

On January 18, 2001, EPA published a rule promulgating more stringent
standards for NOX and PM for heavy-duty highway engines (“the
heavy-duty highway rule”).  The 0.20 gram per brake-horsepower-hour
(g/bhp-hr) NOX standard in the heavy-duty highway rule first applied in
MY 2007.  However, because of phase-in flexibility provisions adopted in
that rule and use of emission credits generated by manufacturers for
early compliance, manufacturers were able to continue to produce engines
with NOX emissions greater than 0.20 g/bhp-hr.  The phase-in provisions
ended after MY 2009 so that the 0.20 g/bhp-hr NOX standard was fully
phased-in for model year 2010.  Because of these changes that occurred
in MY 2010, the 0.20 g/bhp-hr NOX emission standard is often referred to
as the 2010 NOX emission standard, even though it applied to engines as
early as MY 2007.

The heavy-duty highway rule adopted in 2001 also included a PM emissions
standard for new heavy-duty diesel engines of 0.01 g/bhp-hr, effective
for engines beginning with MY 2007.  Due to the flexible nature of the
phase-in schedule described above, manufacturers have had the
opportunity to produce engines that met the PM standard while emitting
higher levels of NOX.  During the phase-in years, manufacturers of
diesel engines generally produced engines that were tuned so the
combustion process inherently emitted lower engine-out NOX while relying
on PM after-treatment to meet the PM standard.  The principles of
combustion chemistry dictate that conditions yielding lower engine-out
NOX emissions generally result in higher engine-out PM emissions.  This
is what we call the NOX-PM trade-off.  For many new low-NOX diesel
engines today, engine-out PM emissions could be at or above the levels
seen with the MY 2004 standards (0.1 g/bhp-hr).  To meet today’s
stringent PM standards, manufacturers rely on diesel particulate filter
after-treatment to clean the exhaust.

Nonroad Standards

EPA adopted similar technology-forcing standards for nonroad diesel
engines on June 29, 2004.  These are known as the Tier 4 standards.
This program includes requirements that will generally involve the use
of NOX after-treatment for engines above 75 hp and PM after-treatment
(likely soot filters) for engines above 25 hp.  These standards phase in
during the 2011 to 2015 time frame.

Direct Final Rule

In addition to this notice of proposed rulemaking, EPA is also
publishing a Direct Final Rule (DFR) addressing the emergency vehicle
provisions described in Section IV of this document.  We are doing this
to expedite the regulatory process to allow engine and vehicle
modifications to occur as soon as possible.  However, if we receive
relevant adverse comment on distinct elements of the emergency vehicle
provisions in this proposal by July 27, 2012, we will publish a timely
withdrawal in the Federal Register indicating which provisions we are
withdrawing.  Any provisions of the DFR that are not withdrawn will
become effective on [Insert date 60 days from date of publication in the
Federal Register], notwithstanding adverse comment on any other
provision. We will address all public comments in the final rule based
on this proposed rule.

As noted above, EPA is publishing the DFR to expedite the deployment of
solutions that will best ensure the readiness of the nation’s
emergency vehicles.  We request that commenters identify in your
comments any portions of the emergency vehicle proposed action described
in Section IV below with which you agree and support as proposed, in
addition to any comments regarding suggestions for improvement or
provisions with which you disagree.  In the case of a comment that is
otherwise unclear whether it is adverse, EPA would interpret relevant
comments calling for more flexibility or less restrictions for emergency
vehicles as supportive of the direct final rule.  In this way, the EPA
will be able to adopt those elements of the DFR that are fully supported
and most needed today, while considering and addressing any adverse
comments received on the proposed rule, in the course of developing the
final rule.

Note that Docket Number EPA-HQ-OAR-2011-1032 is being used for both the
DFR and this Notice of Proposed Rulemaking (NPRM).

Emergency Vehicle Provisions

Background on Regulation of Emergency Vehicles

Typically, the engines powering our nation’s emergency vehicles belong
to the same certified engine families as engines that are installed in
similarly sized vehicles sold for other public and private uses.
Historically, engine and vehicle manufacturers have sought EPA
certification for broad engine families and vehicle test groups that are
defined by similar emissions and performance characteristics.  Engine
families typically only consider the type of vehicle in which the engine
is intended to be installed to the extent that it fits into a broad
vehicle weight class and, to a lesser extent, the vehicle’s intended
duty cycle (i.e. urban or highway).

Because of the above-described manufacturing practices and the narrow
CAA authority for any exemptions, EPA has historically regulated engines
for emergency vehicles, including ambulances as well as police vehicles
and fire-fighting apparatus, in the same manner as other engines.

In the public comments received on the proposed heavy-duty highway rule,
EPA received some comments about DPF technologies and regeneration
cycles on heavy-duty trucks, including one comment that expressed
concerns that the systems may not be failsafe.  However, none of the
comments specifically raised technical feasibility with respect to
emergency vehicles, and EPA’s response was based on the best
information available at the time.  After publishing the final rule
requiring heavy-duty highway engines to meet performance standards that
compelled technologies such as DPF’s, EPA received a letter from the
National Association of State Fire Marshals, requesting some provision
for public safety in implementing this new rule, considering that fire
departments across the nation have trouble covering basic costs and may
not have funds for more expensive trucks.  This letter did not raise any
technical feasibility issues, and EPA did not see a need to take action.

More recently EPA has received letters from fire apparatus manufacturers
and ambulance companies requesting relief from power or speed
inducements related to low levels of DEF for SCR systems on emergency
vehicles.  Power and speed reduction inducements were new on vehicles
equipped with SCR.  These were not specifically mandated by EPA but
designed by manufacturers to occur if DEF levels became low, to induce
operators of the vehicles to perform the required emission-related
maintenance in use. More discussion on this, including why the emergency
response community requested relief and what action EPA took, is found
below in Section IV.C(3).

Recently, beginning in October 2011, EPA received a series of comment
letters from fire chiefs and other interested stakeholders, requesting
regulatory action to relieve emergency vehicles from the burden of
complying with the 2007 PM standards.  EPA promptly opened a dialogue
with the fire chiefs and engine manufacturers to understand the issues.
Power and speed reductions were occurring on some vehicles with soot
filters but without SCR systems, in part related to engine protection
measures designed by manufacturers.  Essentially, these soot filters are
supposed to be self-cleaning by periodically burning off accumulated
soot during normal vehicle use.  The cleaning process is called
regeneration, and when this doesn’t work as designed, the filter
gradually gets more clogged, which can lead to engine problems.  EPA has
determined that while other pathways are available for resolving some
issues related to soot filters on emergency vehicles, there remains a
public safety issue related to design of engines and emission control
systems on emergency vehicles that should be addressed through this
rulemaking. More discussion of this, including why relief was requested
and what other actions can be taken in addition to EPA regulation, is
found below in Sections IV.C and IV.D.

Current Provisions for Other Emergency Vehicles and Engines

On December 1, 2011, in a proposed rule issued jointly with the National
Highway Traffic Safety Administration (NHTSA), EPA proposed to exclude
light-duty emergency and police vehicles from all phases of greenhouse
gas (GHG) emissions standards, in part due to concerns related to
technical feasibility, and in part to harmonize with NHTSA’s program.
Consistent with authority under the Energy Policy and Conservation Act,
NHTSA’s corporate average fuel economy program already provides
manufacturers with the option to exclude emergency vehicles. The
agencies are considering and responding to comments on this proposal,
and plan to finalize this rule in summer 2012.

In addition to the above proposed exemption for on-highway engines from
GHG standards, EPA has provided limited regulatory relief for other
types of emergency-use engines.  First, EPA’s May 6, 2008 final rule
adopting Tier 3 and Tier 4 standards for marine diesel engines allows
for emergency and rescue vessels to meet an earlier, less stringent tier
of standards under 40 CFR parts 89, 94 and 1042.  We adopted these
provisions to avoid compromising engine performance during emergency
operation, and to ensure that more stringent emission standards did not
cause a situation where there were no certified engines available for
emergency vessels.  Such engines are not subject to the Tier 4
standards, which generally involve selective catalytic reduction and
diesel particulate filters.  The regulations also allow for meeting less
stringent standard if there are no suitable engines that are certified
to the current standards.

EPA also adopted limited exemption provisions for emergency rescue
equipment for small spark-ignition nonroad engines in 1999.  Under this
provision, equipment manufacturers needed to demonstrate that no engine
models certified to current emission standards were available to power
the emergency rescue equipment.  We recently moved this provision to 40
CFR part 1054 and included a variety of elements to clarify and improve
oversight of the exemption in a later final rule.  These elements
include a requirement that the engines meet the most stringent standards
feasible (but less than the current standards for certification) and
annual reporting to EPA on the availability of compliant engines that
meet the needs of other emergency equipment using such engines.

In these rules, EPA recognized that equipment and vessels designed and
purpose-built exclusively for use in emergency equipment have demanding
performance specifications and in some cases extreme duty cycles.  The
marine diesel provisions also recognize that engines certified to the
latest emissions standards requiring emissions after-treatment may
create some interference with engine performance or effectiveness that
may be needed in emergency circumstances, when installed in some
emergency equipment or vessels.

While these provisions do offer limited relief from the latest round of
emissions standards for these engines, there is a general requirement to
use engines meeting the most stringent emission standards as practical.
There are also additional administrative responsibilities related to
engine labeling, periodic reporting to EPA, and recordkeeping.  These
provisions in some cases also expire if compliant engines become
available that can practically be used to provide power for the
equipment in question.  Furthermore, these limited exemption provisions
are only applicable to newly certified engines.  The regulations do not
apply these provisions to in-use engines that are certified and deployed
in emergency equipment.

Why is EPA Taking This Action?

EPA is proposing to amend its regulations to facilitate engine
manufacturers’ design and implementation of reliable and robust
emission control systems with regeneration strategies and other features
that do not interfere with the mission of emergency vehicles.  Through
the comments and letters we have received, as well as our own outreach
and data-gathering efforts, we have learned that some emission control
systems on fire trucks and ambulances today, in particular, certain
applications using diesel particulate filters, are requiring an
unexpected amount of operator interventions, and there are currently a
nontrivial number of emergency vehicles that are electronically
programmed to cut power or speed – even while responding to an
emergency - when certain operational parameters are exceeded in relation
to the emission control system.  As we understand it, the experiences of
operators are mixed, with some not reporting any problems and some
reporting problems that raise public safety and welfare concerns.

EPA’s standards are performance-based, and reflect the greatest degree
of emission reduction achievable, according to CAA sections 202(a)(3)
and 213(a)(3).  Our on-highway and nonroad PM standards do not specify
the type of diesel particulate filter for manufacturers to use, nor do
they even mandate the use of such a filter.  Our analysis of the
feasibility of the 2007 on-highway PM standard is presented in Chapter
III of the final Regulatory Impact Analysis (RIA) for that rule.  Our
analysis of the feasibility of the Tier 4 nonroad compression ignition
engine standards that will be phasing in through 2015 is presented in
Chapter 4 of that rule’s final RIA.  For most nonroad engines, these
standards are similar in stringency to the 2007 on-highway heavy-duty
engine and vehicle standards.  As described below in Section VII, these
two rules are providing billions of dollars of annual health benefits by
virtually eliminating harmful PM emissions from the regulated engines.
Even so, EPA is required by sections 202(a)(4)(B) and 213(c) of the Act
to, among other things, consider methods for reducing risk to public
safety and welfare associated with the use of emission control devices
or systems.

Based on the information available to us, we have concluded that there
is an indirect risk to public safety and welfare associated with some
examples of emission control systems when they are deployed on emergency
vehicles that experience extreme duty cycles.  This indirect risk is
related to the readiness of emergency vehicles and the risk that they
may not be able to respond during emergencies with the full power,
torque, or speed that the engine is designed to provide. While this risk
is not inherent to the requirement to reduce emissions or to the use of
diesel particulate filters on emergency vehicles, EPA believes it is
appropriate to ensure that emergency vehicles can perform their
emergency missions without the chance of such consequences.

EPA’s current rules already provide the opportunity for manufacturers
to address many issues through applications for certification of new
engines and new vehicles. There is also currently a mechanism for
manufacturers to deploy field modifications to the in-use fleet,
including those that are substantially similar to approved upgrades for
new vehicles, as well as those that apply only to vehicles that are no
longer in production.  As manufacturers become aware of the need for
upgrades or enhancements, this process occurs within the new and in-use
fleet with various degrees of application.  While that process is
occurring today, EPA views this issue as serious enough that we would be
remiss if we did not act to ensure that our regulations clearly offer
the needed flexibilities for emergency vehicles.

How Does a DPF Work?

To explain more fully the issues that we are addressing with this
action, and hence why we are taking this action, we are providing here
some background information on diesel particulate filters and the
process of DPF regeneration.  DPF’s are exhaust after-treatment
devices that significantly reduce emissions from diesel-fueled vehicles
and equipment.  DPF’s physically trap  HYPERLINK
"http://www.epa.gov/airscience/quick-finder/particulate-matter.htm" PM
and remove it from the exhaust stream.    REF _Ref322528003 \h  \*
MERGEFORMAT  Figure IV-1  depicts a schematic of a wall-flow monolith
style filter, with the black arrows indicating exhaust gas laden with
particles, and the gray arrows indicating filtered exhaust gas. This
style of filter is the most common in today’s heavy-duty diesel
engines, and has very high rates of filtration, in excess of 95 percent.

Figure   STYLEREF 1 \s  IV -  SEQ Figure \* ARABIC \s 1  1  Illustration
of air flow pattern in a wall-flow monolith style PM filter (Source:
Corning)

To be successful, these devices generally must be able to accomplish two
things:  collect PM and clean away accumulated PM.  There are two main
types of PM that can accumulate: combustible and non-combustible, and
two very different types of cleaning methods: regeneration and ash
cleaning.  Regeneration occurs relatively frequently, and is designed to
complete the combustion (oxidation) of the trapped combustible PM
components, releasing them to the exhaust as gas-phase compounds (mostly
H2O and CO2).  In contrast to the PM that can be oxidized and carried
out the tailpipe as gases, the non-combustible PM such as metallic ash
cannot be destroyed through regeneration and will always remain inside a
DPF.  To clean ash from a DPF, the filter unit is removed from the
vehicle and professionally cleaned with a special machine.  Fortunately,
there is very little ash formation from modern diesels so ash cleaning
and ash disposal occurs very infrequently, generally with at least
150,000 mile service intervals, and the mass of accumulated ash is
generally small (a few teaspoons).,  This distinction is made here
because the ash cleaning process is not a source of concern that has
given rise to this EPA action.  The infrequent cleaning of
noncombustible materials from DPF’s is not part of the scope of this
action.

  Regeneration, however, is a type of routine DPF cleaning that must
occur regularly, and for which EPA does not specify a minimum interval
in its regulations, in contrast to the ash cleaning process.  At its
very essence, regeneration involves burning off the accumulated soot.
Since this burning can involve extra heat and/or oxygen or
oxygen-containing compounds, this must be done carefully and safely to
avoid uncontrolled burns.  The discussion below in Section IV.C.(1)(b)
describes the three types of routine DPF regeneration: passive
regeneration, automatic active regeneration, and manual (parked) active
regeneration.  A more detailed discussion is provided in a memorandum to
the docket.  Before discussing the ways that manufacturers achieve
regeneration, though, first we discuss the reason why it is needed at
all.

Failure of a DPF

When the style of filter installed on a diesel vehicle is the wall-flow
type that is predominant in the market today, it physically traps so
much of the PM that the particles accumulate on the inside of the filter
and if not burned off, this PM can over time block the passages through
the filtering media, making it more restrictive to exhaust flow.  This
is commonly referred to as “trap plugging.”  Some other styles of
filter, such as flow-through DPF’s, are less prone to plugging, but do
not generally reduce the PM emission rate sufficiently to meet today’s
stringent PM standard.  Any time something gets in the way of free
flowing air through an engine, it creates what we call “exhaust
backpressure.”  Even a clean, new DPF generates a small amount of
exhaust backpressure due to the porous walls through which all of the
exhaust flows.

Engines can tolerate a certain range of exhaust backpressure.  When an
increase in this backpressure, or resistance, is detected, engines can
compensate to a point.  An increase in exhaust backpressure from a DPF
trapping more and more PM represents increased work demanded from the
engine to force the exhaust gas through the increasingly restrictive
DPF.  However, unless the DPF is frequently cleansed of the trapped PM,
this increased work demand can lead to reductions in engine performance
and increases in fuel consumption.  This loss in performance may be
noticed by the vehicle operator in terms of poor acceleration and
generally poor drivability of the vehicle.

If a DPF is not regenerated and it becomes plugged, there is a risk of
two types of failure. The degree of this risk and which consequence may
be experienced will depend on the engine and emission control system
design.  One consequence is that the lack of air flowing through an
engine will cause an engine to shut down because it can no longer
compensate for the extra work being demanded of it.  The other is a risk
of catastrophic DPF failure when excessive amounts of trapped PM begin
to oxidize at high temperatures (i.e., DPF regeneration temperatures
above 1,000°C) leading to a “runaway” combustion of the PM within
the DPF.  This can cause temperatures in the filter media to increase
beyond its physical tolerance, possibly creating high thermal stresses
where the DPF materials could crack or melt.  This is an unsafe
condition, presenting physical danger to occupants as well as to objects
and persons near the vehicle.  Further, catastrophic failure can allow
significant amounts of the diesel PM to pass through the DPF without
being captured.  That is, the DPF is destroyed and PM emission control
is lost.  For all these reasons, most manufacturers generally design
their emission control systems to prevent uncontrolled shutdown or
runaway DPF regeneration by programming the engine’s electronic
control module (ECM) to limit maximum engine speed, torque and/or power
when excessive backpressures are detected.  This mode of engine
operation at reduced performance may allow a vehicle to “limp home”
to receive service.  In extreme cases the ECM may command the engine to
shut down to prevent a catastrophic failure.

Types of Regeneration

There are three types of routine DPF regeneration. Passive regeneration
refers to methods that rely strictly on the temperatures and
constituents normally available in the vehicle’s exhaust to oxidize PM
from a DPF in a given vehicle application.  Passive regeneration is an
automatic process that occurs without the intervention of an engine’s
on-board diagnostic and control systems, and often without any operator
notice or knowledge.  Passive regeneration is often a continuous
process, because of which, it is sometimes referred to as continuous
regeneration.  In a vehicle whose normal operation does not generate
temperatures needed for passive DPF regeneration, the system needs a
little help to clean itself.  This process is called active
regeneration, and supplemental heat inputs to the exhaust are provided
to initiate soot oxidation. There are two types of active regeneration:
those that may occur automatically either while the vehicle is in
motion, while idling, or while powering an auxiliary device such as a
pump or ladder (power take-off (PTO) mode)), and those that must be
driver-initiated and occur only while the vehicle is stationary and
out-of-service.

Vehicles with automatic active regeneration systems require operators to
be alert to dashboard lamps and indicators.  Written instructions are
provided to operators to explain what each lamp means (such as high
temperatures or need for regeneration) and what action is called for
(such as driving at highway speeds or initiating a manual active
regeneration).  Because EPA emissions standards are performance based;
and therefore, do not dictate any required emission control system
technologies or configurations, each manufacturer has the discretion to
program the timing and sequence of lamps as needed to inform drivers of
the condition of the emission control system.  As noted above, it is not
uncommon in today’s heavy-duty fleet for an engine’s ECM to limit
its maximum speed, torque or power when a plugging DPF is detected.
These engine and emission control system protection measures can alert
drivers to the need to change driving conditions to facilitate automatic
active regeneration or to make plans to allow for a manual active
regeneration.

A manual active regeneration allows the engine’s ECM to increase
engine speed and exhaust temperature to a greater extent than what is
typically allowed during an automatic active regeneration.  Because the
ECM takes full control of an engine during a manual active regeneration,
the vehicle must remain parked and not used for other purposes, such as
pumping water in PTO mode.  Some manual active regenerations may require
towing the vehicle to a special service center, and may occur while the
DPF is on the vehicle, or offline with the DPF removed from the vehicle.
 In such cases, if a spare DPF is not available, the vehicle could be
out of service overnight.  If a driver disregards such warnings, the
risk of uncontrolled engine shutdown or a catastrophic DPF failure may
increase.  EPA encourages the design of robust systems calling for
minimal driver interventions, while providing drivers with clear and
early indicators before any interventions are needed.  EPA also
encourages accurate and thorough operator training to ensure that the
correct remedial action is taken at the earliest available time.

Actively regenerating DPF systems typically require sufficient air flow,
temperature and soot accumulation before an automatic active
regeneration will be requested by the engine’s ECM.  As mentioned
above, this may occur either while the vehicle is in motion or parked,
if pre-set engine operating conditions are met (such as speed and
temperature).  When the engine’s ECM signals the initiation of an
automatic active regeneration and the extra heat is generated, an ideal
DPF system accomplishes this as a transparent process, with no effects
perceivable by the driver.

A variety of manufacturer approaches can be taken to produce the
supplemental heat needed for active regeneration.  Diesel engines of MY
2007 or newer often incorporate one or more of the following approaches:

On-board electrical heaters upstream of the filter.

Air-intake throttling in one or more of the engine cylinders. When
necessary, this device would limit the amount of air entering the
engine, raising the exhaust temperature and facilitating regeneration.

Exhaust brake activation. When necessary, this device would limit the
amount of exhaust exiting the engine, raising the exhaust temperature
and facilitating regeneration.

Engine speed increases.  This approach is sometimes used in combination
with the other approaches to deliver more heat to the filter to
facilitate regeneration.

Post top-dead-center (TDC) fuel injection. Injecting small amounts of
fuel in the cylinders of a diesel engine after pistons have reached TDC
introduces a small amount of unburned fuel in the engine’s exhaust
gases. This unburned fuel can then be oxidized over an oxidation
catalyst upstream of the filter or oxidized over a catalyzed particulate
filter to combust accumulated particulate matter.

Post injection of diesel fuel in the exhaust upstream of an oxidation
catalyst and/or catalyzed particulate filter. This method serves to
generate heat used to combust accumulated particulates by oxidizing fuel
across a catalyst present on the filter or on an oxidation catalyst
upstream of the filter

On-board fuel burners upstream of the filter

These are presented here merely as examples, and are by no means a
complete list of the strategies available to manufacturers when
designing engines that use automatic active DPF regeneration, though not
all may be applicable to all engines.  A common approach that gets a lot
of consumer attention is the use of fuel burners or fuel injection
strategies.  This approach is often called “dosing.”  Vehicle owners
may notice an increase in fuel consumption when driving a vehicle that
relies heavily on fuel dosing for its automatic active regenerations.
In this case, when an engine’s ECM gives the signal, the doser injects
a metered amount of diesel fuel into the exhaust flow (or cylinders),
which reacts with the DPF catalyst to raise the temperature to a point
that enables regeneration.  EPA does not have information about which
manufacturers employ this technique or the number or types of vehicles
with engines that use fuel dosing as part of the active regeneration
strategy.  Estimates of the additional fuel use by a vehicle whose DPF
regeneration system employs fuel dosing are described below in Section
VII.B.  This is also mentioned here because one of the possible outcomes
of this EPA action is that some manufacturers may alter their strategies
for automatic active regenerations on emergency vehicles, which may have
a modest effect on supplemental fuel use due to dosing.  Further
discussion of this is provided below in Section VII.

Why Are Emergency Vehicles Having Problems with DPF Regeneration?

At the time of promulgation of the heavy-duty highway rule, EPA and the
engine manufacturers expected the 2007-compliant engine emission control
systems would be integrated with advanced engine controls to ensure DPF
regeneration under all vehicle operating conditions and environments.
While this is widely true today, the experience of the rule
implementation thus far indicates there are still some exceptions.

Although EPA is aware of a relatively small number of emergency vehicles
that are experiencing problems with DPF regeneration, of those that are
having problems, most of the problems can be related to the vehicle’s
duty cycle, the ambient conditions, and/or the engine’s combustion
characteristics.  A vehicle’s duty cycle means how it is driven,
including its speeds, loads, and distances, as well as time out of
service and time spent idling.  A vehicle’s duty cycle can vary by the
demographic of the service area, including whether the vehicle responds
to emergencies in a rural or urban community, and whether it drives over
flat or hilly terrain.  Because DPF regeneration requires heat and
oxygen (basic ingredients for combustion), the success of DPF
regeneration strategies can also be influenced by ambient conditions
such as extreme cold winter temperatures and whether the vehicle
operates near sea level or at a high elevation.  The engine combustion
and exhaust characteristics can influence the success of a DPF
regeneration strategy since parameters such as engine-out NOX and PM
emission levels can influence how easily the soot can be oxidized, and
how much soot needs to be oxidized and how often.

Both the engine’s duty cycle and the overall control strategy of the
engine’s emission control system play a large role in the success of
integrating a DPF with an engine to control PM emissions.  In this
section we provide additional discussion of how engine combustion
characteristics and vehicle duty cycle can lead to DPF regeneration
problems on emergency vehicles.  In Section IV.E, below, we discuss our
proposed regulatory action to address these issues.  While our proposed
approach specifically targets engine combustion characteristics and
emission control system design, we encourage emergency vehicle owners to
inquire with their dealers and manufacturers regarding suitable vehicle
and engine options that are appropriate for their duty cycle as well as
their demographic and geographic location.

Engine Combustion Characteristics

Engine combustion characteristics can be designed to enable continuous
passive regeneration or to rely heavily on automatic active
regeneration.  As mentioned above, regeneration is a combustion process,
burning off the accumulated PM or soot.  The PM is created because the
initial combustion process in the engine was imperfect.  To completely
convert all fuel to CO2 and water, the combustion process needs more
heat and oxygen.  Both of these things create NOX because nitrogen (N2)
is naturally present in the air and readily oxidizes at high
temperatures.  Thus there is a NOX-PM trade-off of most diesel
combustion processes (homogeneous charge compression ignition being an
exception) where lower combustion temperatures help control NOX but
create more PM, and higher temperatures that destroy PM (or prevent it
from being created) can generate more NOX.

In an engine with a DPF system, combustion settings, or calibrations
that enable continuous passive regeneration, tend to be those with
higher engine-out NOX and lower engine-out PM, partly because of the
higher temperatures that create the NOX, partly because of the NOX
itself that can act as an oxidizer (to burn off soot), and partly
because of the lighter soot loading rate.  In contrast, engine
calibrations that may lead to a heavy reliance on automatic active
regeneration tend to be those with lower engine-out NOX and higher
engine-out PM, partly because of the lower temperatures, partly because
of a lack of helpful NOX, and partly because of a heavier soot loading
rate.  Note that “engine-out” means emissions upstream of any
after-treatment cleaning devices such as DPF or SCR.  An example of a
DPF system that may rely almost exclusively on active regeneration to
maintain a clean PM filter, from an engine calibration perspective,
would be an engine using advanced exhaust gas recirculation, because it
would have very low engine-out NOX and relatively high engine-out PM.
An example of a DPF system that may rarely experience automatic active
regeneration (and frequently passively regenerate), from an engine
calibration perspective, would be an engine using SCR to control NOX,
because it could have comparatively high engine-out NOX and relatively
low engine-out PM.  The SCR after-treatment would then reduce the high
engine-out NOX to provide very low tailpipe NOX.

Thus it is important to note that this NOX-PM trade-off is a critical
design parameter when developing an engine that will be successfully
integrated with a DPF-equipped emission control system.  To date, all of
the concerns expressed to EPA regarding emergency vehicles with DPF
regeneration issues have been for vehicles that do not employ SCR
technology, and thus may have higher engine-out PM.  The differences in
engine combustion characteristics of the MY 2007 vehicles compared to
those of the majority of MY 2010+ vehicles support the concept that the
emergency vehicle fleet may experience fewer DPF regeneration troubles
as it migrates to engines that use after-treatment to meet EPA’s 2010
NOX standards.  Such a trend may indicate that some engine manufacturers
may see a greater need to address in-use emergency vehicles than new
vehicles.

Duty Cycles

As noted above, the duty cycle of a vehicle is one of the factors that
influences how often the DPF regenerates passively or actively.  It is
important to note that all DPF systems with active regeneration
components also have the capability to passively oxidize soot
accumulated on the filter, though some of the above-described factors
may inhibit successful passive regeneration.  Operation at highway
speeds and high engine loads (high load means demanding more work from
the engine, such as accelerating, driving uphill or carrying heavy
cargo) typically leads to successful passive regeneration of a DPF.  An
example from a duty-cycle perspective of a vehicle that frequently
experiences automatic passive regeneration would be a long-haul
tractor-trailer.  There is also often a threshold of speed or load that
is required for automatic active regeneration strategies as well, though
not as great as for passive regeneration – often at least 5 miles/hour
or parked with a PTO engaged.  In some vehicles, passive regeneration
occurs so rarely that a DPF system relies almost exclusively on active
regenerations to maintain a clean PM filter. An example of this from a
duty-cycle perspective would be a vehicle that operates at idle, low
speed and low load over most of its duty cycle.  Many emergency vehicles
fall into this category.

It is possible to collect duty cycle data from trucks by extracting
information that is broadcast by the engine’s ECM.  ECM’s broadcast
information such as engine speed, load, temperature, DPF backpressure,
and many other parameters relevant to engine operation.  In 2004 the
Fire Apparatus Manufacturers Association conducted a data-collection
project, downloading logged data from emergency vehicles in use across
the United States, to document duty cycles and engine conditions
typically experienced in the emergency fleet, including pumpers,
aerials, and rescue vehicles in urban, suburban and rural communities.
The 2004 FAMA data set includes 26 service months of data from 51 pumper
trucks, 31 service months of data from 21 aerial trucks, and 14 service
months of data from 4 rescue vehicles.  Overall, the data reveal that
emergency vehicles in urban centers log more hours than vehicles in
suburban or rural areas, with the urban and suburban vehicles logging
over five and four times the average rural engine hours, respectively,
on an annual basis.  This demographic data could be helpful to fleet
managers who wish to understand why they have or have not experienced
certain troubles with their vehicles.  The data also indicate that
vehicles with PTO capability (pumpers and aerials) operate in PTO mode
on average about 10 percent of their operating time.  Further, the data
indicate the vast majority of emergency fleet operation is at loads
below 10 percent of maximum capacity and engine speeds below 1,000 rpm.
Data of this type could be helpful to engine manufacturers who may wish
to assure that their emission control system designs will be successful
for a given application.  For the vehicles from which operating data
were collected, FAMA determined an average engine load using the total
horsepower, percent load, and percent time at load.    REF _Ref318371286
\h  \* MERGEFORMAT  Table IV-1  presents a summary of the engine load
data compiled in FAMA’s study.    REF _Ref318371297 \h  \* MERGEFORMAT

Table IV-2  presents operating data by both vehicle type and
demographic, and   REF _Ref318371306 \h  \* MERGEFORMAT  Table IV-3
presents an overview of the data by vehicle type.

Table   STYLEREF 1 \s  IV -  SEQ Table \* ARABIC \s 1  1  FAMA Engine
Load Data

Apparatus Type	Capacity Range in Study	Population Average Percent
Running Load

Pumper	315-500 hp	18 %

Aerial	170-500 hp	30 %

Rescue	350-500 hp	20 %

Table   STYLEREF 1 \s  IV -  SEQ Table \* ARABIC \s 1  2  FAMA Duty
Cycle Data by Demographic

Service Area	Operating Condition	Pumper	Aerial	Rescue	Service Area
Average

Rural	Engine Hours (Avg Annual)	301	204	301	295

	PTO Hours (Avg Annual)	70	63	-	-

	Low Speed (% Time < 1,000 RPM)	63	73	51	62a

	Medium Speed (% Time 1,000 < RPM < 1,800)	27	19	42	29a

	High Speed (% Time > 1,800 RPM)	11	9	7	9a

	Low Load (% Time < 10%)	61	83	59	68a

	Medium Load (% Time 10% < Load < 90%)	36	11	39	29a

	High Load (% Time > 90%)	3	6	2	4a

Suburban	Engine Hours (Avg Annual)	1364	1133	367	1272

	PTO Hours (Avg Annual)	168	123b	-	-

	Low Speed (% Time < 1,000 RPM)	71	68	77	72a

	Medium Speed (% Time 1,000 < RPM < 1,800)	23	27	17	22a

	High Speed (% Time > 1,800 RPM)	6	5	7	6a

	Low Load (% Time < 10%)	54	37	78	56a

	Medium Load (% Time 10% < Load < 90%)	44	58	22	41a

	High Load (% Time > 90%)	3	5	0	3a

Urban	Engine Hours (Avg Annual)	1107	2379	1686	1681

	PTO Hours (Avg Annual)	93	213b	-	-

	Low Speed (% Time < 1,000 RPM)	62	73	57	64a

	Medium Speed (% Time 1,000 < RPM < 1,800)	32	22	32	29a

	High Speed (% Time > 1,800 RPM)	5	5	11	7a

	Low Load (% Time < 10%)	73	53	44	57a

	Medium Load (% Time 10% < Load < 90%)	24	42	51	39a

	High Load (% Time > 90%)	3	5	5	4a

Notes:

a Straight average by EPA from summary results. Other values in this
table are weighted averages compiled by FAMA using individual vehicle
data

b Includes both pumping and aerial operating hours

Table   STYLEREF 1 \s  IV -  SEQ Table \* ARABIC \s 1  3  FAMA Duty
Cycle Data by Vehicle Type

Operating Condition	Pumper Class Average	Aerial Class Average	Rescue
Class Average	Fleet Average

Engine Hours (Avg Annual)	924a	1239a	785a	1244

PTO Hours (Avg Annual)	117b	-	-

Low Speed (% Time < 1,000 RPM)	66	71	61	67

Medium Speed (% Time 1,000 < RPM < 1,800)	27	23	30	26

High Speed (% Time > 1,800 RPM)	7	5	9	7

Low Load (% Time < 10%)	62	50	56	58

Medium Load (% Time 10% < Load < 90%)	35	45	41	38

High Load (% Time > 90%)	3	5	3	3

Notes:

a Straight average by EPA from summary results. Other values in this
table are weighted averages compiled by FAMA using individual vehicle
data

b Includes only pumping hours. Aerial operating hours averaged 69 hours
per year.

We can see from this study that engines on emergency vehicles across the
country are commonly operated over duty cycles that offer very limited
opportunities to regenerate DPF’s.  It is also important to note that
emergency vehicles do not typically get deployed on planned duty
schedules with predictable blocks of garage time for servicing or
maintenance.  While some other types of vocational vehicles may have
duty cycles with many characteristics similar to those shown above,
emergency vehicles are unique in their need to be ready to deploy at any
moment for the purpose of protecting public safety and welfare by saving
human lives that may be in immediate danger.

When trucks with an engine-driven PTO are working in a stationary PTO
mode, some engines achieve the conditions to enable an automatic active
regeneration during this time.  While this is normally designed to be a
transparent process, in practice some effects of this type of
regeneration have been noticed by operators.  EPA has received
information from fire chiefs indicating that there have been instances
where engine ECM’s took control from the operator during water pumping
operations.  When an automatic active regeneration is initiated during a
water pumping operation, for example, an ECM may be programmed to alter
throttle position or engine speed to achieve the conditions needed to
complete an automatic active regeneration.  Depending on the design of
the water pumping system’s pressure regulation, this may in turn
affect the water pressure in the fire hoses.  EPA has not heard of this
occurring on a widespread basis, and has reason to believe that affected
engine and truck manufacturers have identified and corrected this issue
on some vehicles.  EPA’s current regulations already allow
manufacturers to develop and request EPA approval for certification of
engines with emission control strategies where the process of undergoing
automatic active regeneration would not interfere with safely pumping
fire suppressant.  EPA requests comment on whether any EPA action should
be taken to explicitly address this situation beyond what we are already
proposing in this action.

While not addressed directly in this proposed action, there are
technologies that could be implemented to decrease the amount of time
emergency vehicles spend with their main engines operating at light
loads and at idle.  These technologies include electronically programmed
automatic engine start/stop systems and hybrids.  Automatic start/stop
systems automatically stop and start an engine depending upon whether or
not it is needed to supply power to the vehicle.  This technology is
already being implemented on other heavy-duty vehicles to decrease
unnecessary engine idling.  Hybrid drivetrains also decrease engine
idling with an integrated alternate power source such as a battery.  We
are currently seeing an increase in the use of hybrid technologies in
heavy-duty diesel vocational vehicles.  Garbage trucks, utility company
trucks, and other work trucks are using hybrid technology to power
on-board hydraulic systems and cab heating and cooling systems.  In
conventional vehicles these systems are powered by a main engine
typically operating at light load or at idle.  Because automatic
start/stop and hybrid technologies improve fuel economy and decrease
greenhouse gas emissions, we believe that they will be used in more and
more vehicles in the future.  We believe there is potential for these
technologies to be integrated into future designs of emergency vehicles
to decrease their operation at light loads and at idle.  Such
technologies would not only improve fuel economy and decrease greenhouse
gas emissions from emergency vehicles, they would also help to prevent
their diesel particulate filters from becoming plugged due to excessive
operation at light loads and at idle.  While we are not proposing any
specific action at this time related to decreasing the amount of time
emergency vehicles operate at light load or at idle, we request comment
on the potential for application of alternate power sources and idle
reduction technologies on emergency vehicles.

What Are the Concerns for Emergency Vehicles Using SCR?

Selective Catalytic Reduction (SCR) is an exhaust after-treatment system
used to control NOX emissions from heavy-duty engines by converting NOX
into nitrogen (N2) and water (H2O).  The technology depends on the use
of a catalytic converter and a chemical reducing agent, which generally
is in an aqueous urea solution, and is often referred to as diesel
exhaust fluid (DEF).  Some trade names for this chemical reductant
include AdBlue,  BlueDef, NOxBlue, and TerraCair.

Most engine manufacturers chose to comply with the 2010 NOX emission
standard by adding SCR to their engine models.  In general, the approach
with an SCR system has been a sound and cost effective pathway to comply
with EPA’s 2010 emissions standards, and it is the primary path being
used today.

DEF is injected into the exhaust upstream of the SCR catalyst where it
forms ammonia and carbon dioxide. The ammonia then reacts with NO and
NO2, so that one molecule of urea can reduce two molecules of NO or one
molecule of NO2.  A robust SCR system can achieve about 90 percent
reduction in cycle-weighted NOX emissions. Improvements have been made
over the last several years to improve the NOX conversion rate and
reduce the impact of lower exhaust temperatures on the conversion
efficiency.

Because an SCR system is only effective when DEF is injected into the
exhaust, we consider refilling a vehicle’s DEF tank to be a critical
emission-related engine maintenance requirement.  We are taking action
elsewhere in this notice (See Section V) to establish this in our
regulations. Therefore, manufacturers have implemented a number of
strategies to induce a vehicle operator to refill a vehicle’s DEF tank
when needed.  These operator inducements generally include first
illuminating one or more dashboard lights to warn the operator that the
DEF tank needs to be refilled soon.  However, if such initial
inducements are persistently ignored by the vehicle operator, eventually
additional inducements are typically activated that decrease the maximum
speed or power of the vehicle.  These additional inducements are
intended to create conditions making operational conditions of the
vehicle increasingly unacceptable if the initial dashboard lamp
illumination inducements are persistently ignored.  Similar inducements
may occur in cases where DEF quality does not meet system
specifications, or if the SCR system is not functioning correctly for
another reason.

While decreasing vehicle performance can be an effective inducement
strategy, we believe it may not be appropriate in all situations for
emergency vehicles because of their special need to be ready at any
moment for the purpose of protecting public safety and welfare by saving
human lives that may be in immediate danger.  We recognized this during
the initial implementation of our 2010 NOX standards, and we worked with
the Fire Apparatus Manufacturers’ Association (FAMA), the Ambulance
Manufacturers Division of the National Truck Equipment Manufacturers
Association, and the International Association of Fire Chiefs to support
the publication of a May 18, 2010 memo that instructed emergency vehicle
manufacturers and engine manufacturers to implement less severe
inducement strategies for emergency vehicles.  In this proposal we are
taking additional steps so that emergency vehicle manufacturers and
engine manufacturers have the option to further reduce the severity or
eliminate altogether any performance related inducements that are or
could be implemented on emergency vehicles and their engines during
emergency situations.  We believe that this additional flexibility will
help to prevent any abnormal condition of a vehicle’s emission control
system from adversely affecting the speed, torque, or power of an
emergency vehicle during emergency situations.

What Would Occur if EPA Took No Action?

The Industry Would Continue to Get Smarter

Improving the components of diesel particulate filters is the current
subject of research and development activities within the automotive and
air pollution control industries.  Aspects that are being improved
include filter ash storage capacity, filter pressure drop, substrate
durability, catalyst activity, as well as other physical and chemical
properties that can optimize the device for heavy-duty vehicle
applications.

Engine manufacturers have taken a systems approach, optimizing the
engine with its after-treatment system to realize the best overall
performance possible.  Manufacturers can manage the functioning of the
emission control system by adjusting parameters such as the thermal
profile of the after-treatment system, the exhaust gas chemical
composition, the rate of consumption of DEF, the rate of particle
deposition, and the conditions under which DPF regenerations (soot
cleaning) may occur.

In a broad and general sense, the trend is that DPF’s are slowly
becoming even more robust without EPA intervention.  Future DPF’s will
need fewer total regenerations during the useful life of the engine and
control system, more passive and fewer active regenerations will occur,
and manual regenerations will become rarer.

In addition, vehicle operators and fleet managers will continue to
become more experienced with this new generation of sophisticated
electronically-controlled vehicles.  Manufacturers across the country
are providing training on actions fleet managers can take to decrease
problems with DPF regenerations. These actions include:

Use low-ash engine oils

Avoid extended idling

Maintain insulation on the exhaust pipe

Maintain the crankcase filter

Periodically operate a vehicle at higher speeds and loads

The Technology & Maintenance Council (TMC) of the American Trucking
Associations conducted a survey in late 2011 to compare user experiences
between EPA 2010, EPA 2007, and EPA 2004 vintage trucks.   According to
TMC, 72 percent of the survey respondents indicated that driver
understanding of the 2007-vintage after-treatment system was worse than
driver understanding of the 2004-vintage after-treatment system, and 33
percent of respondents indicated that driver understanding of the
2010-vintage after-treatment system was worse than driver understanding
of the 2007-vintage after-treatment system.  The responses regarding
driver understanding of fault codes and dash lamps indicated that
drivers have 69 percent poorer understanding of 2007 vs. 2004 fault
codes and dash lamps, and 50 percent poorer understanding of 2010 vs.
2007 fault codes and dash lamps.  We expect that this education
component will gradually improve over time without EPA intervention.

The Fleet Would Continue to Migrate to the 2010 Standards

Vehicles with 2010-compliant heavy-duty diesel engines tend to place
different demands on their DPF systems than pre-2010 vehicles. With the
addition of NOX after-treatment such as SCR, engines may be tuned to
emit lower engine-out PM (recall the NOX-PM trade-off described above).
When an SCR system is integrated, it provides the opportunity to run an
engine at lower soot levels and elevated levels of NO2, which is a
chemical species that efficiently oxidizes the soot in the absence of
elevated temperatures.  It is EPA’s expectation that vehicles of MY
2010 and beyond, particularly those using SCR, will generally experience
fewer troubles with DPF’s than the earlier model year vehicles, due to
the nature of the on-board technology as well as the many years of
experience gained by manufacturers since 2007.  The 2011 TMC survey
included an assessment of relative satisfaction levels between EPA 2010,
EPA 2007, and EPA 2004 vintage trucks.  The survey results indicate that
after-treatment durability is better with EPA 2010 trucks compared to
EPA 2007 trucks, with less time out of service.  As an illustration,
according to a Volvo product brochure, the company’s EPA
2010-compliant trucks eliminate the need for active DPF regeneration,
reducing driver involvement with the emission control system, using a
design that allows for the DPF system to reliably oxidize accumulated
soot using continuous passive regeneration.

Some Trucks Would Continue to Experience Problems

Even though such trends would indicate that instances of emergency
vehicles experiencing difficulty managing regeneration of DPF’s would
decrease, in the absence of this EPA action, some vehicles would be
likely to continue to experience some problems.

EPA has learned that some engine manufacturers have disabled these
engine protection measures on some emergency vehicles.  In these cases
the manufacturer has reasoned that an operator should be allowed to
remain in control of an emergency vehicle even facing risk of
catastrophic failure, with the consequences of that failure being less
severe than the consequences of the vehicle prematurely losing power,
torque and/or speed while performing emergency services.

Without a clear action from EPA to provide the regulatory flexibility
needed for swift deployment of robust remedies throughout the emergency
vehicle fleet, implementation of best practices could be inconsistent,
insufficient, or even impossible due to regulatory constraints.  Some
vehicles would continue to experience frequent plugging of DPF’s,
frequent forced filter regenerations, and reduced engine power, speed or
torque that diminish the ability of first responders to save lives and
property.  There would also remain a heightened risk that an emergency
vehicle could be taken out of service when it is most needed.

Proposed Regulatory Action

As described above in Section IV.C, many DPF-equipped vehicles include
engine controls and driver alerts that lead to decreases in maximum
speed, torque, or power when DPF backpressure exceeds normal levels, as
protective measures for either the engine or the DPF, or as inducements
for the operator to immediately conduct DPF regeneration.  Similarly,
vehicles equipped with selective catalytic reduction (SCR) systems for
NOX reduction currently have engine controls and driver alerts that lead
to eventual loss of speed, torque, or power when the SCR controls detect
abnormal conditions (such as a malfunction, low DEF levels, etc.), as
inducements to take immediate corrective action to allow the SCR to
function normally.  In most vehicles, these alerts and inducements may
be easily avoided with normal driving and routine maintenance, and if
activated, these inducements would not have any significant effect on
public safety and welfare.  In emergency vehicles, however, should any
of these limits on maximum speed, torque, or power occur while a vehicle
is responding to an emergency, it could be a matter of life or death.
To address these issues that could otherwise limit the maximum speed,
torque or power of an emergency vehicle’s engine when it is needed
most, EPA is proposing to amend 40 CFR part 86 to revise the definition
of defeat device; add new definitions of emergency vehicle, ambulance
and fire truck; and add new labeling requirements for new on-highway
engines with approved Auxiliary Emission Control Devices for emergency
vehicles. EPA is also amending its regulations at 40 CFR part 1039 to
revise the definition of defeat device, add a new definition of
emergency equipment, and add a new labeling requirement for nonroad
engines with approved Auxiliary Emission Control Devices for emergency
equipment.

In our current regulations, engine manufacturers may request as part of
an application for new engine or vehicle certification, and EPA may
approve, Auxiliary Emission Control Devices, if they are not determined
to be “defeat devices.”  Auxiliary Emission Control Devices, or
AECD’s, are any design element of an engine’s emission control
system that senses temperature, vehicle speed, engine RPM, transmission
gear, manifold vacuum, or any other parameter for the purpose of
activating, modulating, delaying, or deactivating the operation of any
part of the emission control system.  Some AECD’s can temporarily
decrease the effectiveness of an emission control system. This type of
AECD is only permitted in very limited situations, for example, when
such excursions are deemed to be necessary in order to protect the
vehicle, engine, and or emission control system during limited modes of
operation.

A defeat device is a type of AECD that reduces the effectiveness of
vehicle emission controls in situations when such reduction in
effectiveness is not approved or permitted by EPA.   Defeat devices are
not permitted by the Clean Air Act or EPA.

Approvals of AECD’s are made by EPA on a case-by-case basis.  In
applications for engine certification, manufacturers must include a
detailed description of each AECD to be installed in or on any vehicle
(or engine) covered by the application, as well as a detailed
justification of each AECD that results in a reduction in effectiveness
of the emission control system.  According to 40 CFR
86.094-21(b)(1)(i)(B), EPA may disapprove a request for an AECD based on
consideration of currently available technology.  Use of an unauthorized
or disapproved AECD can be considered a violation of section 203 of the
Act.

In this action, EPA is proposing to revise the definition of defeat
device at 40 CFR 86.004-2, 86.1803-01, and 40 CFR 1039.115 to exclude
AECD’s that apply only for engines on emergency vehicles, where the
need for an AECD is justified in terms of preventing the vehicle or
equipment from losing speed, torque, or power due to abnormal conditions
of the emission control system, or in terms of preventing such abnormal
conditions from occurring during operation related to emergency
response.

In this action, EPA is proposing to define an emergency vehicle as a
vehicle that is an ambulance or a fire truck.  EPA is proposing to adopt
a definition of ambulance consistent with the current U.S. General
Services Administration Star of Life specification.  EPA is proposing to
define fire truck as a vehicle designed to be used under emergency
conditions to transport personnel and equipment and to support the
suppression of fires and mitigation of other hazardous situations,
consistent with the scope of standards for automotive fire apparatus
issued by the National Fire Protection Association.  We are defining
emergency equipment as specialized vehicles to perform aircraft rescue
and firefighting functions at airports, or wildland fire apparatus.
With these definitions, it is EPA’s intent to include vehicles that
are purpose-built and exclusively dedicated to firefighting,
emergency/rescue medical transport, and/or performing other rescue or
emergency personnel or equipment transport functions related to saving
lives and reducing injuries coincident with fires and other hazardous
situations.  EPA requests comment on whether we should refine or expand
our definition of emergency vehicle within the scope of this action to
include those equipped with heavy-duty diesel engines that serve other
civilian rescue, law enforcement or emergency response functions.  We
are especially interested in information regarding instances of such
vehicles experiencing or risking loss of power, speed or torque due to
abnormal conditions of the emission control system, and how that may
inhibit mission-critical life- and property-saving work.

EPA is also proposing an associated engine labeling requirement so that
engines with approved emergency vehicle AECD’s would be clearly
identified and distinguished from other similar engines.

As mentioned above in Section IV.C, some engine manufacturers currently
specify that when an engine is sold for installation in an emergency
vehicle, some of the default power, torque or speed inducements be
de-activated or set to alternate, less severe settings.  In such
applications, when the DPF system requests regeneration, the warning
lights remain illuminated while the vehicle remains in complete control
of the driver.  In these cases the manufacturer has likely reasoned that
the consequences of catastrophic failure would be less severe than the
consequences of the vehicle prematurely losing power, torque and/or
speed while performing emergency services.  EPA has granted related
AECD’s in the past.

However, without the proposed optional flexibilities provided by EPA in
this action, manufacturers could be prevented from implementing truly
failsafe solutions for all affected vehicles.  For example, while
current custom solutions may allow an emergency vehicle to continue
pumping water or transporting a person to safety, its DPF would continue
to accumulate particles and the risk of catastrophic failure would
increase.

In this action, EPA is proposing amendments so that manufacturers could
apply for (and EPA could approve) AECD’s that would be justified in
terms of preventing the occurrence of abnormal conditions of the
emission control systems for emergency vehicles or in terms of
preventing the engines from losing speed, torque, or power due to such
abnormal conditions.  In this context, EPA would consider abnormal
conditions to be parameters outside normal ranges for proper operation,
such as excessive exhaust backpressure from high soot loading on a DPF
or insufficient DEF for use with an SCR system.

EPA is encouraging manufacturers to apply for AECD’s that are tailored
for engines on emergency vehicles, considering the duty cycle
information presented above in Section IV.C(2)(b) along with any other
information needed to design failsafe emission control systems for new
emergency vehicles. EPA is also encouraging manufacturers to design
field modifications to address these issues on in-use emergency
vehicles, including those whose engines are no longer in production.
Further discussion of field modifications is provided below in Section
IV.F(2).

To achieve these goals, EPA understands that increased flexibility would
be needed because EPA’s strict NOX and PM standards present many
design constraints.  Below we describe some solutions that EPA believes
it could approve as part of an emergency vehicle AECD or field
modification, as proposed.  Upon adoption of these amendments, EPA would
encourage requests by engine manufacturers for emergency vehicle
AECD’s and/or field modifications for in-use emergency vehicles for
which service disruptions related to abnormal conditions of emission
control systems may occur or have occurred.  EPA suggests that such
AECD’s or field modifications could include, but are not limited to,
one or more of the following strategies:

Liberalized Regeneration Requests

It is current practice that most modern diesel engine ECM’s are set to
initiate an automatic active regeneration only above a designated DPF
soot load, and those vehicles equipped with manual regeneration switches
are set to not allow the option of initiating manual active regeneration
until an even greater soot load is detected.  The reason why
manufacturers do this is related to certification of engine families and
vehicle test groups. If manufacturers can limit the frequency of
regenerations by design, then they can be assured that average emissions
will remain below the certified average emission level.  Excess
regenerations could lead to higher average emissions, since some exhaust
emissions increase during regeneration.  Particularly for engines not
equipped with SCR systems, NOX emissions can increase by an order of
magnitude during regeneration, and these temporary increases in emission
are accounted for in EPA’s certification process.  See Section VII,
below, for more information about the emissions impacts of DPF
regenerations. In addition, excess regenerations could shorten the
useful life of the DPF system since high temperatures place stress on
filter substrates.

EPA believes that emergency vehicle AECD’s that enable more frequent
automatic active and manual active DPF regenerations, associated with a
wider range of soot loads could improve the reliability of DPF systems
without significantly compromising emissions reductions or durability.
As explained below Section IV.F(4), EPA does not expect this provision
to affect other aspects of certification.  For emergency vehicles with
approved AECD’s that involve changes in the frequency of regeneration,
EPA proposes that the resulting increase in NOX emissions not be counted
against certification levels for applicable engine families or vehicle
test groups.  Furthermore, EPA proposes that emissions certification
testing be conducted with any approved AECD’s for emergency vehicle or
equipment deactivated.  According to EPA’s current engine
certification data, engines from MYs 2008 and 2011 have an average
maximum automatic active regeneration frequency near 20 percent, with
the typical frequency between three and seven percent.  Those with
frequencies near zero rely almost exclusively on passive regeneration.
EPA requests comment on whether an option for more frequent automatic
active and/or manual active DPF regenerations for emergency vehicles
would be beneficial for reliability of those DPF systems, and whether
EPA should apply any constraints on the frequency of manual active DPF
regenerations when approving AECD’s for emergency vehicles.

Engine Recalibration

As mentioned above, in-cylinder combustion chemistry dictates a NOX-PM
trade-off where engines calibrated to reduce in-cylinder NOX tend to
have higher PM levels. These factors lead to higher rates of particle
accumulation and lower rates of particle oxidation on filters.  EPA
believes that AECD’s that incorporate engine calibration modifications
could enable operation in a “low soot mode” with a reduced rate of
particle deposition that would lead to more frequent and effective
passive regenerations.  Such calibration modifications could also extend
the operating time between all types of regenerations, improve active
regeneration effectiveness, and boost reliability of the DPF systems.
On engines with downstream (i.e., SCR) NOX controls, SCR control could
be modulated such that engine recalibration would not significantly
affect NOX emissions.  On engines without downstream NOX controls, EPA
believes that some degree of increased NOX emissions during the
conditions justified by the AECD would be approvable for emergency
vehicles.  As explained below in Section IV.F(4), EPA does not expect
this provision to affect other aspects of certification.  When
manufacturers calculate the average NOX emissions during a test cycle,
they incorporate data regarding both the frequency of regeneration and
the increase in NOX emissions during regeneration. For emergency
vehicles with approved AECD’s that involve recalibration to alter
regeneration frequency or average NOX emissions, EPA proposes that the
resulting increase in NOX emissions not be counted against certification
levels for applicable engine families or vehicle test groups.
Furthermore, EPA proposes that emissions certification testing be
conducted with any approved AECD’s for emergency vehicle or equipment
deactivated.  A discussion of the estimated emissions impacts of
recalibration is found below in Section VII.B.  EPA requests comments on
whether an upper limit of average NOX emissions - considering
regeneration frequency and duration, peak NOX emission rate, and
operating conditions under which the AECD is triggered - should be
established as part of the implementation of this AECD option, and what
levels may be appropriate.

Backpressure Relief

It is EPA’s objective that all of our clean diesel emissions standards
be implemented with reliable technologies that require a minimum amount
of driver intervention and do not compromise the utility of vehicles.
EPA understands that manufacturers are motivated to seek design
solutions that are cost effective and easily deployable.  However, by
focusing solely on preventive measures such as those described above,
manufacturers may not achieve a completely failsafe DPF strategy on all
emergency vehicles.  EPA anticipates that some vehicles may benefit from
an additional failsafe measure that relieves engine exhaust backpressure
as a last resort to prevent loss of engine speed, torque or power.
There are products on the market today that could be configured to
temporarily relieve excessive engine exhaust backpressure when detected,
then return the system to normal at the instant that backpressure
returns to a safe level.  Such a device may be justified as a failsafe
measure, and may be included as part of an overall strategy that also
includes preventive measures, if justified and properly limited, where
excess PM emissions would be expected to be emitted only during a small
fraction of vehicle operation.  That is, the vast majority of DPF
operating cycles would be expected to have continuous PM emission
control, while any temporary backpressure relief that reduced PM control
or allowed bypass of controls would be expected relatively infrequently.
 EPA requests comment on whether a failsafe measure to provide engine
exhaust backpressure relief should be available as an approvable AECD
option, and what constraints, if any, should be established for this
option.

What Engines and Vehicles Would be Affected?

Today’s proposal would apply to new and in-use fire trucks and
ambulances, new and in-use airport fire apparatus and wildland fire
apparatus, and heavy-duty diesel engines on these emergency vehicles and
equipment.

Newly Certified Engines and Vehicles

Of those new diesel engines covered by EPA’s current heavy-duty diesel
standards, only those installed in vehicles or equipment meeting the
definition of emergency vehicle or emergency equipment would be eligible
to obtain an approved AECD of the type discussed above in Section IV.E.
Where a vehicle is chassis-certified and either sold as an incomplete
vehicle to a truck body manufacturer or built and sold as a complete
vehicle, only those sold and built as emergency vehicles would be
eligible to obtain an approved AECD of the type discussed above in
Section IV.E.

Certified Engines and Vehicles In-Use

To address in-use engines and vehicles, EPA proposes to allow engine and
vehicle manufacturers to submit requests for EPA approval of Emergency
Vehicle Field Modifications (EVFMs) for on-highway emergency vehicles
and Emergency Equipment Field Modifications (EEFMs) for nonroad
emergency equipment.  EVFMs and EEFMs would be modifications to existing
hardware and software to be installed on in-use vehicles or equipment to
prevent loss of speed, torque, or power due to abnormal conditions of
emission control systems, or to prevent such abnormal conditions from
occurring, during vehicle or equipment operation related to emergency
response.  EPA proposes to use an approval process similar to the
process that is currently utilized to submit modifications to current
applications for certification, also known as “running changes.”
The information submitted by a manufacturer to EPA as part of this
request and approval process would be similar to the information
submitted for emergency vehicle or equipment AECD’s.

  It is important to emphasize that this proposal would allow only those
approved modifications to be deployed by manufacturers and their
authorized dealers.  Modifications made by end users are not generally
approvable; rather the tampering prohibitions would generally apply to
such modifications.

EPA has identified three types of field modifications that would be
permitted for emergency vehicles and emergency equipment under the
proposed regulations, based on the extent to which the modification is
being incorporated into new production vehicles and equipment.  The
three types are:

	Type A: Any field modification that is a change to a certified
vehicle (i.e., a vehicle, engine or equipment covered by a certificate
of conformity) that is identical in all respects to a running change
that is approved for incorporation in new vehicles by the manufacturer.
Where the running change was approved by
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	Type B: Any field modification that is not identical in all respects
to, but provides for essentially the same purpose as, a running change
that is being incorporated in new vehicles by the manufacturer or that
would have been incorporated if the vehicle were still in production. A
Type B field modification is used when it is not practical to
incorporate the exact running change in vehicles that have left the
assembly line, or when the vehicles are no longer in production.

	Type C: Any field modification that is made selectively only to
vehicles which have left the assembly line and which would not have been
incorporated on the assembly line.  For example, this would apply when
making a field modification to a vehicle that is no longer in production
where there are no similar vehicles in production.

The amount of justification needed for the field modification differs
depending on which type of modification is being requested.

Labeling Requirements

Because the engines and vehicles eligible for the AECD’s described in
this proposal belong to broadly certified engine families and test
groups, when they are sold for installation in an emergency vehicle and
equipped with one or more approved emergency vehicle AECD’s, they must
be labeled as such, to distinguish them from other certified engines.
EPA is proposing adding a labeling requirement to 40 CFR part 86 subpart
A, such that engines with one or more approved AECD’s for emergency
vehicle applications must be labeled with the statement: “THIS ENGINE
IS FOR INSTALLATION IN EMERGENCY VEHICLES ONLY.”  EPA is also
proposing adding a labeling requirement to 40 CFR part 86 subpart S,
such that vehicles with one or more approved AECD’s for emergency
vehicles, include the following statement on the emission control
information label: “THIS VEHICLE HAS A LIMITED EXEMPTION AS AN
EMERGENCY VEHICLE.”  EPA is also adding a labeling requirement to 40
CFR part 1039, such that nonroad engines with one or more approved
AECD’s for emergency equipment include a label with the following
statement: “THIS ENGINE IS FOR INSTALLATION IN EMERGENCY EQUIPMENT
ONLY.”

EPA requests comment on whether these labeling requirements are
satisfactory to ensure that engines and vehicles operating with approved
emergency AECD’s are permanently distinguished from similar certified
engines.  EPA also requests comment on whether a similar label should be
required for an in-use emergency vehicle or equipment where a field
modification is deployed that prevents the engine from losing speed,
torque, or power due to any occurrences of abnormal conditions of the
emission control system, or prevents such abnormal conditions from
occurring.

Other Regulatory Provisions

Today’s proposal would not alter the tampering prohibition in 40 CFR
1068.101(b)(1).  This provision describes a general prohibition against
anyone from removing or rendering inoperative an engine’s emission
controls before or after entering into service, where an exception is
provided in 1068.101(b)(1)(ii) for engine modifications needed to
respond to a temporary emergency, provided that the engine is restored
to proper functioning as soon as possible after the emergency has
passed.  EPA encourages manufacturers to design their emergency vehicle
AECD’s to be engaged only to the extent necessary to prevent the
engine from losing speed, torque, or power due to abnormal conditions of
the emission control system, or to prevent such abnormal conditions from
occurring during operation related to emergency response.  EPA
recognizes that there may be cases where an AECD may need to be engaged
at times other than while actively responding to an emergency, in order
to assure that loss of speed, torque or power does not occur during
operation related to emergency response.  EPA also recognizes that some
AECD’s may involve electronic approaches where the engine’s
functions would be modulated based on exhaust backpressure or other
parameters that are not correlated with any emergency situation.  EPA
may even, in extreme cases, such as at high altitude or with certain
older MY engines allow engagement of AECD’s at all times, if they are
justified as necessary to prevent engine from losing speed, torque, or
power during operation related to emergency response.

We would also encourage manufacturers to design their emission control
systems to discourage tampering.  According to EPA’s tampering
prohibition, a vehicle operator who abuses or alters an approved AECD
may be guilty of tampering.  For example, if an AECD includes enabling
an operator to initiate more frequent manual active regenerations,
engine manufacturers may choose to prevent the abuse of this function by
means such as a daily or weekly cap on the number of manual active
regenerations, or a minimum soot loading for the function to engage.  As
another example, if an emergency vehicle alerts a driver to an abnormal
condition of its emission control system by illuminating dash lamps,
alarms or other warnings that do not limit vehicle performance, it is
the operator’s responsibility to take prompt action to remedy the
problem.  If an operator disregards such warnings beyond the time needed
to respond to the emergency, this may be considered tampering.  It is
important to note that if an emergency vehicle is not equipped to ever
allow an operator to initiate a manual active regeneration, this may in
practice encourage tampering by the end user.

Manufacturers of highway and nonroad engines would be required to
describe any emergency vehicle AECD in an application for certification.
 In this action, we are not proposing any revisions to the information
needed to review and approve AECD’s.  It is common practice for
manufacturers, in describing AECD’s, to identify engine parameters
such as those that would operate differently to preserve adequate engine
performance during an emergency, including information about how the
engine would respond under different in-use operating conditions under
the various sets of conditions that would otherwise cause the engine to
operate at less than full performance levels. Other than the requirement
for a manufacturer to describe the emergency vehicle AECD in its
application for certification, we do not expect this provision to be
relevant for other aspects of certification.  For example, EPA proposes
that emissions certification testing be conducted with any approved
AECD’s for emergency vehicle or equipment deactivated.  Additionally,
manufacturers would not need to consider emergency vehicle AECD’s when
developing infrequent regeneration adjustment factors (IRAFs) or when
developing deterioration factors (DFs).  Thus, EPA proposes that
manufacturers could include emergency and non-emergency engines and
vehicles in the same engine families and test groups.  EPA also proposes
that manufacturers may apply for emergency vehicle AECD’s for new,
existing, and/or formerly approved emissions certificates.  EPA requests
comments on this aspect of the proposal.

Scheduled Maintenance and Maintenance Interval for Replacement of Diesel
Exhaust Fluid

EPA is proposing to include new provisions in its regulations that
explicitly permit replacement of diesel exhaust fluid (DEF) as part of
approved emission-related scheduled maintenance and set out the
permitted maintenance intervals for replacement of DEF on diesel fueled
new motor vehicles, new motor vehicle engines and new nonroad
compression-ignition (NRCI) engines.

Background

EPA’s regulations define the emission-related scheduled maintenance
that may be performed for purposes of durability testing and for
inclusion in maintenance instructions provided to purchasers of new
motor vehicles and new motor vehicle engines.  See 40 CFR 86.094-25(b);
40 CFR 86.004-25(b); 40 CFR 86.1834-01(b).  The regulations include
lists of emission-related maintenance and intervals for this
maintenance.  See 40 CFR 86.004-25(b)(4); 40 CFR 86.1834-01(b)(4).  For
example, in general, the maintenance interval for the adjustment,
cleaning, repair of the following items is 100,000 miles of use, and
then at 100,000 mile intervals thereafter for diesel cycle light-duty
vehicles, diesel cycle light-duty trucks, and light heavy-duty diesel
engines and at 150,000 mile intervals for medium and heavy heavy-duty
diesel engines: fuel injectors, turbochargers, electronic engine control
units, particulate trap or trap-oxidizers, exhaust gas recirculation
systems, and catalytic converters.  The regulations also include a
procedure that allows manufacturers to request a different maintenance
schedule or to request new scheduled maintenance, which includes
maintenance that is a direct result of the implementation of new
technology not found in production prior to the 1980 model year.  See 40
CFR 86.094-25(b)(7); 40 CFR 86.1834-01(b)(7).

Similarly, EPA’s regulations applicable to nonroad
compression-ignition (NRCI) engines define the emission-related
maintenance that may be performed for purposes of providing ultimate
purchasers written instructions for properly maintaining and using the
engine. Such emission-related maintenance and associated intervals apply
to service accumulation on emission-data engines.  See 40 CFR 1039.125.
This regulation includes lists of emission-related maintenance and
intervals for this maintenance.  See 40 CFR 1039.125(a)(2) and
1039.125(a)(3).  For example, in general, the maintenance interval for
adjustment, cleaning, repair or replacement for catalytic converters on
engines below 130 kilowatt (kW) may not occur more frequently than after
3,000 hours and 4,500 hours for engines at or above 130 kW.  This
regulation also includes a procedure that allows manufacturers to
request a different maintenance schedule or to request new scheduled
maintenance, which includes maintenance on emission-related components
that were not in widespread use on NRCI engines prior to 2011.

EPA adopted new emission standards applicable to emissions of NOX from
light-duty vehicles and trucks on February 10, 2000 (65 FR 6698).
Similarly EPA adopted new standards applicable to emissions of NOX from
heavy-duty highway engines and vehicles on January 18, 2001 (66 FR
5002).  These standards have been phased in since model year 2004 and
all were fully phased-in by 2010.  Most manufacturers of affected diesel
engines and vehicles have chosen to use a NOX reduction technology known
as selective catalytic reduction (SCR) in order to meet these
requirements.  SCR systems use a nitrogen-containing reducing agent that
usually contains urea and is known as diesel exhaust fluid (DEF).  The
DEF is injected into the exhaust gas and requires periodic replenishment
by refilling the DEF tank.

In addition, EPA adopted new emission standards applicable to emissions
of NOX from NRCI engines on June 29, 2004 (69 FR 38958).  These
standards have begun to be implemented pursuant to a phase-in that began
in the 2011 model year. EPA conducted a webinar workshop on July 26,
2011 with NRCI engine manufacturers to address the application of SCR
emission technology. Some manufacturers are currently certifying their
NRCI engines with the use of SCR systems and we expect that many
manufacturers will use SCR systems to meet the final Tier IV NOX
reduction requirements for their diesel engines.

In a Guidance Document signed on March 27, 2007 (CISD-07-07), EPA
indicated its belief that the requirements for critical emission-related
maintenance would apply to replenishment of the DEF tank and that
manufacturers wanting to use SCR technology would likely have to request
a change to scheduled maintenance per 40 CFR §86.1834-01(b)(7) or
§86.094-25(b)(7).

Following the completion of the Guidance, EPA received several requests
for new maintenance intervals for SCR-equipped motor vehicles and motor
vehicle engines.  EPA granted these requests for model years 2009
through 2010 for light-duty vehicles and 2009 through 2011 for
heavy-duty engines, in a notice that was published in the Federal
Register (74 FR 57671, November 9, 2009).  In granting the requests, EPA
stated that it

believes the maintenance of performing DEF refills on SCR systems should
be considered as ‘critical emission-related scheduled maintenance.’
EPA believes the existing allowable schedule maintenance mileage
intervals applicable to catalytic converters are generally applicable to
SCR systems which contain a catalyst, but that the DEF refills are a new
type of maintenance uniquely associated with SCR systems.  Therefore,
the 100,000-mile interval at 40 CFR §86.1834-01(b)(4)(ii) for catalytic
converters on diesel-cycle light-duty vehicles and light-duty trucks
(and any other chassis-certified vehicles) and the 100,000-mile interval
(and 100,000 mile intervals thereafter) for light heavy-duty diesel
engines and the 100,000-mile interval (and 150,000 mile intervals
thereafter) for medium and heavy heavy-duty diesel engines at 40 CFR
§86.004-25(b)(4)(iii) are generally applicable to SCR systems.  As
noted, the SCR systems are a new type of technology designed to meet the
newest emission standards and the DEF refill intervals represent a new
type of scheduled maintenance; therefore, EPA believes that
manufacturers may request from EPA the ability to perform the new
scheduled maintenance of DEF refills.

EPA approved a maintenance interval for refill of DEF tanks equal to the
applicable vehicle’s scheduled oil change interval for light-duty
vehicles and light-duty trucks.  For heavy-duty engines, EPA approved a
maintenance interval equal to the range (in miles or hours) of the
vehicle operation that is no less than the vehicle’s fuel capacity
(i.e., a 1:1 ratio), for vocational vehicles such as dump trucks,
concrete mixers, refuse trucks and similar typically centrally fueled
applications.  For all other vehicles equipped with a constantly
viewable DEF level indicator (e.g. a gauge or other mechanism on the
dashboard that will notify the driver of the DEF fill level and the
ability to warn the driver of the need to refill the DEF tank before
other inducements occur), EPA approved a DEF tank refill interval equal
to no less than twice the range of vehicle’s fuel capacity (i.e., a
2:1 ratio).  For all other vehicles that do not have a constantly
viewable DEF level indicator, EPA approved a DEF tank refill interval
equal to no less than three times the range of the vehicle’s fuel
capacity (i.e., a 3:1 ratio).

Engine and vehicle manufacturers provided additional requests for new
maintenance intervals for vehicles and engines in model years not
covered by the November 9, 2009 Federal Register notice.  On January 5,
2012 (77 FR 488), EPA approved new maintenance intervals for the refill
of DEF tanks applicable to light-duty vehicles and light-duty trucks, as
well as for heavy-duty engines for 2011 and later model years.  For
light-duty vehicles and light-duty trucks the approved interval for DEF
refill remains at the scheduled oil change interval.  For heavy-duty
engines the approved maintenance interval for vocational vehicles
remains at 1:1 and for all other types of heavy-duty vehicles the
approved maintenance interval is 2:1.

On July 26, 2011, EPA conducted a webinar workshop for NRCI engine
manufacturers in order to provide EPA’s thinking, at the time, about
the certification of SCR-equipped NRCI engines.  EPA discussed the issue
of maintenance intervals for the refill of DEF and instructed
manufacturers to follow the regulatory provisions in order to petition
EPA for what it thought were appropriate intervals.  Following the
workshop, EPA received several requests for new maintenance intervals
for SCR-equipped NRCI engines.  EPA granted these requests for 2011 and
later model years in a notice that was published in the Federal Register
(77 FR 497, January 5, 2012).  In granting the requests, EPA stated that
it

believes that SCR systems are a new technology and are properly
considered a critical emission-related component.  EPA believes the
existing allowable schedule maintenance mileage intervals applicable to
catalytic converters are generally applicable to SCR systems which
contain a catalyst, but that the SCR systems are a new type of
technology and that DEF refills are a new type of maintenance uniquely
associated with SCR systems.  Therefore, the 3,000 hour (engines below
130 kW) and 4,500 hour (engines at or above 130kW) intervals are
generally applicable to SCR systems.  As noted, the SCR systems are a
new type of technology designed to meet the newest emission standards
and the DEF refill intervals represent a new type of scheduled
maintenance; therefore, EPA believes that manufacturers may request from
EPA the ability to perform the new scheduled maintenance of DEF refills.

EPA approved a maintenance interval for refill of DEF tanks that shall
be no less than the equipment’s fuel capacity (i.e., a 1:1 ratio of
DEF refill to fuel refill).

Proposed Regulatory Action

EPA is today proposing to add DEF replenishment to the list of scheduled
emission-related maintenance for diesel-fueled motor vehicles and motor
vehicle engines, as well as for NRCI engines that use SCR.  EPA is also
proposing to incorporate appropriate maintenance intervals for this
scheduled maintenance.

Scheduled Emission-Related Maintenance

EPA is proposing to list DEF replenishment as scheduled emission-related
maintenance in 40 CFR 86.004-25(b)(4) and 40 CFR 86.1834-01(b)(4) for
diesel-fueled motor vehicles and motor vehicle engines, as well as 40
CFR 1039.125(a)(2)  and 40 CFR 1039.125(a)(3) for NRCI engines that use
SCR.

Over the past several model years, since the implementation of the most
recent standards for NOX, many manufacturers have chosen SCR as the
technology used to meet these stringent NOX standards.  Typically,
should a manufacturer desire new maintenance (that it wishes to
recommend to purchasers and perform during service accumulation on
emission-data engines) not found in 40 CFR 86.004-25(b)(4) and
86.1834-01(b)(4) or at 40 CFR 1039.125(a)(2) and 40 CFR 1039.125(a)(3),
then it utilizes the  provisions allowing manufacturers to request such
maintenance.  Given that SCR use is now common in the industry and
replenishment of DEF is necessary for SCR to be effective, it is
appropriate to add DEF replenishment to the list of scheduled
emission-related maintenance published in the Code of Federal
Regulations (CFR), rather than rely on the provisions of paragraph
(b)(7) for motor vehicles and paragraph 1039.125(a)(5) for NRCI engines.

Maintenance Intervals for On-Highway Diesel Engines

EPA is also proposing to incorporate appropriate maintenance intervals
for this scheduled maintenance.  In general, they are the same as were
approved under the (b)(7) process.  For light-duty vehicles and
light-duty trucks, we are proposing an interval equal to the scheduled
oil change interval for the vehicle.  Light-duty vehicles and trucks do
not have the carrying and storage capacity required for the quantity of
DEF needed to satisfy longer maintenance intervals such as the 100,000
mile scheduled maintenance interval generally applicable to catalytic
converters.  As EPA explained in its previous notices regarding this
issue, automobile manufacturers have stated that it takes approximately
an 8 gallon DEF tank to assure the DEF will last for the length of a
typical scheduled oil change interval.  Assuming an oil change interval
of 10,000 miles, a DEF tank size of approximately 80 gallons would be
required to meet a 100,000 mile DEF refill maintenance interval.  Even a
16-20 gallon DEF tank (to meet a 2 oil change interval) would interfere
with the space that is necessary for typical light-duty vehicle design
and transportation needs of the consumer.  Interior cabin volume and
cargo space are highly valued attributes in light-duty vehicles and
trucks.  Manufacturers have historically strived to optimize these
attributes, even to the point of switching a vehicle from rear-wheel
drive to front-wheel drive to gain the extra interior cabin space taken
up by where the drive shaft tunnel existed, or switching the size of the
spare tire from a conventional sized tire to a small temporary tire to
gain additional trunk space.  Thus any significant interior, cargo or
trunk space used to store a DEF tank would be unacceptable to customers.
 There are also packaging concerns with placing a large DEF tank in the
engine compartment or in the vehicle’s undercarriage.  Most vehicle
undercarriages are already crowded with the engine, exhaust system,
including catalytic converters and mufflers, fuel tank, etc. limiting
any available space for a DEF tank.

 In addition to the inherently space constrained areas on the vehicle to
place both fuel tanks and DEF tanks (an additional 8 gallon tank
represents a very significant demand for space) the addition of the
weight associated with the DEF represents significant concerns (e.g.
performance and efficiency) on the operation of the vehicle.  For
example, assuming a density of 9 lb/gallon, an 8 gallon DEF tank
represents an additional 72 lbs on a vehicle already looking to optimize
performance.  Adding additional DEF tank size to even accommodate a
two-oil change interval is not feasible or practical given these weight
constraints.  A requirement for a larger DEF tank may also have an
adverse effect on the ability of a manufacturer to meet greenhouse gas
emission standards and fuel economy standards.

EPA notes that a DEF refill maintenance interval that is equivalent and
occurring with the oil change interval is a fairly long interval (e.g.
7,500 to 12,500 miles) for light-duty vehicles and trucks and is not
likely to result in overly frequent maintenance under typical vehicle
driving.  EPA also believes that an adequate DEF supply will be
available to perform the DEF refills at the stated intervals.  EPA
believes it important to also consider when, where and how often vehicle
owners or operators are most likely to perform the DEF refill
maintenance.  For light-duty vehicles and light-duty trucks, EPA
believes the requested DEF refill interval’s association with the oil
change interval is appropriate given the likelihood of DEF availability
at service stations and the likelihood that DEF refill would occur
during such service.

EPA also notes that heavy-duty engines that are certified as part of
complete trucks have been treated in the same manner as light-duty
trucks and thus have been subject to the DEF refill interval associated
with the oil change.  We are proposing to continue this treatment in the
regulations.  In addition, EPA is aware that several manufacturers are
exploring whether the DEF refill interval should not be linked to the
oil change interval since the historical oil change interval (e.g.,
7,000-8,500 miles) is potentially increasing to higher mile intervals
(e.g., 15,000 to 30,000 miles, even higher for synthetic oil).  We
invite comment on the necessity and appropriateness of “de-linking”
the DEF refill interval from the oil change interval, as well as
comments on proper methods to increase the likelihood that DEF refill
maintenance would occur in the appropriate interval (e.g., linking to
vehicle fuel capacity, inducement criteria, etc.), should it not be
linked to the oil change interval.

For heavy-duty engines, we are proposing that for vocational vehicles
such as dump trucks, concrete mixers, refuse trucks and similar
typically centrally fueled applications, the DEF tank refill interval
should equal the range (in miles or hours) of the vehicle operation that
is no less than the vehicle’s fuel capacity (i.e., a 1:1 ratio).  For
all other vehicles, the DEF tank refill interval must provide a range of
vehicle operation that is no less than twice the range of vehicle’s
fuel capacity (i.e., a 2:1 ratio).  EPA believes it is reasonable to
base the DEF refilling event on diesel refueling intervals given that it
is likely that the DEF refill maintenance would be undertaken at the
time of fuel refill due to DEF infrastructure developed at diesel
refueling stations.  EPA believes that these DEF refilling intervals are
technologically necessary.  EPA knows of no SCR technology for any
heavy-duty engine application that is capable of operating without a DEF
refill for the high mileage levels associated with other maintenance
intervals.  As an example, assuming that 25,000 gallons of diesel fuel
were consumed to reach a 150,000 mile interval, the amount of DEF
required (assuming a 3% DEF consumption rate) would require 750 gallons
of DEF weighing approximately 6,750 lbs.  A line-haul truck is allowed a
maximum gross vehicle weight of 85,000 lbs. of which approximately
45,000 pounds is for cargo carrying.  A DEF tank of 750 gallons would
reduce the cargo-carrying capacity by 15%.  Another example from the
line haul industry suggests that a DEF tank size of over 900 gallons
would be needed to reach the 150,000 mile interval for a common highway
vehicle with a diesel fuel capacity of 200 gallons and achieving 6.5
miles per gallon fuel economy.  Similarly, a medium heavy-duty engine
(“chassis cabs”) example would require 375 gallons of DEF weighing
3,275 lbs to meet a 150,000 mile interval. EPA believes that such tank
sizes are clearly not technologically feasible in light of the weight
and space demands and constraints on heavy-duty trucks and the consumer
demand to maximize cargo carrying capacity.

The Agency also believes that intervals shorter than 150,000 miles but
longer than those we are proposing would require DEF tanks that are too
large or too heavy to be feasibly incorporated into vehicles.  Available
data show that heavy-duty engines equipped with SCR-based systems will
consume DEF at a rate that is approximately 2%-4% of the rate of diesel
fuel consumption.  Because of inherent space and weight constraints in
the configuration and efficient operation of heavy-duty vehicles, there
are size limits on the DEF tanks.  Currently, there are truck weight
limits that manufacturers must address when making or modifying truck
designs. EPA expects and believes that manufacturers are taking
significant and appropriate steps in order to install reasonably sized
DEF tanks to achieve the DEF refills intervals noted.  For example,
manufacturers are taking such steps as reducing the number of battery
packs on vehicles despite customer demands or designing space saving
configurations, in some instances extending an already very limited
frame rail distance to incorporate the DEF tanks and SCR systems, moving
compressed air tanks inside the frame rails, redesigning fuel tank
configurations at significant costs, and otherwise working with
significant size and weight constraints to incorporate DEF tanks.  There
are several factors that support the good engineering judgment that
underlies the recommended DEF refill intervals.  The great majority of
heavy-duty engines produced with SCR DEF tanks will provide a range of
vehicle operation that is no less than twice the range of the
vehicle’s fuel capacity; thus, the DEF tank size will provide at least
double the vehicle’s operating range as provided by the fuel tank.
Vehicle operators will generally refill DEF at the same time and
location that they refill the tanks thus these vehicles will already be
carrying twice as much DEF as the SCR system could ever consume between
refills.  Also, manufacturers have been incorporating warning signals
and performance-related inducements on their SCR-equipped vehicles to
ensure the substantial likelihood that DEF refilling will occur, and
there is considerable evidence that heavy-duty vehicle operators in the
United States have in practice been refilling their DEF tanks prior to
the tanks becoming empty in virtually all situations.

EPA was provided with examples of the consequences of requiring
heavy-duty vehicles to accommodate a DEF refill interval of 5:1, and the
information provided to the Agency strongly suggested that great
compromises would be required in cost, weight and utility.  Increased
tank sizes and weights on the magnitude of 150 to 325 lbs. would be
required and in some cases diesel fuel volumes would need to be reduced.
 The extra weight associated with the DEF required to meet the 2:1
refill intervals represents a significant challenge to manufacturers
seeking to meet both weight and size requirements for their vehicle
designs.  In addition, requiring a longer DEF refill interval may result
in increased greenhouse gases and decreased fuel economy.  EPA believes
that in light of the existing tight space constraints and the overall
desire to maximize cargo-carrying capacity to minimize emissions and
meet consumer operational demands, and the built-in DEF tank size buffer
to insure DEF refills, that the proposed tank DEF tank sizes are
technologically necessary and are also reasonable and appropriate.  EPA
believes that requiring tank sizes above these ratios will cause
increases in space constraints and weight that would not be appropriate
for these vehicles.  Similarly, manufacturers note that only a small
number of applications will employ the 1:1 refilling ratio and that such
vehicle applications have very limited vehicle space available to house
surplus DEF.  Such applications (e.g., a garbage truck, concrete mixer,
beverage truck, or airport refueler) will also be refueled daily at
central locations. At approximately 0.134 ft3 per gallon, any extra DEF
would displace significant space available to vehicle components and
subsystems on both the vocational trucks at the 1:1 refill interval as
well as the 2:1 vehicles.

During the previous administrative process leading to the January 5,
2012 Federal Register notice approving new maintenance intervals, EPA
received a comment from one manufacturer (Navistar) suggesting that a
longer DEF refill interval in the range of 35,000 to 45,000 miles was
appropriate.  EPA responded to these comments in detail in that notice.
As discussed in that notice, Navistar claimed that other technology is
available that would need a maintenance interval no shorter than this.
However, EPA found no evidence that such technology is actually
available at this time.  More importantly, the fact that other
technology may be able to have a longer maintenance interval does not
mean that a longer maintenance interval is appropriate for DEF-based
SCR.  Navistar suggested that maintenance intervals can be increased by
doubling DEF tank size. EPA does not believe that requiring such an
increase is appropriate given the numerous negative consequences
discussed above.  EPA also explained that Navistar’s suggestion of
reducing engine-out emissions of NOX would likely lead to an increase in
fuel consumption, and possible increases in GHG emissions, and could
either require increases in the size of the fuel tank or more reductions
in the operating range of a vehicle before needing to refill, which
would compromise a critical design parameter of heavy-duty vehicles.
EPA does not believe the desire to increase DEF maintenance intervals
justifies such consequences. After reviewing these data, EPA believes
that longer refill intervals than those proposed above would require
larger and heavier DEF tanks.  The design and engineering work performed
by manufacturers thus far indicates that the recommended DEF refill
intervals noted above approximate the maximum feasible maintenance
intervals associated with reasonable DEF tank sizes. In any case these
refill intervals are appropriate and reasonable given the substantial
negative consequences of longer DEF refill interval requirements.  The
recommended maintenance intervals ensure that the function and
operational efficiency of such vehicles are not overly compromised.
Based on this information we believe the proposed intervals are
warranted.

EPA has received comments from certain manufacturers indicating that EPA
should set the minimum required DEF refill interval at an interval equal
to the vehicle’s fuel capacity (i.e., a 1:1 ratio) for all heavy-duty
engines.  The commenters claim that this shorter maintenance interval is
“necessary and appropriate to reflect current and anticipated changes
in vehicle designs, significant changes in inducement strategies, and
the increased availability of DEF.”  The commenters note that
certification practices of the EPA regarding inducement practices for
SCR-equipped engines make it “essentially impossible for an SCR
vehicle to operate without regular DEF replenishment.”  They state
that the severity of inducements related to DEF levels (e.g. severe
reduction in engine power and/or vehicle speed) is “extraordinary and
must be taken into account” when EPA is determining appropriate
maintenance intervals. They state that “in light of these severe
inducements, it is reasonable to expect that a driver with a 1:1 tank
ratio will operate under a firm discipline that the DEF tank must be
refilled every time the fuel tanks are filled, as opposed to a driver
with a 2:1 or greater tank ratio who may become accustomed to filling
the DEF tank only when necessary, and is therefore more likely to rely
on gauge levels, warnings, and inducements to trigger refills.”

The commenters also state that EPA’s promulgation of new standards
regulating greenhouse gases increase the size and weight restraints
associated with DEF tank size.

EPA has adopted new greenhouse gas standards for heavy-duty on-highway
trucks, and manufacturers have moved to voluntarily increase the fuel
efficiency of their vehicles in advance of the effective dates of those
regulations. Within these regulations, EPA recognizes the impact of
weight savings on fuel efficiency and GHG emissions. In addition,
manufacturers have developed innovative new DEF dosing strategies to
reduce CO2 emissions. These new strategies may involve increasing the
DEF dosing rate. Increasing the DEF dosing rate also makes it more
difficult to satisfy a 2:1 tank size ratio without increasing the size
of the DEF tank above the size EPA previously considered the maximum
reasonable size. For this reason, if the application of the 1:1 tank
ratio is not expanded, EPA will effectively be mandating larger DEF
tanks, with their accompanying weight increase, in order to accommodate
technology advancements developed to reduce CO2 emissions—tanks that
are larger than the tanks EPA determined to be the maximum reasonably
required in 2009.  In addition, this could inadvertently cause
manufacturers to restrict application of the most fuel efficient engines
to vehicles that have reduced range between fuel and DEF refills, such
that they will be unattractive to the line-haul fleets that consume the
most fuel.

The commenters elaborated that:

To meet the next round of GHG reduction requirements, some manufacturers
expect to increase DEF dosing by as much as 100% over current levels.
These increased levels of dosing will require a corresponding increase
in DEF tank capacity and size to meet the existing 2:1 tank ratio
requirements. For example, increasing DEF dosing by 40% on average would
require an increase in DEF tank size of approximately 40% (depending on
how much extra capacity was included in the tanks used in previous model
years).  The shape, size and location of DEF tanks on a truck frame are
constrained by a number of factors including: the need to place the tank
below the filler-neck; the need for clearance from other components such
as fuel tanks, battery boxes, air tanks, diesel particulate filters, and
the drive axle and wheels; the need for gravity feed; body installation
requirements; clear-back-of-cab requirements; weight distribution
requirements; bridge formula and related axle placement issues; and fuel
capacity/driving range demands.

The commenters state that another consequence of the greenhouse gas
regulations is more attention to improved aerodynamics and weight
reduction, which are harmed by the need for a 2:1 DEF tank size
requirement.  They claim that EPA should allow manufacturers to use all
available options to increase fuel efficiency and meet greenhouse gas
standards.  They claim that the possible harm of allowing shorter
maintenance intervals are minimal, given the severe negative inducements
associated with failure to replenish the DEF tank.

EPA is not proposing to allow a 1:1 DEF maintenance interval across the
heavy-duty engine class at this time.  EPA notes that manufacturers have
been meeting a 2:1 ratio for DEF tank size for the past two years and
the commenters have not provided sufficient evidence that this ratio
will be infeasible in the future.  Moreover, the commenters have not
shown that any change in the maintenance interval is necessary or
appropriate throughout the heavy-duty engine category, rather than for
particular applications, or that a refill interval as low as 1:1, rather
than 1.8:1 or 1.5:1, is necessary or appropriate.  The feasibility of
the greenhouse gas standards was not predicated on substantial increases