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Control of Air Pollution From New Motor Vehicles: Announcement of Public Workshop for Heavy-Duty Diesel Engines Employing Selective Catalyst Reduction Technology

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Information about this document as published in the Federal Register.

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This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

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Environmental Protection Agency (EPA).


Notice of Public Workshop and Opportunity for Comment.


A public workshop is being held to discuss the operation of heavy-duty engines equipped with selective catalyst reduction (SCR). EPA will be reviewing its policies regarding the operation of SCR-equipped heavy-duty diesel engines without diesel exhaust fluid (DEF), with improper DEF, or when tampering (or some other defect in the SCR system) is detected.


The workshop will be held on July 20, 2010 from 10 a.m. to 4 p.m. (PST) at the California Air Resources Board, Annex 4 Auditorium, 9528 Telstar Avenue, El Monte, California 91731, and will be conducted with the California Air Resources Board. Parties wishing to present information at the workshop are encouraged to notify Ms. Khesha Reed at the address noted below.

Any party may also submit written comments either before or after the workshop. All comments are due by August 20, 2010.


EPA will make available for public inspection materials submitted by any party at the public workshop and any other written comments submitted to the Agency. Materials relevant to this proceeding are contained in the Air and Radiation Docket and Information Center, maintained in Docket No. EPA-HQ-OAR-2010-0444. The docket is located at the Air Docket, Room 3334, 1301 Constitution Avenue, NW., Washington, DC 20460, and may be viewed between 8 a.m., and 5:30 p.m., Monday through Friday. The telephone is (202) 566-1742. A reasonable fee may be charged by EPA for copying docket material.

Additionally, an electronic version of the public docket is available through the Federal government's electronic public docket and comment system. You may access EPA dockets at After opening the Web site, enter EPA-HQ-OAR-2010-0444 in “Search Documents” to view documents in the record. Although a part of the official docket, the public docket does not include Confidential Business Information (CBI) or other information whose disclosure is restricted by statute.

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Khesha Reed, Compliance and Innovative Strategies Division (6405J), U.S. Environmental Protection Agency, 1200 Pennsylvania Ave, NW., Washington, DC 20460. E-mail address:

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I. Background: Several heavy duty diesel engine manufacturers have recently begun utilizing a NOX emission control technology called selective catalyst reduction (SCR) to meet EPA standards and other requirements. SCR is an established technology that has been shown to meet stringent emissions requirements while enabling fuel efficiency benefits.

Currently certified heavy-duty engines utilizing SCR use a nitrogen containing reducing agent (aqueous urea) injected into the exhaust gas upstream of the catalyst. Other types of reducing agents may also be used by SCR technology. The reducing agent needs to be replenished periodically. Without the reducing agent, the efficiency of the SCR catalyst drops to zero and NOX emissions can potentially increase substantially. The efficiency of the SCR system can also be affected by the use of improper reducing agent or tampering with the SCR system.

The need to replenish the reducing agent (hereafter called diesel exhaust fluid, or DEF, although the reducing agent need not be fluid) and the possibility that SCR technology could be rendered ineffective by operation on an empty DEF tank are addressed by EPA's existing regulations regarding allowable and necessary maintenance and adjustable parameters. These regulations also apply in the case where inadequate DEF could be used or where the SCR system may be subject to tampering. Certified engine configurations include provisions and inducements designed to address these regulatory concerns.

EPA has previously provided guidance to heavy-duty diesel engine manufacturers in March 2007 and December 2009 to facilitate manufacturer planning in advance of certification.[1] In addition, in November 2009 EPA published in the Federal Register the approval of specific maintenance intervals for DEF refills for certain manufacturers.[2]

II. Public Workshop: EPA is commencing a public process designed to provide a thorough review of EPA's policies regarding the operation of SCR-equipped heavy-duty diesel engines without DEF, with improper DEF, or when tampering (or some other defect in the SCR system) is detected for future 2011 and later model year engines, in order to ensure, among other things, that SCR-equipped engines are designed to properly control emissions as required under applicable law and regulations. Although EPA has previously provided guidance to manufactures regarding the initial introduction and certification of SCR-equipped heavy-duty diesel engines, consistent with past practice we believe it is appropriate for EPA to review and reexamine its policies as technologies are introduced into the market place. As part of this process, EPA intends to review any information that has become available to determine whether its policies regarding SCR-equipped engines should be revised. The scope of the review includes review of the “Revised Guidance for Certification of Heavy-Duty Diesel Engines Using Selective Catalyst Reduction (SCR) Technologies” dated December 30, 2009. As part of EPA's Start Printed Page 39252review we will take into consideration the use of other reductants, in addition to current aqueous urea DEF, and will reexamine requisite infrastructure needs, any issues regarding the emission of unregulated pollutants, and any potential safety concerns. EPA is conducting the workshop with the California Air Resources Board in order that all relevant information be timely shared and considered by all affected parties; however, any final policies reached by EPA will be independently made and based upon applicable federal law and regulations. Any representations made by the California Air Resources Board regarding this matter are not binding upon EPA.

Procedures for Public Participation: Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2010-0444, by one of the following methods:


  • Fax: (202) 566-1741.
  • Mail: Air and Radiation Docket, Docket ID No. EPA-HQ-OAR-2010-0444, Environmental Protection Agency, Mailcode: 6102T, 1200 Pennsylvania Avenue, NW., Washington, DC 20460. Please include a total of two copies.
  • Hand Delivery: EPA Docket Center, Public Reading Room, EPA West Building, Room 3334, 1301 Constitution Avenue, NW., Washington, DC 20460. 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-2010-0444. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through or e-mail. The Web site is an “anonymous access” system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e-mail comment directly to EPA without going through, your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional information about EPA's public docket visit the EPA Docket Center homepage at​epahome/​dockets.htm.

Persons with comments containing proprietary information must distinguish such information from other comments to the greatest possible extent and label it as “Confidential Business Information” (CBI). If a person making comments wants EPA to base its decision in part on a submission labeled as CBI, then a non-confidential version of the document that summarizes the key data or information should be submitted for the public docket. To ensure that proprietary information is not inadvertently placed in the docket, submissions containing such information should be sent directly to the contact person listed above and not to the public docket. Information covered by a claim of confidentiality will be disclosed by EPA only to the extent allowed and by the procedures set forth in 40 CFR Part 2. If no claim of confidentiality accompanies the submission when EPA receives it, EPA will make it available to the public without further notice to the person making comments.

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Dated: July 1, 2010.

Margo Tsirigotis Oge,

Director, Office of Transportation and Air Quality.

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1.  See “Certification Procedure for Light-Duty and Heavy-Duty Diesel Vehicles and Heavy-Duty Diesel Engines Using Selective Catalyst Reduction (SCR) Technologies” dated March 27, 2007 and the “Revised Guidance for Certification of Heavy-Duty Diesel Engines Using Selective Catalyst Reduction (SCR) Technologies” dated December 30, 2009.

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2.  See 74 FR 57671 (November 9, 2009).

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[FR Doc. 2010-16702 Filed 7-7-10; 8:45 am]