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Bruce C. Buckheit, Director
Air Enforcement Division
Office of Enforcement and Compiiance Assurance



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(sz) UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
fa WASHINGTON, D.C. 20460

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June 1, 1998
I OFFICE OF
ENFORCEMENT AND
COMPLIANCE
ASSURANCE

Revision to Addendum to Mobile Source Enforcement Memorandum 1A.
SUBJECT: Revised Tampering Enforcement Policy for Alternative Fuel Conversions

A. Purpose: The purpose of this document is to revise the tampering enforcement policy for
alternative fuel conversions as currently provided in the U.S. Environmental Protection Agency’s
(EPA) Addendum to Memorandum 1A in response to comments and suggestions received by the
regulated community and other stakeholders.

B. Background: EPA issued an Addendum to Mobile Source Enforcement Memorandum 1A
(Addendum) on September 4, 1997, to address emissions increases that resulted from the
conversion of gasoline powered vehicles and engines to operate on compressed natural gas
(CNG) and liquefied petroleum gasoline (LPG or propang). The background and basis for the
issuance of the Addendum and the contents of the new policy are fully contained in the
Addendum. Since issuance of the Addendum, EPA has received a number of inquiries and
recommendations that certain revisions to the policy would be in the public interest while not
jeopardizing the effectiveness of the Addendum. EPA believes some of those suggestions are
appropriate and is revising the Addendum as described below.

C. Revised Policy: Effective immediately, the Addendum to Memorandum 1A is revised as
follows:

1. In lieu of meeting the testing requirements under Options 1, 2 or 3 of the Addendum
for model year 1997 and older motor vehicles and engines, compliance with the requirements for
demonstrating a “reasonable basis” may be achieved by completing back-to-back I/M 240
emissions tests as contained in 40 CFR Part 51, Subpart S, for each converted vehicle using
gasoline in the vehicle or engine’s original configuration and with each operational fuel after
conversion provided:

(a) All tests are conducted in accordance with the specified protocols under 40 CFR Part
51, Subpart S,

(b) The vehicle as tested in the original configuration with gasoline meets the applicable
standards under 40 CFR 51.351,

(c) The exhaust emissions of each regulated pollutant after conversion using the
alternative fuel are no greater than .90 times the emissions levels for each pollutant before


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conversion, except that no hydrocarbon standard shall apply for operation exclusively using
CNG, (4d) If dual fuel operation is retained, the exhaust emissions of each regulated pollutant
after conversion using the original certification fuel are no greater than the emissions levels for
each pollutant before conversion, and

(e) No party shall convert more than 25 vehicles or engines of any single vehicle/engine
family combination in any calendar year under this I/M 240 protocol.

2. The final date for both testing and installations under Option 3 of the Addendum is
extended from April 24, 1998 and December 31, 1998, respectively, to June 30, 2000, for up to
and including 1999 model year vehicles and engines. All alternative fuel conversions of model
years 2000 and later vehicles and engines and conversions of model year 1998 and 1999 vehicles
and engines after June 30, 2000, may only be performed in accordance with Options 1 or 2 of the
Addendum.

3. Asan alternate to engine dynamometer testing for heavy duty engine conversions
under Option 3 for a specific heavy duty engine family, the manufacturer may demonstrate a
“reasonable basis” by performing back-to-back chassis dynamometer emission tests in
accordance with the Urban Dynamometer Driving Schedule for Heavy Duty Vehicles (UDDS)
contained in 40 CFR Part 86 Appendix I, Paragraph (d), provided:

(a) The exhaust emissions results for THC, NOx and CO measured during the UDDS
after conversion and when operated exclusively or in combination with the alternative fuel are no
greater than .90 times the baseline emissions for THC and NOx and no greater than 1.00 times
CO before conversion, except that NMHC after conversion shall be compared to the baseline
THC before conversion in the case of operation exclusively with CNG, and

(b) All tests are performed in accordance with all specified protocols in 40 CFR Part 86,
Subpart M, including vehicle preparation, dynamometer loading, emissions measurements and
driving schedule except that commercially available fuel may be used for vehicle preconditioning
and baseline testing.

4. As an alternate to engine dynamometer testing for heavy duty engine conversions
under Option 3 for a specific heavy duty engine family or the alternate procedures provided in
paragraph 3. above or the Addendum, any party may propose an alternate heavy duty vehicle or
engine test procedure which operates the subject test engine through a range of engine speed and
load conditions reasonably representative of both urban and highway driving, measures the
exhaust emissions specified above on a grams per mile or grams per brake horsepower-hour basis
and specifies appropriate pass/fail criteria equivalent to paragraph 3. above for the purpose of
demonstrating a “reasonable basis” under EPA’s tampering enforcement policy. Any such
proposed procedures shall be submitted to the Director, Air Enforcement Division (2242A),
Office of Enforcement and Compliance Assurance, U.S. EPA, 401 M Street, S.W., Washington,
D.C. 20460 for consideration and approval, if appropriate, under this policy prior to the initiation
of any vehicle procurement, modification or testing.

5. The results of federal emissions tests conducted under Option 3 for a specific engine


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family may be applied as a “reasonable basis” for up to a maximum of three additional engine
families to that tested for demonstrating compliance with the applicable Tier 1 emission
standards for that class of vehicle or engine as specified in 40 CFR Part 86 provided:

(a) The engine family tested in accordance with 40 CFR Part 86 meets the applicable
Tier 1 standards for that vehicle or engine class with the application of the appropriate
deterioration factor as provided under Option 3,

(b) The engine family tested above represents the “worst case” for emissions of the
applicable engine families as based on engine or vehicle parameters reasonably expected to
adversely affect the emission results such as maximum gross vehicle weight, maximum engine
displacement and any other reasonable engineering judgements,

(c) The determination of “worst case” is confirmed by conducting I/M 240 emissions tests
of one vehicle or engine of each applicable engine family after conversion,

(d) The results of the I/M 240 tests of the three additional engine families are no greater
than the I/M 240 emission results of the original engine family tested,

(e) The additional engine families meet the criteria specified in paragraphs 3.(b)(4)B.
through D. of the Addendum, and

(f) The evaporative emission control system remains as installed by the original engine
manufacturer if gasoline operation is retained.

6. For both LEV and Tier 1 vehicles or engines, any additional engine families for which
emission data would be carried across under paragraph 5. above or paragraph 3.(b)(4) under
Option 3 of the Addendum must be produced by the same vehicle or engine manufacturer as the
original engine family tested. |

7. Any party responsible for demonstrating compliance, installing, converting, selling or
marketing alternative fuel conversion systems in accordance with the requirements of the
Addendum and this revised policy shall retain the results of all tests, installations and sales of
such systems as specified under Option 3 of the Addendum or this Revision for inspection by
EPA for five (5) years following completion of the testing, installing or marketing of such
systems.

8. Any provisions or requirements of the Addendum not extended or revised herein
remain in effect as provided in the Addendum.

C. Conclusion: EPA believes the revisions described above will provide additional flexibility
and streamlining to manufacturers, installers and marketers of alternative fuel conversion
systems while not jeopardizing the emission reduction purposes of the original Addendum. EPA
will continue to review the progress of the industry in developing and testing of alternative fuel
systems to ensure the emissions benefits are being achieved and to determine if any future
revisions are necessary. Any questions regarding this revised policy should be directed to the
Mobile Source Enforcement Branch at (202) 564-2255.

/s/