Exhibit
10.6


AMENDMENT
NO. 1 TO TRANSITIONAL OPERATING AGREEMENT




AMENDMENT
NO. 1, dated as of February 29, 2008 (this “Amendment”), to that
certain Transitional Operating Agreement, dated as of February 1, 2008
(the “Operating Agreement”), by and among Cenac Towing Co., Inc.,
a Louisiana corporation (“Cenac Towing”), Cenac Offshore, L.L.C., a Louisiana
limited liability company (together with Cenac Towing, the “Cenac Companies”),
Mr. Arlen B. Cenac, Jr., a resident of Houma, Louisiana and the sole owner
of all the stock and equity interests of the Cenac Companies (the “Stockholder”
and, together with the Cenac Companies, the “Operators”), and TEPPCO Marine
Services, LLC, a Delaware limited liability company
(the “Owner”).




RECITALS




WHEREAS,
on February 1, 2008, the Operators agreed to provide the Services to the Owner
upon the terms and subject to the conditions set forth in the Operating
Agreement for the fees and reimbursement of the costs set forth
therein;




WHEREAS,
the Owner, Horizon Maritime, L.L.C., a Louisiana limited liability company
(“Horizon”), the Stockholder and the other members of Horizon have executed an
Asset Purchase Agreement, of date even herewith, providing for the purchase of
substantially all of the business operations and assets of Horizon, as described
and upon the terms and subject to the conditions and exceptions set forth
therein; and




WHEREAS,
the Owner and the Operators wish to amend the Operating Agreement as provided
herein in connection with the acquisition by the Owner of assets from Horizon to
provide for the operation thereby the Operators;




NOW,
THEREFORE, in consideration of the premises, the mutual agreements hereinafter
contained and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree that,
effective as of the date of this Amendment, the Operating Agreement shall be
amended as follows:




ARTICLE
I


DEFINITIONS




1.  Definitions.  Unless
otherwise defined herein, capitalized terms used in this Amendment shall have
the respective meaning ascribed to such terms in the Operating
Agreement.




ARTICLE
II


AMENDMENTS
TO THE OPERATING AGREEMENT




1.  Amendment to the Recitals to
the Operating Agreement.  The first Recital to the Operating
Agreement is hereby amended and restated in its entirety as
follows:




“WHEREAS,
the Owner, TEPPCO Partners, L.P., a Delaware limited partnership (the
“Partnership”), and the Operators have entered into that certain Asset Purchase
Agreement dated as of the date hereof (as amended from time to




time, the “Purchase Agreement”), pursuant to which the Operators have sold to
the Owner certain marine assets and rights relating to the Operations, as
specified and defined in the Purchase Agreement;”




2.  Amendments to Article I of
the Operating Agreement.




(a)  The
definitions of “Asphalt Business Limitation” and “Horizon Maritime” in Section
1.1 of the Operating Agreement are hereby deleted in their
entirety.




(b)  The
definition of “Employee” in Section 1.1 of the Operating Agreement is hereby
amended and restated in its entirety to read as follows:




“Employee” means each
employee of either of the Cenac Companies, including any employees hired or
retained after the date of this Agreement; provided, however, that (i) in no
event shall any Employee be considered to be an employee of the Owner and (ii)
nothing in this Agreement shall be construed as an offer of or contract for
employment with any such Employee.”




(c)  The
definition of “Purchased Operations” in Section 1.1 of the Operating Agreement
is hereby amended by deleting the following therefrom:




“from the
Operators or their Affiliates”




(d)  Section
1.1 of the Operating Agreement is hereby amended by adding the following in the
appropriate alphabetical location:




““Vessel”
shall mean the Vessels, as defined in the Purchase Agreement, the Vessels, as
defined in that certain Asset Purchase Agreement, dated as of February 29, 2008,
by and among Buyer, Horizon Maritime, L.L.C., a Louisiana limited liability
company, and the members of Horizon Maritime, L.L.C. and any other boats, barges
or other marine vessels (including related Vessel Equipment) owned or acquired
by the Owner or by the Operators with Owner funds (for which they are reimbursed
by the Owner).”




2.  Amendment to Article II of
the Operating Agreement.




(a)  Clause
(iii) of Section 2.1(b) of the Operating Agreement is hereby amended and
restated in its entirety to read as follows:




“(iii) in
accordance with the usual and customary practices in the industry in which the
Purchased Operations operate, including the American Waterways Operators
Responsible Carrier Program,”




(b)  Section
2.2 of the Operating Agreement is hereby amended to add the following as the
last sentence thereof:




“The
Operators represent, warrant, acknowledge and agree that any and all Persons
operating the Purchased Operations or performing Services hereunder,






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 including any crew onboard Vessels, are and shall be Service Providers
hereunder.”




3.  Amendment to Article IV of
the Operating Agreement.  Section 4.1(a) of the Operating
Agreement is hereby amended by deleting the following therefrom:






“,
provided that this Section 4.1(a) shall not prohibit Stockholder’s equity
ownership in Horizon Maritime for so long as the Asphalt Business Limitation is
satisfied”




4.  Amendment to Exhibit A to
the Operating Agreement.  Section 2(f) of Exhibit A to the
Operating Agreement is hereby amended and restated in its entirety to read as
follows:




“Maintaining
the requisite level of financial responsibility required under one of the
mechanisms established in 33 C.F.R. § 138.80 with respect to the Purchase
Operations, filing any and all required forms, financial statements and
affidavits and performing any and all audits or certifications that may be
required by such regulations.”




ARTICLE
III


MISCELLANEOUS




1.  Effect on the Operating
Agreement.  The Operating Agreement, as amended by this
Amendment, shall remain in full force and effect and, as so amended, is hereby
ratified and affirmed in all respects.  On and after the date hereof,
each reference in the Operating Agreement to “this Agreement,” “herein,”
“hereunder” or words of similar import shall mean and be a reference to the
Operating Agreement as amended by this Amendment.




2.  Assignment, Successors and
No Third-Party Rights.  No party may assign any of its rights
or delegate any of its obligations under this Amendment without the prior
written consent of the other parties, except that the Owner may assign any of
its rights and delegate any of its obligations under this Amendment to a
subsidiary of the Partnership.  Subject to the preceding sentence,
this Amendment will apply to, be binding in all respects upon and inure to the
benefit of the heirs, executors, administrators, successors and permitted
assigns of the parties.  Nothing expressed or referred to in this
Agreement will be construed to give any Person other than the parties to this
Amendment any legal or equitable right, remedy or claim under or with respect to
this Agreement or any provision of this Agreement, except such rights as shall
inure to a successor or permitted assignee pursuant to this Section 2. of
Article III.




3.  Choice of
Law.  This Amendment shall be governed by the general maritime
laws of the United States, to the extent applicable, and otherwise by the
internal laws of the State of Texas (without regard to the choice of law
provisions thereof).




4.  Construction; Section
Headings; Table of Contents..  The
language used in this Amendment shall be deemed to be the language the parties
hereto have chosen to express their mutual intent, and no rule of strict
construction will be applied against any party hereto.  The section
headings contained in this Amendment are for reference purposes only and shall
not affect the meaning or interpretation of this Amendment.






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5.  Severability.  Any term
or provision (or subpart or portion thereof) of this Amendment which is invalid
or unenforceable in any jurisdiction shall, as to that jurisdiction, be
ineffective to the extent of such invalidity or unenforceability without
rendering invalid or unenforceable the remaining terms and provisions of this
Amendment or affecting the validity or enforceability of any of the terms or
provisions of this Amendment in any other jurisdiction.  If any
provision (or subpart or portion thereof) of this Amendment is so broad as to be
unenforceable, the provision shall be interpreted to be only so broad as is
enforceable.




6.  Counterparts.  This
Amendment may be executed in any number of counterparts, each of which shall be
deemed to be an original and all of which together shall be deemed to be one and
the same instrument.

















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IN
WITNESS WHEREOF, the parties hereto have executed this Amendment on the date
first above written.









TEPPCO
MARINE SERVICES, LLC











By:           /s/ WILLIAM G.
MANIAS


William
G. Manias


Vice President and


Chief Financial Officer








CENAC TOWING CO.,
INC.











By:           /s/
ARLEN B. CENAC, JR.


Arlen B. Cenac, Jr.


President








CENAC OFFSHORE,
L.L.C.











By:           /s/
ARLEN B. CENAC, JR.


Arlen B. Cenac, Jr.


Managing Member








/s/ ARLEN B. CENAC, JR.
              Arlen
      B. Cenac, Jr.