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                                                                    EXHIBIT 10.2



                             CONTRIBUTION AGREEMENT

                  THIS CONTRIBUTION AGREEMENT dated as of __________, 2001 (this
"Agreement"), is entered into by and among SHAMROCK LOGISTICS, L.P., a Delaware
limited partnership (the "Partnership"), SHAMROCK LOGISTICS OPERATIONS, L.P. a
Delaware limited partnership (the "Operating Partnership"), RIVERWALK LOGISTICS,
L.P., a Delaware limited partnership (the "General Partner"), SHAMROCK LOGISTICS
GP, LLC, a Delaware limited liability company ("Shamrock Logistics GP"), UDS
LOGISTICS, LLC, a Delaware limited liability company ("UDS Logistics"), DIAMOND
SHAMROCK REFINING AND MARKETING COMPANY, a Delaware corporation ("DSRMC") and
SIGMOR CORPORATION, a Delaware corporation ("Sigmor").

                                    RECITALS

                  WHEREAS, the General Partner and Todd Walker (the
"Organizational Limited Partner") have heretofore formed the Partnership
pursuant to the Delaware Revised Uniform Limited Partnership (the "Delaware
Act") for the purpose of serving as a limited partner of the Operating
Partnership; and

                  WHEREAS, the General Partner contributed $10.00 to the capital
of the Partnership and received a 1% general partner interest therein, and the
Organizational Limited Partner contributed $990.00 to the capital of the
Partnership and received a 99% limited partner interest therein; and

                  WHEREAS, the General Partner and the Organizational Limited
Partner have heretofore formed the Operating Partnership pursuant to the
Delaware Act for the purpose of


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owning and operating certain crude oil and refined product pipeline,
terminalling and storage assets previously owned and operated by certain
subsidiaries of Ultramar Diamond Shamrock Corporation ("UDS") (the "Business"),
which assets have previously been transferred to the Operating Partnership by
mergers with and by conveyances and assignments from subsidiaries of UDS; and

                  WHEREAS, the General Partner contributed $10.00 to the capital
of the Operating Partnership and received a 1% general partner interest therein,
and the Organizational Limited Partner contributed $990.00 to the capital of the
Operating Partnership and received a 99% limited partner interest therein; and

                  WHEREAS, the Operating Partnership has entered into a bank
credit agreement (the "Bank Credit Agreement") providing for a $120 million
revolving credit facility; and

                  WHEREAS, concurrently with the consummation of the
transactions contemplated by this Agreement, the General Partner and the
Partnership have entered into that certain Second Amended and Restated Agreement
of Limited Partnership of the Operating Partnership (the "Operating Partnership
Agreement"); and

                  WHEREAS, concurrently with the consummation of the
transactions contemplated by this Agreement, the General Partner and the
Organizational Limited Partner have entered into that certain Second Amended and
Restated Agreement of Limited Partnership of the Partnership (the "Partnership
Agreement");

                  NOW, THEREFORE, in consideration of their mutual undertakings
and agreements hereunder, the parties to this Agreement undertake and agree as
follows:


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                                    ARTICLE I

                                   DEFINITIONS

         1.1 Definitions. The following capitalized terms shall have the
meanings given below.

                  "Agreement" means this Contribution Agreement.

                  "Bank Credit Agreement" has the meaning assigned to such term
in the Recitals to this Agreement.

                  "Business" has the meaning assigned to such term in the
Recitals to this Agreement.

                  "Common Units" means common limited partner interests in the
Partnership.

                  "Delaware Act" has the meaning assigned to such term in the
Recitals to this Agreement.

                  "DSRMC" has the meaning assigned to such term in the opening
paragraph of this Agreement.

                  "Effective Time" means 12:01 a.m. Eastern Standard Time on
__________, 2001.

                  "General Partner" has the meaning assigned to such term in the
opening paragraph of this Agreement.

                  "OLP Interests" means limited partnership interests in the
Operating Partnership.

                  "Operating Partnership" has the meaning assigned to such term
in the opening paragraph of this Agreement.

                  "Operating Partnership Agreement" has the meaning assigned to
such term in the Recitals to this Agreement.


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                  "Organizational Limited Partner" has the meaning assigned to
such term in the Recitals to this Agreement.

                  "Partnership" has the meaning assigned to such term in the
opening paragraph of this Agreement.

                  "Partnership Agreement" has the meaning assigned to such term
in the Recitals to this Agreement.

                  "Shamrock Logistics GP" has the meaning assigned to such term
in the opening paragraph of this Agreement.

                  "Sigmor" has the meaning assigned to such term in the opening
paragraph of this Agreement.

                  "Subordinated Units" means subordinated limited partner
interests in the Partnership.

                  "UDS" has the meaning assigned to such term in the Recitals to
this Agreement.

                  "UDS Logistics" has the meaning assigned to such term in the
opening paragraph of this Agreement.

                                   ARTICLE II

                            CONTRIBUTIONS AT CLOSING

         2.1 DSRMC Contribution to Shamrock Logistics GP. DSRMC hereby
contributes OLP Interests to Shamrock Logistics GP and Shamrock Logistics GP
hereby accepts such OLP Interests as a contribution to the capital of Shamrock
Logistics GP.


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         2.2 DSRMC Contribution to UDS Logistics. DSRMC hereby contributes OLP
Interests to UDS Logistics and UDS Logistics hereby accepts such OLP Interests
as a contribution to the capital of UDS Logistics.

         2.3 Shamrock Logistics GP Contribution to the General Partner. Shamrock
Logistics GP hereby contributes the OLP Interests received in Section 2.1 above
to the General Partner in exchange for a 0.1% general partner interest in the
General Partner and the General Partner hereby accepts such OLP Interests as a
contribution to the capital of the General Partner.

         2.4 UDS Logistics Contribution to the General Partner. UDS Logistics
hereby contributes the OLP Interests received in Section 2.2 above to the
General Partner in exchange for 99.9% limited partner interest in the General
Partner and the General Partner hereby accepts such OLP Interests as a
contribution to the capital of the General Partner.

         2.5 Conversion of OLP Interests. The parties acknowledge that pursuant
to the Operating Partnership Agreement, a portion of the OLP Interests held by
the General Partner have been converted into general partner interests so that
the General Partner holds a 1.0101% general partner interest in the Operating
Partnership.

         2.6 DSRMC Contribution to UDS Logistics. DSRMC hereby contributes OLP
Interests to UDS Logistics in exchange for member interests in UDS Logistics and
UDS Logistics hereby accepts such OLP Interests as a contribution to the capital
of UDS Logistics.

         2.7 Sigmor Contribution to UDS Logistics. Sigmor hereby contributes OLP
Interests to UDS Logistics in exchange for member interests in UDS Logistics and
UDS Logistics hereby accepts such OLP Interests as a contribution to the capital
of UDS Logistics.


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         2.8 GP Contribution to the Partnership. General Partner hereby
contributes its OLP Interests to the Partnership in exchange for a 1% general
partner interest in the Partnership and the Partnership hereby accepts such OLP
Interests as a contribution to the capital of the Partnership.

         2.9 UDS Logistics Contribution to the Partnership. UDS Logistics hereby
contributes its OLP Interests to the Partnership in exchange for 8,999,222
Subordinated Units and 4,399,322 Common Units and the Partnership hereby accepts
such OLP Interests as a contribution to the capital of the Partnership.

         2.10 Bank Credit Agreement Borrowing. The parties acknowledge that the
Operating Partnership has borrowed $__________ under the Bank Credit Agreement.

                                   ARTICLE III

                       PUBLIC OFFERING AND USE OF PROCEEDS

         3.1 Public Cash Contribution. The parties to this Agreement acknowledge
a cash contribution to the Partnership of $__________ ($__________ after payment
of underwriting discounts and commissions) from the public in exchange for
4,000,000 Common Units.

         3.2 Partnership Cash Contribution. The Partnership hereby contributes
cash in the amount of $[net amount received from public] to the Operating
Partnership in exchange for OLP Interests and the Operating Partnership hereby
accepts such cash contribution as a contribution to the capital of the Operating
Partnership.

         3.3 Operating Partnership Use of Proceeds. The parties to this
Agreement acknowledge that the Operating Partnership has used the cash received
as set forth in Section 3.2


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above along with $ ___________ from the Bank Credit Agreement as follows: (a)
reimbursement to the General Partner and others for certain capital expenditures
in the amount of $20.52 million; (b) payment of certain transaction expenses in
the aggregate amount of $ ___________ million including, without limitation, all
of the syndication costs incurred by the Partnership in connection with the
public offering of the Common Units; (c) payment in the aggregate amount of [$9]
million to DSRMC as repayment of a working capital loan previously made by DSRMC
to the Operating Partnership; (d) repayment of qualified debt previously assumed
by the Operating Partnership pursuant to certain mergers and asset conveyances
related to the Business in the aggregate amount of $98.68 million; and (e) $5.0
million for working capital and general corporate purposes.

                                   ARTICLE IV

                               FURTHER ASSURANCES

         4.1. Further Assurances. From time to time after the date hereof, and
without any further consideration, each party upon request from another shall
execute, acknowledge and deliver all such additional instruments, notices and
other documents, and will do all such other acts and things, all in accordance
with applicable law, as may be reasonably necessary or appropriate to more fully
and effectively carry out the purposes and intent of this Agreement.


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                                    ARTICLE V

                                  MISCELLANEOUS

         5.1. Order of Completion of Transactions; Effective Time. The
transactions provided for in Articles II and III of this Agreement shall be
completed on the date of this Agreement in the following order:

                  First, the transactions provided for in Article II shall be
completed; and

                  Second, the transactions provided for in Article III shall be
completed.

         5.2. Costs. The Operating Partnership shall pay all sales, use and
similar taxes arising out of the contributions and deliveries to be made
hereunder, and shall pay all documentary, filing, recording, transfer, deed, and
conveyance taxes and fees required in connection therewith, if any.

         5.3. Headings: References: Interpretation. All Article and Section
headings in this Agreement are for convenience only and shall not be deemed to
control or affect the meaning or construction of any of the provisions hereof.
The words "hereof," "herein" and "hereunder" and words of similar import, when
used in this Agreement, shall refer to this Agreement as a whole, including,
without limitation, all Schedules and Exhibits attached hereto, if any, and not
to any particular provision of this Agreement. All references herein to
Articles, Sections, Schedules and Exhibits, if any, shall, unless the context
requires a different construction, be deemed to be references to the Articles
and Sections of this Agreement and the Schedules and Exhibits attached hereto,
and all such Schedules and Exhibits attached hereto are hereby incorporated
herein and made a part hereof for all purposes. All personal pronouns used in
this Agreement, whether used in the masculine, feminine or neuter gender, shall
include all other genders, and the singular shall include the plural and vice
versa. The use herein of the word "including" following any general


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statement, term or matter shall not be construed to limit such statement, term
or matter to the specific items or matters set forth immediately following such
word or to similar items or matters, whether or not non-limiting language (such
as "without limitation," "but not limited to," or words of similar import) is
used with reference thereto, but rather shall be deemed to refer to all other
items or matters that could reasonably fall within the broadest possible scope
of such general statement, term or matter.

         5.4. Successors and Assigns. The Agreement shall be binding upon and
inure to the benefit of the parties signatory hereto and their respective
successors and assigns.

         5.5. No Third Party Rights. The provisions of this Agreement are
intended to bind the parties signatory hereto as to each other and are not
intended to and do not create rights in any other person or confer upon any
other person any benefits, rights or remedies and no person is or is intended to
be a third party beneficiary of any of the provisions of this Agreement.

         5.6. Counterparts. This Agreement may be executed in any number of
counterparts, all of which together shall constitute one agreement binding on
the parties hereto.

         5.7. Governing Law. This Agreement shall be governed by, and construed
in accordance with, the laws of the State of Texas applicable to contracts made
and to be performed wholly within such state without giving effect to conflict
of law principles thereof.

         5.8. Severability. If any of the provisions of this Agreement are held
by any court of competent jurisdiction to contravene, or to be invalid under,
the laws of any political body having jurisdiction over the subject matter
hereof, such contravention or invalidity shall not invalidate the entire
Agreement. Instead, this Agreement shall be construed as if it did not contain
the particular provision or provisions held to be invalid, and an equitable
adjustment shall be made and


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necessary provision added so as to give effect to the intention of the parties
as expressed in this Agreement at the time of execution of this Agreement.

         5.9. Amendment or Modification. This Agreement may be amended or
modified from time to time only by the written agreement of all the parties
hereto.

         5.10 Integration. This Agreement supersedes all previous understandings
or agreements between the parties, whether oral or written, with respect to its
subject matter. This document is an integrated agreement which contains the
entire understanding of the parties. No understanding, representation, promise
or agreement, whether oral or written, is intended to be or shall be included in
or form part of this Agreement unless it is contained in a written amendment
hereto executed by the parties hereto after the date of this Agreement.

         5.11 Power of Attorney. Each of the parties hereby constitutes and
appoints the General Partner and its successors and assigns as its true and
lawful attorney with full power of substitution, having full right and authority
in each of the parties' name and their respective successors and assigns, to
demand, sue for, recover, collect and receive any and all accounts receivable
hereby distributed and delivered to the General Partner, and to use and take any
and all lawful means for the recovery thereof by legal process or otherwise; to
give receipts, releases and acquittances for or in respect of the same or any
part thereof; to institute and prosecute in the name of each of the parties or
otherwise, and to defend and compromise, any and all actions, suits or
proceedings in respect of any accounts receivable hereby distributed and
delivered to the General Partner, which the General Partner and its successors
and assigns shall deem desirable. Each of the parties hereby declares that the
foregoing powers are coupled with an interest and shall be irrevocable by it in
any manner or for any reason.


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         IN WITNESS WHEREOF, this Agreement has been duly executed by the
parties hereto as of the date first above written.

                                   SHAMROCK LOGISTICS, L.P.,
                                   a Delaware limited partnership

                                   By: Riverwalk Logistics, L.P.
                                       its general partner

                                       By: Shamrock Logistics GP, LLC


                                            By:
                                               -----------------------------


                                   SHAMROCK LOGISTICS OPERATIONS, L.P.,
                                   a Delaware limited partnership

                                   By: Riverwalk Logistics, L.P.
                                       its general partner

                                       By: Shamrock Logistics GP, LLC


                                            By:
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                                   RIVERWALK LOGISTICS, L.P.,
                                   a Delaware limited partnership

                                   By: Shamrock Logistics GP, LLC
                                       its general partner

                                       By: Diamond Shamrock Refining and
                                           Marketing Company, a Delaware
                                           corporation


                                            By:
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                                   DIAMOND SHAMROCK REFINING AND
                                   MARKETING COMPANY,
                                   a Delaware corporation


                                   By:
                                      ----------------------------------------


                                   SIGMOR CORPORATION,
                                   a Delaware corporation


                                   By:
                                      ----------------------------------------


                                   SHAMROCK LOGISTICS GP, LLC,
                                   a Delaware limited liability company

                                   By: Diamond Shamrock Refining and Marketing
                                       Company, a Delaware corporation


                                       By:
                                          ------------------------------------


                                   UDS LOGISTICS LLC,
                                   a Delaware limited liability company

                                   By: Diamond Shamrock Refining and Marketing
                                       Company, a Delaware corporation


                                       By:
                                          ------------------------------------