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                                                                    EXHIBIT 10.7

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                                OMNIBUS AGREEMENT

                                      among

                      ULTRAMAR DIAMOND SHAMROCK CORPORATION

                           SHAMROCK LOGISTICS GP, LLC

                            RIVERWALK LOGISTICS, L.P.


                                       and

                            SHAMROCK LOGISTICS, L.P.



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                                OMNIBUS AGREEMENT

         THIS OMNIBUS AGREEMENT is entered into on, and effective as of, the
Closing Date by and among Ultramar Diamond Shamrock Corporation, a Delaware
corporation ("UDS"), Shamrock Logistics GP, LLC, a Delaware limited liability
company ("Shamrock GP"), Riverwalk Logistics, L.P., a Delaware limited
partnership and general partner of the MLP ("Riverwalk") and Shamrock Logistics,
L.P., a Delaware limited partnership (the "MLP").

                                    RECITAL:

         UDS, the MLP, Shamrock GP in its capacity as the general partner of
Riverwalk, and Riverwalk in its capacity as the general partner of each of the
MLP and Shamrock Logistics Operations L.P., a Delaware limited partnership (the
"OLP"), desire by their execution of this Agreement to evidence their
understanding, (i) as more fully set forth in Article II of this Agreement, with
respect to (a) those business opportunities that UDS will not pursue unless the
MLP has declined to engage in such business opportunity for its own account and
(b) the procedures whereby such business opportunities are to be offered to the
MLP and accepted or declined; and (ii) as more fully set forth in Article III of
this Agreement, with respect to the indemnification obligations of UDS in favor
of relating to certain environmental liabilities.

         In consideration of the premises and the covenants, conditions, and
agreements contained herein, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
hereby agree as follows:

                                   ARTICLE I.
                                   DEFINITIONS

         1.1 DEFINITIONS. (a) Capitalized terms used herein but not defined
herein shall have the meanings given them in the MLP Agreement.

                  (b) As used in this Agreement, the following terms shall have
the respective meanings set forth below:

                  "Affiliate" shall have the meaning attributed to such term in
         the MLP Agreement.

                  "Agreement" means this Omnibus Agreement, as amended,
         modified, or supplemented from time to time in accordance with the
         terms hereof.

                  "Authority" shall mean any governmental, regulatory or
         administrative body, agency, subdivision or authority, any court or
         judicial authority, any public, private or industry regulatory
         authority, whether in the United States of America or any foreign
         country and whether national, Federal, state or local or otherwise, or
         any Person lawfully empowered by any of the foregoing to enforce or
         seek compliance with any Regulation.

                  "Change of Control" shall have the meaning attributed to such
         term in Section 2.4.




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                  "Claim" means any claim, lawsuit, demand, suit, inquiry made,
         hearing, investigation, notice of a violation, litigation, proceeding,
         arbitration, or other dispute, whether civil, criminal, administrative
         or otherwise.

                  "Closing Date" means the date of the closing of the initial
         public offering of common units representing limited partner interests
         in the MLP.

                  "Conflicts Committee" shall have the meaning attributed to
         such term in the MLP Agreement.

                  "Contaminant" means any substance regulated under any
         Environmental Law, or any substance defined as or included in the
         statutory or regulatory definitions of hazardous substances, hazardous
         wastes, hazardous materials, or "toxic substances" under any
         Environmental Law.

                  "Contract" means any agreement, contract, commitment, or other
         binding arrangement or understanding, whether written or oral.

                  "Environmental Law" means any and all laws, statutes,
         judgments, ordinances, rules, regulations, orders, determinations,
         interpretations, or guidance of any Governmental Authority pertaining
         to health or the environment in effect in any and all jurisdictions in
         which any UDS Entity or Partnership Entity or any of their respective
         Affiliates is conducting or at any time has conducted business, or
         where any property of any UDS Entity or Partnership Entity or any of
         their respective Affiliates, whether leased or owned, is located, or
         where any hazardous substances generated or disposed of by any UDS
         Entity or Partnership Entity or any of their respective Affiliates are
         located.

                  "Environmental Liabilities and Costs" means all Losses from
         any Claim by any Person whether based on Contract, tort, implied or
         express warranty, strict liability, criminal or civil statute,
         including under any Remedial Action, Environmental Law, Environmental
         Permit, Environmental Lien, Order or agreement with any Authority,
         arising from environmental, health or safety conditions, or the release
         of a Contaminant into the environment.

                  "Environmental Lien" means any Lien in favor of any Authority
         for Environmental Liabilities and Costs.

                  "Environmental Permit" shall mean any Permit, license,
         approval, consent or other authorization required by or pursuant to any
         applicable Environmental Law.

                  "Exchange Act" means the Securities Exchange Act of 1934, as
         amended.

                  "Formation Transactions" means (i) the contributions to the
         OLP of certain crude oil pipeline and storage assets and refined
         product pipeline and terminalling assets pursuant to that certain
         Conveyance, Assignment and Bill of Sale Agreements dated effective as
         of July 1, 2000, by and among the OLP and certain subsidiaries of UDS
         and



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         (ii) the transfers of certain crude oil pipeline and storage assets and
         refined product pipeline and terminalling assets and certain ownership
         interests in Skelly-Belvieu Pipeline Company, L.L.C. to the OLP by
         virtue of the mergers of certain subsidiaries of UDS with and into the
         OLP effective as of July 1, 2000.

                   "Governmental Authority" shall mean (a) the United States of
         America, (b) any state, county, municipality, or other governmental
         subdivision within the United States of America, and (c) any court or
         any governmental department, commission, board, bureau, agency, or
         other instrumentality of the United States of America or of any state,
         county, municipality, water rights, taxing, or zoning authority, or
         other governmental subdivision within the United States of America.

                  "Indemnified Party" shall have the meaning assigned to such
         term in Section 3.2(a).

                  "Indemnifying Party" shall have the meaning assigned to such
         term in Section 3.2(a).

                  "Losses" means all liabilities, losses, costs, damages
         (including punitive, consequential and treble damages), penalties or
         expenses (including, without limitation, reasonable attorneys' fees and
         expenses and costs of investigation and litigation), and also including
         any expenditures or expenses incurred to cover, remedy or rectify any
         such Losses.

                  "MLP" means Shamrock Logistics, L.P., a Delaware limited
         partnership, and any successors thereto.

                  "MLP Agreement" means the Second Amended and Restated
         Agreement of Limited Partnership of the MLP, dated as of the Closing
         Date, as such agreement is in effect on the Closing Date, to which
         reference is hereby made for all purposes of this Agreement. No
         amendment or modification to the MLP Agreement subsequent to the
         Closing Date shall be given effect for the purposes of this Agreement
         unless consented to by each of the parties to this Agreement.

                  "OLP" means Shamrock Logistics Operations, L.P., a Delaware
         limited partnership, and any successors thereto.

                  "Partnership Entities" means Shamrock GP, Riverwalk, the MLP
         and the OLP.

                   "Person" means an individual, partnership, corporation,
         limited liability company, trust, incorporated or unincorporated
         association, joint venture, joint stock company, Governmental Authority
         or other legal entity of any kind.

                  "Permits" means any licenses, permits, registrations,
         variances, interim permits, permit applications, certificates,
         approvals or other authorizations under any Regulation applicable to
         any UDS Entity or Partnership Entity.



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                  "Order" means any decree, order, injunction, rule, judgment,
         consent of or by an Authority.

                  "Regulation" means any law, statute, regulation, ruling, rule,
         Order or Permit, of, administered or enforced by or on behalf of any
         Authority, as may be amended from time to time.

                  "Remedial Action" means all actions required to (a) clean up,
         remove, treat or in any other way address Contaminants in the indoor or
         outdoor environment; (b) prevent the release or threat of release or
         minimize the further release of Contaminants so they do not migrate or
         endanger or threaten to endanger public health or welfare or the indoor
         or outdoor environment; or (c) perform pre-remedial studies and
         investigations and post-remedial monitoring and care.

                  "Restricted Business" has the meaning attributed to such term
         in Section 2.1.

                  "Riverwalk" means Riverwalk Logistics, L.P., a Delaware
         limited partnership and general partner of the MLP.

                  "Shamrock GP" means Shamrock GP, LLC, a Delaware limited
         liability company and general partner of Riverwalk.

                  "UDS" means Ultramar Diamond Shamrock Corporation.

                  "UDS Entities" means UDS and any of its Affiliates, other than
         the Partnership Entities.

                  "Voting Stock" means securities or membership interests of any
         class or series of either UDS, Shamrock GP or Riverwalk entitling the
         holders thereof to vote on a regular basis in the election of members
         of the board of directors, board of managers or other governing body of
         such entity.

                                  ARTICLE II.
                             BUSINESS OPPORTUNITIES

         2.1 RESTRICTED BUSINESSES. Subject to the terms of the MLP Agreement,
for as long as (i) Shamrock GP (or any Affiliate of UDS) is the general partner
of Riverwalk and (ii) Riverwalk (or any Affiliate of UDS) is the general partner
of the MLP or the OLP, each of the UDS Entities are prohibited from engaging in,
whether by acquisition or otherwise, the business of transporting crude oil or
refined petroleum products (including petrochemicals) or operating crude oil
storage or refined petroleum products terminalling assets in the United States
(a "Restricted Business").

         2.2 PERMITTED EXCEPTIONS. Notwithstanding any provision of Section 2.1,
an UDS Entity may pursue an opportunity to purchase or invest in, and may
ultimately purchase, own and/or operate, a Restricted Business under any of the
following circumstances:



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                  (a)      Any business retained by a UDS Entity at the Closing;

                  (b)      Any further development of the Diamond-Koch Joint
                           Venture petrochemicals business;

                  (c)      Any business with a fair market value of less than
                           $10 million;

                  (d)      Any business acquired by a UDS Entity that
                           constitutes less than 50% of the fair market value of
                           a larger acquisition by such UDS Entity; provided the
                           MLP has been offered and declined (with the
                           concurrence of the Conflicts Committee) the
                           opportunity to purchase such business in accordance
                           with the procedures set forth in Section 2.3;

                  (e)      The Wichita Falls crude oil pipeline, the Nuevo
                           Laredo refined product pipeline and the Ringold crude
                           oil storage facility should the MLP decline to
                           exercise its option to purchase them pursuant to the
                           [Option Agreement(s) dated effective as of July 1,
                           2000 among the UDS Entities and the MLP]; or

                  (f)      Any logistics assets newly constructed by a UDS
                           Entity that the MLP has not offered to purchase
                           within one year of construction at fair market value,
                           not to exceed 105% of the cost to such UDS Entity.

         2.3 PROCEDURES.

                  (a) In the event that an UDS Entity becomes aware of an
opportunity to purchase a Restricted Business, then, as soon as practicable,
such UDS Entity shall notify Shamrock GP of such opportunity and deliver to
Shamrock GP all information prepared by or on behalf of such UDS Entity relating
to such potential purchase. As soon as practicable but in any event within 30
days after receipt of such notification and information, Shamrock GP, on behalf
of the Partnership, shall notify the UDS Entity that either (i) Shamrock GP, on
behalf of the Partnership, has elected, with the approval of the Conflicts
Committee, not to cause the MLP to pursue the opportunity to acquire such
Restricted Business, or (ii) Shamrock GP, on behalf of the Partnership, has
elected to cause the MLP to pursue the opportunity to acquire such Restricted
Business. If, at any time, Shamrock GP or its Affiliates abandons such
opportunity (as evidenced in writing by Shamrock GP or such Affiliates following
the request of the UDS entity), the UDS Entity may pursue such opportunity. Any
Restricted Business which is permitted to be purchased by an UDS Entity must be
so purchased (i) within 12 months of the time the UDS Entity becomes able to
pursue such acquisition in accordance with the provisions of this Section 2.3
and (ii) on terms not materially more favorable to the UDS Entity than were
offered to the Partnership. If either of these conditions are not satisfied, the
opportunity must be reoffered to the Partnership.

                  (b) In the event that an UDS Entity acquires a Restricted
Business as part of a larger transaction in accordance with the provisions of
Section 2.2(d), then, within 30 days of the consummation of such purchase, such
UDS Entity shall notify Shamrock GP of such purchase and offer the MLP the
opportunity to purchase the Restricted Business constituting a portion of



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such purchase and deliver to Shamrock GP all information prepared by or on
behalf of or in the possession of such UDS Entity relating to the Restricted
Business. As soon as practicable but in any event within 30 days after receipt
of such notification, Shamrock GP shall notify the UDS Entity that either (i)
Shamrock GP, on behalf of the Partnership, has elected, with the approval of the
Conflicts Committee, not to cause the MLP to purchase such Restricted Business,
in which event the UDS Entity shall be free to continue to engage in such
Restricted Business, or (ii) Shamrock GP, on behalf of the Partnership, has
elected to cause the MLP to purchase such Restricted Business, in which event
the following procedures shall be followed:

                           (i) The UDS Entity shall submit a good faith offer to
         Shamrock GP to sell the Restricted Business (the "Offer") to any member
         of the Partnership Group designated by Shamrock GP on the terms and for
         the consideration stated in the Offer.

                           (ii) The UDS Entity and Shamrock GP shall negotiate
         in good faith, for 60 days after receipt of such Offer by Shamrock GP,
         the terms on which the Restricted Business will be sold to the MLP. The
         UDS Entity shall provide all information concerning the business,
         operations and finances of such Restricted Business as may be
         reasonably requested by Shamrock GP.

                                    (A) If the UDS Entity and Shamrock GP agree
                  on such terms within 60 days after receipt by Shamrock GP of
                  the Offer, the MLP shall purchase the Restricted Business on
                  such terms as soon as commercially practicable after such
                  agreement has been reached.

                                    (B) If the UDS Entity and Shamrock GP are
                  unable to agree on the terms of a sale during such 60-day
                  period, the UDS Entity shall attempt to sell the Restricted
                  Business to a Person that is not an Affiliate of the UDS
                  Entity (a "NonAffiliate Purchaser") within nine months of the
                  termination of such 60-day period. Any such sale to a
                  NonAffiliate Purchaser must be for a purchase price, as
                  determined by the board of directors of UDS, not less than 95%
                  of the purchase price last offered by the MLP.

                           (iii) If, after the expiration of such nine-month
         period, the UDS Entity has not sold the Restricted Business to a
         NonAffiliate Purchaser, it shall submit another Offer (the "Second
         Offer") to Shamrock GP within seven days after the expiration of such
         nine-month period. The UDS Entity shall provide all information
         concerning the business, operations and finances of such Restricted
         Business as may be reasonably requested by Shamrock GP.

                                    (A) If Shamrock GP, with the concurrence of
                  the Conflicts Committee, elects not to cause the MLP to pursue
                  the Second Offer, the UDS Entity shall be free to continue to
                  engage in such Restricted Business.

                                    (B) If Shamrock GP shall elect to cause the
                  MLP to purchase such Restricted Business, then Shamrock GP and
                  the UDS Entity shall negotiate the terms of such purchase for
                  60 days. If the UDS Entity and Shamrock GP agree on such terms
                  within 60 days after receipt by Shamrock GP of the Second



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                  Offer, the MLP shall purchase the Restricted Business on such
                  terms as soon as commercially practicable after such agreement
                  has been reached.

                                    (C) If during such 60-day period, no
                  agreement has been reached between the UDS Entity and Shamrock
                  GP or a member of the Partnership Group, the UDS Entity and
                  Shamrock GP will engage an independent investment banking firm
                  with a national reputation to determine the value of the
                  Restricted Business. Such investment banking firm will
                  determine the value of the Restricted Business within 30 days
                  and furnish the UDS Entity and Shamrock GP its opinion of such
                  value. The UDS Entity and Shamrock GP shall share equally the
                  fees and expenses of such investment banking firm. Upon
                  receipt of such opinion, Shamrock GP will have the option,
                  subject to the approval of the Conflicts Committee, to (A)
                  cause the MLP to purchase the Restricted Business for an
                  amount equal to the value determined by such investment
                  banking firm or (B) decline to purchase such Restricted
                  Business, in which event the UDS Entity will be free to
                  continue to engage in such Restricted Business.

         2.4 TERMINATION. The provisions of this Article II may be terminated by
UDS upon or at any time after a "Change of Control" of UDS or each of Shamrock
GP or Riverwalk by written notice to the MLP. A Change of Control of UDS or each
of Shamrock GP or Riverwalk shall be deemed to have occurred upon the occurrence
of one or more of the following events: (i) any sale, lease, exchange or other
transfer (in one transaction or a series of related transactions) of all or
substantially all of the assets of the UDS or Shamrock GP to any Person or its
Affiliates, unless immediately following such sale, lease, exchange or other
transfer such assets are owned, directly or indirectly, by the UDS Entities or
Shamrock GP; (ii) the consolidation or merger of UDS or Shamrock GP with or into
another Person pursuant to a transaction in which the outstanding Voting Stock
of UDS or Shamrock GP is changed into or exchanged for cash, securities or other
property, other than any such transaction where (a) the outstanding Voting Stock
of UDS or Shamrock GP is changed into or exchanged for Voting Stock of the
surviving corporation or its parent and (b) the holders of the Voting Stock of
UDS or Shamrock GP immediately prior to such transaction own, directly or
indirectly, not less than a majority of the Voting Stock of the surviving
corporation or its parent immediately after such transaction; or (iii) a
"person" or "group" (within the meaning of Sections 13(d) or 14(d)(2) of the
Exchange Act) being or becoming the "beneficial owner" (as defined in Rules
13d-3 and 13d-5 under the Exchange Act) of more than 50% of all Voting Stock of
UDS or Shamrock GP then outstanding, other than in a merger or consolidation
which would not constitute a Change of Control under clause (ii) above.

         2.5 SCOPE OF RESTRICTED BUSINESS PROHIBITION. Except as provided in
this Article II and the Partnership Agreement, each UDS Entity shall be free to
engage in any business activity whatsoever, including those that may be in
direct competition with any Partnership Entity.

         2.6 ENFORCEMENT. The UDS Entities agree and acknowledge that the
Partnership Group does not have an adequate remedy at law for the breach by the
UDS Entities of


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the covenants and agreements set forth in this Article II, and that any breach
by the UDS Entities of the covenants and agreements set forth in Article II
would result in irreparable injury to the Partnership Group. The UDS Entities
further agree and acknowledge that any member of the Partnership Group may, in
addition to the other remedies which may be available to the Partnership Group
hereunder or under applicable law, file a suit in equity to enjoin the UDS
Entities from such breach, and consent to the issuance of injunctive relief
hereunder.

                                  ARTICLE III.
                                 INDEMNIFICATION

         3.1 Indemnification of Partnership Entities by UDS(a) . In addition to
its indemnification obligations under that certain (i) Indemnification
Agreements entered into in connection with the mergers of certain subsidiaries
of UDS with and into the OLP effective as of July 1, 2000, and (ii) Conveyance,
Assignment and Bill of Sale Agreements dated effective as of July 1, 2000, by
and among the OLP and certain subsidiaries of UDS, UDS, on behalf of each of the
respective UDS Entities, shall indemnify, defend and hold harmless the
Partnership Entities from and against any and all Losses that are caused by,
arise out of or are attributable to Environmental Liabilities and Costs related
to the assets transferred by the UDS Entities to the MLP in connection with the
Formation Transactions that arose prior to Closing and which are discovered by
the MLP within 10 years of the Closing (excluding Environmental Liabilities and
Costs resulting from a change in law after closing).

         3.2 INDEMNIFICATION PROCEDURES.

                  (a) As used in this Section 3.2, the term "Indemnifying Party"
refers to UDS in the case of any indemnification obligation arising under
Section 3.1, and the term "Indemnified Party" refers to the Partnership
Entities, as applicable, in the case of any indemnification obligation arising
under Section 3.1.

                  (b) If any action, suit or proceeding shall be brought against
an Indemnified Party, or if the Indemnified Party should otherwise become aware
of facts giving rise to a claim for indemnification pursuant to Section 3.1 the
Indemnified Party shall promptly notify the Indemnifying Party in writing
specifying the nature of and specific basis for such claim.

                  (c) The Indemnifying Party shall have the right to control all
aspects of the defense of (and any counterclaims with respect to) any claims
brought against the Indemnified Party that are covered by the indemnification
set forth in Section 3.1, including, without limitation, the selection of
counsel, determination of whether to appeal any decision of any court and the
settling of any such matter or any issues relating thereto; provided, however,
that no such settlement shall be entered into without the consent of the
Indemnified Party unless it includes a full release of the Indemnified Party
from such matter or issues, as the case may be.

                  (d) The Indemnified Party agree, at its own cost and expense,
to cooperate fully with the Indemnifying Party with respect to all aspects of
the defense of any claims covered by the indemnification set forth in Section
3.1, including, without limitation, the prompt furnishing to the Indemnifying
Party of any correspondence or other notice relating thereto that the
Indemnified Party may receive, permitting the name(s) of the Indemnified Party
to be utilized in connection with such defense, the making available to the
Indemnifying Party of any files,


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records or other information of the Indemnified Party that the Indemnifying
Party considers relevant to such defense and the making available to the
Indemnifying Party of any employees of the Indemnified Party; provided, however,
that in connection therewith the Indemnifying Party agrees to use reasonable
efforts to minimize the impact thereof on the operations of such Indemnified
Party. In no event shall the obligation of the Indemnified Party to cooperate
with the Indemnifying Party as set forth in the immediately preceding sentence
be construed as imposing upon the Indemnified Party an obligation to hire and
pay for counsel in connection with the defense of any claims covered by the
indemnification set forth in this Article III; provided, however, that the
Indemnified Party may, at their own option, cost and expense, hire and pay for
counsel in connection with any such defense. The Indemnifying Party agrees to
keep any such counsel hired by the Indemnified Party reasonably informed as to
the status of any such defense, but the Indemnifying Party shall have the right
to retain sole control over such defense.

                  (e) In determining the amount of any loss, liability or
expense for which any Indemnified Party is entitled to indemnification under
this Article III, the gross amount thereof will be reduced by any insurance
proceeds realized or to be realized by such Indemnified Party, and such
correlative insurance benefit shall be net of any insurance premium that becomes
due as a result of such claim.

                                  ARTICLE IV.
                                  MISCELLANEOUS

         4.1 CHOICE OF LAW; SUBMISSION TO JURISDICTION. This Agreement shall be
subject to and governed by the laws of the State of Delaware, excluding any
conflicts-of-law rule or principle that might refer the construction or
interpretation of this Agreement to the laws of another state.

         4.2 NOTICE. All notices or requests or consents provided for or
permitted to be given pursuant to this Agreement must be in writing and must be
given by depositing same in the United States mail, addressed to the Person to
be notified, postpaid, and registered or certified with return receipt requested
or by delivering such notice in person or by telecopier or telegram to such
party. Notice given by personal delivery or mail shall be effective upon actual
receipt. Notice given by telegram or telecopier shall be effective upon actual
receipt if received during the recipient's normal business hours, or at the
beginning of the recipient's next business day after receipt if not received
during the recipient's normal business hours. All notices to be sent to a party
pursuant to this Agreement shall be sent to or made at the address set forth
below such party's signature to this Agreement, or at such other address as such
party may stipulate to the other parties in the manner provided in this Section
5.2.

         4.3 ENTIRE AGREEMENT; SUPERSEDURE. This Agreement constitutes the
entire agreement of the parties relating to the matters contained herein,
superseding all prior contracts or agreements, whether oral or written, relating
to the matters contained herein.

         4.4 EFFECT OF WAIVER OR CONSENT. No waiver or consent, express or
implied, by any party to or of any breach or default by any Person in the
performance by such Person of its obligations hereunder shall be deemed or
construed to be a consent or waiver to or of any other breach or default in the
performance by such Person of the same or any other obligations of


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such Person hereunder. Failure on the part of a party to complain of any act of
any Person or to declare any Person in default, irrespective of how long such
failure continues, shall not constitute a waiver by such party of its rights
hereunder until the applicable statute of limitations period has run.

         4.5 AMENDMENT OR MODIFICATION. This Agreement may be amended or
modified from time to time only by the written agreement of all the parties
hereto; provided, however, that the MLP may not, without the prior approval of
the Conflicts Committee, agree to any amendment or modification of this
Agreement that, in the reasonable discretion of Shamrock GP, will adversely
affect the holders of Common Units. Each such instrument shall be reduced to
writing and shall be designated on its face an "Amendment" or an "Addendum" to
this Agreement.

         4.6 ASSIGNMENT. No party shall have the right to assign its rights or
obligations under this Agreement without the consent of the other parties
hereto.

         4.7 COUNTERPARTS. This Agreement may be executed in any number of
counterparts with the same effect as if all signatory parties had signed the
same document. All counterparts shall be construed together and shall constitute
one and the same instrument.

         4.8 SEVERABILITY. If any provision of this Agreement or the application
thereof to any Person or circumstance shall be held invalid or unenforceable to
any extent, the remainder of this Agreement and the application of such
provision to other Persons or circumstances shall not be affected thereby and
shall be enforced to the greatest extent permitted by law.

         4.9 GENDER, PARTS, ARTICLES AND SECTIONS. Whenever the context
requires, the gender of all words used in this Agreement shall include the
masculine, feminine and neuter, and the number of all words shall include the
singular and plural. All references to Article numbers and Section numbers refer
to Parts, Articles and Sections of this Agreement, unless the context otherwise
requires.

         4.10 FURTHER ASSURANCES. In connection with this Agreement and all
transactions contemplated by this Agreement, each signatory party hereto agrees
to execute and deliver such additional documents and instruments and to perform
such additional acts as may be necessary or appropriate to effectuate, carry out
and perform all of the terms, provisions and conditions of this Agreement and
all such transactions.

         4.11 WITHHOLDING OR GRANTING OF CONSENT. Each party may, with respect
to any consent or approval that it is entitled to grant pursuant to this
Agreement, grant or withhold such consent or approval in its sole and
uncontrolled discretion, with or without cause, and subject to such conditions
as it shall deem appropriate.

         4.12 LAWS AND REGULATIONS. Notwithstanding any provision of this
Agreement to the contrary, no party hereto shall be required to take any act, or
fail to take any act, under this Agreement if the effect thereof would be to
cause such party to be in violation of any applicable law, statute, rule or
regulation.




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         4.13 NEGOTIATION OF RIGHTS OF LIMITED PARTNERS, ASSIGNEES, AND THIRD
PARTIES. The provisions of this Agreement are enforceable solely by the parties
to this Agreement, and no Limited Partner, Assignee or other Person shall have
the right, separate and apart from the MLP, to enforce any provision of this
Agreement or to compel any party to this Agreement to comply with the terms of
this Agreement.



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         IN WITNESS WHEREOF, the parties have executed this Agreement on, and
effective as of, the Closing Date.

                                             ULTRAMAR DIAMOND SHAMROCK
                                             CORPORATION


                                             By:
                                                --------------------------------
                                             Name:
                                                  ------------------------------
                                             Title:
                                                   -----------------------------


                                             Address for Notice:
                                                                ----------------


                                             Telecopy Number:
                                                             -------------------


                                             SHAMROCK LOGISTICS GP, LLC


                                             By:
                                                --------------------------------
                                             Name:
                                                  ------------------------------
                                             Title:
                                                   -----------------------------


                                             Address for Notice:
                                                                ----------------


                                             Telecopy Number:
                                                             -------------------



<PAGE>   14



                                             RIVERWALK LOGISTICS, L.P.


                                             By: Shamrock Logistics GP, LLC
                                                 its general partner

                                             By:
                                                -------------------------------
                                             Name:
                                                  -----------------------------
                                             Title:
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                                             Address for Notice:
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                                             Telecopy Number:
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                                             SHAMROCK LOGISTICS, L.P.


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

                                             By: Shamrock Logistics GP, LLC
                                                 Its general partner


                                             By:
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                                             Name:
                                                  -----------------------------
                                             Title:
                                                   ----------------------------

                                             Address for Notice:
                                                                ---------------


                                             Telecopy Number:
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