Document:

<PAGE>

                                                                   EXHIBIT 10.36

                      FOURTH AMENDMENT TO CREDIT AGREEMENT
                      ------------------------------------

     THIS FOURTH AMENDMENT TO CREDIT AGREEMENT (the "Amendment"), dated as of
                                                     ---------
April 13, 2001 is among SCHLOTZSKY'S, INC., a Texas corporation ("Borrower"),
                                                                  --------
each of the Lenders party to the Agreement referred to below, and WELLS FARGO
BANK TEXAS, NATIONAL ASSOCIATION, a national banking association (successor by
consolidation to Wells Fargo Bank (Texas), National Association), as Agent for
itself and the other Lenders (in such capacity, together with its successors in
such capacity the "Agent") and as the Issuing Bank.
                   -----

                                   RECITALS:

     A.   Borrower, Agent, Lenders and Issuing Bank have previously entered into
that certain Credit Agreement dated as of December 7, 1999, as amended by (a)
that certain First Amendment to Credit Agreement dated as of December 31, 1999,
(b) that certain Second Amendment to Credit Agreement dated as of May 1, 2000
and (c) that certain Third Amendment to Credit Agreement dated as of September
30, 2000 (the Credit Agreement as so amended is hereinafter referred to as the
"Agreement").
----------

     B.   Borrower, Agent, Lenders and Issuing Bank now desire to amend (i) the
Agreement (a) to amend the definition of "Debt"; (b) to amend the delivery
requirements of the Quarterly Certificate; (c) to amend Section 10.6 of the
Agreement; and (d) to make such other modifications, in each case, as
hereinafter more specifically provided.

     NOW, THEREFORE, in consideration of the premises and mutual covenants
herein contained, the parties hereto agree as follows:

                                   ARTICLE I

                                  Definitions
                                  -----------

     1.1  Definitions. All capitalized terms not otherwise defined herein, shall
          -----------
have the same meanings as in the Agreement, as amended hereby.

                                  ARTICLE II

                                  Amendments
                                  ----------

     2.1  Amendment to Section 1.1. Effective as of the date hereof, the
          ------------------------
following definitions in Section 1.1 of the Agreement are amended and restated
to read in their entirety as follows:

          "Contingent Liabilities" means, at any particular time, the contingent
           ----------------------
     liabilities of the Borrower and its Subsidiaries determined on a
     consolidated basis in accordance with GAAP.

          "Debt" means as to any Person at any time (without duplication):  (a)
           ----
     all obligations of such Person for borrowed money, (b) all obligations of
     such Person evidenced by bonds, notes, debentures, or other similar
     instruments whether
<PAGE>

     secured or unsecured, (c) all Capital Lease Obligations of such Person, (d)
     all obligations secured by a Lien existing on property owned by such
     Person, whether or not the obligations secured thereby have been assumed by
     such Person or are non-recourse to the credit of such Person, but excluding
     those obligations secured by landlord's liens or liens for taxes not yet
     due and payable, (e) all reimbursement obligations of such Person (whether
     contingent or otherwise) in respect of letters of credit (whether drawn or
     undrawn), bankers' acceptances, surety or other bonds and similar
     instruments, and (f) all liabilities of such Person in respect of unfunded
     vested benefits under any Plan; provided however, the term "Debt" shall not
     include, except for clause (e) above, any items which are not required to
                         ----------
     be reflected as debt on the Borrower's balance sheet in accordance with
     GAAP.

          "Debt to EBITDA Ratio" means, for each Fiscal Quarter, the quotient
           --------------------
     determined by dividing (i) the sum of (1) those items described in clauses
                                                                        -------
     (a), (b), (c) and (d) of the definition of "Debt" of the Borrower and its
     ---  --- ----     ---
     consolidated Subsidiaries, plus (2) all Debt or other obligations of others
     Guaranteed by the Borrower and/or its consolidated Subsidiaries, by (ii)
     EBITDA for such Fiscal Quarter and the prior three (3) Fiscal Quarters.

     2.2  Addition to Section 1.1. Effective as of the date hereof, the
          -----------------------
following definition is added to Section 1.1 of the Agreement in alphabetical
order to read in its entirety as follows:

          "New Guaranty" means that certain Limited Guaranty Agreement dated as
           ------------
     of April 10, 2001 executed by the Borrower in favor of The Frost National
     Bank, pursuant to which the Borrower guarantees the indebtedness of
     Schlotzsky's National Advertising and Marketing Fund, Inc. and Schlotzsky's
     National Advertising Association, Inc.

     2.3  Amendment to Section 8.1(c).  Effective as of the date hereof, Section
          ---------------------------
8.1(c) of the Agreement is amended and restated to read in its entirety as
follows:

          (c) Quarterly Certificate.  As soon as available, and in any event
              ---------------------
     within (i) forty-five (45) days after the end of each of the first three
     Fiscal Quarters of each Fiscal Year of the Borrower and the Subsidiaries,
     and (ii) ninety (90) days after the end of the fourth Fiscal Quarter of
     each Fiscal Year of the Borrower and the Subsidiaries, beginning with the
     Fiscal Quarter ending March 31, 2001, a certificate (the "Quarterly
                                                               ---------
     Certificate") of the chief financial officer of the Borrower (1) stating
     -----------
     that to the best of such officer's knowledge, no Default has occurred and
     is continuing, or if a Default has occurred and is continuing, a statement
     as to the nature thereof and the action that is proposed to be taken with
     respect thereto, and (2) showing in reasonable detail the most recent
     Fiscal Quarter calculations demonstrating compliance with Article X;
                                                               ----------

     2.4  Amendment to Section 10.6. Effective as of the date hereof, Section
          -------------------------
10.6 of the Agreement is amended and restated to read in its entirety as
follows:

                                       2
<PAGE>

          Section 10.6  Contingent Liabilities.  The Borrower will not permit at
                        ----------------------
     any time (a) the aggregate amount of Contingent Liabilities (excluding that
     portion of Contingent Liabilities of the Borrower incurred in connection
     with a transaction in which the Borrower received cash to the extent of
     cash received) to exceed $30,000,000, and (b) the aggregate amount of that
     portion of Contingent Liabilities of the Borrower incurred in connection
     with a transaction in which the Borrower received cash to the extent of
     cash received to exceed the sum of (i) the New Guaranty amount plus (ii)
     $2,000,000.

                                  ARTICLE III

                             Conditions Precedent
                             --------------------

     3.1  Conditions.  The effectiveness of this Amendment is subject to the
          ----------
satisfaction of the following conditions precedent:

          (a)  Loan Documents. Agent shall have received all of the following,
               --------------
     each dated (unless otherwise indicated) the date of this Amendment, in form
     and substance satisfactory to the Agent:

               (i)       This Amendment executed by all parties hereto;

               (ii)      Resolutions of the Board of Directors of the Borrower
          certified by its secretary or assistant secretary which authorize the
          execution, delivery and performance by the Borrower of this Amendment,
          and the other Loan Documents executed in connection herewith;

               (iii)     A certificate of incumbency certified by the secretary
     or the assistant secretary of the Borrower certifying the names of the
     officers thereof authorized to sign this Amendment and the other Loan
     Documents together with specimen signatures of such officers;

               (iv)      Resolutions of the Board of Directors or comparable
     authority of each of the Obligated Parties certified by its secretary or
     assistant secretary which authorize the execution, delivery and performance
     by each of the Obligated Parties of this Amendment and the Loan Documents
     executed in connection herewith; and

               (v)       A certificate of incumbency certified by the secretary
     or the assistant secretary of each Obligated Party certifying the names of
     the officers thereof authorized to sign this Amendment and the other Loan
     Documents together with specimen signatures of such officers.

     (b)  No Default.  No Default shall have occurred and be continuing.
          ----------

     (c)  Representations and Warranties. All of the representations and
          ------------------------------
     warranties contained in Article VII of the Agreement, as amended hereby and
     in the other Loan Documents shall be true and correct on and as of the date
     of this Amendment with the

                                       3
<PAGE>

     same force and effect as if such representations and warranties had been
     made on and as of such date, except to the extent such representations and
     warranties speak to a specific date.

          (d)  Additional Documentation. The Agent shall have received such
               ------------------------
     additional approvals, opinions or documents as the Agent may request.

                                  ARTICLE IV

                 Ratifications, Representations and Warranties
                 ---------------------------------------------

     4.1  Ratifications. The terms and provisions set forth in this Amendment
          -------------
shall modify and supersede all inconsistent terms and provisions set forth in
the Agreement and except as expressly modified and superseded by this Amendment,
the terms and provisions of the Agreement and the other Loan Documents are
ratified and confirmed and shall continue in full force and effect. Borrower,
Lenders, Issuing Bank and Agent agree that the Agreement as amended hereby and
the other Loan Documents shall continue to be legal, valid, binding and
enforceable in accordance with their respective terms.

     4.2  Representations and Warranties. Borrower hereby represents and
          ------------------------------
warrants to the Lenders, Agent and Issuing Bank that (i) the execution, delivery
and performance of this Amendment and any and all other Loan Documents executed
and/or delivered in connection herewith have been authorized by all requisite
corporate action on the part of Borrower and will not violate the articles of
incorporation or bylaws of Borrower, (ii) the representations and warranties
contained in the Agreement, as amended hereby, and any other Loan Document are
true and correct on and as of the date hereof as though made on and as of the
date hereof, except to the extent such representations and warranties speak to a
specific date, (iii) no Default has occurred and is continuing, and (iv)
Borrower is in full compliance with all covenants and agreements contained in
the Agreement as amended hereby.

                                   ARTICLE V

                                 Miscellaneous
                                 -------------

     5.1  Survival of Representations and Warranties. All representations and
          ------------------------------------------
warranties made in this Amendment or any other Loan Document including any Loan
Document furnished in connection with this Amendment shall survive the execution
and delivery of this Amendment and the other Loan Documents, and no
investigation by the Lenders, Agent or Issuing Bank or any closing shall affect
the representations and warranties or the right of the Lenders, Agent or Issuing
Bank to rely upon them.

     5.2  Reference to Agreement. Each of the Loan Documents, including the
          ----------------------
Agreement and any and all other agreements, documents, or instruments now or
hereafter executed and delivered pursuant to the terms hereof or pursuant to the
terms of the Agreement as amended hereby, are hereby amended so that any
reference in such Loan Documents to the Agreement shall mean a reference to the
Agreement as amended hereby.

                                       4
<PAGE>

     5.3  Severability. Any provision of this Amendment held by a court of
          ------------
competent jurisdiction to be invalid or unenforceable shall not impair or
invalidate the remainder of this Amendment and the effect thereof shall be
confined to the provision so held to be invalid or unenforceable.

     5.4  Applicable Law. This Amendment and all other Loan Documents executed
          --------------
pursuant hereto shall be deemed to have been made and to be performable in
Austin, Travis County, Texas and shall be governed by and construed in
accordance with the laws of the State of Texas.

     5.5  Successors and Assigns. This Amendment is binding upon and shall inure
          ----------------------
to the benefit of the Lenders, Agent, Issuing Bank and Borrower and their
respective successors and assigns, except Borrower may not assign or transfer
any of its rights or obligations hereunder without the prior written consent of
the Lenders.

     5.6  Counterparts. This Amendment may be executed in one or more
          ------------
counterparts, each of which when so executed shall be deemed to be an original,
but all of which when taken together shall constitute one and the same
instrument.

     5.7  ENTIRE AGREEMENT. THIS AMENDMENT AND ALL OTHER INSTRUMENTS, DOCUMENTS
          ----------------
AND AGREEMENTS EXECUTED AND DELIVERED IN CONNECTION WITH THIS AMENDMENT
REPRESENT THE FINAL AGREEMENT AMONG THE PARTIES HERETO AND MAY NOT BE
CONTRADICTED OR VARIED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL
AGREEMENTS OR DISCUSSIONS OF THE PARTIES HERETO. THERE ARE NO UNWRITTEN ORAL
AGREEMENTS AMONG THE PARTIES HERETO.

                  [Remainder of Page Intentionally Left Blank]

                                       5
<PAGE>

     Executed as of the date first written above.

                              BORROWER:
                              --------

                              SCHLOTZSKY'S, INC.

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

                              Address for Notices:

                              203 Colorado St.
                              Austin, TX  78701
                              Fax No.:  (512) 236-3650
                              Telephone No.:  (512) 236-3600
                              Attention:  Chief Financial Officer

                              AGENT, ISSUING BANK AND LENDER:
                              ------------------------------

                              WELLS FARGO BANK TEXAS, NATIONAL
                              ASSOCIATION

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

                              Address for Notices:

                              111 Congress Avenue, Suite 300
                              Austin, TX  78701
                              Fax No.:  (512) 344-7318
                              Telephone No.:  (512) 344-7037
                              Attention:  Richard Gan

                                       6
<PAGE>

                              OTHER LENDERS:
                              -------------

                              THE FROST NATIONAL BANK

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

                              Address for Notices:

                              2728 North Harwood, Suite 100
                              Dallas, TX  75201
                              Fax No.:  (214) 515-4955
                              Telephone No.:  (214) 515-4907
                              Attention:  Shannon Bettis

                                       7
<PAGE>

                              TEXAS CAPITAL BANK, NATIONAL
                              ASSOCIATION

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

                              Address for Notices:

                              2100 McKinney Avenue, Suite 900
                              Dallas, TX  75201
                              Fax No.:  (214) 932-6604
                              Telephone No.:  (214) 932-6675
                              Attention:  Tim Monter

                                       8
<PAGE>

                           Obligated Parties Consent
                           -------------------------

     Each of the undersigned Obligated Parties (i) consent and agree to this
Amendment; and (ii) agree that the Loan Documents to which it is a party shall
remain in full force and effect and shall continue to be the legal, valid and
binding obligation of such Obligated Party enforceable against it in accordance
with their respective terms.

                              OBLIGATED PARTIES:
                              -----------------

                              RAD ACQUISITION CORP.
                              SCHLOTZSKY'S REAL ESTATE, INC.
                              SCHLOTZSKY'S RESTAURANTS, INC.
                              DFW RESTAURANT TRANSFER CORP.
                              SGC CONSTRUCTION CORP. (fka Schlotzsky's Equipment
                              Corporation)
                              SREI TURNKEY DEVELOPMENT, L.L.C.
                              56TH & 6TH, INC.
                              SCHLOTZSKY'S BRANDS, INC.

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

                              SCHLOTZSKY'S BRANDS I, L.L.C.

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

                              SCHLOTZSKY'S BRAND PRODUCTS, L.P.

                              By:   Schlotzsky's Brands, Inc., as general
                                    partner

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

                                       9<PAGE>

                                 EXHIBIT 10.20

                                LEASE AGREEMENT

                                    BETWEEN

                THE CITY OF TULSA-ROGERS COUNTY PORT AUTHORITY

                                      AND

                            MATRIX SERVICE COMPANY

                                 MARCH 1, 2001
<PAGE>

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                 Page
                                                                                                 ----
<S>                                                                                              <C>
RECITALS                                                                                         4

ARTICLE 1.    PREMISES                                                                           4
         1.1      Leased Premises                                                                4
         1.2      Use of Premises                                                                4
         1.3      Building and Development Regulations                                           4
         1.4      Acceptance of Leased Premises in Present Condition                             5
         1.5      Covenant to Build                                                              5
         1.6      Eminent Domain                                                                 5

ARTICLE II.   LEASE TERM                                                                         6
         2.1      Primary Lease Term                                                             6
         2.2      Renewal Terms                                                                  6
         2.3      Assignment of Lease                                                            6

ARTICLE III.  RENTALS                                                                            6
         3.1      Primary Term Rentals                                                           6
         3.2      Additional Rentals                                                             7
         3.3      Renewal Term(s) Rentals                                                        8

ARTICLE IV.   IMPROVEMENTS                                                                       9
         4.1      Notice and Submission of Plans                                                 9
         4.2      Improvements                                                                   9
         4.3      Utilities and Services                                                         9
         4.4      Easements                                                                      9
         4.5      Access                                                                         10
         4.6      Signs                                                                          11
         4.7      Lien Claims                                                                    11
         4.8      Inspection and/or Repair of Premises                                           11

ARTICLE V.    OPERATIONS                                                                         12
         5.1      Pollution Control                                                              12
         5.2      Compliance with Laws and Regulations                                           12
         5.3      Maintenance of Adjoining Grounds                                               12
         5.4      Indemnification                                                                12
         5.5      Use Prohibition and Duties (Environmental)                                     13
         5.6      Site Assessments                                                               14
         5.7      Environmental Indemnification                                                  14
         5.8      Insurance                                                                      15

ARTICLE VI.   TERMINATION                                                                        16
         6.1      Termination                                                                    16
         6.2      Lessee Events of Default                                                       16
         6.3      Cancellation                                                                   16
         6.4      Lessor Events of Default                                                       17
         6.5      Right of Re-entry                                                              17
         6.6      Holding Over                                                                   18
         6.7      Waiver of Breach or Default Cumulative Remedies                                18
</TABLE>
<PAGE>

<TABLE>
<S>                                                                                              <C>
ARTICLE VII. MISCELLANEOUS                                                                       19
         7.1      Examination of Lessee's Records                                                19
         7.2      Lessor's Leasehold Interest                                                    19
         7.3      Quiet Enjoyment                                                                19
         7.4      Notices                                                                        19
         7.5      Nondiscrimination                                                              20
         7.6      Navigability                                                                   20
         7.7      Substitution of Performance                                                    20
         7.8      Exhibits and Attachments                                                       20
         7.9      Authority                                                                      20
         7.10     Entire Agreement                                                               21
         7.11     Captions                                                                       21
         7.12     Severability                                                                   21
         7.13     Successors and Assigns                                                         21
         7.14     Governing Law                                                                  21
         7.15     Counterparts                                                                   21
         7.16     Modification                                                                   21
         7.17     Recording                                                                      21

EXECUTION BLANKS                                                                                 22

ACKNOWLEDGMENTS                                                                                  23
</TABLE>

EXHIBITS

         Exhibit "A"             Leased Premises
         Exhibit "B"             Building and Development Regulations
         Exhibit "C"             Additional Charges
         Exhibit "D"             Miscellaneous Provisions

<PAGE>

                                LEASE AGREEMENT

         This Lease Agreement ("Lease") is entered into effective as of March 1,
2001, between THE CITY OF TULSA-ROGERS COUNTY PORT AUTHORITY, an agency of the
State of Oklahoma ("Lessor"), with offices at 5350 Cimarron Road, Catoosa,
Oklahoma 74015, and Matrix Service Company, a corporation organized and existing
under the laws of the State of Delaware, duly authorized to do business in the
State of Oklahoma ("Lessee"), with principal offices at 10701 E. Ute' Tulsa,
Oklahoma, and local offices and place of business at 5605 N. Verdigris Road,
Catoosa, Oklahoma. Lessor and Lessee are collectively referred to herein as the
"Parties".

                             W I T N E S S E T H :

         A.   Lessor is the governing body for and the sole and principal
operator of a water port terminal and related industrial park located in Rogers
County, State of Oklahoma, referred to herein as the "Tulsa Port of Catoosa".
Lessor operates the Tulsa Port of Catoosa in part under a Master Lease Agreement
with the City of Tulsa, Oklahoma, a municipal corporation ("City").

         B.   Lessor desires to lease certain lands and/or facilities,
comprising a portion of the Tulsa Port of Catoosa, to industries involved in
moving raw materials and finished products in water commerce and to such other
industries as may be engaged in industrial activities.

         C.   Lessee desires to lease a portion of the industrial park premises
for the use and purposes set forth in this Lease.

         NOW, THEREFORE, for and in consideration of the terms, covenants and
conditions hereinafter set forth and contained, the Lessor and Lessee mutually
contract and agree as follows:

                              ARTICLE I. PREMISES

         1.1  Leased Premises. Lessor hereby leases, and lets unto Lessee and
Lessee hereby leases and lets from Lessor a certain parcel and tract of land,
together with certain easements, located at and within the Tulsa Port of
Catoosa, comprising approximately 50.0 acres, together with improvements located
thereon, all of which real and personal property is referred to collectively as
the "Leased Premises" and is more fully described on Exhibit "A", attached
hereto and by this reference made a part of this Lease.

         1.2  Use of Premises. The Leased Premises are to be occupied and used
              ---------------
by Lessee for engineering. fabrication and repair of storage tanks and the
              ----------------------------------------------------
operation of services and conduct of business activities related and incident
thereto. In the event Lessee for any reason desires hereafter to modify and/or
change its use of the Leased Premises, the nature and terms of such modified
use, if approved by Lessor, shall be reduced to a written agreement of the
Parties and made a part of this Lease. Lessor agrees that it will not
unreasonably withhold or delay its consent to any proposed compatible change in
use.

         1.3  Building and Development Regulations. Lessee covenants that any,
              ------------------------------------
every and all uses of the Leased Premises hereunder shall comply with Lessor's
Building and Development Regulations and certain provisions of its Master Plan
of Development (collectively the "Building and Development Regulations"), copies
of which are attached hereto designated Exhibit "B" and by this reference made a
part of this Lease. The Parties understand that the Building and
<PAGE>

Development Regulations may from time to time be amended and/or otherwise
modified by Lessor. Lessor and Lessee agree that the Building and Development
Regulations in effect on the date Lessee shall have submitted its improvement or
premises utilization plans for approval, pursuant to the provisions of Section
4.1, shall control Lessee's construction efforts and utilization of the Leased
Premises (so long as such utilization is substantially similar to that initially
approved in connection with this Lease). Notwithstanding the foregoing, Lessor
hereby acknowledges that Lessee's construction plan and use of the Leased
Premises, as provided to Lessor prior to the date of this Lease, is generally
consistent with the Building and Development Regulations.

         1.4  Acceptance of Leased Premises in Present Condition. Lessee
              --------------------------------------------------
acknowledges that it has inspected the Leased Premises and accepts the same in
its present condition "as is" and that all terms and conditions of this Lease
are fully binding upon Lessee as if, and to the same extent that, the existing
improvements had been made by Lessee as original lessee. (See Exhibit "D", Rider
1)

         1.5  Covenant to Build. The Parties agree that Lessee shall cause
              -----------------
construction of certain improvements and facilities for its occupancy and use of
the Premises as set forth in Section 1.2 hereof (such undertaking referred to
hereinafter as the "Project"), to be commenced on or before August 1, 2001, with
the same to be substantially completed and in operation by March 1, 2003. In the
event that Lessee does not cause the Project to be commenced and completed
within such time, unless delayed by circumstances beyond its control, such as
through force majeure or acts or omissions of Lessor, then, in any or all such
events, this Lease, together with any and all rights afforded Lessee hereunder
shall, at the election of Lessor, cease and terminate and, not withstanding the
language of Exhibit D, rider 2, all rentals as scheduled in Exhibit D, Rider 3
(up to the date of said termination) shall immediately become payable as
liquidated damages.

         1.6  Eminent Domain. If the whole of the Leased Premises shall be taken
              --------------
or condemned, or purchased in lieu thereof, by any government authority for any
public or quasi-public use or purpose, then, in that event, the Lease term shall
cease and terminate from the time when the possession shall be required for such
use or purpose. In such case, rent and all other amounts that are due hereunder
shall be apportioned to the date of such taking or purchase, as the case may be.
In the event of a partial taking only of the Leased Premises, Lessor shall
notify Lessee in writing and in the event the partial taking shall render the
Leased Premises untenantable, Lessee shall have the option to terminate this
Lease by giving Lessor written notice within twenty (20) days after receipt of
such notice from Lessor; and in the event the said taking or purchase does not
render the Leased Premises untenantable, rent and all other amounts that are due
hereunder shall be apportioned on the basis of the portion of the Leased
Premises that is rendered untenantable. If Lessee is entitled to exercise said
option to terminate and does so, then such termination shall be effective and
rent and all other amounts that are due hereunder shall in such case be
apportioned to the date of such taking or purchase, as the case may be.

         Lessor and Lessee hereby agree that any award or proceeds resulting
from a condemnation or sale in lieu thereof of the whole or part of the Leased
Premises shall be apportioned between Lessor and Lessee with the intent to
provide equitable compensation to Lessee for the Improvements. Provided,
however, in the event any such condemnation award is specifically allocated as
between Lessor and Lessee, such allocation shall control.
<PAGE>

                            ARTICLE II. LEASE TERM

         2.1  Primary Lease Term. The primary term of this Lease ("Primary
              ------------------
Term") shall be for a period of fifteen years from and after March 1, 2001
                                -------                      -------    --
("Commencement Date"), and terminating on February 28, 2016, unless otherwise
                                                         --
terminated, renewed or extended pursuant to other terms of this Lease. The term
of the Lease, which includes the Primary Term and all effective renewals and
extensions, shall for convenience be referred to as the "Lease Term."

         2.2  Renewal Terms. Provided Lessee is not in default and this Lease is
              -------------
otherwise in full force and effect, Lessee is granted the option to renew this
Lease upon the same terms and conditions (subject to adjustment of rentals as
set forth in Section 3.3 and subject to modifications required to conform this
Lease to the terms of Lessor's then current form of lease agreement), for five
additional term(s) of five years each; such option to be exercisable upon the
giving of written notice of intent to renew by Lessee to Lessor not earlier than
180 days and not later than 120 days prior to the expiration date of the then
current primary or option term.

         2.3  Assignment of Lease. Lessee shall not sublet, mortgage or pledge
              -------------------
this Lease or any interest herein or in the Leased Premises or any part of the
same or assign this Lease or any interests herein or portion hereof, nor shall
any assignment of any interest(s) of Lessee herein by operation of law or by
reason of Lessee's bankruptcy become effective, without the prior written
consent of the Lessor, which consent shall not be unreasonably withheld or
delayed. No sublease or assignment arrangement conditionally consented to by
Lessor shall be or become effective unless and until Lessee has delivered to
Lessor a written assignment and assumption agreement by the sublessee or
assignee in a form approved by Lessor, together with adequate assurance of
sublessee's or assignee's ability to perform, accept, observe and be bound by
each and all of the terms, provisions and stipulations of this Lease provided in
a form acceptable to Lessor in the exercise of its sole discretion; and provided
further, that any subletting or transfer shall not extend beyond the Primary
Term or permitted extension(s) hereof nor shall any subletting or transfer
release or relieve Lessee of any obligations to Lessor hereunder. Written
approval shall not be required with respect to any mortgages, assignments or
pledges respecting any improvements for facilities constructed, erected,
installed or maintained by Lessee upon the Leased Premises except as now or
hereafter otherwise provided herein.

                             ARTICLE III. RENTALS

         3.1   Primary Term Rentals. Lessee shall pay to Lessor lease rental
               --------------------
during the Primary Term as follows:

(a)      Monthly Rentals. Commencing see exhibit "D" rider 2, and continuing
         ---------------             -----------------------
thereafter on the first day of each consecutive month of the Primary Term,
Lessee shall pay to Lessor the sum of see exhibit "D" rider 3 . Monthly rentals
                                      -----------------------
shall be adjusted during and after the Primary Term in accordance with the other
provisions of the Lease.

(b)      Rental Rate Adjustment. To provide for changes in land values, the
         ----------------------
monthly rentals as set forth in 3.1(a) above will, at the election of Lessor, be
adjusted to reflect any increase in the Consumer Price Index ("Index"), All
Items - U.S. Cities Average, published in the monthly labor review by the Bureau
of Labor Statistics, U.S. Department of Labor (1982-1984 = 100). Implementation
of the cost of living index rent adjustment will be made on the fifth
anniversary date of the lease and every five years thereafter (on the
anniversary date) for the primary term and any extensions thereof. The rental
adjustments will be made by multiplying the monthly rent by a fraction,
<PAGE>

the numerator of which is the Index published two (2) months prior to the date
of adjustment, and the denominator of which is the Index as of 60 months prior
to the date of the Index used in establishing the numerator. The rental rate
adjustment for each five-year period will not exceed 25 percent of the monthly
rent for the rental term immediately prior to the adjustment. If for any reason
there is a major change in the method of calculation or formulation of the
Consumer Price Index, or should the Consumer Price Index no longer be published,
then the parties will mutually select the commodity index satisfactory to both.
If the parties cannot agree upon a substitute index, then the index shall be
established through the arbitration procedures set forth in Section 3.3.
Notwithstanding the provisions of this Subsection, in no event will the adjusted
rental rate exceed the rental rate on a per acre basis for other available real
property at the Tulsa Port of Catoosa similarly classified by Lessor, in its
sole discretion, hereafter and from time to time.

         3.2   Additional Rentals. In addition to the rentals provided in
               ------------------
Section 3.1, and as additional rental charges, Lessee shall pay to Lessor the
following sums:

               (a)  Security. Lessor will contract to provide cooperatively
                    --------
         financed and administered security services at Tulsa Port of Catoosa on
         behalf of its lessees, invitees, operators and users. Lessee agrees to
         pay its pro rata share of the costs of such security services based on
         a degree-of-risk formula established by Lessor for all of Lessor's
         lessees. The Parties agree that Lessor makes no representations as to
         the adequacy of the security services. Neither Lessor nor its officers,
         directors, agents, servants, representatives or employees shall be
         directly or indirectly liable to Lessee for any losses or damage to
         Lessee's property or to the property of others for which Lessee may be
         liable, attributable to the acts of third parties. The agreed upon
         contributions to be paid by Lessee for security services shall be
         $375/month, commencing the 1st day of December, 2001. The agreed upon
         security cost may be modified by Lessor if the cost of providing the
         services either increases or decreases during the Lease Term.

               (b)  Barge and Rail Charges. Lessor and Lessee recognize the
                    ----------------------
         importance of having reliable barge and railcar moving services readily
         available. Lessor and Lessee agree that Lessor currently provides this
         service and the initial barge or railcar placement costs are included
         in the rate prescribed by the barge owner or railroad. Lessor and
         Lessee agree, however, that charges for initial placements, as
         appropriate, and for any subsequent moves or shifting of a barge or
         railcar for the convenience of Lessee shall be paid by Lessee at the
         rates and in the manner established by the Port's Operational Circular
         and, if done after established working periods, such moves or shifts
         shall be paid by Lessee at overtime rates established therefor.

               (c)  Other Charges. Lessee shall also pay to Lessor, on the same
                    -------------
         payment dates provided in Subsection 3.1(a), all other sums and charges
         approved from time to time with the written concurrence of the Parties
         to be set forth and stated on Exhibit "C", attached hereto and by this
                                       -----------
         reference made a part of this Lease. Exhibit "C" may be amended and
         replaced from time to time by agreement of the Parties, evidenced by
         the signatures of their authorized representatives thereon. Lessee
         covenants to timely prepare and deliver to Lessor accurate and
         certified reports of events giving rise to other charges properly
         includable on Exhibit "C."

               (d)  Taxes. Lessee agrees to cause to be paid all taxes, levies,
                    -----
         imposts and assessments which may be legally made upon or levied and/or
         assessed against the Leased Premises, any interests therein, and/or any
         improvements or property located thereupon before the same become
         delinquent. Lessee shall have the right, at its sole
<PAGE>

         cost and expense and after having given Lessor prior written notice of
         its intent to do so, to contest by appropriate legal proceedings
         diligently conducted in good faith, the validity, amount or
         application, in whole or in part of such taxes, levies, imposts and/or
         assessments, provided (i) the proceedings will suspend the collection
         of the tax, levy, impost or assessment, (ii) neither the Leased
         Premises, nor any rent therefrom, nor any portion of either is in
         danger of seizure, forfeiture, sale, loss or similar consequences, and
         (iii) Lessee shall first furnish Lessor and the City with security
         which in Lessor's opinion is adequate, satisfactory and sufficient to
         protect against loss, penalty, interest or costs incurred by reason of
         the contest.

         3.3   Renewal Term(s) Rentals. Lease rentals covering each renewal
               -----------------------
period shall be negotiated by the Parties and reduced to writing as an addendum
or addenda to this Lease at least 120 days prior to the commencement of each
renewal term. Renewal period rentals shall be paid by Lessee to Lessor in
accordance with the procedure for payment and adjustments set forth in Section
3.1. In the event the Parties hereto cannot agree upon the amount of the renewal
term lease rentals, then at least 120 days prior to the expiration of the then
existing term, the Parties shall make a bona fide effort to agree upon the then
fair market value of the Leased Premises, exclusive of the value of any
improvements made by Lessee thereon. If the Parties are unable to agree upon
said value, then at least 105 days prior to the expiration of such term the
following procedure for determining rental shall be followed:

               (a)  A Board of Appraisers shall be appointed consisting of I
      member appointed by each of the Parties and a third member appointed by
      the first two appointees.

               (b)  The Board of Appraisers shall thereupon, at least 15 days
         prior to the expiration of such term, determine the then fair market
         value of the Leased Premises, exclusive of the value of any
         improvements made by Lessee thereon, and the valuation fixed by the
         Board of Appraisers shall be conclusive and bind the Parties.

Based upon the fair market value of the Leased Premises, whether determined by
agreement or by Board of Appraisers, Lessee agrees to pay Lessor as rent for the
next succeeding term hereof an amount equal to 8% per annum of such fair market
value during said term, payable in the same manner as the installments during
the Primary Term of this Lease and subject to the provision for future
adjustment set forth in Subsection 3.1(c). If the Board of Appraisers shall not
have determined the fair market value of the Leased Premises at the time of the
commencement of the succeeding renewal term, Lessee may nevertheless continue
this Lease in effect by paying provisional lease rentals equal to the lease
rentals required during the immediately preceding term until such time as the
Board of Appraisers makes its determination. Upon such determination Lessee
shall, in order to continue this Lease in effect for the renewal period, within
30 days after receipt of notice of the determination, pay to Lessor the amount
by which the rental calculation pursuant to the determination of the Board of
Appraisers exceeds the provisional rental paid by Lessee retroactive to the
first day of the renewal term. To the extent to which the provisional lease
rentals paid by Lessee to Lessor exceed the amount of the determination of the
Board of Appraisers, Lessee shall be entitled to credit the overpayment to the
rentals next due under the Lease. Costs and expenses incident to an appraisal
pursuant to this Section shall be borne equally by the Parties.
<PAGE>

                           ARTICLE IV. IMPROVEMENTS

         4.1   Notice and Submission of Plans. Prior to the commencement of any
               ------------------------------
construction at or upon the Leased Premises, Lessee shall first cause Lessor to
be given written notice of the nature and extent of any specific improvements
and/or improvement projects proposed to be undertaken. Lessee shall submit to
Lessor for review and approval all of its architectural plans and drawings of
proposed facilities and/or improvements, together with such additional
specifications as Lessor may reasonably request. Lessee may not commence to
construct any proposed improvements until it has secured Lessor's written
approval, which shall not be unreasonably withheld or delayed. Lessor's approval
shall be based on compliance with Lessor's Building and Development Regulations
(except as otherwise provided in Section 1.3), the terms of this Lease, and all
other applicable rules and regulations of Lessor in effect at the time
construction is commenced.

         4.2   Improvements. Except as may otherwise be specifically provided in
this Lease, all improvements made by Lessee, including without limitation,
structures, electric power and light, water, telephone, sanitary facilities, and
accessory structures from and to the Leased Premises, including all chattels,
goods, tools, equipment and personal property, will be constructed, erected,
installed and/or maintained as between the Parties, at the sole expense and risk
of Lessee (collectively, the "Lessee Improvements"). Except as set forth herein,
Lessee shall at all times retain full right, title and interest in and to the
Lessee Improvements. Within a period of 90 days following the date of Lease
termination, Lessee, at its sole cost and expense, shall remove the Lessee
Improvements (other than such Lessee Improvements as Lessee has designated in
writing to Lessor as items Lessee desires to leave on the Leased Premises and
Lessor has given its written consent thereto, which consent may be withheld by
Lessor in its sole discretion), and the Leased Premises shall be reasonably
restored by Lessee to its original condition. At the election of Lessor, any and
all property of Lessee not timely removed by Lessee from the Leased Premises
shall become the property of Lessor. Notwithstanding, Lessee shall have the
right to sell the Lessee Improvements and assign the Lease to a third party so
long as such assignment of the Lease complies with the requirements of Section
2.3 above. Certain other Improvements, including but not limited to roadways,
roadway material, parking areas, railways, rail switches and/or turnouts, rail
and track material (the Parties acknowledge that all railway-related
improvements shall always remain the property of Lessor), shell, slag, gravel or
concrete used to stabilize the soil, pavement, and underground utilities shall
remain in place and remain or become the property of Lessor and may not be
removed by Lessee.

         4.3   Utilities and Services. Except as may otherwise be specifically
               ----------------------
provided in this Lease, Lessee shall at its sole cost and expense provide for
servicing the Leased Premises and all improvements thereon with water, sewer,
gas, electricity, telephone or other utility services as may be required for the
use and operation of the Leased Premises. Lessor, however, at its sole cost and
expense, shall cause such utilities to be installed adjacent to the Leased
Premises in a manner that will allow Lessee to service the Leased Premises as
set forth above. Lessee shall be responsible for all costs and charges in
connection with its utility installation and service and shall pay the same
promptly as the charges accrue to protect, fully indemnify and hold Lessor
harmless from and against any and all liability for such costs or charges.

         4.4   Easements. Lessor agrees to grant to Lessee, when required by
               ---------
Lessee, nonexclusive easements over, across and through Lessor's unleased
property which it has the right to grant and which are reasonably necessary for
the operation of Lessee's facilities on the Leased Premises or reasonably
required by Lessee, including but not limited to, the following:
<PAGE>

               (a)  Access to railroad lines and spurs, if any, located within
         the Leased Premises, together with the right to place railroad track
         switches or turnouts necessary to accommodate Lessee's use of railroad
         trackage constructed and used by Lessee at or upon the Leased Premises.
         All tracks, lines, spurs, switches and turnarounds to be utilized by
         Lessee shall be identified on Exhibit "A" to be considered a part of
         the Leased Premises covered by this Lease. Lessee hereby grants to
         Lessor an easement and right to use for switching and/or storage of
         railcars any trackage constructed by Lessee, provided that such use by
         Lessor shall not interfere with Lessee's use of such trackage.

               (b)  Connection of water and sanitary sewer facilities as
         approved by the City of Tulsa Public Works Department along designated
         routes as shown on the Master Plan of Development and/or other relevant
         documents of Lessor for the Tulsa Port of Catoosa.

               (c)  Connection of telephone, electric and gas lines, as approved
         by the appropriate utility companies, to those installed at or upon the
         Leased Premises.

               (d)  Connection of streets and/or roads for vehicular traffic to
         roads immediately adjacent or near the Leased Premises, subject to
         Lessor's prior approval of any proposed curb cuts and roadway
         improvements for the Leased Premises.

               (e)  Location, placement and maintenance of production and/or
         handling pipelines connecting the Leased Premises to wharves and/or
         barge mooring dolphins, as may be necessary for Lessee's activities
         and/or operations, to the extent the same are permitted and approved by
         Lessor and upon payment or arrangements for payment to Lessor of
         appropriate fees therefor.

Lessor shall have no obligation to furnish any easement which would in the
exercise of its sole discretion interfere with the orderly development and/or
utilization of Lessor's Industrial Park and/or Terminal Area, in whole or in
part, nor shall any easement exceed the height, depth or width reasonably
necessary to permit the reasonable operation of Lessee's facilities on the
Leased Premises. Any and all easements in which rights shall be granted
hereunder shall be described on and made a part of Exhibit "A" to this Lease to
be included within the Leased Premises and the privileges extended to Lessee
under this Lease.

         4.5   Access. Lessor covenants that so long as Lessee is not in default
               ------
under any of the terms and conditions of this Lease, Lessee shall have and enjoy
the right of ingress and egress in and to the Leased Premises with a
nonexclusive right to use any railroad, road, roadway or areas used in common by
Lessor and/or its other lessees by, about or adjacent to the Leased Premises;
subject, however, to the following provisions:

               (a)  This Lease does not grant any tenancy in railroad, road,
         roadway or common area by, about or adjacent to the Leased Premises.

               (b)  Lessor shall have the right to relocate any railroad, road,
         roadways or common areas or any portion thereof so long as the
         relocation does not deprive Lessee of access to the Leased Premises for
         railroad, vehicular, barge and/or utility facilities as are
         contemplated herein to be constructed by Lessee. Lessor shall have no
         liability to Lessee for any damage or loss incurred by Lessee as a
         result of any relocation which is not occasioned by the destruction,
         removal or relocation of any of Lessee's facilitates or improvements.
<PAGE>

               (c)  Lessee shall not use the railroad, roads, roadways or common
         areas, or any portions thereof, in any way which would interfere with
         the use of the same by Lessor or any of its lessees, operators,
         invitees or users.

Provided however, nothing contained in this Section 4.5 is intended to diminish
Lessee's rights or Lessor's obligations under Section 4.4.

         4.6   Signs. Lessee shall be entitled to erect, install and maintain on
               -----
the Leased Premises identification and advertising signs appropriate to its
business. All Lessee's signs at all times shall be subject to the prior written
approval of Lessor's Port Director as to location, size, shape, color and
content.

         4.7   Lien Claims. Lessee covenants to unconditionally indemnify Lessor
               -----------
and the City, as fee owner of the Leased Premises, from and against and save
them harmless from any and all lien claims of any nature whatsoever arising out
of or in any manner connected with the construction, installation, erection,
maintenance, repair, occupancy, use and/or operation of any improvements,
facilities and/or equipment erected by Lessee or Lessee's agents on or about the
Leased Premises. Lessee further agrees that it shall, in the event any liens are
filed encumbering the Leased Premises, effect their removal and/or satisfaction.
Lessee shall have the right, at its sole cost and expense and after having given
Lessor prior written notice of its intent to do so, to contest by appropriate
legal proceedings diligently conducted in good faith, the amount, validity or
application, in whole or in part, of any lien(s), provided (i) such proceedings
shall suspend the collection of the lien(s), (ii) neither the Leased Premises
nor any rent therefrom, or any portion of either, would be in danger of
attachment, forfeiture, loss or similar consequence, and (iii) that Lessee shall
first furnish Lessor and the City with the security which in Lessor's opinion is
adequate, satisfactory and sufficient to protect Lessor and the City from any
loss, penalty, interest, cost or injury incurred by reason of the contest.
Except as otherwise provided hereinabove, at Lessor's request Lessee shall
furnish Lessor with written proof of payment of any item .which would or might
constitute the basis for such a lien on the Leased Premises or upon its interest
in this Lease if not paid.

         4.8   Inspection and/or Repair of Premises. Lessor shall at all
               ------------------------------------
reasonable times be permitted and allowed to enter the Leased Premises to
inspect the condition of the Lease Premises and Lessee's operations and/or
improvements to determine compliance with the terms of this Lease, and further,
Lessor shall be permitted to make repairs and/or engage in maintenance necessary
in respect to any facilities as it may have installed upon or about the Leased
Premises. If the obligation to make repairs and/or to engage in maintenance is
Lessee's hereunder and Lessee fails to fulfill such obligations within a
reasonable period of time, Lessor may elect to undertake to perform the same,
then Lessee shall reimburse Lessor for the cost of charges therefor upon receipt
of invoices therefor.
<PAGE>

                             ARTICLE V. OPERATIONS

         5.1   Pollution Control. Lessee agrees that it shall not pollute the
               -----------------
air, water or ground at or upon the Leased Premises and/or in the vicinity of
its operations or activities, and/or at or upon other premises as it may by
these covenants have the right to use or occupy, whether or not in connection
with others, in violation of applicable governmental statute, rule or regulation
and/or in violation of standards and/or requirements as Lessor may from time to
time reasonably and uniformly adopt in pursuit of governmental regulations. In
this connection, Lessee shall obtain and maintain current all required permits,
local, state and federal, needed to construct facilities and/or conduct the
operations or activities contemplated under this Lease.

         5.2   Compliance with Laws and Regulations. Lessee's exercise of rights
               ------------------------------------
and/or privileges extended hereunder shall at all times be in full compliance
with all applicable laws, rules and regulations, including safety regulations,
of the State of Oklahoma, the United States and other governmental authorities
now or hereafter having jurisdiction and/or any of their duly empowered agencies
and/or instrumentalities. Lessee further agrees to comply with all applicable
rules and regulations of Lessor pertaining to the Leased Premises and the Tulsa
Port of Catoosa now in existence and hereafter promulgated for the general
safety and convenience of Lessor, its various tenants, invitees, licensees and
the general public, provided such rules and regulations shall not materially
conflict with the provisions of this Lease. A copy of all Lessee's building
permits, Corps of Engineers and Coast Guard permits, licenses and similar
authorizing documents shall be provided by Lessee to Lessor as and when
reasonably requested by Lessor.

         5.3   Maintenance of Adjoining: Grounds. As part of the consideration
               ---------------------------------
for this Lease, Lessee agrees to regularly perform all "grounds maintenance" of
the area between the Leased Premises and the pavement of any road, bed of any
railroad or centerline of any rights-of-way within the boundaries of and
abutting the Leased Premises. "Grounds maintenance" will include keeping areas
clean, mowed, orderly and free from debris and waste materials. Lessor retains
full rights to utilize the areas concerned, including the right to grant
easements for utilities, installation of signs, etc., and Lessee shall not be
deemed as having any tenancy in these areas. Lessee shall not be responsible for
any additional maintenance costs arising out of the foregoing acts of Lessor.
Lessor shall have the right to withdraw all or part of Lessee's responsibility
under this Section 5.3, if Lessor so desires and so informs Lessee in writing.
In any instance in which construction of roads or railroads has been commenced
but not completed within or adjacent to the Leased Premises, Lessee shall be
responsible for ground maintenance of the areas between the Leased Premises and
existing road and railroad improvements as have been or are in the process of
being constructed in the adjoining rights-of-way therefor. If no road or
railroad improvements shall exist, Lessee shall maintain the areas from the
Leased Premises to the centerline of future roads and railroads as are shown on
the Tulsa Port of Catoosa Master Development Plan, and as may be reflected in
Exhibit "A". Notwithstanding the requirements of this Section, Lessee shall not
be required to undertake ground maintenance with respect to any areas between
the Leased Premises and any road or railroad improvements or rights-of-way
therefor in excess of a 50-foot distance from the Leased Premises.

         5.4   Indemnification. Lessee hereby releases and discharges Lessor and
               ---------------
the City from and shall fully protect, indemnify and keep, hold and save Lessor
and the City harmless from and against any and all costs, including, but not
limited to, clean-up costs, charges, expenses, penalties, damages (including
contamination) and consequences imposed for or arising from the violation of any
law or regulations of the United States, the State of Oklahoma, any local
authorities, or any of such entities' agencies and instrumentalities
(collectively "Governmental
<PAGE>

Authorities"), occasioned, in whole or in part, by any act or omission of Lessee
or its representatives, assigns, agents, servants, employees, licensees,
invitees, and any other person(s) occupying under Lessee (except to the extent
that any such costs are attributable to the negligent or willful act or omission
of Lessor or the City, or their representatives, assigns, agents, servants,
employees, licensees, invitees, or any other person acting under or on behalf of
Lessor). Lessee shall further protect, fully indemnify and save forever harmless
Lessor and the City from and against any and all liability, cost, damage
(including clean-up costs and contamination) and expense, incident to injury
(including injury resulting in death) of third parties or damage to or
destruction of their property incident to, arising out of or in any way
connected with Lessee's use and occupancy or rights of use and occupancy of the
Leased Premises (whether by omission or commission and irrespective of exclusive
or nonexclusive rights therein) including, but not limited to, the operation of
Lessee's business, the construction, erection, installation, existence, repair,
maintenance, alteration and/or demolition of any improvements, facilities and/or
equipment or the conduct of any other activities, and which would not have
arisen but for the exercise or pursuit by Lessee of the rights and privileges
accorded hereby or the failure on Lessee's part in any respect to comply with
the requirements hereof, except as a loss occasioned by the negligent or willful
act or omission of Lessor or the City or their representatives, assigns, agents,
servants, employees, licensees, invitees, or any other person acting under or on
behalf of Lessor.

         5.5   Use Prohibition and Duties (Environmental). Lessee covenants and
               ------------------------------------------
agrees that it will not use, generate, manufacture, produce, store, release,
discharge or dispose of on, under or about the Leased Premises or transport to
or from the Leased Property any Hazardous Materials, except in strict compliance
with all applicable laws. "Hazardous Materials" shall mean (i) any "hazardous
waste" as defined by the Resource Conservation and Recovery Act of 1976 (42
U.S.C. ss. 6901, et seq.), as amended from time to time, and regulations
promulgated thereunder; (ii) any "hazardous substance" as defined by the
Comprehensive Environmental Response, Compensation and Liability Act of 1980 (42
U.S.C. ss. 9601, et seq.) ("CERCLA"), as amended from time to time, and
regulations :promulgated thereunder; (iii) asbestos; (iv) polychlorinated
biphenyls; (v) underground storage tanks, whether empty, filled or partially
filled with any substance; (vi) any substance the presence of which on the
Leased Premises is prohibited by any applicable governmental requirements and
regulations; and (vii) any other substance which by any governmental
requirements requires special handling or notification of any federal, state or
local governmental entity in its collection, storage, treatment or disposal.
Lessee will keep and maintain the Leased Premises in compliance with, and shall
not cause or permit the Leased Premises to be in violation of any governmental
requirements and will not allow any other person or entity to do so. Lessee
shall allow Lessor to join and participate in, as a party if it so elects, any
legal proceedings or actions initiated in connection with violation of any
governmental requirements and Lessee hereby agrees to pay any attorneys' fees
incurred by Lessor in connection therewith. Without Lessor's prior written
consent, which shall not be unreasonably withheld, Lessee shall not take any
remedial action in response to the presence of any Hazardous Materials on,
under, or about the Leased Premises, nor enter into any settlement, agreement,
consent, decree or other compromise in respect to any claims regarding the
presence of Hazardous Materials. Lessor's consent may be withheld, without
limitation, if Lessor, in its reasonable judgment, determines that remedial
action, settlement, consent or compromise might impair the value of the Leased
Premises; provided, however, that Lessor's prior consent shall not be necessary
in the event that the presence of Hazardous Materials in, on, under or about the
Leased Premises either poses an immediate threat to the health, safety, or
welfare of any individual or is of such a nature that an immediate remedial
response is necessary, and it is not possible to obtain Lessor's consent before
taking such action. In such event Lessee shall notify Lessor as soon as
practicable of any action so taken. Lessee agrees to (a) give notice to Lessor
immediately upon its acquiring knowledge of the presence of any Hazardous
Materials on the Leased Premises or of any
<PAGE>

hazardous substance contamination with a full description thereof; (b) promptly
comply with any governmental requirement of removal, treatment or disposal of
Hazardous Materials or hazardous substance contamination and provide Lessor with
satisfactory evidence of compliance; and (c) provide Lessor, within 30 days
after demand by Lessor, a bond, letter of credit or similar financial assurance
evidencing to Lessor's satisfaction that the necessary funds are available to
pay the cost of removing, treating and disposing of Hazardous Materials or
hazardous substance contamination and discharging any assessments which may be
established on the Leased Premises as a result thereof.

         5.6   Site Assessments. If Lessor shall have an objective reason to
               ----------------
believe that there are Hazardous Materials or Hazardous Materials contamination,
such reason being based upon a visible, apparent or documented condition of the
Leased Premises or any contiguous Leased Premises, then Lessor (by its officers,
employees and agents), at any reasonable time and from time to time, may first
provide Lessee with notice of its concern and request that Lessee retain a
qualified industrial hygienist approved by Lessor (the "Site Reviewers") to
perform a Phase I site assessment and a Phase II site assessment, as required or
recommended in the Phase I report, ("Site Assessments"). If Lessee fails to
deliver the requested Site Assessment to Lessor within a prompt, yet reasonable,
period of time, then Lessor may contract for the services of Site Reviewers to
perform Site Assessments. The Site Assessments on the Leased Premises will be
reasonable in scope and based upon the suspected condition for the purpose of
determining whether there exists on the Leased Premises any environmental
condition which could reasonably be expected to result in any liability, cost or
expense to the owner, occupier or operator of such Leased Premises arising under
any state, federal or local law, rule or regulation relating to Hazardous
Materials. The Site Assessments may be performed at any time(s), upon reasonable
notice, and under reasonable conditions established by Lessee which do not
impede the performance of the Site Assessments. Site Reviewers are authorized to
enter upon the Leased Premises for such purposes. Site Reviewers are further
authorized to perform both above and below the ground testing for environmental
damage or the presence of Hazardous Materials on the Leased Premises and such
other tests on the Leased Premises as may be necessary to conduct the Site
Assessments in the reasonable opinion of the Site Reviewers. Lessee will supply
to the Site Reviewers such historical and operational information regarding the
Leased Premises as may be reasonably requested by the Site Reviewers to
facilitate the Site Assessments and will make available for meetings with the
Site Reviewers appropriate personnel having knowledge of such matters. On
request, the results of any Site Assessments shall be made fully available to
Lessee and Lessor. Unless otherwise agreed by Lessor and Lessee, the cost of
performing Site Assessments shall be paid by Lessee, and if incurred by Lessor
shall be paid by Lessee to Lessor upon its demand. This monetary obligation
shall constitute additional rental due on demand made by Lessor. In addition,
Lessee shall have the right to perform Phase I and Phase II Site Assessments,
within 120 days of the effective date of this Lease, and Lessor shall reimburse
Lessee for costs, up to $1,750.00 of the Phase I Site Assessment.

         5.7   Environmental Indemnification. Lessee shall defend,
               -----------------------------
indemnify and hold harmless Lessor and the City from any and all liabilities
(including strict liability), actions, demands, penalties, losses, costs or
expenses (including without limitation attorneys' fees and expenses, and
remedial costs), suits, costs of any settlement or judgment and claims of any
and every kind whatsoever which may now or in the future (whether before or
after the termination of this Lease) (hereafter, "Environmental Claims") be
paid, incurred or suffered by or asserted against Lessor or the City by any
person or entity or governmental agency for, with respect to, or as a direct or
indirect result of, the presence on or under, or the escape, seepage, leakage,
spillage, discharge, emission, or release from the Leased Premises of any
Hazardous Materials or any Hazardous Materials contamination or arise out of or
result from the environmental condition of the Leased
<PAGE>

Premises or the applicability of any governmental requirements relating to
Hazardous Materials (including without limitation CERCLA or any federal, state
or local so-called "Superfund" or "Superlien" laws, statute, law, ordinance,
code, rule, regulation, order or decree). The representations, covenants,
warranties and indemnifications contained in this Section shall survive the
termination of this Lease. Provided however, notwithstanding anything contained
herein to the contrary, Lessee shall have no obligation whatsoever to Lessor,
the City or any third party for Environmental Claims to the extent such claims
are based on the condition of the Leased Premises existing prior to the
"baseline" created by the Phase I and Phase II (if conducted) Site Assessments.

         5.8   Insurance. In pursuit, but not in derogation of or by way of
               ---------
substitution for Lessee's obligations under Article V, Lessee shall at all times
cause to be maintained at its sole cost and expense minimum insurance coverage
and policies with the following prescribed terms:

               (a) Commercial General Liability Insurance - with a combined
         single limit of $1,000,000 each occurrence and $2,000,000 annual
         aggregate, applicable to bodily injury and property damage, including
         pollution liability.

               (b) The Commercial General Liability Insurance shall be
         issued on an "occurrence" basis and shall include coverage for all
         operations of Lessee, including independent contractor's coverage,
         blanket contractual liability and the policy will be endorsed to
         eliminate exclusion for work, construction or demolition within 50 feet
         of railroad trackage, broad form property damage, including completed
         operations, and, where applicable, property damage liability resulting
         from blasting or explosion, collapse or structural injury and/or
         subsurface operations. The policy shall not be modified to reduce the
         standard coverages provided under a Commercial General Liability policy
         form. The pollution liability endorsement may be on a "claims made"
         basis.

               (c) Lessor shall be designated as additional named insured under
         the policy required by Lessor.

               (d) As respects all insurance policies applicable to this Lease,
         Lessee shall, prior to the commencement of this Lease and upon the
         annual anniversaries, furnish to Lessor certificates of insurance
         evidencing the maintenance of all coverages required and the payment of
         premiums.

               (e) Lessor shall have the right to review Lessee's insurance
         coverages, and/or to obtain upon request certified copies of the
         insurance policies, periodically, to insure full and adequate
         protection and to otherwise reasonably require additional and/or other
         forms of coverage, in accordance with current generally accepted
         coverages in the industry and/or within the Tulsa Metropolitan Area in
         respect to operations and/or activities similar to those of Lessee,
         whether similar in whole or in part. The cost of additional coverage
         and/or forms of coverage shall be borne by Lessee.

               (f) All policies of insurance shall require that Lessor and
         Lessee be given 30 days' prior written notice of any modification,
         termination and/or cancellation of coverages.

               (g) All insurance policies shall be issued by an insurance
         company rated A (Excellent) or better and be included in financial size
         category VII, or better, in Best's Insurance Guide, and be otherwise
                                     ------ ---------------
         reasonably satisfactory to Lessor with respect to form and content. If
         Lessee refuses or neglects to secure and maintain insurance policies
<PAGE>

         complying with the provisions of this Section, Lessor may, but shall
         not be required to, secure and maintain insurance policies, and Lessee
         shall reimburse Lessor for the cost thereof as additional rent, upon
         demand.

               (h) Lessee shall not use the Leased Premises in any manner which
         would increase the existing rates of insurance premiums paid by Lessor
         with respect to its operations and activities at the Tulsa Port of
         Catoosa and/or in the vicinity of the Leased Premises. If it
         nevertheless does so, then, at the option of the Lessor, the full
         amount of any resulting increase in premiums, to the extent allocable
         to the remaining rent for the year in which the increase is recognized,
         may be added to the amount of rentals specified herein and shall be
         paid by Lessee to Lessor commencing upon the monthly rental day next
         thereafter occurring.

                            ARTICLE VI. TERMINATION

         6.1   Termination. Upon the termination of this Lease, however
               -----------
termination may be brought about, whether by expiration of the term hereof, or
otherwise, Lessee shall quit and surrender the Leased Premises to Lessor in good
condition, excepting only natural wear and tear from a reasonable use thereof
and destruction of the Leased Premises by covered peril and subject to the
provisions of Section 4.2.

         6.2   Lessee Events of Default. The following shall be "Lessee
               ------------------------
events of default" under this Lease, and the terms "Lessee events of default" or
"Lessee default" shall mean whenever they are used in this Lease, any one or
more of the following events:

               (a)  Failure or refusal of Lessee to pay or cause to be paid any
         lease rental, charges and/or assessments hereunder or any installment
         thereof when due and the continuance of such failure for a period of 10
         days;

               (b)  Failure by Lessee to perform any agreement, covenant,
         condition, obligation and/or undertaking herein contained and/or to
         observe or comply with any of the terms, provisions and conditions of
         this Lease;

               (c)  In the event Lessee, before the expiration of this Lease,
         without the written consent of Lessor, vacates the Leased Premises or
         abandons possession of all or any portion thereof, or uses the same for
         purposes other than the purposes for which the Leased Premises are let
         hereunder, or ceases to use the Leased Premises for the purposes herein
         specified;

               (d)  Issuance of execution against Lessee's interest in this
         Lease or any legal process which by operation of law would cause
         Lessee's interest in this Lease to pass to any person other than Lessee
         or its successor assignee pursuant to Section 2.3; and/or

               (e)  Insolvency, assignment for the benefit of creditors,
         adjudication as a bankrupt or the appointment of a receiver for
         substantially all of Lessee's property and/or Lessee's interest in this
         Lease.

         6.3   Cancellation. Save and except for defaults occurring under
               ------------
Subsections 6.2 (a) and (e), in which cases no notice of default shall be
required of Lessor, if any Lessee default shall occur and continue unremedied or
uncorrected for a period of 60 days after Lessor shall have given Lessee notice
in writing specifying Lessee default, then at the written option of Lessor this
<PAGE>

Lease and all Lessee's interests and rights hereunder shall immediately cease
and terminate. In the case of a default occurring under Section 6.2(b) or (d)
which does not endanger or impair or threaten to endanger or impair Lessor or
any of its lessees or operators or any of their facilities or operations and
which is remediable but will reasonably require in excess of 60 days to remedy,
if Lessee shall, upon receipt of notice of default from Lessor, have notified
Lessor of the probability of such delay and thereupon undertaken to remedy with
due diligence and reasonable dispatch, then termination shall be stayed so long
as, and only so long as, Lessee in good faith continues its best efforts to
remedy with due diligence and reasonable dispatch.

         6.4   Lessor Events of Default. The occurrence of any of the following
               ------------------------
events shall constitute an event of default by Lessor ("Lessor Event of
Default") under this Lease:

         (a)   Failure by Lessor to perform any agreement, covenant, condition,
obligation and/or undertaking herein contained and/or observe or comply with any
of the terms, provisions and conditions of this Lease, and such failure is not
corrected within sixty (60) days except as to a breach of the covenant of quiet
enjoyment which is not corrected within five (5) days after written notice from
Lessee to Lessor;

         (b)   Any third party claiming an interest in the Leased Premises
through or under Lessor breaches the covenant of quiet enjoyment and such breach
is not cured within a period of ten (10) days after written notice from Lessee
to Lessor;

         (c)   Lessor makes any representation or warranty herein or in any
other statement or certificate at any time given in writing pursuant to or in
connection with this Lease, which is false or misleading in any material
respect, and such failure is not corrected within sixty (60) days;

         (d)   Lessor materially breaches any other agreement between Lessor and
Lessee, and such breach is not cured within sixty (60); or

         (e)   Insolvency, assignment for the benefit of creditors, adjudication
as a bankrupt or the appointment of a receiver for substantially all of Lessor's
property and/or Lessor's interest in this Lease.

         In the event of a Lessor Event of Default that is not cured within the
time periods set forth above, Lessee may exercise all remedies available to it
under this Lease or applicable law, including without limitation: (i) Lessee may
terminate this Lease, whereupon all obligations of Lessee to pay rent and any
other amount due hereunder shall cease; and (ii) Lessee may immediately set off
against all amounts Lessee may owe to Lessor any damages suffered by Lessee as a
result of Lessor's default.

         6.5   Right of Re-entry. Upon the termination of this Lease, however
               -----------------
such termination is brought about, whether by Lessor's election to terminate
under any one or more of the foregoing provisions, or otherwise, and in the
event that Lessee fails to exercise its rights under Section 4.2, Lessor may re-
enter the Leased Premises without notice or demand and remove all persons and
things therefrom with or without legal process and without prejudice to any of
Lessor's other legal rights, using such force as may be necessary or proper for
the purpose. Any and all claims for damages by reason of Lessor's re-entry or
the form or manner of re-entry or the taking possession of the Leased Premises
are hereby waived as also are all claims for damage by reason of any proceedings
in the nature of execution, attachment, sequestration, forcible detainer or
other legal action which Lessor may employ to recover possession of the Leased
Premises or rentals and charges due. Provided however, Lessee does not waive any
claims it may have for damages
<PAGE>

resulting from Lessor's actions that are willful or grossly negligent. If upon
Lessor's reentry there remains any personal property of Lessee or any person
holding under or through it pursuant to Section 2.3, other than property as
either or both shall hold as actual or constructive bailee(s), Lessor may take
possession of the property and sell it at public or private sale without notice
to Lessee, and this right to take and sell shall be a prior lien and claim
against the property, subject, however, to any prior duly perfected third party
encumbrance thereof. Subject to any legal and priority encumbrances, Lessor may,
without obligation to do so take possession of the property and hold it for the
owners thereof or may place the same in a public garage or warehouse, all at the
expense and risk of the owners thereof. Lessee shall reimburse Lessor for any
expenses it incurs in connection with removal and storage of property upon
Lessor's presentment of invoices therefor. If Lessor elects to take possession
of the property and sell it, the proceeds of sale shall be applied first to the
costs of the sale, second to the payment of the charges for storage, if any, and
third to the payment of any other amounts which may then be due from Lessee to
Lessor, with the balance, if any, to be paid to Lessee. Notwithstanding any
reentry upon default by Lessee or a termination of this Lease occasioned by
reason thereof, the lease rentals due hereunder for the remainder of the then
current lease term and such other charges and/or obligations, if any as may be
otherwise payable under this Lease, shall be and become immediately due and
payable and the liability of Lessee for the full amount provided herein shall
not be extinguished for the balance of the term of this Lease. Lessee shall make
good to Lessor any deficiency arising from a reletting of the Leased Premises at
a lesser rental than that hereinbefore agreed upon. Lessee shall pay the rental
deficiency each month as the amount thereof is ascertained by Lessor, upon the
presentment of invoices therefor. Provided however, nothing in this Section 6.5
is intended to waive or diminish Lessee's rights or Lessor's obligations under
Section 4.2.

         6.6   Holding Over. If Lessee shall, with the consent of the Lessor,
               ------------
hold over after the expiration or sooner termination of the term of this Lease,
the resulting tenancy shall, unless otherwise mutually agreed, before an
indefinite period of time or on a month-to-month basis. During any month-to-
month tenancy, Lessee shall pay to Lessor the same rate of rental as set forth
herein, unless a different rate shall be agreed upon, and Lessee shall be bound
by all of the provisions of this Lease insofar as they may be pertinent.

         6.7   Waiver of Breach or Default Cumulative Remedies. Waiver by
               -----------------------------------------------
either of the Parties of any breach or default of this Lease shall not be deemed
a waiver of similar or other breaches or defaults, nor shall the failure of
either of the Parties to take any action by reason of any such breach or default
deprive that party of the right to take action at any time while the breach or
default continues. The rights and remedies created by this Lease shall be
cumulative and nonexclusive of those to which the Parties may be entitled at law
and equity. The right to exercise all remedies is hereby reserved. The use and
availability of one remedy shall not be taken to exclude or waive the right to
use of another. In order to entitle either of the Parties to exercise any remedy
reserved to it in this Lease it shall not be necessary to give any notice, other
than notice expressly required.
<PAGE>

                          ARTICLE VII. MISCELLANEOUS

         7.1   Examination of Lessee's Records. Lessor shall at all reasonable
               -------------------------------
times be permitted to examine and/or audit and, to the extent necessary,
duplicate Lessee's books and records maintained with respect to its operations
and activities hereunder but only for the purpose of determining Lessee's
compliance with the terms and conditions of this Lease. In the event books and
records are maintained at other than Lessee's local office identified above,
Lessee, upon the receipt of written notice by Lessor specifying the nature and
extent of its intended inquiry and/or examination, agrees to immediately furnish
Lessor with full, true and accurate copies of all its books and records as may
be appropriate thereto. Lessor covenants to keep any such books and records and
the information contained therein confidential upon the request of Lessee
(except to the extent disclosure is required as a matter of law).

         7.2   Lessor's Leasehold Interest. It is mutually understood and
               ---------------------------
agreed by the Parties that: (i) Lessor has only a leasehold interest in the
property covered by this Lease which has been granted to Lessor by the City,
(ii) this instrument is a sublease and the Parties are sublessees and sublessors
as the case may be, (iii) this Lease is subject to the terms and conditions of a
lease from the City to Lessor, and (iv):

               (a)  The City has fee simple title to the Leased Premises.

               (b)  Lessor is authorized to enter into this Lease for the
         primary and renewal terms provided herein, pursuant to the terms of its
         lease with the City.

               (c)  The lease between the City and Lessor dated June 22, 1971,
         has been modified subsequent to the date of its original execution.

               (d)  This Lease is generally in accordance with the Master Plan
         of Development of the Port Authority, as amended, and as required in
         Article III of Lessor's lease with the City.

               (e)  Pursuant to the lease between the City and Lessor: (i) any
         dissolution of Lessor or termination of such lease shall not adversely
         affect Lessee's rights hereunder, and (ii) such lease may not be
         amended or modified in any manner so as to have a material adverse
         effect on Lessee's rights hereunder without the prior written consent
         of Lessee.

         7.3   Quiet Enjoyment. Lessor covenants that during the entire
               ---------------
Lease Term and for so long as Lessee (i) shall make timely payment of rentals
due hereunder and (ii) shall perform all covenants on its part to be performed,
Lessee shall and may peaceably and quietly have, hold and enjoy the Leased
Premises.

         7.4   Notices. All notices under this Lease must be sent by United
               -------
States mail, postage prepaid, addressed as follows, except that either Party may
by written notice given as aforesaid change its address for subsequent notices
to be given hereunder;
<PAGE>

                  (a) Lessor:

                  THE CITY OF TULSA-ROGERS COUNTY PORT AUTHORITY
                  5350 Cimarron Road
                  Catoosa, Oklahoma 74015

                  (b) Lessee:

                  Matrix Service, Inc.
                  10701 E. Ute
                  Tulsa, Oklahoma, 74116
                  Attention: Glen Rogers, Vice President

Provided, however, that payments made by Lessee may be sent first class mail,
postage prepaid, to Lessor at the address above given or paid in such other
manner as Lessor may designate. Any and all notices given by either of the
Parties hereto shall be deemed effective upon their receipt by the primary
addressee, as set forth hereinabove.

         7.5      Nondiscrimination. Lessee agrees that it shall not, with
                  -----------------
respect to its operations conducted on the Leased Premises, discriminate against
any employee or applicant for employment because of race, color, religion, sex,
age, national origin or handicap. Lessee shall take affirmative action to ensure
that applicants are employed, and employees are treated during employment,
without regard to race, color, religion, sex, age, national origin or handicap.
Such action shall include, but not be limited to, the following: employment,
upgrading, demotion, or transfer; recruitment or recruitment advertising; layoff
or termination; rates of pay or other forms of compensation; and selection for
training, including apprenticeship.

         7.6      Navigability. The United States Corps of Engineers endeavors
                  ------------
to maintain the water level in the Tulsa Port of Catoosa channel at 532 feet
above mean sea level. Lessor assumes no responsibility for any increase or
decrease in the water level caused by the raising or lowering of the water level
in the Verdigris River, the backwater provided by said river in the channel, the
erosion of water channel banks or sediment.

         7.7      Substitution of Performance. Except as may be otherwise
                  ---------------------------
provided in this Lease, if Lessee shall fail to do anything required to be done
by it under the term(s) of this Lease, except to pay rent and other charges,
Lessor may, after 30 days, written notice to Lessee, at Lessor's sole option, do
such act or thing on behalf of Lessee, and upon notification of the cost thereof
to Lessor, Lessee shall promptly pay to Lessor the amount of that cost.

         7.8      Exhibits and Attachments. All exhibits, attachments, riders
                  ------------------------
and addenda referred to in this Lease, together with the exhibits listed
hereinbelow, are incorporated into this Lease and made a part hereof by this
reference for all intents and purposes.

         Exhibit "A":               Leased Premises
         Exhibit "B":               Building and Development Regulations
         Exhibit "C":               Other Charges
         Exhibit " D":              Miscellaneous Provisions

         7.9      Authority. Each of the Parties to this Lease represents to
                  ---------
the other that it has taken all action necessary to authorize the execution,
delivery and performance of this Lease and that it has executed and delivered
all other documents as required herein and that its
<PAGE>

representative who has signed this Lease has all requisite power and authority
to enter into this Lease and bind the party on whose behalf execution is
provided. Each of the Parties to this Lease represents and warrants to the other
that this Lease is the legal, valid and binding obligation of that Party,
enforceable in accordance with its terms and performance of said Party does not
require the consent of or approval of any other person, agency or court, and
will not conflict with, result in the breach of any term of, or constitute a
default under any material agreement or instrument to which that Party is party,
or to which that Party is subject.

         7.10     Entire Agreement. This Lease embodies the entire agreement
                  ----------------
between the Parties with respect to the leasing and use of the Leased Premises.
There are no representations, terms, conditions, covenants or agreements between
the Parties relating thereto which are not mentioned or contained herein. This
Lease shall completely and fully supersede all other prior agreements, both
written and oral, between the Parties pertaining to the Leased Premises. No
party to any such prior agreement hereafter will have any rights thereunder, and
shall look solely to this Lease for definition and determination of its rights,
liabilities or responsibilities or relating to the matters set forth herein.

         7.11     Captions. The article and section headings and captions
                  --------
contained herein are included for convenience only and shall not be considered a
part hereof or affect in any manner of the construction or interpretation of
this Lease.

         7.12     Severability. The Parties agree that if it should ever be
                  ------------
held by a court of competent jurisdiction that any one or more sections, clauses
or provisions of this Lease are invalid or ineffective for any reason, any such
section, clause or provision shall be deemed separate from the remainder of this
Lease and shall not affect the validity and enforceability of such remainder.

         7.13     Successors and Assigns. The covenants, terms, conditions and
                  ----------------------
obligations set forth and contained in this Lease shall be binding upon and
inure to the benefit of Lessor and Lessee and their respective successors and
assigns.

         7.14     Governing Law. The Parties understand and agree this Lease,
                  -------------
its terms and conditions, and any interpretation thereof shall be governed by
the laws of the State of Oklahoma.

         7.15     Counterparts. This Lease may be executed in two or more
                  ------------
counterparts, each of which when so executed shall be deemed an original, and
which together shall constitute one and the same instrument.

         7.16     Modification. Lessor and Lessee agree that this Lease shall
                  ------------
not be amended, altered or changed except by a written agreement signed by the
parties hereto.

         7.17     Recording. Lessor agrees that this Lease and the Exhibits
                  ---------
hereto may be recorded and placed of public record by Lessee.
<PAGE>

         IN WITNESS WHEREOF, this Lease has been executed in multiple
counterparts, each of which, for all purposes, shall be deemed an original and
all of which shall evidence one agreement between the Parties.

                                     LESSOR:
                                     ------

                                     THE CITY OF TULSA-ROGERS COUNTY
                                     PORT AUTHORITY, a State Agency

[SEAL]                               By:  /s/
                                        ------------------------------
                                                       Chairman
ATTEST:                              APPROVED:

  /s/
---------------------------
Assistant) Secretary
                                          /s/
                                     ---------------------------------
                                     Port Attorney

                                     LESSEE:
                                     ------

                                     MATRIX SERVICE COMPANY, a Delaware
                                     Corporation

[SEAL]                               By:  /s/
                                        ------------------------------
                                                      (Vice) President
ATTEST:

  /s/
---------------------------
(Assistant) Secretary

     This Lease Agreement is approved and consented to as of APR 5 2001, 2001.
                                                             ----------
                                     CITY:
                                     ----

                                     CITY OF TULSA, OKLAHOMA,
                                     a Municipal Corporation

[SEAL]                               By:  /s/
                                        ------------------------------
                                                                 Mayor
ATTEST:                              APPROVED

                                     /s/
                                     ---------------------------------
  /s/                                City Attorney - Asst.
---------------------------
City Clerk
<PAGE>

STATE OF OKLAHOMA                  )
                                   )
COUNTY OF ROGERS                   )

              The foregoing instrument was acknowledged before me on March 27,
                                                                     --------
2001, by James G. Goodwin Chairman of The City of Tulsa-Rogers County
         ----------------
Port Authority, a State agency, on behalf of said agency

          /s/  Weida J. Young
        ------------------------------------
                                            Notary Public
My Commission Expires:

             06-17-2003
--------------------------------

STATE OF OKLAHOMA                  )
         --------
                                   )
COUNTY OF TULSA                    )
          -----

              The foregoing instrument was acknowledged before me on March 27,
                                                                     --------
2001, by Glen Rogers, Vice President of Matrix Service Company, a Delaware
         -----------  --------------
corporation, on behalf of said corporation.

          /s/  Patsy R. Priddy
        ------------------------------------
                                            Notary Public
My Commission Expires:

              8-15-2002
--------------------------------

STATE OF OKLAHOMA                  )
                                   )
COUNTY OF TULSA                    )

              The foregoing instrument was acknowledged before me on April 5,
                                                                     -------
2001, by M. Susan Savage, Mayor of the City of Tulsa, a municipal corporation,
         ---------------
on behalf of said corporation.

          /s/  Sherry Cartwright
        ------------------------------------
                                            Notary Public
My Commission Expires:

              7-12-2004
--------------------------------
<PAGE>

                                  EXHIBIT "A"

                        PORT OF CATOOSA INDUSTRIAL PARK
                    CITY OF TULSA, ROGERS COUNTY, OKLAHOMA

{In the original document, this page contains a diagram of the tract of land
more fully described on the following page located at the Port of Catoosa
Industrial Park, City of Tulsa, Rogers County, Oklahoma. The diagram, dated
01/19/01, was prepared by Sisemore Weisz & Associates, Inc., Tulsa, Oklahoma.}
<PAGE>

                               LEGAL DESCRIPTION

A TRACT OF LAND THAT IS PART OF THE SOUTHEAST QUARTER (SE/4) OF SECTION SIX (6),
PART OF THE NORTHEAST QUARTER (NEl4) OF SECTION SEVEN (7) AND PART OF THE
NORTHWEST QUARTER (NW/4) OF SECTION EIGHT (8), ALL IN TOWNSHIP TWENTY (20)
NORTH, RANGE FIFTEEN (15) EAST OF THE INDIAN BASE AND MERIDIAN, ROGERS COUNTY,
OKLAHOMA, SAID TRACT OF LAND BEING DESCRIBED AS FOLLOWS, TO-WIT:

STARTING AT THE SOUTHEAST CORNER OF SAID SECTION 6; THENCE DUE WEST FOR 1;268.58
FEET; THENCE DUE SOUTH FOR 877.98 FEET TO THE POINT OF BEGINNING OF SAID TRACT
OF LAND; THENCE NORTH 08(degree)23'24" EAST FOR 2,075.19 FEET; THENCE SOUTH
36(degree)59'43" EAST FOR 2,675.12 FEET TO A POINT OF CURVE; THENCE
SOUTHEASTERLY ALONG A CURVE TO THE RIGHT WITH A CENTRAL ANGLE OF
22(degree)22'51" AND A RADIUS OF 611.62 FEET, FOR 238.91 FEET; THENCE NORTH
81(degree)36'36" WEST FOR 2,031.69 FEET TO THE POINT OF BEGINN1NG OF SAID TRACT
OF LAND, CONTAINING 49.995 ACRES.
<PAGE>

                                  EXHIBIT "B"

                             TULSA PORT OF CATOOSA
                     BUILDING AND DEVELOPMENT REGULATIONS

                                      I.
                              DEFINITION OF TERMS

Building Site
-------------

A.      "Building site" shall mean any parcel of land upon which an industrial
building or buildings or appurtenant structures may be erected.

Improvements
------------

B.      "Improvements" shall mean and include all buildings, out buildings
appurtenant thereto, parking areas, loading areas, fences, masonry walls,
hedges, lawns, mass plantings and any structure of any type or kind located on a
building site.

Building Line
-------------

C.      "Building line" shall mean the minimum distance which buildings,
improvements or any structures located above ground shall be set back from the
property or street lines as herein set forth.

Side Building Site Line
-----------------------

D.      "Side building site line" shall mean the boundary or property line
dividing two adjoining building sites.

                                      II.
                        GENERAL PURPOSES OF CONDITIONS

     These conditions, regulations, restrictions and reservations are imposed to
insure proper use and appropriate development of each building site herein; to
protect the owners or tenants of buildings against the improper use of
surrounding building sites that might depreciate the value of the property; to
guard against erection thereof of structures built of improper or unsuitable
materials; to insure adequate and reasonable development of said property; to
encourage the erection of attractive improvements thereon, with appropriate
location on building sites; to secure and maintain proper setbacks from streets,
and adequate free spaces between structures; and, in general, to insure a high
quality improvement on said property.

                                     III.
                          ENVIRONMENTAL RESTRICTIONS

Noxious or Offensive Activities
-------------------------------

A.   Pursuant to the terms of their lease, no lessee shall create or maintain a
     public or private nuisance.

Pollution Prohibitions
----------------------

B.   Pursuant to the terms of their lease, lessees shall maintain compliance
     with all applicable federal, state or local environmental laws,
     regulations, ordinances or orders and shall maintain all valid permits,
     licenses or other governmental approval required for operations by any
     applicable federal, state or local environmental laws, regulations,
     ordinances or orders (collectively, "Environmental Laws").
<PAGE>

Notices of Violations
---------------------

     C.   Any lessee shall furnish the Port Authority with a copy of the
          following documents within five (5) business days of their receipt by
          such lessee: any written notice (including notice of commencement of
          an investigations), administrative order, consent order and agreement,
          complaint or settlement which concerns the presence on the lessee's
          leased premises of any substance regulated by Environmental Laws with
          respect to such leased premises or demands payment or contribution for
          environmental damage to or clean-up of such leased premises.

                                      IV.
                             GENERAL RESTRICTIONS
Height Limitations
------------------

     A.   Improvements erected on property subject to these restrictions hereof
          shall be in compliance with all applicable laws, rules and
          regulations.

Submittal of Plans
------------------

     B.   No improvement as herein defined shall be constructed, erected,
          placed, altered or enlarged on any building site in said development
          until the building or other improvement, plans, specifications and
          plot plants have first been submitted to and approved in writing by
          the Port Authority; provided, however, it is the intention of the Port
          Authority hereunder to regulate primarily exterior structures and
          additions, rather than interior design or processes, and to assure
          uniform development and aesthetic qualities. It is not the intention
          of the Port Authority to interfere with or in any way delay matters of
          common concern. "Improvements" therefore shall mean exterior
          structures and additions and shall exclude (and this Article B. and
          Article V shall not apply to) improvements or changes in interior
          design or processes and minor projects having no significant effect on
          regulated matters of common concern. The location of all improvements
          shall have due regard to the anticipated use thereof as same may
          affect adjoining structures, uses and operations, and as to location
          of the improvements with respect to topography, grade and finished
          ground elevation. However, Port authority shall not be liable in
          damages to anyone so submitting plans for approval or to any lessee or
          tenant of land covered by this instrument by reason of mistake in
          judgment, negligence or nonfeasance for itself, its agents or
          employees, arising out of or in connection with the approval or
          disapproval or failure to approve any such plans. The Port Authority
          shall approve or disapprove all of such plans within (7) days after
          the draft thereof has been submitted to it, or this requirement will
          be deemed to have been fully complied with. Any violation of this
          requirement shall be grounds for the Port Authority, at its option, to
          either (1) sue to enjoin such construction until final plans therefor
          are approved by the Port Authority or (2) cancel the lease if such
          violation is not corrected within sixty (60) days after the lessee
          receives notice of such violation or such longer period as may be
          reasonably required to correct such violation. Further, upon
          completion of construction, lessee shall file with the Port Authority
          to set of "as built" plans. Provided, however, that lessees may
          withhold, at their discretion, any proprietary or confidential
          information.

Location of Structures
----------------------

     C.   No structures or buildings shall be located closer than twenty (20)
          feet to any side building site line or rear property line. An open
          area of at least forty (40) feet shall exist between all adjacent but
          separately owned improvements, provided, however, that where a
          right-of-way has been granted for the operation of lead tracks and
          railways facilities, either at the rear or side of any building site,
          no structures or buildings shall be constructed on said right-of-way
          or any part thereof.

Landscaping and Parking
-----------------------

     D.   No building or structures above ground shall extend beyond the
          building setback lines and it is hereby declared that said area
          between the building lines and the property lines is to be used either
          for open landscaping or for off-street surface parking areas with
          peripheral landscaping. Final plans for such landscaping or parking
          must be approved, in writing, by the Port Authority before
          commencement of any work thereon. All landscaping and parking areas
          shall be properly maintained in a sightly and well-kept condition.
<PAGE>

Loading Docks
-------------

     E.   In order to confine the maneuvering of trucks and trailers to the
          premises of each establishment, the actual depth of any loading dock
          within the building line shall be determined in connection with the
          building plans or improvement plans to be approved in writing by the
          Port Authority.

Power Installations
-------------------
     F.   Power used in, developed or obtained for the operation of any
          establishment within the confines of the area subject to these
          restrictions shall be confined to those fuels, which, when controlled,
          do not produce excessive smoke, odor, smog or fumes.

Bulk Commodities
----------------

     G.   The storage of dry bulk commodities shall comply with rules and
          regulations of any governmental agency or agencies having jurisdiction
          over such matters, and shall be screened from public view.

Signs
-----

     H.   All advertising signs must be approved in writing by the Port
          Authority before the construction, placement or painting thereof.

Walls and Hedges
----------------

     I.   No masonry wall, hedge or mass planning shall extend beyond the
          building set-back lines established herein except upon written
          approval by the Port Authority. Fences shall not be extended beyond
          the property lines.

Oil Activities
--------------

     J.   No oil drilling, oil development operations, mining operations of any
          kind or quarrying shall be permitted in or upon any of the building
          sites, nor shall oil wells, tunnels, mineral excavations or shafts be
          permitted in or upon any of the building sites. Fuel oil storage tanks
          as a part of the equipment of any establishment shall be permitted
          only if located above ground and in full compliance with rules and
          regulations of any governmental agency or agencies having jurisdiction
          over such matters. Bulk storage of all liquids including gasoline or
          petroleum products on the outside of buildings shall comply with rules
          and regulations of any governmental agency or agencies having
          jurisdiction over such matters.

Nature of Regulation
--------------------

     K.   Each of the conditions, regulations, restrictions and reservations set
          forth above shall run with the land and be finding upon the Port
          Authority, its lessees and their successors and assigns, and all
          persons claiming under them for a period co-extensive with the primary
          term of any lessee's lease and any extensions or renewals thereof.
          Provided, however, that these regulations may be supplemented or
          modified by the Port Authority at any time and from time to time so
          long as any such modification does not prejudice the then existing
          operations and improvements of any lessee which is then in compliance
          with these regulations and so long as notice to all lessees of the
          Port Authority is given of the proposed supplement or modification and
          a majority of the total number of the lessees, weighted as provided
          below, thereafter approves such supplement or modification. Each
          lessee's vote shall be weighted by multiplying it by the number of
          acres leased by such lessee if more than one acre is so leased;
          provided, however, under no circumstances shall any lessee's weighted
          vote value at any election exceed 20% of the total weighted value of
          all votes which are entitled to be cast at such election.

No Waiver
---------

     L.   The failure of the Port Authority or any lessee of said property to
          enforce the violation of any of the restrictions herein set forth at
          the time of its violation shall in no event be deemed to be a waiver
          of the right to do so as to any subsequent violation. The violation of
          these restrictions shall not defeat or render invalid the lien or
          mortgage (or deed of trust) made in good faith and for value.
<PAGE>

Partial Invalidation
--------------------

     M.   Invalidation of any one of these regulations or any part thereof by
          judgment or court order shall in nowise affect any of the other
          provisions, which will remain in full force and effect.

                                      V.
                             TULSA PORT OF CATOOSA
                          MASTER PLAN OF DEVELOPMENT
                           DEVELOPMENT RESTRICTIONS

Development Controls and Standards
----------------------------------

     The Master Plan policies are designed to be broad statements allowing
maximum flexibility in the future development of the Port. The following
guidelines, procedures and standards supplement the Master Plan, in order to
insure that "flexibility" does not create poor quality design, layout, conflicts
of use, congestion or other undesirable developments.

     The Port Authority will require that future development proposals conform
to the procedures and development standards outlined in the following sections.

Site Selection
--------------

     In order to eliminate wasted time and costs to both the Port staff and
potential developers, a site selection process should be initiated in advance of
any preliminary engineering for buildings or facilities to insure that the
proposed site and the proposed use are in conformance with the Master Plan for
the Port.

     A.  Site Selection Process
         ----------------------

Through this site selection process the prospective developer and the Port staff
will have an opportunity to exchange information concerning site requirements
and facility and/or utility needs. The developer will be presented copies of the
Master Plan and existing development maps, as well as the current development
policies and standards of the Port. The Rogers County Zoning Ordinance and Map
will also be reviewed in light of existing zoning and permitting uses.

     B.  Site Clearance Letter
         ---------------------

When the prospective developer and the Port Staff have agreed on one or more
sites, the Port staff will issue a "site clearance letter". The developer may
then proceed to obtain a zoning permit from the City of Claremore-Rogers County
Planning Commission and submit a copy of this permit to the Port staff. These
two items will serve as authorization to the prospective developer to proceed
with preliminary plans and engineering for the specific site or sites approved.
All water and sewer permits shall be obtained from the City of Tulsa and power
requirements shall be reviewed and approved by the servicing utility companies.

     C.  Agency Approval
         ---------------

If,  in the opinion of the Port staff, the proposed development will be of a
      nature that will emit considerable noise, odor, heat, dust, vibration or
      smoke, the prospective developer will be informed of the need to meet the
      minimum requirement of any and all local, state or federal agencies
      regulating such matters.

Preliminary Plans
-----------------

     After the prospective developer has received all necessary site development
clearances he may proceed with developing preliminary plans for engineering for
the layout of facilities, buildings and utilities on the site. The preliminary
plans will be submitted to the Port staff prior to a scheduled "preliminary
review meeting".
<PAGE>

Two copies of the preliminary plans will be sent to the Port staff, and should
contain the following data:

A.     A map at a scale of 1" = 100' (or other appropriate scale) showing the
       following data:

       1)  Date, scale and north point.

       2)  Topographic data, showing contours at two (2) foot intervals.

       3)  The location and dimensions of the leasehold lines.

       4)  The location and dimensions of existing buildings, utilities,
           facilities, paving, easements and rights-of-way that are within the
           leasehold lines.

       5)  The location and width of all proposed buildings, facilities, paving,
           easements and rights-of-way.

       6)  The approximate radii of all curves and lengths of all tangents.

B.       A description of the improvements such as grading, paving, landscaping
       and installation of utilities which the prospective developer proposes.

C.       A map at a scale of 1" = 400' (or other appropriate scale) showing the
       location of all existing and proposed buildings, paving, facilities,
       easements, rights-of-way and exterior property lines of the proposed
       sites.

D.       A description of the type of construction of all buildings and
       facilities shown on the maps.

E.       Any additional data required by the Port staff.

Preliminary Review Meeting
--------------------------

     The Port staff will conduct a "preliminary review meeting" with the
prospective developer and will recommend any modifications or adjustments
required in order to obtain approval of the preliminary plans. When the
recommended modification and adjustments to the preliminary plans are agreed to,
the Port staff will issue a "preliminary plan approval" letter which shall serve
as authorization to proceed in developing "final plans" for the proposed
development.

Final Plans
-----------

     After the prospective developer has received all necessary preliminary plan
clearances he may proceed with developing final plans and detailed engineering
for the proposed development of the site. The final plans will be submitted to
the Port staff prior to a scheduled "final review meeting" with the Port staff.

Two copies of the final plans will be sent to the Port staff, and should contain
the following data:

A.     A map at a scale of 1" = 100' (or other appropriate scale) showing the
       following data:

       1)  Name of developer and registered engineer.

       2)  Date, north point, scale (written and graphic).

       3)  The location and dimensions of existing, adjacent or adjoining
       property or leasehold lines.

       4)  Boundaries of development or leasehold site with accurate distances
       and bearings noted thereon with the description of all monuments found or
       placed in making the survey.

       5)  The exact location and dimensions of all existing and proposed
       buildings, paving, facilities, easements and rights-of-way.

       6) The purposes of all easements and the location of utilities within
       easements and rights-of-way.
<PAGE>

       7)  The exact radii of all curve and lengths of all tangents.

B.Cross-section drawings (at suitable scale) of all buildings, facilities and
paving, with dimensions as appropriate.

C.       A description of all improvements including type of construction of
       buildings and facilities to be placed on the site.

D.       A map at a scale of 1 " = 400' (or other appropriate scale) showing the
       location of all existing and proposed buildings, paving, facilities,
       easements, rights-of-way and exterior property lines of the proposed
       site.

E.       Any additional data required by the Port staff.

Final Review Meeting
--------------------

     The Port staff will conduct a "final review meeting" with the prospective
developer. If the final plans are in conformance with all requirements, the Port
staff will issue a "final plan approval" letter which will authorize the
developer to proceed with site preparation work and detailed building and
construction plans.

Construction Plans
------------------

     After the developer has received approval of all site development plans and
before construction of buildings and facilities begin, he must submit
construction plans to the Port staff for review and approval.

Authorization to Proceed Letter
-------------------------------

     The construction plans will be reviewed by the City of Claremore-Rogers
County Planning Commission in light of the current building and construction
codes. Upon issuance of the Planning Commission's permit, the plans will be
approved by the Port Authority. If so approved, the Port staff will issue a
letter which will authorize the developer to proceed with construction according
to the approved construction plans.

Development Standards
---------------------

     In order to insure coordinated development of the Port, the following
standards constitute official development policy of the Port Authority. These
standards apply primarily to the industrial park area. The terminal area will
not be entirely subject to these requirements due to the nature of activities
along the Port channel.

Area and Bulk Requirements
--------------------------

     Each parcel of land is required to have frontage and access on a dedicated
street for a minimum distance of 200 feet.

     Minimum setbacks of buildings or facilities from adjacent streets will be
required as follows:

              (i)  Sixty (60) foot setback from primary and secondary roadways
              (Parkways and Avenues); and

              (ii) Forty (40) foot setback from minor roadways (Roads) and
              twenty (20) feet from other property lines and easements.

     A minimum land-to-building ratio may be established by the Port staff for
various parcels of land within the industrial park.

Off-Street Parking
------------------

     On-street parking will be prohibited, except within the terminal area, and
then only where adequate parking lanes have been installed.

     Adequate off-street parking for employees and visitors will be provided.
The number of parking spaces
<PAGE>

required will be determined by the Port staff.
<PAGE>

Loading Requirements
--------------------

Adequate loading spaces will be provided on the rear or side of buildings away
from the street fronts. No truck loading docks or doors are permitted on the
front of buildings except upon express written consent of the Port Authority.

Surfacing
---------

     Off-street parking and loading areas shall be surfaced with an all-weather
material, and shall be graded and drained so as to carry surface water to the
nearest public street, accessible storm sewer or other approved drainage control
system.

Outside Storage
---------------

     Goods and materials stored outside of buildings shall be screened from view
of all streets if required by the Port Authority.

     Goods or materials that are untreated and may produce undesirable effects
when exposed to the elements will be required to be treated or placed in
enclosed building.

Building Exteriors
------------------

     Building exteriors on all four sides shall be constructed of materials
considered high standard exterior finishes. Materials for exterior finishes
shall require review and approval prior to use.

Access Standards
----------------

     All parcels of land must have access to a secondary or minor roadway before
operators can begin operations on the property.

     Access drives off secondary and minor roadways will have a minimum width of
forty (40) feet or a maximum of sixty (60) feet.

     All curb cuts will be a minimum distance of 150 feet from an intersecting
street, measured from the centerline of paving.

Curb cuts must be a minimum of forty (40) feet apart, and a minimum of twenty
(20) feet from interior property lines.

A minimum turning radius of forty (40) feet must be maintained for all access
points to a roadway.
<PAGE>

                      ACCESS CONTROL AND SETBACK STANDARDS
                      ------------------------------------

{In the original document, this page contains a diagram of the Primary,
Secondary and Minor Roadways and rights-of-way.}
<PAGE>

                          ROADWAY AND UTILITY STANDARDS
                          -----------------------------

{In the original document, this page contains a diagram of the Primary Roadway
and Utility Standards.}
<PAGE>

                         RAILWAY AND UTILITY STANDARDS
                         -----------------------------

     {In the original document, this page contains a diagram of the Railway and
Utility Standards.}

<PAGE>

EXHIBIT "C"

Additional Charges
------------------

There are presently no additional charges.
<PAGE>

EXHIBIT "D"
Miscellaneous Provisions
------------------------

Rider 1, Lessor's Work

Upon lease commencement and subject to the public bid process, Lessor will
promptly commence the construction of two concrete driveways (bridges) into the
Premises from Main Parkway in locations and of design mutually agreed to by the
Parties. Lessor will also construct a rail spur of not more than 700 feet in
length as measured from the mainline track to serve Lessee's operations. Said
construction shall be coordinated with Lessee's site improvements and Lessee
shall provide the final base grade for the rail spur. Lessor shall provide the
aforementioned driveway and rail spur improvements without any charge to Lessee,
however, Lessee agrees that, during the Lease Term, it shall maintain said
improvements at its sole expense. Lessor shall also promptly commence
construction of the Verdigris Road extension which will bound the Premises on
the west. Lessor will allow Lessee up to three driveways from said road at a
minimum spacing of 125 feet and otherwise in compliance with Exhibit "B",
Building and Development Regulations.

Rider 2, Rent Abatement

In consideration of Lessee's time and expense to develop the Premises, Lessor
hereby agrees that the Monthly Rentals as referenced in paragraph 3.1.a shall be
abated in their entirety for the first eighteen (18) months or until Lessee's
earlier commencement of business operations on the Premises. In addition, the
Parties agree that, Lessee's present intent is to not use the northern most 3.82
acres of the Premises for any purpose. Accordingly, there will be no rentals
payable on said acreage unless and until Lessee commences use of any portion
thereof, at which time rentals shall be charged on the entire 3.82 acres for the
remainder of the primary and any renewal terms at the then effective rate.

Rider 3, Schedule of Monthly Rentals

Subject to Rider 2 above, and the other provisions of paragraph 3.1, the Primary
Term Monthly Rentals as referenced in paragraph 3.1.a shall be payable according
to the following schedule:

For the period 3/01 -2/06;  $10,005.67   (based on 46.18 acres at $2,600 per
acre per year)
For the period 3/06 -2/11;  $11,160.17   (based on 46.18 acres at $2,900 per
acre per year)
For the period 3/11 -2/16;  $12,314.67   (based on 46.18 acres at $3,200 per
acre per year)

Lessee will execute Lessor's acknowledgement, amending this Rider should the
unused acreage referenced in Rider 2 become activated per its terms.

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