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                                                                    EXHIBIT 10.1

              REVISED AGREEMENT TO NDE ENVIRONMENTAL CORPORATION'S
                            SECURED PROMISSORY NOTE

         This Revised Agreement to the Secured Promissory Note, is dated
September 15, 1996, and is made by and between NDE Environmental Corporation, a
Delaware corporation ("NDE"), and Gilbarco Inc., a Delaware corporation
("Gilbarco") referred to as the "Parties."

                                  I. RECITALS:

         1.1  ASSET PURCHASE.  Whereas, Gilbarco and NDE entered into an Asset
    Purchase Agreement dated February 24, 1994.

         1.2  SECURED PROMISSORY NOTE.  Whereas, NDE executed a Secured
    Promissory Note ("Note") in the amount of Two Million Four Hundred Fifty 
    Thousand and no/100 Dollars ($2,450,000.00) on April 11, 1994, for a 
    portion of the purchase price.

         1.3  FIRST AMENDMENT.  Whereas, on February 28, 1995, the Parties
    entered into the First Amendment revising the principal amortization 
    schedule.

         1.4  SECOND AMENDMENT.  Whereas, on March 22, 1996, the Parties entered
    into the Second Amendment providing, among other matters, for NDE to have 
    the right to make a prepayment pursuant to Section 2.3 on or before June 
    30, 1996.

         1.5  EXTENSION AGREEMENT.  Whereas, on June 28, 1996, the Parties
    entered into an Extension Agreement from June 30, 1996 to July 12, 1996.

         1.6  REVISED AGREEMENT.  Whereas, it is in the best interest of the
    Parties to revise the terms of the current Extension Agreement.

         Now, therefore, in consideration of the above recitals, the mutual
    covenants herein and other good and valuable consideration, the Parties 
    agree:

                               II. REVISED TERMS

         2.1  PREPAYMENT RIGHTS.  The right to make prepayment for 
    extinguishment of the Note pursuant to Section 2.3 of the second
    Amendment dated March 22, 1996, shall be modified to an amount of Three
    Hundred Thousand and no/100 Dollars ($300,000.00) for the period ending
    September 30, 1996.
        
                             III. OTHER PROVISIONS

         3.1  APPLICABLE LAWS.  This Revised Agreement shall be construed in
    accordance with the laws of the State of New York.




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         3.2  ENTIRE AGREEMENT.  The terms of this Revised Agreement are the
    only changes to the Secured Promissory Note, and all other provisions of 
    the Note as amended previously and Security Agreement shall remain in full 
    force and effect.

         3.3  COUNTERPARTS.  This Revised Agreement may be entered into in any
    number of counterparts, each of which will be deemed an original and all of
    which, taken together, constitute one and the same agreement.


                                NDE ENVIRONMENTAL CORPORATION
                             
                             
                                By: /s/ JAY ALLEN CHAFFEE
                                    ------------------------------------------
                                    Jay Allen Chaffee, Chairman of the Board

                                    Address: 8900 Shoal Creek Blvd., Bldg. 200
                                             Austin, TX  78758
                             
                             
                             
                                GILBARCO INC.
                             
                             
                                By: /s/ J.L. JOHNSON
                                   -------------------------------------------
                                   Name: J.L. Johnson 
                                        --------------------------------------
                                   Title: CFO, Gilbarco Inc.
                                         -------------------------------------
                                   
                                   Address:  Gilbarco North America
                                             7300 W. Friendly Avenue
                                             Greensboro, NC  27420-2087