EXHIBIT 10.6

                                AMENDMENT NO. 4
                                       TO
                              EMPLOYMENT AGREEMENT

     THIS AMENDMENT NO. 4 TO EMPLOYMENT AGREEMENT ("AMENDMENT NO. 4") is made
as of the date set forth below by and between INSITUFORM TECHNOLOGIES, INC., a
Delaware corporation (the "COMPANY"), and ROBERT W. AFFHOLDER (the "EMPLOYEE").

                                    Recitals

     A.   The Company and Employee entered into an Employment Agreement dated
October 25, 1995, as amended as of October 25, 1998, as of December 31, 1999,
and as of December 31, 2000 (collectively, the "AMENDED AGREEMENT").

     B.   The Company and Employee desire to extend the term of the Amended
Agreement as provided herein.

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

     1.   Paragraph A of Section II of the Amended Agreement is hereby deleted
in its entirety and replaced with the following:

               "A.  Subject to the provisions of this Agreement
          hereinafter contained, for purposes of this Agreement the period
          (herein referred to as the "Employment Term") of the Employee's
          obligations under Section I hereof shall commence on the date
          hereof and continue until December 31, 2002."

     2.   Except as set forth herein, the Amended Agreement shall remain in
full force and effect and continue to bind the parties hereto. This Amendment
No. 4 contains the entire agreement of the parties with respect to the subject
matter herein and supersedes all other understandings, oral or written, with
respect thereto. This Amendment No. 4 may be executed in counterparts, each of
which shall constitute one and the same agreement.

     IN WITNESS WHEREOF, the undersigned have executed this Amendment No. 4 as
of December 31, 2001.

EMPLOYEE:                              COMPANY:

                                       INSITUFORM TECHNOLOGIES, INC.

     /s/ Robert W. Affholder           By:     /s/ Anthony W. Hooper
---------------------------------          -------------------------------------
Robert W. Affholder                        Anthony W. Hooper, Chairman,
                                           President and Chief Executive Officer