EXHIBIT 7

                               H. WAYNE HUIZENGA



                                                                January 15, 1998


To OHM CORPORATION:

          With reference to the First Option Agreement, dated as of March 28,
1995 (the "First Option Agreement"), between OHM Corporation (the "Company") and
H. Wayne Huizenga (the "Holder") and the Second Option Agreement, dated as of
March 28, 1995 (the "Second Opinion Agreement"), between the Company and the
Holder, and the Agreement and Plan of Merger, dated the date hereof (the "Merger
Agreement"), among the Company, International Technologies Corporation and IT-
Ohio, Inc. ("Merger Sub"), this letter agreement will confirm our agreement as
follows:

1.   Terms used herein but not defined herein shall have the respective meanings
     set forth in the Merger Agreement.

2.   In consideration of the agreement set forth in paragraphs 3, 4 and 5 of
     this letter agreement, the Company agrees that, as promptly as practicable
     after the earliest to occur of (i) the acceptance by Merger Sub of Shares
     for payment in the Offer, or (ii) the Effective Time, the Company shall pay
     to the Holder, in immediately available funds, $1,500,000 (the "Termination
     Payment").

3.   In consideration of the payment of the Termination Payment, the First
     Option Agreement and the Second Option Agreement are hereby terminated,
     effective as of the time of payment of the Termination Payment.

4.   The Holder shall not exercise his rights pursuant to Sections 3.1 or 3.2 of
     the First Option Agreement or Sections 3.1 or 3.2 of the Second Option
     Agreement prior to the earliest to occur of (i) the second business day
     subsequent to the Effective Time, and (ii) the termination of the Merger
     Agreement in accordance with its terms.

 
5.   The Holder hereby waives his rights under Section 2.2 of the First Option
     Agreement and Section 2.2 of the Second Merger Agreement with respect to
     the NSC Distribution.

6.   This letter agreement shall terminate upon the termination of the Merger
     Agreement, but shall not otherwise be terminable.

7.   This letter agreement and rights and obligations of the parties hereunder
     shall be governed by, construed and interpreted in accordance with the laws
     of the State of Ohio applicable to agreements executed by residents of that
     state, and fully to be performed, in that state.

          If the foregoing is in accordance with your understanding, please
execute one counterpart of this letter agreement, whereupon this letter
agreement shall constitute a binding agreement among the parties hereto.

                                    Very truly yours,



                                    ______________________
                                      (H. Wayne Huizenga)


Accepted and agreed
as of the date hereof:


OHM CORPORATION


By:_____________________
   Name:
   Title: