EXHIBIT 3

                            COMPANY VOTING AGREEMENT


          COMPANY VOTING AGREEMENT (this "Agreement"), dated as of January 15,
1998, among International Technology Corporation, a Delaware corporation
("Parent"), OHM Corporation, an Ohio corporation (the "Company") and the
undersigned shareholders of the Company (the "Shareholders").

          WHEREAS, concurrently with the execution of this Agreement, the
Company, Parent and IT-Ohio, Inc., an Ohio Corporation and a wholly owned
subsidiary of Parent ("Merger Sub"), have entered into an Agreement and Plan of
Merger (as it may be hereafter amended from time to time, the "Merger
Agreement"), which provides that Merger Sub shall make a tender offer (the
"Offer") for 13,933,000 shares of common stock of the Company and that Merger
Sub shall thereafter merge (the "Merger") with and into the Company pursuant to
the terms and conditions of the Merger Agreement, and sets forth certain
representations, warranties, covenants and agreements of the parties thereto in
connection with the Offer, the Merger and the other transactions contemplated
therein (the "Merger Transactions"); and

          WHEREAS, the Shareholders are the record holders of shares of Common
Stock, par value $0.10 per share ("Company Common Stock"), of the Company; and

          WHEREAS, in order to induce the Company, Parent and Merger Sub to
enter into the Merger Agreement, the Shareholders wish to agree (i) to vote the
shares of Company Common Stock and any other shares of capital stock of the
Company held by them so as to facilitate the consummation of the Merger
Transactions, (ii) except as provided in this Agreement, not to transfer or
otherwise dispose of any of the shares of Company Common Stock or any other
shares of capital stock held by them, or any other shares of capital stock of
the Company acquired by them hereafter and prior to the Effective Time (as
defined in the Merger Agreement), and (iii) to deliver to Parent an irrevocable
proxy to vote the shares of Company Common Stock and any other shares of capital
stock held by them, and any other shares of capital stock of the Company
acquired by them hereafter and prior to the Effective Time.

          NOW, THEREFORE, for good and valuable considera  tion, the receipt,
sufficiency and adequacy of which is hereby acknowledged, the parties hereto
agree as follows:

 
          1.   Representations of Shareholders.  Each of the Shareholders
               -------------------------------                           
represents and warrants to the Company, Parent and Merger Sub that (a) such
Shareholder lawfully owns beneficially (as such term is defined in the
Securities Exchange Act of 1934, as amended (the "1934 Act")), and of record the
number of shares of Company Common Stock set forth opposite such Shareholder's
name on Exhibit A (such Shareholder's "Shares") free and clear of all liens,
claims, charges, security interests or other encumbrances and, except for this
Agreement and the Merger Agreement, there are no options (other than options
described in the Company Disclosure Letter or annexes thereto), warrants or
other rights, agreements, arrangements or commitments of any character to which
such Shareholder is a party relating to the pledge, disposition or voting of any
shares of capital stock of the Company (other than, with respect to Mr. James L.
Kirk, a pledge of his Shares made in connection with a loan financing the
acquisition of real property) and there are no voting trusts or voting
agreements with respect to such Shares, (b) such Shareholder does not
beneficially own any shares of Company Common Stock or any other shares of
capital stock of the Company other than such Shares and, except for such Shares,
does not have any options, warrants or other rights to acquire any additional
shares of capital stock of the Company or any security exercisable for or
convertible into shares of capital stock of the Company, (c) such Shareholder
has full power and authority to enter into, execute and deliver this Agreement
and to perform fully such Shareholder's obligations hereunder, and (d) this
Agreement has been duly executed and delivered by such Shareholder, constitutes
the legal, valid and binding obligation of such Shareholder, and is enforceable
against such Shareholder in accordance with its terms.

          2.   Agreement to Vote Shares.  Each of the Shareholders agrees that
               ------------------------                                       
during the term of this Agreement it will vote such Shareholder's Shares and any
New Shares (as defined in Section 6 hereof), and will cause any holder of record
of such Shares or New Shares to vote such Shareholder's Shares and New Shares:
(a) in favor of adoption of the Merger Agreement and in favor of consummation of
the Merger Transactions at every meeting of the shareholders of the Company at
which such matters are considered and at every adjournment thereof and in
connection with any written consent of the shareholders of the Company, (b) in
favor of the election to the Company's Board of Directors of such number of
Parent Representatives as Parent is permitted to cause to be elected to the
Company's Board of Directors pursuant to Section 1.4 of the Merger Agreement,
(c) against any action or agreement that would compete with, impede, interfere
with or attempt to discourage the Merger Transactions, or inhibit the timely
consummation of the Merger Transactions, (d) against any action or agreement
that would result in a breach in any material respect of any covenant,
representation or warranty or 

                                      -2-

 
any other obligation of the Company under the Merger Agreement and (e) against
any merger, consolidation, business combination, reorganization,
recapitalization, liquidation or sale or transfer of any material assets of the
Company or its subsidiaries that could compete with, impede, interfere with or
attempt to discourage the Merger Transactions or inhibit the timely consummation
of the Merger Transactions. Each Shareholder agrees to deliver to Parent upon
request a proxy substantially in the form attached hereto as Exhibit B, which
proxy shall be irrevocable during the term of this Agreement to the fullest
extent permitted under Delaware law.

          3.   No Voting Trusts.  Each of the Shareholders agrees that they will
               ----------------                                                 
not, nor will they permit any entity under their control to, deposit any of
their Shares or any New Shares held by them in a voting trust or subject any of
their Shares or any New Shares held by them to any arrangement with respect to
the voting of such Shares or New Shares that could result in a shareholder's
vote or action by consent of the shareholders of the Company in opposition to or
in competition with the consummation of the Merger Transactions.

          4.   No Proxy Solicitations.  Each of the Shareholders agrees that
               ----------------------                                       
such Shareholder will not, nor will such Shareholder permit any entity under
such Shareholder's control to, (a) solicit proxies or become a "participant" in
a "solicitation" (as such terms are defined in Regulation 14A under the 1934
Act) in opposition to or competition with the consummation of the Merger
Transactions or otherwise encourage or assist any party in taking or planning
any action which would compete with, impede, interfere with or attempt to
discourage the Merger Transactions or inhibit the timely consummation of the
Merger Transactions, (b) directly or indirectly encourage, initiate or cooperate
in a shareholders' vote or action by consent of Parent's shareholders in
opposition to or in competition with the consummation of the Merger
Transactions, or (c) become a member of a "group" (as such term is used in
Section 13(d) of the 1934 Act) with respect to any voting securities of Parent
for the purpose of opposing or competing with the consummation of the Merger
Transactions.

          5.   Transfer and Encumbrance.  On or after the date hereof and during
               ------------------------                                         
the term of this Agreement, each of the Shareholders agrees not to transfer,
sell, offer, exchange, pledge or otherwise dispose of or encumber any of such
Shareholder's Shares or New Shares, except for tenders of such Shares into the
Offer, unless the transferee agrees in written form satisfactory to Parent to be
bound by the terms of this Agreement.

          6.   Additional Purchases.  Each of the Shareholders agrees that such
               --------------------                                            
Shareholder will not purchase or otherwise 

                                      -3-

 
acquire beneficial ownership of any shares of Company Common Stock or any other
capital stock of the Company after the execution of this Agreement ("New
Shares"), nor will any Shareholder voluntarily acquire the right to vote or
share in the voting of any shares of Company Common Stock or any other capital
stock of the Company other than the Shares, unless such Shareholder agrees to
deliver to Parent immediately after such purchase or acquisition an irrevocable
proxy in the form attached hereto as Exhibit B with respect to such shares. Each
of the Shareholders also severally agrees that any New Shares acquired or
purchased by such Shareholder shall be subject to the terms of this Agreement to
the same extent as if they constituted Shares.

          7.   Specific Performance.  Each party hereto acknowledges that it
               --------------------                                         
will be impossible to measure in money the damage to the other party if a party
hereto fails to comply with any of the obligations imposed by this Agreement,
that every such obligation is material and that, in the event of any such
failure, the other party will not have an adequate remedy at law or damages.
Accordingly, each party hereto agrees that injunctive relief or other equitable
remedy, in addition to remedies at law or damages, is the appropriate remedy for
any such failure and will not oppose the granting of such relief on the basis
that the other party has an adequate remedy at law. Each party hereto agrees
that it will not seek, and agrees to waive any requirement for, the securing or
posting of a bond in connection with any other party's seeking or obtaining such
equitable relief.

          8.   Entire Agreement.  This Agreement supersedes all prior
               ----------------                                      
agreements, written or oral, among the parties hereto with respect to the
subject matter hereof and contains the entire agreement among the parties with
respect to the subject matter hereof.  This Agreement may not be amended,
supplemented or modified, and no provisions hereof may be modified or waived,
except by an instrument in writing signed by all the parties hereto.  No waiver
of any provisions hereof by any party shall be deemed a waiver of any other
provisions hereof by any such party, nor shall any such waiver be deemed a
continuing waiver of any provision hereof by such party.

          9.   Notices.  Any notice, request, instruction or other document to
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be given hereunder by any party to the others shall be in writing and delivered
personally or sent by registered or certified mail, postage prepaid, or by
facsimile:

          if to any Shareholder:
          --------------------- 

          to the address listed on Exhibit A hereto.

                                      -4-

 
          if to the Company:
          ----------------- 

          Steven E. Harbour
          OHM Corporation
          5445 Triangle Parkway, Suite 400
          Norcross, Georgia  30092
          Telecopier:  (770) 849-3110

          with a copy to:

          Joseph B. Frumkin
          Sullivan & Cromwell
          125 Broad Street
          New York, New York 10004
          Telecopier:  (212) 558-3588

          and a copy to:

          Thomas C. Daniels
          Jones Day Reavis & Pogue
          North Point
          901 Lakeside Avenue
          Cleveland, Ohio 44114
          Telecopier:  (216) 579-0212

          if to Parent or Merger Sub:
          -------------------------- 

          James G. Kirk
          International Technology Corporation
          2790 Mosside Boulevard
          Monroeville, PA  15146-2792
          Telecopier:  (412) 858-3978

          with a copy to:

          Peter F. Ziegler
          Gibson, Dunn & Crutcher LLP
          333 South Grand Avenue
          Los Angeles, California 90071
          Telecopier:  (213) 229-7520

or to such other persons or addresses as may be designated in writing by the
party to receive such notice as provided above.

          10.  Miscellaneous.
               ------------- 

          (a) This Agreement shall be deemed a contract made under, and for all
purposes shall be construed in accordance with, the laws of the State of
Delaware applicable to agreements executed in and solely to be performed within
such state.

                                      -5-

 
          (b)  If any provision of this Agreement or the application of such
provision to any person or circumstances shall be held invalid or unenforceable
by a court of competent jurisdiction, such provision or application shall be
unenforceable only to the extent of such invalidity or unenforceability and the
remainder of the provision held invalid or unenforceable and the application of
such provision to persons or circumstances, other than the party as to which it
is held invalid, and the remainder of this Agreement, shall not be affected.

          (c)  This Agreement may be executed in one or more counterparts, each
of which shall be deemed to be an original but all of which together shall
constitute one and the same instrument.

          (d)  This Agreement shall terminate automatically upon the termination
of the Merger Agreement or upon the Effective Time of the Merger.  This
Agreement shall not otherwise be terminable.

          (e)  Each party hereto shall execute and deliver such additional
documents as may be necessary or desirable to effect the transactions
contemplated by this Agreement.

          (f)  All Section headings herein are for convenience of reference only
and are not part of this Agreement, and no construction or reference shall be
derived therefrom.

          (g) The obligations of the Shareholders set forth in this Agreement
shall not be effective or binding upon any Shareholder until after such time as
the Merger Agreement is executed and delivered by the Company, Parent and Merger
Sub, and the parties agree that there is not and has not been any other
agreement, arrangement or understanding between the parties hereto with respect
to the matters set forth herein.

                                      -6-

 
          IN WITNESS WHEREOF, the parties hereto have executed and delivered
this Agreement as of the date first written above.

                                        OHM CORPORATION
                                     
                                     
                                     
                                        By:
                                           ----------------------------- 
                                           Name:
                                           Title:
                                     
                                     
                                     
                                           -----------------------------
                                                (Shareholder)

 


                                           -----------------------------
                                                (Shareholder)



                                           -----------------------------
                                                (Shareholder)



                                           -----------------------------
                                                (Shareholder)



                                        INTERNATIONAL TECHNOLOGY
                                          CORPORATION



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

 
                                                                     (EXHIBIT A)



       Name and Address of          
           Shareholder                  Number of Shares
       -------------------              ---------------- 
     
H. Wayne Huizenga                          1,000,000
Huizenga Holdings
450 E. Las Olas Boulevard
Ft. Lauderdale, FL  33301

Huizenga Family Foundation, Inc.             500,000
450 E. Las Olas Boulevard
Ft. Lauderdale, FL  33301

James L. Kirk                              1,223,716
OHM Corporation
16406 U.S. Rt. 224 East
Findlay, OH  45840

Joseph R. Kirk                             2,088,060
OHM Corporation
16406 U.S. Rt. 224 East
Findlay, OH  45840
 

 
                                                                     (EXHIBIT B)
                                 FORM OF PROXY


          The undersigned, for consideration received, hereby appoints Anthony
J. Deluca and James G. Kirk and each of them my proxies, with power of
substitution and resubstitution, to vote all shares of Common Stock, par value
$0.10 per share, of OHM Corporation, an Ohio corporation (the "Company"), [and
[insert any other Shares (as defined in the Voting Agreement) owned by
Shareholder]] owned by the undersigned at the Special Meeting of Shareholders of
the Company to be held [insert date, time and place] and at any adjournment
thereof IN FAVOR OF adoption of the Agreement and Plan of Merger, dated as of
January 15, 1998 (the "Merger Agreement"), among the Company, International
Technology Corporation ("Parent") and IT-Ohio, Inc., IN FAVOR OF consummation of
the Merger Transactions, IN FAVOR OF [List such number of Parent Representatives
(as defined in Section 1.4 of the Merger Agreement) as Parent is permitted to
cause to be elected to the Company's Board of Directors pursuant to Section 1.4
of the Merger Agreement], and AGAINST [insert description of any action or
agreement that would compete with, impede, interfere with or attempt to
discourage the Merger Transactions or inhibit the timely consummation of the
Merger Transactions or any action or agreement that would result in a breach in
any material respect of any covenant, representation or warranty or any other
obligation of the Company under the Merger Agreement or any merger,
consolidation, business combination, reorganization, recapitalization,
liquidation or sale or transfer of any material assets of the Company or its
subsidiaries].  This proxy is coupled with an interest, revokes all prior
proxies granted by the undersigned and is irrevocable until such time as the
Voting Agreement, dated as of January 15, 1998 among certain shareholders of the
Company, including the undersigned, Parent, and the Company terminates in
accordance with its terms.


                                               Dated ______, 1998
                                            
                                            
                                            
                                               ___________________________
                                                      (Shareholder)