EXHIBIT 3

                             CERTIFICATE OF INCORPORATION

                                          OF

                               THERMO REMEDIATION INC.

                                    * * * * * * * 


                  FIRST:  The name of the corporation is:

                               Thermo Remediation Inc.

                  SECOND:  The address of its registered office in the
             State of Delaware is 1209 Orange Street, in the City of
             Wilmington, County of New Castle.  The name of its
             registered agent at such address is The Corporation Trust
             Company.

                  THIRD:  The purpose of the corporation is to engage in
             any lawful act or activity for which corporations may be
             organized under the General Corporation Law of the State of
             Delaware.

                  FOURTH:  The total number of shares of capital stock
             which the corporation shall have authority to issue is
             twenty million (20,000,000), and the par value of each of
             such shares is one cent ($0.01), amounting in the aggregate
             to two hundred thousand dollars ($200,000.00) of capital
             stock.

                  FIFTH:  The name and mailing address of the sole
             incorporator is as follows:

                  NAME                          MAILING ADDRESS

                  Barbara J. Lucas              81 Wyman Street
                                                Waltham, Massachusetts 02254

                  SIXTH:  The names and mailing addresses of the persons
             who are to serve as directors until the first annual meeting
             of the stockholders or until their successors are elected
             and qualified are as follows:
PAGE

                  NAME                          MAILING ADDRESS
                  ----                          ---------------

                  John P. Appleton              81 Wyman Street
                                                Waltham, Massachusetts 02254

                  John N. Hatsopoulos           81 Wyman Street
                                                Waltham, Massachusetts 02254

                  Fred Holubow                  2 N. LaSalle Street
                                                Suite 605
                                                Chicago, Illinois 60603

                  Theo Melas-Kyriazi            81 Wyman Street
                                                Waltham, Massachusetts 02254

                  William A. Rainville          81 Wyman Street
                                                Waltham, Massachusetts 02254

                  SEVENTH:  The corporation is to have perpetual
             existence.

                  EIGHTH:  The private property of the stockholders shall
             not be subject to the payment of the corporation debts to
             any extent whatever.

                  NINTH:  The following provisions are inserted for the
             management of the business and for the conduct of the
             affairs of the corporation and for defining and regulating
             the powers of the corporation and its directors and
             stockholders and are in the furtherance and not in
             limitation of the powers conferred upon the corporation by
             statute:

                       (a)  The by-laws of the corporation may fix and
                  alter, or provide the manner for fixing and altering,
                  the number of directors constituting the whole Board.
                  In case of any vacancy on the Board of Directors or any
                  increase in the number of directors constituting the
                  whole Board, the vacancies shall be filled by the
                  directors or by the stockholders at the time having
                  voting power, as may be prescribed in the by-laws.
                  Directors need not be stockholders of the corporation,
                  and the election of directors need not be by ballot.

                       (b)  The Board of Directors shall have the power
             and authority:

                            (1)  to make, alter or repeal by-laws of the
                       corporation, subject only to such limitation, if
                                         -2-PAGE

                       any, as may be from time to time imposed by law or
                       by the by-laws; and

                            (2)  to the full extent permitted or not
                       prohibited by law, and without the consent of or
                       other action by the stockholders, to authorize or
                       create mortgages, pledges or other liens or
                       encumbrances upon any or all of the assets, real,
                       personal or mixed, and franchises of the
                       corporation, including after-acquired property,
                       and to exercise all of the powers of the
                       corporation in connection therewith; and

                            (3)  subject to any provision of the by-laws,
                       to determine whether, to what extent, at what
                       times and places and under what conditions and
                       regulations the accounts, books and papers of the
                       corporation (other than the stock ledger), or any
                       of them, shall be open to the inspection of the
                       stockholders, and no stockholder shall have any
                       right to inspect any account, book or paper of the
                       corporation except as conferred by statute or
                       authorized by the by-laws or by the Board of
                       Directors.

                  TENTH:  Meetings of stockholders may be held outside
             the State of Delaware, if the by-laws so provide.  The books
             of the corporation may be kept outside of the State of
             Delaware at such place or places as may be designated from
             time to time by the Board of Directors or in the by-laws of
             the corporation.

                  ELEVENTH:  The corporation shall indemnify each
             director and officer of the corporation, his heirs,
             executors and administrators, and may indemnify each
             employee and agent of the corporation, his heirs, executors,
             administrators and all other persons whom the corporation is
             authorized to indemnify under the provisions of the General
             Corporation Law of the State of Delaware, to the maximum
             extent permitted by law (a) against all expenses (including
             attorney's fees), judgments, fines and amounts paid in
             settlement actually and reasonably incurred by him in
             connection with any action, suit or proceeding, whether
             civil, criminal, administrative or investigative (except an
             action by or in the right of the corporation), or in
             connection with any appeal therein, or otherwise, and (b)
             against all expenses (including attorney's fees) actually
             and reasonably incurred by him in connection with the
             defense or settlement of any action or suit by or in the
             right of the corporation, or otherwise; and no provision of
             this Article Eleventh is intended to be construed as
             limiting, prohibiting, denying or abrogating any of the
             general or specific powers or rights conferred by the
             General Corporation Law of the State of Delaware upon the
                                         -3-PAGE

             corporation to furnish, or upon any court to award, such
             indemnification, or indemnification as otherwise authorized
             pursuant to the General Corporation Law of the State of
             Delaware or any other law now or hereafter in effect.

                  The Board of Directors of the corporation may, in its
             discretion, authorize the corporation to purchase and
             maintain insurance on behalf of any person who is or was a
             director, officer, employee or agent of the corporation, or
             is or was serving at the request of the corporation as a
             director, officer, employee or agent of another corporation,
             partnership, joint venture, trust or other enterprise
             against any liability asserted against him or incurred by
             him in any such capacity, or arising out of his status as
             such, whether or not the corporation would have the power to
             indemnify him against such liability under the foregoing
             paragraph of this Article Eleventh.

                  TWELFTH:  To the maximum extent that Delaware law in
             effect from time to time permits limitation of the liability
             of directors, no director of the corporation shall be liable
             to the corporation or its stockholders for money damages.
             Neither the amendment nor repeal of this Article, nor the
             adoption or amendment of any other provision of the
             corporation's Certificate of Incorporation or by-laws
             inconsistent with this Article, shall apply to or affect in
             any respect the applicability of the preceding sentence with
             respect to any act or failure to act which occurred prior to
             such amendment, repeal or adoption.  The limitation on
             liability provided by this Article applies to events
             occurring at the time a person serves as a director of the
             corporation whether or not such person is a director at the
             time of any proceeding in which liability is asserted.

                  THIRTEENTH:  The corporation reserves the right to
             amend, alter, change or repeal any provisions contained in
             this Certificate of Incorporation, in the manner now or
             hereafter prescribed by statute, and all rights conferred
             upon stockholders herein are granted subject to this
             reservation.

                  THE UNDERSIGNED, being the sole incorporator
             hereinbefore named, for the purpose of forming a corporation
             pursuant to the General Corporation Law of the State of
             Delaware, does make this certificate, hereby declaring and
             certifying that this is my act and deed and the facts stated
             herein are true, and accordingly have hereunto set my hand
             this 23rd day of September, 1993.




                                           Barbara J. Lucas 
                                           --------------------
                                           Barbara J. Lucas
                                         -4-PAGE

                            CERTIFICATE OF AMENDMENT

                                       OF
                          CERTIFICATE OF INCORPORATION

                                       OF
                             THERMO REMEDIATION INC.



             Thermo Remediation Inc.  (the "Corporation"), a  corporation
        organized and existing under the  laws of the State of  Delaware,
        hereby certifies  as  follows, pursuant  to  Section 242  of  the
        General Corporation Law of the State of Delaware:

             1.   That Article FOURTH of the Certificate of Incorporation
        of the Corporation,  as filed  on September 23,  1993, is  hereby
        amended to  increase  the  number of  authorized  shares  of  the
        Corporation's Common Stock,  $.01 par  value per  share, from  20
        million shares to 50  million shares and  that such amendment  is
        hereby effected  by deleting  said Article  in its  entirety  and
        inserting the following in substitution therefor:

             "FOURTH:  The total number of shares of capital stock  which
                       the Corporation shall have authority to issue is:

                       Fifty Million  (50,000,000)  shares, and  the  par
                       value of each such share in One Cent ($.01)."

             2.   That the  Board  of  Directors of  the  Corporation  by
        unanimous written consent dated as of July 22, 1996, duly adopted
        the following resolutions:

        RESOLVED,      that  it  is   in  the  best   interests  of   the
                       Corporation that  the authorized  common stock  of
                       the Corporation, $.01 par  value, be increased  to
                       50 million shares, and that, upon the approval  of
                       such increase by  the Corporation's  Stockholders,
                       the proper  officers of  the Corporation  be,  and
                       each of them hereby are, authorized, empowered and
                       directed to execute on behalf of the Corporation a
                       Certificate  of  Amendment  to  the  Corporation's
                       Certificate  of  Incorporation  to  reflect   such
                       increase, and to file, or cause to be filed,  such
                       Certificate of  Amendment  with the  Secretary  of
                       State of the State of Delaware.

        RESOLVED,      that the  Board  of  Directors  recommend  to  the
                       Stockholders for  approval at  the Annual  Meeting
                       the  increase   in   authorized  shares   of   the
                       Corporation's common stock to 50 million shares as
                       previously approved by the Directors.
PAGE

             3.   That on September 25, 1996, at the Corporation's Annual
        Meeting of  Stockholders,  the  Amendment  to  the  Corporation's
        Certificate of Incorporation was duly adopted by the  affirmative
        vote of Stockholders of the Corporation holding a majority of the
        shares of  Common  Stock,  $.01  par  value  per  share,  of  the
        Corporation in accordance with the  provisions of Section 242  of
        the General Corporation Law of the State of Delaware.

             IN WITNESS WHEREOF, this  Certificate of Amendment has  been
        executed on behalf  of the  undersigned corporation  by its  duly
        authorized  officer  and  attested  to  by  its  duly  authorized
        Secretary this 31st day of October, 1996.


                                           THERMO REMEDIATION INC.


                                            By:_______________________________
                                                John P. Appleton
                                                Chief Executive Officer


        ATTEST:

        By:__________________________
             Sandra L. Lambert
             Secretary
PAGE

        
                               AGREEMENT OF MERGER


                  THIS AGREEMENT OF MERGER is made as of November 1,
        1993, by and between THERMO REMEDIATION INC., a California
        corporation (hereinafter sometimes called "TRI California"), and
        THERMO REMEDIATION INC., a Delaware corporation (hereinafter
        sometimes called "TRI Delaware") (TRI California and TRI Delaware
        being herein sometimes collectively referred to as the
        "Constituent Corporations").

                  The authorized capital stock of TRI California consists
        of 1,500,000 shares of Capital Stock, par value $1.00 per share
        (the "California Common Stock"), and the authorized capital stock
        of TRI Delaware consists of 20,000,000 shares of Capital Stock,
        par value $0.01 per share (the "Delaware Common Stock").  The
        Directors of the Constituent Corporations deem it advisable and
        to the advantage of said corporations that TRI California merge
        with and into TRI Delaware in accordance with the following
        terms, conditions and other provisions:


                                    ARTICLE I

                  1.1  Merger.  TRI California shall be merged with and
        into TRI Delaware (the "Merger"), and TRI Delaware shall be the
        surviving corporation, effective upon the date when this
        Agreement is filed with the Secretaries of State of the States of
        California and Delaware (the "Effective Date").

                  1.2  Effect of Merger.  Upon the Effective Date, TRI
        Delaware shall succeed to all of the rights, privileges, powers
        and property of TRI California in the manner and as more fully
        set forth in Section 259 of the General Corporation Law of the
        State of Delaware.

                  1.3  Common Stock of TRI California.  Upon the
        Effective Date, by virtue of the Merger and without any action on
        the part of the holder thereof, each share of California Common
        Stock outstanding immediately prior thereto shall be converted
        into four fully paid and non-assessable shares of Delaware Common
        Stock.

                  1.4  Common Stock of TRI Delaware.  Upon the Effective
        Date, by virtue of the Merger and without any action on the part
        of the holder thereof, each share of Delaware Common Stock
        outstanding immediately prior thereto shall be canceled and
        returned to the status of authorized but unissued shares.

                  1.5  Stock Certificates.  On and after the Effective
        Date, all of the outstanding certificates which prior to that

                                        1PAGE

        time represented shares of California Common Stock shall be
        deemed for all purposes to evidence ownership of and to represent
        the shares of TRI Delaware into which the shares of TRI
        California represented by such certificates have been converted
        as herein provided.  The registered owner on the books and
        records of TRI California of any such outstanding stock
        certificate shall, until such certificate shall have been
        surrendered for transfer or conversion or otherwise accounted for
        to TRI Delaware or its transfer agent, have and be entitled to
        exercise any voting and other rights with respect to and to
        receive any dividend and other distributions upon the shares of
        TRI Delaware evidenced by such outstanding certificate as above
        provided.


                                   ARTICLE II

                  2.1  Certificate of Incorporation and Bylaws.  The
        Certificate of Incorporation of TRI Delaware as in effect on the
        Effective Date, shall continue to be the Certificate of
        Incorporation of TRI Delaware as the surviving corporation
        without change or amendment until further amended in accordance
        with the provisions thereof and applicable law.  The Bylaws of
        TRI Delaware, as in effect on the Effective Date, shall continue
        to be the Bylaws of TRI Delaware as the surviving corporation
        without change or amendment until further amended in accordance
        with the provisions thereof and applicable law.

                  2.2  Directors.  The directors of TRI Delaware as of
        the Effective Date shall continue to be the Directors of TRI
        Delaware and such directors shall serve until the first meeting
        of stockholders of TRI Delaware and until their successors are
        elected and qualified.

                  2.3  Officers.  The officers of TRI Delaware shall
        remain officers of TRI Delaware on the effective date until their
        successors are elected and qualified or their prior resignation,
        removal or death.


                                   ARTICLE III

                  3.1  Further Assurances.  From time to time, as and
        when required by TRI Delaware or by its successors and assigns,
        there shall be executed and delivered on behalf of TRI California
        such deeds and other instruments, and there shall be taken or
        caused to be taken by it such further and other action, as shall
        be appropriate or necessary in order to vest or perfect in or to
        confirm of record or otherwise in TRI Delaware the title to and
        possession of all the property, interests, assets, rights,
        privileges, immunities, powers, franchises and authority of TRI
        California, and otherwise to carry out the purposes of this
        Agreement, and the officers and directors of TRI Delaware are
        fully authorized in the name and on behalf of TRI California or

                                        2PAGE

        otherwise to take any and all such action and to execute and
        deliver any and all such deeds and other instruments.

                  3.2  Abandonment.  At any time before the Effective
        Date, this Agreement may be terminated and the Merger may be
        abandoned by the Board of Directors of either TRI California or
        TRI Delaware or both, notwithstanding approval of this Merger
        Agreement by the shareholders of TRI California.

                  3.3  Counterparts.  In order to facilitate the filing
        and recording of this Merger Agreement, the same may be executed
        in any number of counterparts, each of which shall be deemed to
        be an original.


                  IN WITNESS WHEREOF, this Agreement, having first been
        duly approved by the Board of Directors of TRI California and TRI
        Delaware, is hereby executed on behalf of each of said
        corporations by their respective officers thereunto duly
        authorized.


                                          THERMO REMEDIATION INC.,
                                          a California corporation


                                           By: James Lousararian
                                              --------------------------
                                               James Lousararian, Vice President

         
        ATTEST:                                Sandra L. Lambert
                                              ---------------------------
                                               Sandra L. Lambert, Secretary


                                          THERMO REMEDIATION INC.,
                                          a Delaware corporation


                                           By: James Lousararian
                                              ---------------------------
                                               James Lousararian, Vice President

         
        ATTEST:                                Sandra L. Lambert
                                              ----------------------------
                                               Sandra L. Lambert, Secretary

                                        PAGE


                            CERTIFICATE OF SECRETARY
                                       OF
                             THERMO REMEDIATION INC.
                            (a Delaware corporation)


                  I, Sandra L. Lambert, the Secretary of Thermo
        Remediation Inc., a Delaware corporation, hereby certify that the
        Agreement of Merger to which this Certificate is attached, after
        having been first duly signed on behalf of the corporation by the
        Vice President and Secretary under the corporate seal of said
        corporation, was duly approved and adopted by written consent of
        the stockholders of Thermo Remediation Inc. on November 1, 1993,
        by the holders of all of the outstanding stock entitled to vote
        thereon.

                  WITNESS my hand and seal of said Thermo Remediation
        Inc. this 1st day of November, 1993.



        (SEAL)
                                       Sandra L. Lambert
                                      -----------------------------------
                                       Sandra L. Lambert, Secretary



                            CERTIFICATE OF SECRETARY
                                       OF
                             THERMO REMEDIATION INC.
                           (a California corporation)


                  I, Sandra L. Lambert, the Secretary of Thermo
        Remediation Inc., a California corporation, hereby certify that
        the Agreement of Merger to which this Certificate is attached,
        after having been first duly signed on behalf of the corporation
        by the Vice President and Secretary under the corporate seal of
        said corporation, was duly approved and adopted by written
        consent of the shareholders of Thermo Remediation Inc. on
        November 1, 1993, by the holders of a majority of the outstanding
        stock entitled to vote thereon.

                  WITNESS my hand and seal of said Thermo Remediation
        Inc. this 1st day of November, 1993.



        (SEAL)
                                       Sandra L. Lambert
                                      -----------------------------------
                                       Sandra L. Lambert, Secretary
PAGE


                             CERTIFICATE OF APPROVAL
                                       OF
                               AGREEMENT OF MERGER



        James Lousararian and Sandra L. Lambert certify that:

                  1.   They are the Vice President and the Secretary,
                       respectively, of Thermo Remediation Inc., a
                       Delaware corporation.

                  2.   The Agreement of Merger in the form attached was
                       duly approved by the board of directors and
                       shareholders of the corporation.

                  3.   The shareholder approval was by the holders of
                       100% of the outstanding shares of the corporation.

                  4.   There is only one class of shares and the number
                       of shares outstanding is 100.

                  5.   The percentage vote required is more than 50%.


                  We further declare under penalty of perjury under the
        laws of the State of California that the matters set forth in
        this certificate are true and correct of our own knowledge.

        DATE:  November 1, 1993



                                       James Lousararian
                                      -----------------------------------
                                       James Lousararian, Vice President




                                       Sandra L. Lambert
                                      -----------------------------------
                                       Sandra L. Lambert, Secretary
PAGE

                             CERTIFICATE OF APPROVAL
                                       OF
                               AGREEMENT OF MERGER



        James Lousararian and Sandra L. Lambert certify that:

                  1.   They are the Vice President and the Secretary,
                       respectively, of Thermo Remediation Inc., a
                       California corporation.

                  2.   The Agreement of Merger in the form attached was
                       duly approved by the board of directors and
                       shareholders of the corporation.

                  3.   The shareholder approval was by the holders of 84%
                       of the outstanding shares of the corporation.

                  4.   There is only one class of shares and the number
                       of shares outstanding is 1,350,953.

                  5.   The percentage vote required is more than 50%.

                  We further declare under penalty of perjury under the
        laws of the State of California that the matters set forth in
        this certificate are true and correct of our own knowledge.

        DATE:  November 1, 1993



                                       James Lousararian
                                      -----------------------------------
                                       James Lousararian, Vice President


                                       Sandra L. Lambert
                                      -----------------------------------
                                       Sandra L. Lambert, Secretary