EXHIBIT 10.9.4
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          THIS INSTRUMENT AND THE OBLIGATIONS REPRESENTED THEREBY IS
          SUBORDINATE IN ALL RESPECTS TO CERTAIN OBLIGATIONS OF CHEMPOWER,
          INC. AND ITS SUBSIDIARIES TO FIRST NATIONAL BANK OF OHIO,
          INCLUDING A PROMISSORY NOTE IN THE MAXIMUM PRINCIPAL AMOUNT OF
          $15,700,000 DATED AS OF FEBRUARY 28, 1997.

                                       GUARANTY
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                         THIS GUARANTY (this "Guaranty") is made as of this
          28th day of February, 1997, by AMERICAN ECO CORPORATION, an
          Ontario, Canada corporation ("Guarantor") in favor of TOOMAS J.
          KUKK, his executors, administrators, successors, or assigns, as
          Agent ("Agent") for TOOMAS J. KUKK and MARK L. ROCHESTER (jointly
          and severally, the "Principal Shareholders").


                                 W I T N E S S E T H:
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                         WHEREAS, pursuant to that certain Agreement and
          Plan of Merger by and among Guarantor, Sub Acquisition Corp.
          ("Merger Sub"), and Chempower, Inc., an Ohio corporation
          ("Chempower") dated as of September 10, 1996 (the "Merger
          Agreement"), Merger Sub has agreed to pay certain Merger
          Consideration (as defined in the Merger Agreement) to, among
          others, the Principal Shareholders; and

                         WHEREAS, pursuant to that certain Financing
          Agreement by and among Guarantor, Chempower, the Principal
          Shareholders and the Agent, of even date herewith (the "Financing
          Agreement"), Merger Sub's obligation to pay to the Principal
          Shareholders all or part of the Merger Consideration is evidenced
          by the Principal Shareholders' Note (as defined in the Financing
          Agreement); and

                         WHEREAS, the transactions contemplated by the
          Financing Agreement, including the issuance of the Principal
          Shareholders' Note, will inure to the benefit of Guarantor; and

                         WHEREAS, the execution and delivery of this
          Guaranty by the Guarantor is required by the Financing Agreement;

                         NOW, THEREFORE, for good and valuable
          consideration, the Guarantor agrees as follows:

                         1.   Definitions. Capitalized terms used and not
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          defined herein shall have the meaning given to them in the
          Financing Agreement. The term "Guaranteed Obligations shall mean
          the obligation of Chempower to pay all of the principal of,
          interest on and other indebtedness evidenced by the Principal
          Shareholders' Note and any and all other indebtedness of
          Chempower to the Agent pursuant to the terms of and transactions
          and agreements provided for in the Financing Agreement.

                         2.   Unconditional Guarantee. Guarantor hereby
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          represents and warrants to the Agent that it is the sole
          shareholder of Chempower and that it will receive substantial
          benefits in respect of the Financing Agreement. Guarantor hereby
          absolutely and unconditionally guarantees to the Agent, its
          successors and assigns:

                         (a)  the punctual and full payment when due of all
               the Guaranteed Obligations; it being the intention of
               Guarantor that this Guaranty be an absolute, irrevocable,
               and unconditional guarantee of payment; and

                         (b)  the performance and observance by Chempower
               of all its obligations, agreements, and covenants with the
               Agent under the Financing Agreement, the Principal
               Shareholders' Note, and the Security Agreement; the
               guarantee of such performance and observance to be absolute,
               irrevocable, and unconditional (the obligations, agreements,
               and covenants referred to in this subparagraph (b) also
               being included within and being a part of the Guaranteed
               Obligations).

                         Guarantor further agrees that its guarantee
          hereunder will not be discharged or affected by the fact that the
          Guaranteed Obligations or any of them shall be or become invalid
          or unenforceable for any reason. Guarantor represents and
          warrants to the Agent that it has full power, authority, and
          capacity to enter into and to fully perform all of its
          obligations under this Guaranty.

                         3.   Costs. In addition to its obligations under
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          Section 2 above, Guarantor agrees to pay all costs and expenses
          incurred by the Agent in the enforcement and/or collection of any
          and all of the Guaranteed Obligations, including, without
          limitation, reasonable attorneys' fees. 

                         4.   Dealing with Guaranteed Obligations.
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          Guarantor hereby grants to the Agent full power and authority,
          and without notice to or the consent of Guarantor:

                         (a)  to modify, supplement, or otherwise change
               any terms of the Guaranteed Obligations, from and after the
               occurrence of an Event of Default; to grant any extensions
               or renewals of the Guaranteed Obligations; to grant any
               other waiver or indulgence with respect to the Guaranteed
               Obligations; and to effect any release, compromise, or
               settlement with respect to the Guaranteed Obligations; and

                         (b)  to accelerate the maturity of the Guaranteed
               Obligations from and after the occurrence of a default
               thereunder; to fail to set off any amounts owing by
               Chempower to the Agent; to waive or enter into any agreement
               of forbearance with respect to the Guaranteed Obligations;
               and to change the term of any such waiver or agreement of
               forbearance.

          No action which the Agent may take or fail to take pursuant to
          the foregoing powers shall operate to release or terminate this
          Guaranty or impose any liability on the Agent.

                         5.   The Agent Not Required to Pursue Chempower or
                              ---------------------------------------------
          Exhaust Collateral.  Guarantor hereby waives any right to require
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          payment of the Guaranteed Obligations by Chempower, or to require
          the Agent to proceed against any collateral or security for the
          Guaranteed Obligations, or to require any action or proceeding
          against Chempower on the Guaranteed Obligations, or otherwise to
          require the Agent to exhaust any and all remedies against
          Chempower or any other person before proceeding against Guarantor
          on this Guaranty.

                         6.   Waiver of Acceptance, Etc. Guarantor waives
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          acceptance and notice of acceptance hereof, presentment, demand,
          protest or other notice of any kind, promptness in commencing
          suit and/or giving notice to or in making any claim or demand
          upon it, and agrees that no act or omission of any kind on the
          part of the Agent shall in any event affect or impair this
          Guaranty. 

                         7.   Notices. If the Agent desires to give notice
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          to Guarantor, such notice shall be deemed given when mailed,
          certified mail, return receipt requested, postage prepaid,
          addressed to Guarantor at 11011 Jones Road, Houston, Texas 77070,
          or to such other address as Guarantor may from time to time file
          in writing with the Agent for notices to it.

                         8.   Binding Effect. All of the terms, provisions,
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          and agreements of this Guaranty shall inure to the benefit of and
          be enforceable by the Agent, its successors and assigns, and
          shall be binding upon and be enforceable against Guarantor and
          its successors and assigns.

                         9.   No Right of Subrogation. Guarantor shall not
                              -----------------------
          have any right of reimbursement, subrogation, or setoff with
          respect to the Guaranteed Obligations unless and until the Agent
          shall have received payment in full of all Guaranteed
          Obligations.

                         10.  Reinstatement of Guaranty. This Guaranty
                              -------------------------
          shall continue to be effective, or be reinstated, as the case may
          be, if at any time payment, or any part thereof, of any amount
          paid by or on behalf of Chempower with respect to the Guaranteed
          Obligations is rescinded or must otherwise be restored or
          returned upon the insolvency, bankruptcy, dissolution,
          liquidation or reorganization of Chempower or, upon or as a
          result of the appointment of a receiver, intervenor, or
          conservator of, or trustee or similar officer for, or any
          substantial part of its property, or otherwise, all as though
          such payments had not been made.

                         11.  Governing Law. This Guaranty is a contract
                              -------------
          entered into under and pursuant to the laws of the State of Ohio,
          and shall be in all respects governed, construed, applied and
          enforced in accordance with the laws of such state.

                         12.  Termination of Guaranty. This Guaranty shall
                              -----------------------
          remain in full force and effect until all Guaranteed Obligations
          have been paid and performed in full.

                         13.  Warrant of Attorney. Guarantor hereby
                              -------------------
          irrevocably authorizes any attorney-at-law to appear for
          Guarantor in an action on this Guaranty at any time after the
          same becomes due, whether by acceleration or otherwise, in any
          court of record in the State of Ohio or elsewhere and to waive
          the issuing of service of process against Guarantor and to
          confess judgment in favor of the Agent, its successors and
          assigns, and against Guarantor, for all amounts that may be due,
          together with costs of suit, and thereupon to waive all errors
          and all rights of appeal and stays of execution in respect of the
          judgment rendered. Guarantor hereby expressly (a) waives any
          conflict of interest in an attorney retained by the Agent
          confessing judgment against the Guarantor upon this Guaranty, and
          (b) consents to any attorney retained by the Agent receiving a
          legal fee or other value from the Agent for legal services
          rendered for confessing judgment against the Guarantor upon this
          Guaranty. The foregoing warrant of attorney shall survive any
          judgment, and if any judgment is vacated for any reason, the
          Agent may thereafter use the foregoing warrant of attorney to
          obtain additional judgment or judgments against Guarantor. A copy
          of this Guaranty, certified by the Agent, may be filed in any
          proceeding in place of filing the original as a warrant of
          attorney.

                        IN WITNESS WHEREOF, Guarantor has caused this
          Guaranty to be executed and delivered to the Agent as of the date
          first above written.


          "WARNING--BY SIGNING THIS PAPER YOU GIVE UP YOUR RIGHT TO NOTICE
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          AND COURT TRIAL. IF YOU DO NOT PAY ON TIME A COURT JUDGMENT MAY
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          BE TAKEN AGAINST YOU WITHOUT YOUR PRIOR KNOWLEDGE AND THE POWERS
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          OF A COURT CAN BE USED TO COLLECT FROM YOU REGARDLESS OF ANY
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          CLAIMS YOU MAY HAVE AGAINST THE CREDITOR WHETHER FOR RETURNED
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          GOODS, FAULTY GOODS, FAILURE ON HIS PART TO COMPLY WITH THE
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          AGREEMENT, OR ANY OTHER CAUSE."
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                                        AMERICAN ECO CORPORATION



                                        By:/s/Michael E. McGinnis
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                                           Name:Michael E. McGinnis
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                                           Title:President
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