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                       ASSIGNMENT AND ASSUMPTION AGREEMENT

The Prudential Insurance Company of America ("Prudential") and PERC Management
Company Limited Partnership, a Maine limited partnership ("PERC Management") are
entering into this Assignment and Assumption Agreement (this "Agreement"), as of
this ____ day of September, 1997.

      Section 1. Recitals.

      1.1 Prudential and Orrington Waste Ltd., Limited Partnership, an Oregon
      limited partnership (the "Partnership") have entered into that certain
      Capital Contribution Agreement dated as of January 15, 1993, as amended
      (the "OWL Capital Contribution Agreement").

      1.2 Morgan Guaranty Trust Company of New York (the "Bank") has issued
      Irrevocable Letter of Credit No. S-866156 (the "Morgan Letter of Credit")
      dated January 22, 1993, in the original stated amount of $1,000,000 (of
      which $200,000 is available as of the date hereof) for the account of the
      Partnership in favor of Jensen, Baird, Gardner & Henry, as trustee (the
      "Trustee") under a Trust Agreement dated as of January 15, 1993, between
      the Trustee and the City of Ellsworth, and the Towns of Pittsfield,
      Newport, Detroit, Winterport, Frankfort, Prospect and Monroe.

      1.3 The Partnership has assigned and granted a security interest in its
      interests in the OWL Capital Contribution Agreement to the Bank pursuant
      to an Assignment of Capital Contribution Agreement dated as of January 15,
      1993 (the "Assignment"), in order to secure its obligations under the
      Reimbursement Agreement dated as of January 15, 1993 (the "Reimbursement
      Agreement").

      1.4 Key Bank of New York ("Key Bank") has issued to the Bank a letter of
      credit in the stated amount of $200,000 (the "Key Bank LOC") and, in
      consideration of its receipt thereof, the Bank has entered into a First
      Amendment of Reimbursement Agreement dated the date hereof, pursuant to
      which the Bank has consented to this Agreement and released Prudential
      from its obligations under the OWL Capital Contribution Agreement upon the
      assumption thereof by PERC Management pursuant to this Agreement.

      1.5 PERC Management and Prudential have entered into that certain Purchase
      and Option Agreement dated as of the date hereof (the "LP Purchase
      Agreement"), pursuant to which PERC Management has purchased Prudential's
      limited partnership interests in the Partnership and, in connection
      therewith, Prudential agreed to assign to PERC Management, and PERC
      Management agreed to assume, the rights and obligations of Prudential
      under the OWL Capital Contribution Agreement.

            1.6 Capitalized terms used herein and not otherwise defined have the
      meanings given them in the Reimbursement Agreement.


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      Section 2. Assignment, Assumption and Release. Prudential hereby assigns
to PERC Management, and PERC Management hereby assumes, each of the rights and
obligations of Prudential in, under and to the OWL Capital Contribution
Agreement, and the Partnership hereby releases Prudential from any and all
obligations under the OWL Capital Contribution Agreement and acknowledges that
the obligations of PERC Management under the OWL Capital Contribution Agreement
shall be satisfied (to the extent received by the Bank) by the payment of a
drawing or drawings under the Key Bank LOC.

      Section 3. Ratification of OWL Capital Contribution Agreement. In all
other respects the OWL Capital Contribution Agreement is hereby ratified and
confirmed, and all references to Prudential with respect thereto contained
therein shall hereafter be to PERC Management, as assignee of Prudential under
this Agreement.

      Section 4.  Counterparts.  This Agreement may be executed in any number
of counterparts, each of which shall be an original, but all of which
together shall constitute one and the same instrument.

      Section 5.  Governing Law.  This Agreement shall be governed by the
laws of the State of New York without regard to principles of conflicts of
law.

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      IN WITNESS WHEREOF, the parties have caused this Amendment to be duly
executed as of the date first written above.

                                          PERC MANAGEMENT COMPANY LIMITED
                                          PARTNERSHIP

                                           By PERC, Inc.,
                                          Its General Partner

                                          By    /s/ Martin J. Sergi
                                                ------------------------------
                                                Its: President

                                          THE PRUDENTIAL INSURANCE
                                          COMPANY OF AMERICA

                                          By    /s/ John Wand
                                                ------------------------------
                                                Its: Vice President


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Accepted and agreed to as of the date first set forth above.

                                          ORRINGTON WASTE LTD., LIMITED
                                          PARTNERSHIP

                                          By Pacific Orrington Energy, Inc.,
                                           General Partner

                                          By: /s/ Franklin D. Wareham
                                              --------------------------------
                                               Its:  Vice Presdident


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