
<PAGE>   1

                                                                   EXHIBIT 10.36





                                 ALLWASTE, INC.

                   DEFERRED COMPENSATION PLAN TRUST AGREEMENT
<PAGE>   2
                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                                     PAGE
<S>                                                                                                                    <C>
ARTICLE I - GENERAL TRUST PROVISIONS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
         1.1     ESTABLISHMENT OF TRUST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
         1.2     SEPARATE SUB-TRUSTS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
         1.3     TRUST IRREVOCABLE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
         1.4     NON-ALIENATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
         1.5     ACCEPTANCE BY TRUSTEE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

ARTICLE II - GENERAL DUTIES OF THE PARTIES  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
         2.1     GENERAL DUTIES OF THE COMPANY AND THE TRUSTEE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
         2.2     ADDITIONAL GENERAL DUTIES OF TRUSTEE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

ARTICLE III - INVESTMENT, ADMINISTRATION AND DISBURSEMENT
                          OF TRUST FUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
         3.1     INVESTMENT OF TRUST FUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
         3.2     VALUATION OF TRUST FUND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
         3.3     ADDITIONAL INVESTMENT POWERS OF TRUSTEE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
         3.4     ADMINISTRATIVE POWERS OF TRUSTEE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
         3.5     DEALINGS WITH TRUSTEE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
         3.6     DISTRIBUTIONS FROM TRUST FUND  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

ARTICLE IV - SETTLEMENT OF ACCOUNTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  10

ARTICLE V - TAXES, EXPENSES AND COMPENSATION OF TRUSTEE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
         5.1     TAXES  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
         5.2     EXPENSES AND COMPENSATION  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11

ARTICLE VI - FOR PROTECTION OF TRUSTEE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
         6.1     COMMUNICATIONS WITH THE COMPANY, THE PLAN ADMINISTRATOR
                 AND THE MEMBERS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
         6.2     ADVICE OF COUNSEL  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
         6.3     FIDUCIARY RESPONSIBILITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  12

ARTICLE VII - INDEMNITY OF TRUSTEE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  13

ARTICLE VIII - RESIGNATION AND REMOVAL OF TRUSTEE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  14
         8.1     RESIGNATION OF TRUSTEE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  14
         8.2     REMOVAL OF TRUSTEE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  15
</TABLE>





                                      -i-
<PAGE>   3
<TABLE>
<S>                                                                                                                    <C>
         8.3     SUCCESSOR TRUSTEE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  15
         8.4     TRANSFER OF TRUST FUND TO SUCCESSOR  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  15

ARTICLE IX - DURATION AND TERMINATION OF TRUST AND AMENDMENT  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  15
         9.1     DURATION AND TERMINATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  15
         9.2     DISTRIBUTION UPON TERMINATION  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  16
         9.3     AMENDMENT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  16

ARTICLE X - CLAIMS OF COMPANY'S CREDITORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  17
         10.1    INSOLVENCY OF COMPANY  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  17
         10.2    TRUSTEE'S RESPONSIBILITIES IF COMPANY MAY BE INSOLVENT . . . . . . . . . . . . . . . . . . . . . . .  17
         10.3    TRUST RECOVERY OF PAYMENTS TO CREDITORS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  18

ARTICLE XI - ADOPTING ENTITIES  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  18

ARTICLE XII - MISCELLANEOUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  18
         12.1    LAWS OF THE STATE OF TEXAS TO GOVERN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  18
         12.2    TITLES AND HEADINGS NOT TO CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  18
         12.3    CHANGE IN CONTROL  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
         12.4    SUCCESSORS AND ASSIGNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  21
         12.5    CONTROLLING DOCUMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  21
</TABLE>





                                      -ii-
<PAGE>   4
                                 ALLWASTE, INC.
                   DEFERRED COMPENSATION PLAN TRUST AGREEMENT


         THIS AGREEMENT AND DECLARATION OF TRUST, made this ______ day of
__________________, 1997, by and between ALLWASTE, INC. and TEXAS COMMERCE BANK
NATIONAL ASSOCIATION (hereinafter referred to as the "TRUSTEE").

         WHEREAS, ALLWASTE, INC. has established the ALLWASTE, INC. DEFERRED
COMPENSATION PLAN (hereinafter referred to as the "PLAN") for the benefit of
certain individuals who are eligible for benefits under the terms of the Plan
(such individuals being referred to herein as the "MEMBERS"), which Plan
provides for the payment of certain deferred compensation benefits (the
"BENEFITS") to the Members and the beneficiaries of the respective Members who
may become entitled to any payments under the terms of the Plan in the event of
the Member's death ("BENEFICIARIES"); and

         WHEREAS, other adopting entities may adopt the Plan (such other
adopting entities, if any, along with ALLWASTE, INC. hereinafter referred to as
the "COMPANY," jointly and severally); and

         WHEREAS, the Plan contemplates that the Company will pay the entire
cost of the Benefits from its general assets; and

         WHEREAS, ALLWASTE, INC. desires to establish the ALLWASTE, INC.
DEFERRED COMPENSATION PLAN TRUST AGREEMENT (the "TRUST") to aid the Company in
meeting the obligations under the Plan; and

         WHEREAS, the Trust is intended to be a "grantor trust" with the corpus
and income of the Trust treated as assets and income of the Company for federal
income tax purposes; and

         WHEREAS, the Company intends that the assets of the Trust shall at all
times be subject to the claims of general creditors of the Company as provided
in Article X; and

         WHEREAS, the Company intends that the existence of the Trust shall not
alter the characterization of the Plan as "unfunded" for purposes of the
Employee Retirement Income Security Act of 1974, as amended ("ERISA"), and
shall not be construed to provide income to any Member prior to actual payment
of Benefits under the Plan; and

         WHEREAS, under the Trust, the Trustee covenants that it will hold all
property which it may receive hereunder, IN TRUST, for the uses and purposes
and upon the terms and conditions hereinafter stated;





                                      -1-
<PAGE>   5
         NOW, THEREFORE, the parties hereto adopt this Trust Agreement, 
effective May 15, 1997, and agree, as follows:

                                   ARTICLE I

                            GENERAL TRUST PROVISIONS

         1.1     ESTABLISHMENT OF TRUST.  Allwaste, Inc. hereby adopts the
Trust Agreement, establishing the Trust with the Trustee, consisting of such
sums of money and other property acceptable to the Trustee as from time to time
shall be paid or delivered to the Trustee by the Company.  All such money and
other property, all investments and reinvestments made therewith or proceeds
thereof and all earnings and profits thereon, less all payments and charges as
authorized herein, shall constitute the "TRUST FUND."  The Trust Fund shall at
all times be subject to the claims of general creditors of the Company as
provided in Article X.  No Member or Beneficiary shall have any preferred claim
to, or any beneficial ownership interest in, any assets of the Trust Fund prior
to the time such assets are paid to such Member or Beneficiary as Benefits.

         1.2     SEPARATE SUB-TRUSTS.  Contrary provisions of the Trust
notwithstanding, except as provided in Article XI, the provisions of the Trust
shall apply separately and equally to Allwaste, Inc. and to each adopting
entity that has entered into this Trust Agreement pursuant to Article XI.  Each
Company shall bear the cost of providing Benefits for its own Members and their
Beneficiaries, and the portion of the Trust Fund attributable to the
contributions of each Company shall be available only to provide benefits to
such Company's Members and their Beneficiaries or to satisfy claims of such
Company's Bankruptcy Creditors in the event such Company becomes Insolvent (as
such terms are defined in Section 10.1).

         1.3     TRUST IRREVOCABLE.  The Trust shall be irrevocable and shall
be held for the exclusive purpose of providing benefits under the Plan to
Members and their Beneficiaries and defraying expenses of the Trust in
accordance with the provisions of this Trust Agreement.  Except as provided in
Sections 3.6(c) and 3.6(d) and Articles IX and X hereof, no part of the income
or corpus of the Trust Fund shall be recoverable by or for the Company.

         1.4     NON-ALIENATION.  No right or interest to receive benefits from
the Trust may be assigned, sold, anticipated, alienated or otherwise
transferred by any Member or Beneficiary.

         1.5     ACCEPTANCE BY TRUSTEE.  The Trustee accepts the Trust
established under this Trust Agreement on the terms and subject to the
provisions set forth herein, and it agrees to discharge and perform fully and
faithfully all of the duties and obligations imposed upon it under this Trust
Agreement.





                                      -2-
<PAGE>   6
                                   ARTICLE II

                         GENERAL DUTIES OF THE PARTIES

         2.1     GENERAL DUTIES OF THE COMPANY AND THE TRUSTEE.

                 (a)      The Company has provided or will provide the Trustee
with a copy of the Plan and shall provide the Trustee with a copy of any
amendment to the Plan promptly upon its adoption.  The Plan, as of the date of
execution of this Trust Agreement, is hereby incorporated by reference into and
shall form a part of this Trust Agreement as fully as if set forth herein
verbatim.  Any amendment to the Plan shall also be incorporated by reference
into and form a part of this Trust Agreement, effective as of the effective
date of such amendment.  Schedule A to this Trust Agreement sets forth the name
and mailing address of each Member entitled to receive Benefits, the
Beneficiaries, if any, designated by each Member, each Member's aggregate
balance ("ACCOUNT BALANCE") in the accounts maintained under the Plan on his
behalf, and each Member's vested rights ("Vested Interest") in his Account
Balance.  Such Schedule (as amended from time to time as provided herein) is
hereinafter referred to as the "BENEFIT SCHEDULE."  The Company shall be
responsible for notifying the Trustee of any changes in the information set
forth on the Benefit Schedule, including, but not limited to, the addition of
new Members and a change in the mailing address of a Member.

                 (b)      Subject to the provisions of Section 2.1(c), the
Trustee shall keep the Benefit Schedule accurate and current based entirely
upon information provided by the administrator established pursuant to the Plan
(the "PLAN ADMINISTRATOR"), including but not limited to, preparing within 90
days of the Company's fiscal year end a completely updated Benefit Schedule as
of such fiscal year end in order to permit distributions from the Trust Fund to
be made in accordance with the provisions of Section 3.6.  The Company shall
keep accurate books and records with respect to the eligibility of individuals
to participate in the Plan and the Benefits payable under the Plan, and shall
provide such information to the Trustee and any independent third party
referred to in the immediately preceding sentence and shall also provide access
to such books and records at such time or times as the Trustee shall reasonably
request.

                 (c)      If, at any time, the Company fails or refuses to give
the Trustee data or access to such books and records in accordance with Section
2.1(b), the Trustee shall deliver a written request to the Company to provide
access to books and records of the Company and to provide such data as required
in accordance with Section 2.1(b).  If the Company fails or refuses to comply
with the Trustee's written request pursuant to the preceding sentence prior to
the expiration of thirty days from the date of delivery thereof by the Trustee,
the Trustee shall, after ten days written notice to the Company, immediately
pay to each Member an amount equal to such Member's Vested Interest in his
Account Balance as set forth on the most recent Benefit Schedule, reduced by
any taxes to be withheld pursuant to Section 3.6.  Such payment shall be made
in accordance with the provisions of Section 3.6.  For this purpose, the
Company shall be deemed to have complied with the Trustee's written request if,
in the Trustee's judgment, it





                                      -3-
<PAGE>   7
shall have substantially complied at the end of the thirty-day period and is
endeavoring in good faith to complete compliance without delay.

                 (d)      The Plan Administrator shall notify each Member and
Beneficiary of a then deceased Member in writing of any changes in the Benefit
Schedule with respect to such Member or Beneficiary.  The Trustee shall notify
all Members and such Beneficiaries of any failure of the Company to provide
information required in this Section 2.1.

                 (e)      It is intended that Benefits payable to Members shall
be determined under the provisions of the Plan and shall be calculated under
the provisions of the Plan as of the date of payment.  The Company shall
contribute such amounts to the Trust Fund so as to provide the Benefits under
the Plan.  Payment of Benefits shall be based upon the amounts set forth on the
Benefit Schedule only under the circumstances set forth in Section 2.1(c).  If
the actual Benefits payable to a Member under the provisions of the Plan
exceeds the amount set forth on the Benefit Schedule which is paid pursuant to
Section 2.1(c), the Company shall be liable for payment of the remaining
portion of such Benefits.

                 (f)      Trust provisions to the contrary notwithstanding, the
Company shall have the right at any time, and from time to time, in its sole
discretion, to substitute marketable securities of equal fair market value for
any asset held by the Trust.  This right is exercisable by the Company in a
nonfiduciary capacity without the approval or consent of any person in a
fiduciary capacity.

         2.2     ADDITIONAL GENERAL DUTIES OF TRUSTEE.  The Trustee shall
manage, invest and reinvest the Trust Fund as the Trustee may determine in the
exercise of its fiduciary duties hereunder, consistent with the provisions of
Article III.  The Trustee shall collect the income on the Trust Fund, and make
distributions therefrom, all as hereinafter provided.

                                  ARTICLE III

           INVESTMENT, ADMINISTRATION AND DISBURSEMENT OF TRUST FUND

         3.1     INVESTMENT OF TRUST FUND.  The following provisions shall
apply with respect to investment of the Trust Fund:

                 (a)      At any time prior to the occurrence of a Change in
         Control (as such term is defined in Section 12.3), the Trustee shall
         invest and reinvest the assets of the Trust Fund in accordance with
         the written directions received from time to time by the Trustee from
         the Plan Administrator.  Specifically, but not by way of limitation,
         the Plan Administrator may, in its discretion, direct the Trustee to
         follow the deemed investment directions of each Member or Beneficiary
         of a deceased Member, whether written or telephonic, with respect to a
         portion of the Trust Fund assets equal in value to the





                                      -4-
<PAGE>   8
         Account Balance maintained under the Plan on behalf of such
         individual, within parameters established by, and as agent for, the
         Plan Administrator;

                 (b)      To the extent that the Trustee is directed by the
         Plan Administrator, the Trustee may invest in securities (including
         stock or rights to acquire stock) or obligations issued by the
         Company;

                 (c)      To the extent that the Trustee is directed by the
         Plan Administrator, the Trustee may establish one or more separate
         investment accounts within the Trust Fund, each separate account being
         hereinafter referred to as an Investment Fund.  Except as otherwise
         provided, the Trustee shall transfer to each such Investment Fund such
         portion of the assets of the Trust Fund as the Plan Administrator
         directs.  The Trustee shall be under no duty to question, and shall
         not incur any liability on account of following, any direction of the
         Plan Administrator.  The Trustee shall be under no duty to review the
         investment guidelines, objectives, and restrictions established, or
         the specific investment directions given by the Plan Administrator for
         any Investment Fund, or to make suggestions to the Plan Administrator
         in connection therewith.  To the extent that directions from the Plan
         Administrator to the Trustee represent deemed investment elections of
         the Members, the Trustee shall have no responsibility for such
         investment elections and shall incur no liability on account of
         investing the assets of the Trust Fund in accordance with such
         directions.  All interest, dividends, and other income received with
         respect to, and any proceeds received from the sale or other
         disposition of securities or other property held in, an Investment
         Fund shall be credited to and reinvested in such Investment Fund.  All
         expenses of the Trust Fund which are allocable to a particular
         Investment Fund shall be so allocated and charged.  The Plan
         Administrator may direct the Trustee to eliminate an Investment Fund
         or Funds, and the Trustee shall thereupon dispose of the assets of
         such Investment Fund and reinvest the proceeds thereof in accordance
         with the directions of the Plan Administrator; and

                 (d)      From and after the occurrence of a Change in Control,
         or if the Plan Administrator fails to provide the Trustee with such
         written directions, the Trustee shall have, with respect to the Trust
         Fund, power in its discretion to invest and reinvest such assets in
         (i) common and preferred stocks, bonds, notes and debentures
         (including convertible stocks and securities but not including any
         stock, debt instruments, or other securities of the Company, the
         Trustee or their affiliates) which are readily marketable and listed
         on a United States national securities exchange or the NASDAQ national
         market, (ii) interest-bearing deposit accounts or certificates of
         deposit maturing within one year after acquisition thereof, entered
         into or issued by a United States national or state bank or trust
         company having capital, surplus and undivided profits, at the holding
         company level, of at least $75 million, (iii) direct obligations of,
         and obligations fully guaranteed by, the United States of America or
         any agency of the United States of America which is backed by the full
         faith and credit of the United States of America (so long as such
         obligations shall mature within one year after acquisition thereof),
         (iv) any





                                      -5-
<PAGE>   9
         common, collective or commingled fund, including a fund maintained by
         the Trustee, established and maintained primarily for the purpose of
         investing and reinvesting in assets of the type described in (i), (ii)
         and (iii) above, and (v) insurance contracts issued by one or more
         insurance companies.  Further, notwithstanding the provisions of the
         preceding sentence, after the occurrence of a Change in Control or in
         the event the Plan Administrator fails to provide the Trustee with
         written directions pursuant to the first sentence of this Section, the
         Trustee shall have the power in its discretion to retain, maintain,
         continue, sell, or take any other actions relative to any assets then
         held in the Trust Fund (including, without limitation, to take actions
         in accordance with deemed investment directions obtained directly from
         a Member or Beneficiary of a deceased Member with respect to a portion
         of the Trust Fund assets equal in value to the Account Balance
         maintained under the Plan on behalf of such individual).

         3.2     VALUATION OF TRUST FUND.  As soon as practicable after the
Company's fiscal  year end and as of such other dates as may be specified by
the Company or the Plan Administrator, the Trustee shall report to the Company
and the Plan Administrator the assets held in the Trust Fund as of such day and
shall determine and include in such report the fair market value as of such day
of each such asset.  In determining such fair market values, the Trustee shall
use such market quotations and other information as are available to it and may
in its discretion be appropriate.  The report of any such valuation shall not
constitute a representation by the Trustee that the amounts reported as fair
market values would actually be realized upon the liquidation of the Trust
Fund.  The Trustee shall not be accountable to the Company or to any other
person on the basis of any such valuation, but its accountability shall be in
accordance with the provisions of Article IV hereof.

         3.3     ADDITIONAL INVESTMENT POWERS OF TRUSTEE.  Subject to the
provisions of Sections 3.1, 3.6 and 9.2 hereof, the Trustee shall have, with
respect to the Trust Fund, the power in its discretion:

                 (a)      To retain any property at any time received by it;

                 (b)      To sell, exchange, convey, transfer or dispose of,
         and to grant options for the purchase or exchange with respect to, any
         property at any time held by it;

                 (c)      To register and carry any securities or any other
         property in the name of the Trustee, or in the name of the nominee of
         the Trustee (or to hold any such property unregistered) without
         increasing or decreasing the fiduciary liability of the Trustee, and
         to exercise any option, right or privilege to convert any convertible
         securities, including shares or fractional shares of the Trustee so
         long as the conversion privilege is offered pro rata to all
         shareholders;

                 (d)      To cause any securities to be held in book-entry or
         in bearer form;





                                      -6-
<PAGE>   10
                 (e)      To hold uninvested, without liability for interest
         thereon, any moneys received by it until the same shall be invested or
         disbursed; and

                 (f)      To hold property for investment that may be
         unproductive of income.

         3.4     ADMINISTRATIVE POWERS OF TRUSTEE.  The Trustee shall have the
power in its discretion:

                 (a)      To exercise all voting rights with respect to the
         shares of stock held in the Trust Fund and to grant proxies,
         discretionary or otherwise; provided, however, voting rights with
         respect to stock issued by the Company or its affiliates shall be
         exercised by the Plan Administrator prior to the occurrence of a
         Change in Control;

                 (b)      To cause any shares of stock to be registered and
         held in the name of one or more of its nominees, or one or more
         nominees of any system for the central handling of securities, without
         increase or decrease of liability;

                 (c)      To collect and receive any and all money and other
         property due to the Trust Fund and to give full discharge therefor;

                 (d)      Subject to the provisions of Section 3.6 hereof:  to
         settle, compromise or submit to arbitration any claims, debts or
         damages due or owing to or from the Trustee; to commence or defend
         suits or legal proceedings to protect any interest of the Trust; and
         to represent the Trust in all suits or legal proceedings in any court
         or before any other body or tribunal;

                 (e)      To organize under the laws of any state a corporation
         or limited liability company for the purpose of acquiring and holding
         title to any property which it is authorized to acquire under this
         Trust Agreement and to exercise with respect thereto any or all of the
         powers set forth in this Trust Agreement;

                 (f)      To determine how all receipts and disbursements shall
         be credited, charged or apportioned as between income and principal;

                 (g)      To determine the amount and time of Benefit payments
         in accordance with  directions from the Plan Administrator or its
         delegates and in compliance with the provisions of Section 3.6;

                 (h)      To employ and compensate such attorneys, counsel,
         brokers or other agents or employees and to delegate to them such of
         the duties, rights and powers of the Trustee as may be deemed
         advisable in handling and administering the Trust; and





                                      -7-
<PAGE>   11
                 (i)      Generally to do all acts, whether or not expressly
         authorized, which the Trustee may deem necessary or desirable for the
         protection of the Trust Fund.

         3.5     DEALINGS WITH TRUSTEE.  Persons dealing with the Trustee shall
be under no obligation to see to the proper application of any money paid or
property delivered to the Trustee or to inquire into the Trustee's authority as
to any transaction.

         3.6     DISTRIBUTIONS FROM TRUST FUND.

                 (a)      Except as set forth in Section 3.6(c), Section
3.6(d), Section 9.2 and Article X hereof, distributions from the Trust Fund
shall be made by the Trustee to the Members and Beneficiaries at the times and
in the amounts set forth in the Plan and, to the maximum extent permitted by
applicable law, the Trustee shall be fully protected in so doing.  Any amounts
so paid shall be reduced by the amount of any federal, state, or local income
or other taxes that may be required by law to be withheld or paid by the
Trustee and the Trustee shall withhold, pay and report such amounts to the
appropriate governmental authorities; provided, that the Company shall
withhold, pay and report any FICA, or FUTA or other applicable taxes; and,
provided, further, that the Company, the Plan Administrator, the Members, and
the Beneficiaries shall provide the Trustee with all of the information
necessary for the Trustee to determine the amount of such taxes required to be
withheld or paid by the Trustee and the Trustee shall be fully protected in
relying upon such information.  Notwithstanding any provision of this Trust
Agreement to the contrary, the Company shall be obligated to pay the Benefits.
To the extent that the Trust Fund is not sufficient to pay any Benefit when
due, the Company shall pay such Benefit directly.  In the event Benefits are
due to more than one Member or Beneficiary on the same date and the Trust Fund
is not sufficient to pay all such Benefits, the Trust Fund shall be applied pro
rata among such Members and Beneficiaries on the basis of the Benefits due to
be paid such individuals on such date, as determined by the Plan Administrator
or its delegates.  Nothing in this Trust Agreement shall relieve the Company of
its liabilities to pay Benefits except to the extent such liabilities are met
by application of Trust Fund assets.

                 (b)      Prior to the occurrence of a Change in Control, the
Plan Administrator shall direct the Trustee in writing as to the time and
amount of Benefits to be distributed to the Members and Beneficiaries.  From
and after the occurrence of a Change in Control, a Member or Beneficiary who
believes that he or she is entitled to Benefits may apply in writing directly
to the Trustee for payment of such Benefits.  Such application shall advise the
Trustee of the circumstances which entitle such Member or Beneficiary to
payment of such Benefits.  The Trustee shall, in such case, reach its own
independent determination as to the Member's or Beneficiary's entitlement to
Benefits, even though the Trustee may be informed from another source
(including the Company or the Plan Administrator) that payments are not due
under the Plan.  If the Trustee so desires, it may, in its sole discretion,
make such additional inquiries and/or take such additional measures as it deems
necessary in order to enable it to determine whether Benefits are due and
payable, including, but not limited to, interviewing appropriate





                                      -8-
<PAGE>   12
persons, requesting affidavits, soliciting oral or written testimony under
oath, or holding a hearing or other proceeding.  After the occurrence of a
Change in Control, the Trustee shall determine whether Benefits are payable as
promptly as possible.

                 (c)      If the Net Fair Market Value of the Trust Assets (as
such term is hereinafter defined) exceeds the aggregate Account Balances for
all Members and Beneficiaries, the Plan Administrator may, at such time or
times, direct the Trustee in writing to distribute to the Company cash held by
the Trustee as part of the Trust Fund in an amount equal to the Benefits
accrued under the Plan that have been forfeited under the terms of the Plan.
As soon as practicable after receipt of such a direction and, if such direction
is received by the Trustee after the occurrence of a Change in Control, the
Trustee's independent determination that such benefits have, in fact, been
forfeited in accordance with the terms of the Plan, the Trustee shall
distribute such amount to the Company.

                 (d)      At any time and from time to time prior to the
occurrence of a Change in Control, the Company may apply in writing to the
Trustee for a distribution by the Trustee to the Company of assets held by the
Trustee as part of the Trust Fund ("TRUST ASSETS") in an amount (the "REFUND
AMOUNT") equal to or less than the difference, if any, between (i) the Net Fair
Market Value of the Trust Assets (as such term is hereinafter defined) as of
the last day of the month coincident with or immediately preceding the date of
such application, and (ii) 105% of the aggregate Account Balances for all
Members and Beneficiaries as of such date.  Such application shall advise the
Trustee of the manner in which the Refund Amount was calculated.  Upon the
receipt of such an application from the Company, the Trustee shall reach its
own independent determination as to the Company's entitlement to the Refund
Amount, even though the Trustee may be informed from another source (including
a Member) that the Company is not entitled to the Refund Amount.  If the
Trustee so desires, it may, in its sole discretion, make such additional
inquiries and/or take such additional measures as it deems necessary in order
to enable it to determine whether the Company is entitled to the Refund Amount,
including, but not limited to, interviewing appropriate persons, requesting
affidavits, soliciting oral or written testimony under oath, or engaging such
independent third parties as the Trustee may deem necessary to assist in making
such determination.  The Trustee shall determine whether the Company is
entitled to all or any portion of the Refund Amount as promptly as possible.
If the Trustee determines that the Company is entitled to all or any portion of
the Refund Amount, then the Trustee shall distribute such amount to the Company
in cash or in kind as determined by the Trustee in its sole discretion.  As
used herein, the term "NET FAIR MARKET VALUE OF THE TRUST ASSETS" shall mean
the fair market value of the Trust Assets, as determined by the Trustee in its
sole discretion, reduced by all liabilities of the Trust, whether or not such
liabilities are secured by any or all of the Trust Assets, other than
liabilities to Members or Beneficiaries under the Plan.  In determining such
fair market value, the Trustee shall use such market quotations and other
information as are available to it and may in its discretion be appropriate;
provided, however, that the fair market value of any life insurance contract
which constitutes a portion of the Trust Assets shall be its net cash surrender
value.  The determination of the Net Fair Market Value of the Trust Assets by
the Trustee shall not constitute a representation by the





                                      -9-
<PAGE>   13
Trustee that the amounts reported as fair market values would actually be
realized upon the liquidation of the Trust Assets.  The Trustee shall not be
accountable to the Company or to any other person, including the Members or
Beneficiaries, on the basis of any such valuation except as otherwise provided
in this Trust Agreement.

                 (e)      The Trustee shall not itself commence any legal
action, whether in the nature of an interpleader action, request for
declaratory judgment or otherwise, requesting a court to make a determination
under Section 3.6(a), (b), (c) or (d) hereof in the Trustee's stead without
first using its best efforts to make such determination.

                 (f)      Notwithstanding any other provision of this Trust
Agreement, if any amounts held in the Trust are found in a "determination"
(within the meaning of Section 1313(a) of the Internal Revenue Code of 1986, as
amended) to have been includible in gross income of a Member or Beneficiary
prior to payment of such amounts from the Trust, the Trustee shall, as soon as
practicable, pay such amounts to such Member or Beneficiary, as applicable,
(but not in excess of such Member's or Beneficiary's Vested Interest in his
Account Balance at the time of such payment).  For purposes of this Section
3.6, the Trustee shall be entitled to rely on an affidavit by a Member or
Beneficiary, as applicable, and a copy of the determination to the effect that
a determination described in the preceding sentence has occurred.

                                   ARTICLE IV

                             SETTLEMENT OF ACCOUNTS

         The Trustee shall keep full accounts of all of its receipts and
disbursements.  Its books and records with respect to the Trust Fund shall be
open to inspection by the Company, any Member or any Beneficiary of a deceased
Member or their representatives at all times during business hours of the
Trustee.  Within sixty days after the Company's fiscal year end, or any
termination of the duties of the Trustee, the Trustee shall prepare, sign and
mail to the Company and the Plan Administrator an account of its acts and
transactions as Trustee hereunder.  If, within sixty days after the mailing of
the account or any amended account, the Company and the Plan Administrator have
not filed with the Trustee notice of any objection to any act or transaction of
the Trustee, the account or amended account shall become an account stated.  If
any objection has been filed, and if the objecting party is satisfied that it
should be withdrawn or if the account is adjusted to the objecting party's
satisfaction, the objecting party shall in writing filed with the Trustee
signify its approval of the account and it shall become an account stated.
When an account becomes an account stated, such account shall be finally
settled, and the Trustee shall be completely discharged and released, as if
such account had been settled and allowed by a judgment or decree of a state or
federal court of competent jurisdiction in an action or proceeding in which the
Trustee, the Company and the Plan Administrator were parties.  The Trustee, the
Company or the Plan Administrator shall have the right to apply at any time to
a state or federal court of competent jurisdiction for judicial settlement of
any account of the Trustee not previously settled as hereinabove provided.  In
any such action or proceeding it shall





                                      -10-
<PAGE>   14
be necessary to join as parties the Trustee, the Company and the Plan
Administrator and any judgment or decree entered therein shall be conclusive
upon all such parties.

                                   ARTICLE V

                  TAXES, EXPENSES AND COMPENSATION OF TRUSTEE

         5.1     TAXES.  The Company agrees that all income, deductions and
credits of the Trust Fund belong to it as owner for income tax purposes and
will be included on the Company's income tax returns.  The Company shall from
time to time pay taxes (references in this Trust Agreement to the payment of
taxes shall include interest and applicable penalties) of any and all kinds
whatsoever which at any time are lawfully levied or assessed upon or become
payable in respect of the Trust Fund, the income or any property forming a part
thereof, or any security transaction pertaining thereto.  To the extent that
any taxes levied or assessed upon the Trust Fund are not paid by the Company or
contested by the Company pursuant to the last sentence of this Section 5.1, the
Trustee shall pay such taxes out of the Trust Fund and the Company shall upon
demand by the Trustee deposit into the Trust Fund an amount equal to the amount
paid from the Trust Fund to satisfy such tax liability.  If requested by the
Company, the Trustee shall, at Company expense, contest the validity of such
taxes in any manner deemed appropriate by the Company or its counsel, but only
if it has received an indemnity bond or other security satisfactory to it to
pay any expenses of such contest.  Alternatively, the Company may itself
contest the validity of any such taxes, but any such contest shall not affect
the Company's obligation to reimburse the Trust Fund for taxes paid from the
Trust Fund.

         5.2     EXPENSES AND COMPENSATION.  The Trustee shall be paid
compensation by the Company as the Company and the Trustee may from time to
time agree.  The Trustee shall be reimbursed by the Company for its reasonable
expenses of management and administration of the Trust, including reasonable
compensation of counsel and any agent engaged by the Trustee to assist it in
such management and administration.  In the event that the Company shall fail
or refuse to pay such compensation or make such reimbursement within sixty days
of demand, the Trustee may satisfy such obligations out of the assets of the
Trust Fund; in that event, the Company shall immediately upon demand by the
Trustee deposit into the Trust Fund a sum equal to the amount paid by the Trust
Fund for such fees and expenses.





                                      -11-
<PAGE>   15
                                   ARTICLE VI

                           FOR PROTECTION OF TRUSTEE

         6.1     COMMUNICATIONS WITH THE COMPANY, THE PLAN ADMINISTRATOR AND
THE MEMBERS.

                 (a)      The Company shall certify to the Trustee the name or
names of any person or persons authorized to act for the Company and for the
Plan Administrator.  Such certification shall be signed by the President or a
Vice President and the Secretary or an Assistant Secretary of the Company.
Until the Company notifies the Trustee, in a similarly signed notice, that any
such person is no longer authorized to act for the Company or for the Plan
Administrator, as applicable, the Trustee may continue to rely upon the
authority of such person.

                 (b)      The Trustee may rely upon any certificate, notice or
direction of the Company or the Plan Administrator which the Trustee reasonably
believes to have been signed by a duly authorized officer or agent of the
Company or the Plan Administrator, as applicable.

                 (c)      Communications to the Trustee shall be sent in
writing to its principal address, Attention:  Legal Department, or to such
other address as the Trustee may specify.  No communication shall be binding
upon the Trust Fund or the Trustee until it is received by the Trustee and
unless it is in writing and signed by an authorized person.

                 (d)      Communications to the Company shall be sent in
writing to the Company at 5151 San Felipe, Suite 1600, Houston, Texas  77056,
Attention:  General Counsel, or to such other address as the Company may
specify in writing to the Trustee.  Communications to the Plan Administrator
shall be sent in writing to the Company's address, Attention:  Chief
Administrative Officer.  Communications to a Member or Beneficiary shall be
sent in writing to the address of such person as stated on the Benefit
Schedule, or to such other address as such person may specify in writing to the
Trustee.  No communication shall be binding upon the Company, the Plan
Administrator, or a Member or Beneficiary until it is received by such person.

         6.2     ADVICE OF COUNSEL.  The Trustee may consult with any legal
counsel with respect to the construction of this Trust Agreement, its duties
hereunder or any act which it proposes to take or omit, and shall not be liable
for any action taken or omitted in good faith pursuant to such advice.
Expenses of such counsel shall be deemed to be expenses of management and
administration of the Trust within the meaning of Section 5.2 hereof.

         6.3     FIDUCIARY RESPONSIBILITY.

                 (a)      The Trustee shall discharge its duties under this
Trust Agreement in effectuating the Plan in a manner consistent with the
objectives of this Trust Agreement and the





                                      -12-
<PAGE>   16
Plan.  The Trustee shall not be liable for any loss sustained by the Trust Fund
by reason of the purchase, retention, sale or exchange of any investment in
good faith and in accordance with the provisions of this Trust Agreement.  The
Trustee shall have no responsibility or liability for any failure of the
Company to make contributions to the Trust Fund or for any insufficiency of
assets in the Trust Fund to pay Benefits when due.  The Trustee shall not be
liable hereunder for any act taken or omitted to be taken in good faith, except
for its own negligence or misconduct.

                 (b)      The Trustee shall not be responsible for any act or
failure to act of another fiduciary except to the extent otherwise provided by
law.

                 (c)      No bond shall be required of the Trustee unless
otherwise required by law.

                 (d)      The Trustee shall have no responsibility to negotiate
any insurance contracts respecting the Plan and Trust, nor shall the Trustee
have any responsibility to conduct any due diligence as to such insurance
contracts.

                 (e)      The Trustee's duties and obligations shall be limited
to those expressly imposed upon it by this Trust Agreement.

                 (f)      The Company at any time may employ as agent (to
perform any act, keep any records or accounts, or make any computations
required of the Company or the Plan Administrator by this Trust Agreement or
the Plan) the individual, corporation or association serving as Trustee
hereunder.  Nothing done by said individual, corporation or association as such
agent shall affect its responsibilities or liability as Trustee hereunder.

                                  ARTICLE VII

                              INDEMNITY OF TRUSTEE

         The Company hereby indemnifies and holds the Trustee harmless from and
against any and all losses, damages, costs, expenses or liabilities (herein,
"LIABILITIES"), including reasonable attorneys' fees and other costs of
litigation, to which the Trustee may become subject pursuant to, arising out
of, occasioned by, incurred in connection with or in any way associated with
this Trust Agreement, including the acts or omissions of other fiduciaries,
except for any act or omission constituting negligence or misconduct of the
Trustee.  If one or more Liabilities shall arise, or if the Company fails to
indemnify the Trustee as provided herein, or both, then the Trustee may engage
counsel of the Trustee's choice, but at the Company's expense, either to
conduct the defense against such Liabilities or to conduct such actions as may
be necessary to obtain the indemnity provided for herein, or to take both such
actions.  The Trustee shall notify the Company within fifteen days after the
Trustee has so engaged counsel of the name and address of such counsel.  If the
Trustee shall be entitled to indemnification by the Company pursuant to this
Article VII and the Company shall not provide such indemnification upon demand,
the Trustee may apply assets of the Trust Fund in full satisfaction of the
obligations for





                                      -13-
<PAGE>   17
indemnity by the Company, and any legal proceeding by the Trustee against the
Company for such indemnification shall be on behalf of the Trust.

                                  ARTICLE VIII

                       RESIGNATION AND REMOVAL OF TRUSTEE

         8.1     RESIGNATION OF TRUSTEE.  The Trustee may resign upon sixty
days' prior written notice to the Board of Directors of Allwaste, Inc. (the
"BOARD"), the Plan Administrator, each Member and each Beneficiary of a
deceased Member, except that any such resignation shall not be effective until
the Board have appointed in writing a successor trustee, which must be a bank,
trust company, or an individual, and such successor has accepted the
appointment in writing; provided, however, that if such appointment is to
become effective at any time after the occurrence of a Change in Control, then
the consent of a majority of the Members to the appointment of such successor
trustee must be obtained.  For all purposes of this Trust Agreement where the
consent of a majority of the Members is required, the determination of majority
consent shall be based upon receiving the consent of any combination of Members
whose sum of Account Balances as of the time of determination is greater than
fifty percent of the sum of Account Balances for all Members at such time,
rather than upon receiving the consent of a majority of the number of Members.
For purposes of this determination, Beneficiaries of deceased Members shall be
considered Members.  The Board shall make a good faith effort, following
receipt of notice of resignation from the Trustee, to find and appoint a
successor Trustee who will adhere to the obligations imposed on such successor
under the terms of this Trust Agreement, and in particular, but without
limitation, the obligation to exercise judgment independent of the Company in
the circumstances described in Section 3.6 hereof.  The appointment of a
successor trustee shall also be conditioned upon obtaining from such successor
a written statement that the successor has read the Trust Agreement and
understands its obligations thereunder.  If the consent of a majority of the
Members is required for the appointment of a successor Trustee, then the
Trustee shall be responsible for securing such Member consents in a timely
fashion and, unless ordered by a court of competent jurisdiction, shall not
reveal to the Board, the Plan Administrator or any other person any information
concerning such consents, except whether the required majority has been
achieved.  Any notice sent to Members by the Trustee canvassing the Members as
to their consent to a successor trustee, shall include the name and address of
the proposed successor trustee.  Any consent of a Member required under this
Section 8.1 shall be deemed given if no written objection is received by the
Trustee from such Member within fourteen days after request for such consent is
sent postpaid by United States registered or certified mail with return receipt
requested to such Member.  Provisions of the Trust Agreement to the contrary
notwithstanding, if the Trustee gives notice of resignation to the Plan
Administrator and no successor Trustee has been appointed within sixty days of
receipt of such written notice, the compensation of the Trustee then in effect
shall increase by 50%, effective as of the lapse of such sixty-day time period.





                                      -14-
<PAGE>   18
         8.2     REMOVAL OF TRUSTEE.  The Board may remove the Trustee upon
sixty days' prior written notice to the Trustee, the Plan Administrator, each
Member and each Beneficiary of a deceased Member, except that any such removal
shall not be effective until the close of such notice period and (a) delivery
by the Board to the Trustee of an instrument in writing appointing a successor
trustee meeting the requirements of Section 8.1, and (b) an acceptance of such
appointment in writing executed by such successor.  Notwithstanding the
provisions of the preceding sentence, if such appointment of a successor
trustee is to become effective at any time after the occurrence of a Change in
Control, then the removal of the Trustee and the appointment of a successor
trustee shall not be effective until the Trustee has received the consent of a
majority of the Members (as determined in accordance with the provisions of
Section 8.1 hereof) to such removal and such appointment.  Upon the receipt by
the Trustee of a written notice of removal, the Trustee shall be responsible
for securing the Member consents (if such consents are required pursuant to the
preceding provisions of this Section 8.2) in a timely fashion and, unless
ordered by a court of competent jurisdiction, shall not reveal to the Board,
the Plan Administrator or any other person any information concerning such
consents, except whether the  required majority has been achieved.  Any notice
sent to Members by the Trustee canvassing the Members as to their consent to
removal of the Trustee and the appointment of a proposed successor trustee,
shall include the name and address of the proposed successor trustee.  Any
consent of a Member required under this Section 8.2 shall be deemed given if no
written objection is received by the Trustee from such Member within fourteen
days after request for such consent is sent postpaid by United States
registered or certified mail with return receipt requested to such Member.

         8.3     SUCCESSOR TRUSTEE.  All of the provisions set forth herein
with respect to the Trustee shall relate to each successor with the same force
and effect as if such successor had been originally named as the Trustee
hereunder.

         8.4     TRANSFER OF TRUST FUND TO SUCCESSOR.  Upon the resignation or
removal of the Trustee and appointment of a successor, the Trustee shall
transfer and deliver the Trust Fund to such successor.  Following the effective
date of the appointment of the successor, the Trustee's responsibility
hereunder shall be limited to managing the assets in its possession and
transferring such assets to the successor, and settling its final account.
Neither the Trustee nor the successor shall be liable for the acts of the
other.

                                   ARTICLE IX

                DURATION AND TERMINATION OF TRUST AND AMENDMENT

         9.1     DURATION AND TERMINATION.  The Trust is hereby declared to be
irrevocable and shall continue until (a) all payments required by Section 3.6
have been made or (b) until the Trust Fund contains no assets and retains no
claims to recover assets from the Company or any other person or entity,
whichever shall first occur.  Notwithstanding the preceding provisions of this
Section 9.1, unless earlier terminated, the Trust shall terminate twenty-one
(21) years





                                      -15-
<PAGE>   19
after the death of the last to die of all of the Members and their issue living
on the date of execution of this Trust Agreement; provided, however, that if at
that time the Trust may be continued in force without violating the rule
against perpetuities or any other law of the State of Texas, then the Trust
shall remain in effect until otherwise terminated as provided hereunder.

         9.2     DISTRIBUTION UPON TERMINATION.  If this Trust terminates under
the provisions of Section 9.1, the Trustee shall liquidate the Trust Fund and,
after its final account has been settled as provided in Article IV, shall
distribute to the Company the net balance of any assets of the Trust remaining
after all expenses have been paid and all Benefits, whether or not due and
payable under the terms of the Plan on the date of such termination, have been
paid to the Members and Beneficiaries.  Upon making such distribution, the
Trustee shall be relieved from all further liability.  The powers of the
Trustee hereunder shall continue so long as any assets of the Trust Fund remain
in its hands.

         9.3     AMENDMENT.  The Board may from time to time amend, in whole or
in part, any or all of the provisions of this Trust Agreement; provided,
however, that (a) no amendment will be made to this Trust Agreement or the Plan
which will cause this Trust Agreement, the Plan or the assets of the Trust Fund
to be governed by or subject to Part 2, 3 or 4 of Title I of ERISA, (b) no such
amendment shall adversely affect any Benefits to the date of such amendment in
respect of any Member or Beneficiary or the amount of assets of the Trust Fund
available to pay such Benefits, (c) no such amendment shall purport to alter
the irrevocable character of the Trust established under this Trust Agreement,
(d) no such amendment shall increase the duties or responsibilities of the
Trustee unless the Trustee consents thereto in writing, and (e) after the
occurrence of a Change in Control, no amendment will be made to this Trust
Agreement without the consent of a majority of the Members (as determined
pursuant to the provisions of Section 8.1 hereof).  Upon receipt of a request
from the Board for an amendment which requires the consent of a majority of the
Members, the Trustee shall be responsible for securing Member consents in a
timely fashion, and unless ordered by a court of competent jurisdiction, shall
not reveal to the Board, the Plan Administrator or any other person any
information concerning such consents, except whether the required majority has
been achieved.  Any consent of a Member required under this Section 9.3 shall
be deemed given if no written objection is received by the Trustee from such
Member within fourteen days after request for such consent is sent postpaid by
United States registered or certified mail with return receipt requested to
such Member.  This Trust Agreement may be amended, to the extent permitted in
this Section 9.3, by an instrument in writing executed on behalf of Allwaste,
Inc. by its authorized representatives, consents to which instrument have been
obtained from the required majority of Members if such consents are required.





                                      -16-
<PAGE>   20
                                   ARTICLE X

                         CLAIMS OF COMPANY'S CREDITORS

         10.1    INSOLVENCY OF COMPANY.  As used in this Article X, the Company
shall be deemed to be "INSOLVENT" if (a) the Company is unable to pay its debts
as they come due, or (b) the Company is subject to a pending proceeding as a
debtor under the United States Bankruptcy Code (or any successor federal
statute).  In the event that the Company shall be deemed Insolvent, the assets
of the Trust Fund shall be held for the benefit of the general creditors of the
Company (hereinafter referred to as "BANKRUPTCY CREDITORS").

         10.2    TRUSTEE'S RESPONSIBILITIES IF COMPANY MAY BE INSOLVENT.

                 (a)      If at any time the Company or a person claiming to be
a creditor of the Company alleges in writing to the Trustee that the Company
has become Insolvent, the Trustee shall within thirty days independently
determine whether the Company is Insolvent and, pending such determination, the
Trustee shall discontinue any payment of Benefits under the Plan and this Trust
Agreement and shall hold the Trust Fund for the benefit of Bankruptcy
Creditors.  As a condition of being a Member of the Plan and this Trust
Agreement, each Member hereby waives his priority credit position, if any,
under applicable state law.  The Trustee shall resume payments of Benefits
under the Plan and this Trust Agreement in accordance with Section 3.6 hereof
only after the Trustee has determined that the Company is not Insolvent (or is
no longer Insolvent, if the Trustee initially determined the Company to be
Insolvent) or upon receipt of an order of a court of competent jurisdiction
requiring such payments.  The Company, by its Chief Executive Officer and its
Board, shall further be obligated to give the Trustee prompt notice in writing
in the event that the Company becomes Insolvent, with the same consequences as
provided in the preceding two sentences.  In determining whether the Company is
Insolvent, the Trustee may rely conclusively upon, and shall be protected in
relying upon, court records showing that the Company is Insolvent, or a current
report or statement from a nationally recognized credit reporting agency
showing that the Company is Insolvent.  For purposes of this Trust Agreement,
knowledge and information concerning the Company which is not in the possession
of the Trustee, or its employees, shall not be imputed to the Trustee.  The
Trustee shall have no duty or obligation to ascertain whether the Company is
Insolvent unless and until it receives a writing that the Company is Insolvent
as described in the first or third sentence of this Section 10.2(a).

                 (b)      If the Trustee determines that the Company is
Insolvent, the Trustee shall hold the assets of the Trust Fund for the benefit
of the Bankruptcy Creditors, and shall disburse the assets of the Trust Fund to
satisfy such claims as a court of competent jurisdiction shall direct.

                 (c)      If the Trustee discontinues payment of Benefits
pursuant to Section 10.2(a) and subsequently resumes such payments, the first
payment to a Member or Beneficiary





                                      -17-
<PAGE>   21
following such discontinuance shall include an aggregate amount equal to the
difference between the payments that would have been made to such Member or
Beneficiary, as applicable, under this Trust Agreement but for this Section
10.2 and the aggregate payments actually made to such Member or Beneficiary, as
applicable, by the Company pursuant to the Plan during any such period of
discontinuance.  In the event that upon resumption of payments pursuant to the
preceding sentence, the assets of the Trust Fund are insufficient to pay
Benefits in full, Benefit payments to the affected Members and Beneficiaries
shall be prorated so as to equitably apportion the assets of the Trust Fund
among all affected Members and Beneficiaries in proportion to their Benefits.

         10.3    TRUST RECOVERY OF PAYMENTS TO CREDITORS.  In the event that at
any time an amount is paid from the Trust Fund to Bankruptcy Creditors of the
Company, the Trustee shall demand that the Company deposit into the Trust Fund
a sum equal to the amount paid by the Trust Fund to such Bankruptcy Creditors
and, if such payment is not made within ninety days of such demand, the Trustee
shall take such action as it deems prudent or advisable to recover payment.

                                   ARTICLE XI

                               ADOPTING ENTITIES

         It is contemplated that other corporations, associations, partnerships
or proprietorships that have adopted the Plan may adopt this Trust Agreement
and thereby become the Company.  Any such entity, whether or not presently
existing, may become a party hereto by appropriate action of its officers
without the need for approval of its board of directors or noncorporate
counterpart or of the Board.  The provisions of the Trust Agreement shall apply
separately and equally to each Company and its Members and their Beneficiaries
in the same manner as is expressly provided for Allwaste, Inc.  and its Members
and their Beneficiaries, except that (a) the power to appoint or otherwise
affect the Trustee and the power to amend the Trust Agreement shall be
exercised by the Board alone, and (b) the determination of whether a Change in
Control has occurred shall be based solely on Allwaste, Inc.

                                  ARTICLE XII

                                 MISCELLANEOUS

         12.1    LAWS OF THE STATE OF TEXAS TO GOVERN.  This Trust Agreement
and the Trust hereby created shall be construed and regulated by the laws of
the State of Texas.

         12.2    TITLES AND HEADINGS NOT TO CONTROL.  The titles to Articles
and headings of Sections in this Trust Agreement are placed herein for
convenience of reference only and, in





                                      -18-
<PAGE>   22
case of any conflict, the text of this Trust Agreement, rather than such titles
or headings, shall control.

         12.3    CHANGE IN CONTROL.  As used in this Trust Agreement, the term
"CHANGE IN CONTROL" shall mean the occurrence of one or more of the following
events:

                 (a)      The acquisition by any individual, entity or group
         (within the meaning of Section 13(d)(3) or 14(d)(2) of the Securities
         Exchange Act of 1934, as amended (the "EXCHANGE ACT")) (a "PERSON") of
         beneficial ownership (within the meaning of Rule 13d-3 promulgated
         under the Exchange Act) of 30% or more of either (1) the then
         outstanding shares of Common Stock of Allwaste, Inc. (the "OUTSTANDING
         COMPANY COMMON STOCK") or (2) the combined voting power of the then
         outstanding voting securities of Allwaste, Inc. entitled to vote
         generally in the election of directors (the "OUTSTANDING COMPANY
         VOTING SECURITIES"); provided, however,that the following acquisitions
         shall not constitute a Change in Control:  (i) any acquisition
         directly from Allwaste, Inc. (excluding an acquisition by virtue of
         the exercise of a conversion privilege), (ii) any acquisition by
         Allwaste, Inc., (iii) any acquisition by any employee benefit plan(s)
         (or related trust(s)) sponsored or maintained by Allwaste, Inc. or any
         corporation controlled by Allwaste, Inc., or (iv) any acquisition by
         any corporation pursuant to a reorganization, merger or consolidation,
         if, immediately following such reorganization, merger or
         consolidation, the conditions described in clauses (1), (2) and (3) of
         subsection (c) below are satisfied; or

                 (b)      Individuals who, as of the date hereof, constitute
         the entire Board of Directors of Allwaste, Inc. (the "INCUMBENT
         BOARD") cease for any reason to constitute at least a majority of the
         Board of Directors of Allwaste, Inc.; provided, however, that any
         individual becoming a director subsequent to the date hereof whose
         election, or nomination for election by Allwaste, Inc.'s stockholders,
         was approved by a vote of at least a majority of the directors then
         comprising the Incumbent Board shall be considered as though such
         individual were a member of the Incumbent Board, but excluding, for
         this purpose, any such individual whose initial assumption of office
         occurs as a result of either (1) an actual or threatened election
         contest (as such terms are used in Rule 14a-11 of Regulation 14A
         promulgated under the Exchange Act), or an actual or threatened
         solicitation of proxies or consents by or on behalf of a Person other
         than the Board of Directors of Allwaste, Inc. or (2) a plan or
         agreement to replace a majority of the members of the Board of
         Directors of Allwaste, Inc. then comprising the Incumbent Board; or

                 (c)      Approval by the stockholders of Allwaste, Inc. of a
         reorganization, merger or consolidation, in each case unless,
         immediately following such reorganization, merger or consolidation,
         (1) more than 60% of, respectively, the then outstanding shares of
         common stock of the corporation resulting from such reorganization,
         merger or consolidation (including, without limitation, a corporation
         which as a result of such





                                      -19-
<PAGE>   23
         transaction owns Allwaste, Inc. through one or more subsidiaries) and
         the combined voting power of the then outstanding voting securities of
         such corporation entitled to vote generally in the election of
         directors is then beneficially owned, directly or indirectly, by all
         or substantially all of the individuals and entities who were the
         beneficial owners, respectively, of the Outstanding Company Common
         Stock and Outstanding Company Voting Securities immediately prior to
         such reorganization, merger or consolidation in substantially the same
         proportions as their ownership immediately prior to such
         reorganization, merger or consolidation, of the Outstanding Company
         Common Stock and Outstanding Company Voting Securities, as the case
         may be, (2) no Person (excluding Allwaste, Inc., any employee benefit
         plan(s) (or related trust(s)) of Allwaste, Inc. and/or its
         subsidiaries or any Person beneficially owning, immediately prior to
         such reorganization, merger or consolidation, directly or indirectly,
         30% or more of the Outstanding Company Common Stock or Outstanding
         Company Voting Securities, as the case may be) beneficially owns,
         directly or indirectly, 30% or more of, respectively, the then
         outstanding shares of common stock of the corporation resulting from
         such reorganization, merger or consolidation or the combined voting
         power of the then outstanding voting securities of such corporation
         entitled to vote generally in the election of directors, and (3) at
         least a majority of the members of the board of directors of the
         corporation resulting from such reorganization, merger or
         consolidation were members of the Incumbent Board at the time of the
         execution of the initial agreement providing for such reorganization,
         merger or consolidation; or

                 (d)      Approval by the stockholders of Allwaste, Inc. of (1)
         a complete liquidation or dissolution of Allwaste, Inc. or (2) the
         sale or other disposition of all or substantially all of the assets of
         Allwaste, Inc., other than to a corporation, with respect to which
         immediately following such sale or other disposition, (A) more than
         60% of, respectively, the then outstanding shares of common stock of
         such corporation and the combined voting power of the then outstanding
         voting securities of such corporation entitled to vote generally in
         the election of directors is then beneficially owned, directly or
         indirectly, by all or substantially all of the individuals and
         entitles who were the beneficial owners, respectively, of the
         Outstanding Company Common Stock and Outstanding Company Voting
         Securities immediately prior to such sale or other disposition in
         substantially the same proportion as their ownership, immediately
         prior to such sale or other disposition, of the Outstanding Company
         Common Stock and Outstanding Company Voting Securities, as the case
         may be, (B) no Person (excluding Allwaste, Inc. and any employee
         benefit plan (or related trust) of Allwaste, Inc. and/or its
         subsidiaries or such corporation and any Person beneficially owning,
         immediately prior to such sale or other disposition, directly or
         indirectly, 30% or more of the Outstanding Company Stock or
         Outstanding Company Voting Securities, as the case may be)
         beneficially owns, directly or indirectly, 30% or more of,
         respectively, the then outstanding shares of common stock of such
         corporation or the combined voting power of the then outstanding
         voting securities of such corporation entitled to vote generally in
         the election of directors, and (C) at least a majority of the members
         of the board of





                                      -20-
<PAGE>   24
         directors of such corporation were members of the Incumbent Board at
         the time of the execution of the initial agreement or action of the
         Board of Directors of Allwaste, Inc. providing for such sale or other
         disposition of assets of Allwaste, Inc.

         Notwithstanding the foregoing, the merger of Allwaste, Inc. with and
into Philip Environmental Inc. shall not constitute a Change of Control for
purposes of this Trust Agreement.

         Allwaste, Inc., by its Chief Executive Officer and its Board, shall be
obligated to give the Trustee prompt notice in writing of the occurrence of a
Change in Control.  In the event the Trustee receives such a notice or if at
any time a Member or a Beneficiary of a deceased Member alleges in writing to
the Trustee that a Change in Control has occurred, the Trustee shall within
thirty days independently determine whether a Change in Control has occurred
and, pending such determination, the Trustee shall assume that a Change in
Control has occurred for all purposes of this Trust Agreement and the Plan.
The Trustee shall have no duty or obligation to ascertain whether a Change in
Control has occurred unless it receives a written notice as described in either
of the preceding two sentences.  In determining whether a Change in Control has
occurred, the Trustee may, in its sole discretion, make such additional
inquiries and/or take such additional measures as it deems necessary,
including, but not limited to, interviewing appropriate persons, requesting
affidavits, soliciting oral or written testimony under oath, or engaging such
independent third parties as the Trustee may deem necessary to assist in making
such determination.  Notwithstanding the foregoing, if at any time Allwaste,
Inc. notifies the Trustee in writing that the Trustee should interpret this
Trust Agreement and the Plan as if a Change in Control had occurred, then for
all purposes of this Trust Agreement and the Plan, the Trustee shall so
interpret this Trust Agreement and the Plan.  Once the notice described in the
preceding sentence is received by the Trustee, it may not be rescinded by
Allwaste, Inc.

         12.4    SUCCESSORS AND ASSIGNS.  This Trust Agreement may not be
assigned by either party without the prior written consent of the other, and
any purported assignment without such prior written consent shall be null and
void.  This Trust Agreement shall be binding upon the successors and permitted
assigns of each party hereto.

         12.5    CONTROLLING DOCUMENT.  Should an inconsistency or conflict
exist between the specific terms of this Trust Agreement and those of the Plan,
then the relevant terms of this Trust Agreement shall govern and control.





                                      -21-
<PAGE>   25
         IN WITNESS WHEREOF, the parties hereto have caused this Trust
Agreement to be executed as of the day and year first above written.

                                 ALLWASTE, INC.


                                 BY:  /s/ JAMES E. RIEF
                                      -----------------------------------------
                                 NAME:  James E. Rief
                                        ---------------------------------------
                                 TITLE:  Sr. V.P. Technology & Admin.
                                         --------------------------------------


                                 TEXAS COMMERCE BANK
                                   NATIONAL ASSOCIATION, TRUSTEE


                                 BY:  /s/ MARY GRACE GREENWOOD
                                      -----------------------------------------
                                 NAME:  MARY GRACE GREENWOOD
                                        ---------------------------------------
                                 TITLE:  Vice President
                                         --------------------------------------




                                      -22-
<PAGE>   26
                                   SCHEDULE A

                               BENEFITS SCHEDULE



                                 [TO BE ADDED]





                                      -23-
