
<PAGE>   1

                                                                   EXHIBIT 10.48

                        AMENDMENT AND RESTATEMENT OF
                        EXECUTIVE SEVERANCE AGREEMENT

         THIS  AMENDMENT AND  RESTATEMENT OF  EXECUTIVE SEVERANCE  AGREEMENT,
by  and  between ALLWASTE, INC.,  a Delaware corporation (the "COMPANY"), and
T. WAYNE WREN,  JR. (the "EMPLOYEE"), which was effective as of November 11,
1996 (as so amended and restated, the "AGREEMENT"), is entered into this  5th
day of March 1997, to become effective only as provided in Section 1 hereof.

                            W I T N E S S E T H:

         WHEREAS, the Employee  is a  key employee of  the Company, and  the
Employee's  experience and  knowledge of  the affairs of the Company are
extremely valuable to the Company; and

         WHEREAS,  the Company and  the Employee have  entered into that
certain Employment  Agreement dated November 11, 1996 governing the Employee's
employment with the Company (the "EMPLOYMENT AGREEMENT"); and

         WHEREAS, the Board  of Directors of the Company (the "BOARD")
believes it imperative that the Company be able to rely  on the Employee to
continue his services to the Company  without concern that the Employee may be
distracted by the personal uncertainties and risks created by the possibility
of a change in control; and

         WHEREAS,  the Company  is entering  into  this Agreement  with  the
Employee  in order  to ensure  the Employee's continued services,  dedication
and objectivity  during such  period as  the Company may  be susceptible  to a
change  in control and  to define  the nature  and terms  of the Employee's
severance benefits  following a  Change in Control  (as defined in Section 9
below); and

         WHEREAS,  an  Agreement and  Plan  of Merger  is being  executed
currently herewith  among  the Company,  Philip Environmental Inc., Taro
Aggregates Ltd., and Philip/Atlas Merger Corp. (the "MERGER AGREEMENT");

         NOW,  THEREFORE,  for and  in  consideration of  the premises  and
the mutual  covenants  and agreements  herein contained, the Company and the
Employee hereby agree as follows.

         SECTION 1.       TERM.  Subject  to the second sentence of this
Section 1, this  Agreement shall become effective (the "EFFECTIVE TIME")
immediately prior to (and subject to  the occurrence of) approval of the
Merger Agreement by the Company's stockholders  and shall continue until  the
expiration or termination  of the Employment Agreement,  and to the extent that
the  Employment Agreement  is renewed  for successive  one-year periods,  this
Agreement  shall be  similarly renewed (the "TERM").   If this Agreement
becomes effective,  the Employee's original Executive Severance  Agreement (and
any prior amendments thereto) described in the preamble hereto shall
simultaneously become null and void; provided  that, if the Merger Agreement is
terminated, then, on the date of such termination, this Agreement shall
terminate


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and the  Employee's original Executive Severance  Agreement shall remain in
full force and effect.   Notwithstanding any provision of this Agreement  to
the contrary, termination of this  Agreement shall not alter or impair any
rights of the Employee (or the Employee's estate or beneficiaries) that have
arisen under this Agreement prior to such termination.

         SECTION 2.       TERMINATION OF EMPLOYMENT FOLLOWING A CHANGE IN
                          CONTROL.

         2.1     GENERAL.    For purposes  of  this Agreement,  the  "PROTECTED
PERIOD"  shall  mean the  period  of time beginning  with a Change in Control
which  occurs during the Term and ending  18 months following such Change in
Control; provided, however, if  the Employee's employment with  the Company
terminates  for any reason  (other than a  termination (i) due to  the
Employee's death, (ii) by the Company on account  of the Employee's Disability
as provided in Section 2.2 below, (iii) by  the Company for  Cause as provided
in Section 2.3 below,  or (iv) by the  Employee for other  than Good Reason as
provided in Section 2.4 below) prior to, but within  six months of, the date on
which such a Change  in Control occurs,  then, for all purposes  of this
Agreement:   (A) the Employee shall be deemed  to have continued employment
with the Company until the date of the Change in Control and then terminated
his employment on  such date for Good Reason, and (B) the Protected Period
shall be deemed to  have commenced immediately  prior to the  Employee's actual
termination  of employment.

         2.2     TERMINATION BY COMPANY  ON ACCOUNT OF DISABILITY.   If a
Change  in Control occurs during  the Term, and if,  as a result of  the
Employee's illness,  physical or mental disability,  or other incapacity which
continues for an uninterrupted period  in excess of three  (3) months or a
cumulative period of six  (6) months in any  twelve (12) month period  during
the Protected Period, and  if, within 30 days after  the Company has given the
Employee written notice of the Company's intention to terminate the Employee
on account of such incapacity, the Employee shall not have returned to the
full-time  performance of the Employee's duties, then the Company  may
thereafter terminate the Employee's employment on account  of "DISABILITY";
provided, however,  such termination  shall not by  itself alter  or impair
the Employee's rights as a "DISABLED EMPLOYEE" or otherwise under any of the
Company's employee benefits plans.

         2.3     TERMINATION BY COMPANY FOR CAUSE.   If a Change in Control
occurs during the Term, the Company  may, at any  time during the Protected
Period, terminate the Employee's  employment for Cause.  For  purposes of this
Agreement, the Company shall have "CAUSE" to terminate the Employee's
employment hereunder only if:  (a) the  Employee willfully and continually
fails to perform substantially the Employee's duties  with the Company (other
than any such failure resulting from the Employee's  incapacity due to physical
or mental  illness), which failure continues unabated  after a demand for
substantial performance is delivered  to the Employee by the  Board that
specifically identifies the manner  in which the Board believes  that the
Employee has  not substantially performed  the Employee's duties, or  (b) the
Employee willfully engages in  gross  misconduct that  is materially  and
demonstrably  injurious  to the  Company.   For  purposes of  this Section 2.3,
an act or failure to act on the Employee's part shall be considered "WILLFUL"
if  done or omitted to be done by  the Employee otherwise than in good faith
and without reasonable belief that the Employee's action or omission was in the
best interest of the Company.  Notwithstanding the foregoing, the Employee
shall not be deemed to





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have been terminated by the Company  for Cause unless and until the Company
shall have delivered to the Employee a  copy of a resolution duly  adopted by
the  affirmative vote of not  less than three-quarters of  the entire
membership of  the Board, at  a meeting  of the  Board called and  held for
the purpose  (after reasonable  notice to the  Employee and  an opportunity for
the  Employee, together with the Employee's counsel, to be  heard before the
Board), finding that, in the good  faith opinion  of the Board,  the Employee
was guilty of  conduct set forth  in clauses  (a) or (b)  of the second
sentence of this Section 2.3 and specifying the particulars thereof in
reasonable detail.

         2.4     TERMINATION BY EMPLOYEE  FOR GOOD REASON.  If a  Change in
Control occurs during the  Term, the Employee may terminate the Employee's
employment for Good Reason at any time  during the Protected Period.  For
purposes of this Agreement "GOOD REASON" shall mean any of the following:

                 (a)      The  Employee is  assigned any  duties  materially
         inconsistent  with,  or diminished  from, the Employee's  positions,
         duties,  responsibilities   and  status  with  the   Company
         immediately  prior  to  the commencement of  the Protected Period, or
         the Employee's  status, reporting responsibilities, titles  or offices
         are materially diminished  from those in effect  immediately prior to
         the  commencement of the  Protected Period, or the Employee  is
         removed from  or is  not re-elected  or appointed  to any of  such
         responsibilities,  titles, offices or positions,   except in each
         case in connection with the  termination of the Employee's  employment
         by the Company for Cause or  on account of Disability, or  as a result
         of the Employee's  death, or by  the Employee for  other than Good
         Reason;  provided, however, that  Good Reason  shall not be triggered
         under this subsection (a) by an  insubstantial action  not taken  in
         bad faith  and which  is remedied  by the  Company promptly  after
         receipt of written notice  from the Employee; and provided further
         that  Good Reason shall not be triggered under this subsection (a) by
         any such alteration primarily attributable to the fact that the
         Company  may no longer be a public company; or

                 (b)      The  Employee's annual rate  of base salary is
         reduced from  that in effect immediately prior to the commencement of
         the Protected Period  or as  the same may  be increased from time  to
         time thereafter  (such annual  rate of  base salary,  as  so increased
         (if applicable)  but prior  to such  reduction,  is  referred to
         hereinafter  as the "ANNUAL  BASE SALARY"); provided, however, with
         respect  to a termination of employment prior to a Change  in Control
         that  is deemed  to have occurred  on the date  of the  Change in
         Control, "ANNUAL  BASE SALARY" shall be  the Employee's  annual rate
         of  base salary as  in effect immediately  prior to the  Employee's
         actual date of termination, but disregarding any  reduction therein
         made within 30 days  of the Employee's actual termination date; or

                 (c)      The  Company  fails  to  continue  in  effect any
         benefit  or  compensation  plan  (except  the Supplemental Executive
         Retirement Plan) which is material  to the Employee's  total
         compensation, including, but not  limited to,  the Company's  annual
         bonus  plan,  qualified retirement  plan,  executive life  insurance
         plan and/or  health and accident  plan, in which the  Employee is
         participating immediately  prior to the commencement of the Protected
         Period, or plans providing the Employee with





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         substantially similar  benefits, or  the Company  takes any  action
         that  would materially  adversely affect  the Employee's participation
         in or  reduce the  Employee's  benefits under  any of  such plans
         (excluding any  such action by the Company that is required by law);
         or

                 (d)      The  Company's principal  executive offices  are
         relocated  at any  time following  a Change  in Control more than 35
         miles from where such offices were located immediately prior to such
         Change in Control; or

                 (e)      The Company  requires the Employee at  any time
         following  a Change in Control  to relocate more than  35 miles  from
         where  the Company's  principal executive  offices were  located
         immediately prior  to such Change in Control; or

                 (f)      The Company fails to obtain  the assumption of the
         obligation to  perform this Agreement  by any successor as
         contemplated in Section 7.1 hereof; or

                 (g)      Any purported  termination of  the Employee's
         employment  by the  Company that  is not  effected pursuant  to a
         Notice of Termination  satisfying the requirements of  Section 2.5
         below and,  if applicable, the procedures described in Section 2.3
         above; or

                 (h)      The  Company shall violate or breach  any obligation
         of the Company in  effect immediately prior to the commencement of
         the Protected Period (regardless whether such  obligation be set forth
         in the  Employment Agreement or any other  separate agreement entered
         into  between the Company  and the Employee) to  indemnify the
         Employee against  any claim,  loss, expense or  liability sustained
         or incurred  by the Employee  by reason,  in whole or in part, of the
         fact that the Employee is or was an officer or director of the
         Company; or

                 (i)      The  Company shall violate  or breach any other
         material obligation  of the Company owing to the Employee  in effect
         immediately  prior to  the commencement  of the Protected  Period
         relating  to the Employee's employment with the Company,  but only if
         such violation or breach (if capable of  being remedied) shall
         continue unremedied for more than 15 days after written notice thereof
         is given by the Employee to the Company; or

                 (j)      The  Board (or  any nominating  committee  of the
         Board)  fails to  recommend and  support  the Employee's re-election
         as a director of  the Company if the  Employee is a  director of the
         Company  immediately prior to the commencement of the Protected
         Period.

         2.5     NOTICE  OF TERMINATION.  Any termination by  the Company
pursuant to Section 2.2 or  2.3 above or by the Employee pursuant to Section
2.4 above shall be communicated  by written Notice of Termination to the other
party hereto; provided, however,  that in  the  case of  events of  Good
Reason enumerated  in subsections  (f), (h),  (i)  or (l)  of Section 2.4
hereof, the Company  shall have the obligation to provide the Employee with
written notice of the occurrence of any of such events and the Employee shall
then have the opportunity





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to provide the Company with Notice  of Termination if he so elects.   The
Employee shall retain the ability to  terminate his employment for Good  Reason
under subsections (f), (h), (i)  or (l) of Section 2.4 hereof, even if  the
Company fails to  provide written notice of the occurrence of any of the
events specified in such subsections as provided herein.  For purposes of  this
Agreement, a "NOTICE OF TERMINATION"  shall mean a notice that shall  indicate
the specific termination provision in this Agreement relied on  and, except in
the case of the  termination referred to in the last subsection  of Section 2.4
above, shall  set forth in  reasonable detail  the facts and  circumstances
claimed  to provide a  basis for termination of the Employee's  employment
under the provision so indicated.  Any  purported termination of this Agreement
not in compliance  with the requirements of this  Section 2.5 or, if
applicable, the  procedures described in Section 2.3 above shall be
ineffective.

         2.6     DATE OF TERMINATION.   For purposes of  this Agreement, "DATE
OF TERMINATION" shall  mean:  (a) if  the Employee  is terminated on account
of Disability pursuant to Section 2.2  above, 30 days after  Notice of
Termination is given, provided that the  Employee shall not  have returned to
the  performance of the  Employee's duties on a  full-time basis during such
30-day period; (b) if the Employee's  employment is terminated for Cause
pursuant to Section 2.3 above, the date specified in  the Notice of
Termination; (c)  with respect to a  termination of employment prior to a
Change in Control that is deemed  to have occurred on the  date of the Change
in Control,  the date of such Change in  Control; and (d) if  the Employee's
employment is terminated for any other reason on or after a Change in Control,
the date on which a Notice of Termination is  given; provided, however, in the
event of any  dispute or controversy concerning the Employee's entitlement to
payment under this Agreement, solely for  purposes of Section 3.3 and 3.4
below, concerning the timing  of the payment of amounts under this Agreement,
the "DATE OF TERMINATION" shall mean  the date of final resolution of  such
dispute or controversy.

         SECTION 3.       COMPENSATION DURING DISABILITY, DURING PROTECTED
                          PERIOD OR ON TERMINATION.

         3.1     If a Change  in Control occurs during the Term  and if, during
the Protected Period,  the Employee fails to perform the Employee's normal
duties as a result of Disability (as defined in Section 2.2  hereof), the
Employee shall continue during the  period of Disability to  receive:  (i) the
Employee's full Annual Base  Salary at the rate  then in effect, (ii) any
awards, deferred and  non-deferred, payable during such period of disability
under the Company's annual bonus plan, less any amounts paid to  the Employee
during such period of Disability pursuant to the  Company's sick-leave or
disability program until  the Employee's employment  is terminated on  account
of Disability  pursuant to Section 2.2 hereof, and (iii) all other applicable
perquisites, insurance and other employee benefits.

         3.2     If a Change  in Control  occurs during  the Term and  if,
during  the Protected  Period, the  Employee's employment  shall be  terminated
by  the Company  for Cause  pursuant to  Section 2.3 above,  the Company  shall
pay  the Employee's earned but unpaid Annual  Base Salary through the Date of
Termination at the rate in effect at the time Notice of Termination is  given,
and the Company shall have no further obligations to  the Employee under this
Agreement, except those arising hereunder prior to the Date of Termination.





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         3.3     If a Change  in Control occurs during  the Term pursuant to
the Merger Agreement, then,  subject to the conditions stated in  the last
sentence of this Section 3.3,  the Company shall pay the Employee  the
following amount by certified or bank cashier's check on each of two dates:

         An amount equal to 1.25 times the sum of the Annual  Base Salary and
         an annual target bonus of  75% of the Annual Base Salary

The  foregoing amount shall  be paid  to the Employee  on each of  the
following dates,  if the conditions  stated in the following sentence  are met:
(1)  the date (the "MERGER  EFFECTIVE DATE") on which  the Effective Time of
the Merger as defined  in the Merger Agreement (the "MERGER EFFECTIVE TIME")
occurs, and  (2) the later of January 1, 1998, or the six- month anniversary
of the Merger Effective Date.   The amounts shall be  paid on those two dates
only  if the Employee is employed by  the Company on  the Merger Effective
Date, or if  the Company shall  have terminated the employment  of the Employee
during  the Protected Period  prior to  the Merger  Effective Date other  than
pursuant  to Sections 2.2 or  2.3 hereof, or  if the Employee  shall have
terminated the Employee's  employment during the  Protected Period prior  to
the Merger Effective Date for Good Reason in accordance with Section 2.4
hereof.

         3.4     If a  Change in Control occurs during  the Term and if,
during the Protected Period,  the Company shall terminate  the Employee  other
than  pursuant to  Sections 2.2 or  2.3 hereof  or if,  during  the Protected
Period, the Employee shall terminate the Employee's  employment for Good Reason
in accordance with  Section 2.4 hereof, then, subject to Section 5 below and
the following provisions of  this Section 3.4, the Company shall pay to the
Employee,  in a single lump  sum by certified  or bank  cashier's check within
five days of  such Date of  Termination, the sum  of the amounts specified in
clauses (a) and (b) below:

                 (a)      an amount equal  to that portion of  the Annual Base
         Salary earned,  but not paid, and  vacation earned, but not taken,  in
         each case,  to the Date of Termination,  and all other amounts
         previously  deferred by the Employee  (except any amounts in  any
         tax-qualified retirement  or savings plan, which  shall be governed
         by the terms  of such  plan) or  earned  but not  paid as  of such
         date  under all  Company  incentive or  deferred compensation plans or
         programs; and

                 (b)      an amount equal to (i) the amount of the maximum
         monthly premium payment that may be charged  to continue coverage for
         the  Employee and the  Employee's eligible dependents under the
         Company's health insurance plan under COBRA, multiplied by (ii) 30
         months.

         SECTION 4.       ACCELERATION OF OPTION AND RESTRICTED STOCK GRANTS

         4.1     If a Change in Control  occurs during the Term pursuant  to
the Merger Agreement and the  Employee holds outstanding unexercisable  options
under the  Company's stock  option plan(s) immediately  prior to the  Merger
Effective Time (the "UNEXERCISABLE OPTIONS"),  then, notwithstanding any
provisions of  such plans or prior agreements  between the Company and the
Employee (and in lieu of any exercisability or vesting schedules therein), each





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date on which a portion  of an Unexercisable Option would otherwise vest and
become exercisable  (a "VESTING DATE") shall be accelerated by  two years;
provided, however, that no  accelerated Vesting Date shall be deemed  to occur
earlier than immediately prior to the Merger Effective Time.  Notwithstanding
the foregoing provisions of this Section 4.1, a  portion of  an Unexercisable
Option  shall become exercisable  on a projected  accelerated Vesting  Date
only if  the Employee is employed by the Company on such date; provided,
however,  in the event the Employee's employment is terminated subsequent to
the Effective Time of  this Agreement while the Employee holds Unexercisable
Options, (i) due to the Employee's death, (ii) by the Company  on account of
the Employee's Disability  as provided in  Section 2.2 hereof, (iii)  by the
Company other  than  for Cause  as  provided in  Section 2.3 hereof,  or (iv)
by  the  Employee for  Good  Reason as  provided in Section 2.4 hereof,  then,
notwithstanding any  provision of  this Agreement to  the contrary, each
Unexercisable Option shall become fully vested and exercisable  on the later of
(x) the date  of such termination or (y) immediately prior  to the Merger
Effective Time.

         4.2     If a Change in Control occurs  during the Term pursuant to the
Merger Agreement and the Employee  holds any outstanding  shares of  restricted
stock  issued by the  Company to  the Employee under  the Company's  stock
plan(s) (including those  granted under  the Company's Target  2000: One, Two,
Four Plan)  which remain subject  to restrictions and/or performance  or other
criteria  relating thereto  (the "RESTRICTIONS") immediately  prior to the
Merger Effective Time  (the "RESTRICTED  SHARES"), then,  notwithstanding any
provisions  of such  plans or  prior agreements  between the Company and the
Employee (and in lieu  of any schedules for the lapsing of restrictions
contained  therein), each date on which Restrictions  on a portion  of the
Restricted Shares  would otherwise lapse  or be  deemed satisfied  in full,  as
applicable (a  "Lapsing Date"), shall be  accelerated by two years;  provided,
however, that no  accelerated Lapsing Date shall be deemed  to occur earlier
than  immediately prior to  the Merger Effective Time.   Notwithstanding the
foregoing provisions  of this  Section 4.2, Restrictions  shall lapse  on  such
portion  of the  Restricted Shares  on  a projected accelerated Lapsing Date
only if  the Employee is employed by the  Company on such date; provided,
however, in  the event the Employee's  employment is  terminated subsequent to
the Effective Time  of this  Agreement while the  Employee holds Restricted
Shares, (i) due  to the  Employee's death,  (ii) by the Company  on account  of
the  Employee's Disability  as provided  in Section 2.2 hereof, (iii) by the
Company other than for  Cause as provided in Section 2.3 hereof, or (iv) by the
Employee for Good Reason as  provided in Section 2.4 hereof, then,
notwithstanding any provision of this Agreement to the contrary, all
Restrictions on  all such Restricted Shares shall lapse or be deemed satisfied
in full, as applicable, on the later of (x)  the date of such termination or
(y)  immediately prior to the Merger Effective Time.   No later than the fifth
day following any  such lapse of  Restrictions, the  Company shall cause  the
relevant unrestricted  shares of stock to be delivered to the Employee.

         SECTION 5.       GROSS-UP OF PARACHUTE PAYMENT.

         5.1     To provide  the Employee with  adequate protection in
connection with his  ongoing employment  with the Company,  this Agreement
provides the  Employee with  various benefits  in the  event of  termination of
the Employee's employment with the Company during the Protected Period.  If the
Employee's employment is terminated following a  "CHANGE IN CONTROL" of the
Company, within the meaning of Section 280G of the Internal Revenue Code of
1986, as





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<PAGE>   8
amended (the "CODE"),  a portion  of those  benefits could be  characterized as
"EXCESS PARACHUTE  PAYMENTS" within  the meaning  of Section 280G of the  Code.
The parties hereto  acknowledge that the protections set  forth in this Section
5 are important,  and it is agreed  that the Employee should not  have to bear
the  burden of any excise  tax that might be levied under Section 4999 of the
Code,  in the event that a portion of  the benefits payable to the Employee
pursuant  to this Agreement are  treated as an excess  parachute payment.  The
parties, therefore, have agreed  as set forth  in this Section 5.

         5.2     Anything in  this Agreement to the contrary notwithstanding,
if it  shall be determined that any payment or distribution by the  Company or
any other  person to or for  the benefit of the Employee  (whether paid or
payable  or distributed or  distributable pursuant to the terms of this
Agreement  or otherwise, but determined without regard to any additional
payments  required  under this  Section 5)  (a "PAYMENT")  would  be subject
to  the excise  tax  imposed  by Section 4999 of the Code or  any interest or
penalties are incurred by the Employee with respect to such excise tax (such
excise tax, together  with any  such interest  and penalties, are  hereinafter
collectively  referred to  as the  "EXCISE TAX"), then the Company  shall pay
an additional payment (a  "GROSS-UP PAYMENT") in an amount such  that after
payment by the Employee of all  taxes (including any interest or  penalties
imposed with respect to such  taxes), including, without limitation, any income
taxes (and any interest and penalties imposed with respect thereto)  and Excise
Tax imposed on the Gross-Up Payment,  the Employee  retains  an amount  of the
Gross-Up Payment  equal to  the Excise  Tax  imposed on  the Payments.

         5.3     Subject  to the  provisions of  Section 5.4 below,  all
determinations  required to  be made  under this Section 5, including  whether
and when  a Gross-Up Payment is  required and the  amount of such Gross-Up
Payment and the assumptions to be  utilized in arriving  at such determination,
shall  be made by  an independent public  accounting firm with a  national
reputation  that is  selected  by the  Employee (the  "ACCOUNTING FIRM")  which
shall  provide  detailed supporting calculations both to  the Company and to
the Employee within  15 business days after  each receipt of  notice from the
Employee that there has been a Payment, or such earlier time as is requested by
the Company.  In the event that the Accounting  Firm is serving  as accountant
or  auditor for the  individual, entity or  group effecting the  change in
control  of  the  Company,  the  Employee  shall  appoint another  nationally
recognized  accounting  firm  to  make the determinations required hereunder
(which accounting firm shall  then be referred to  as the Accounting  Firm
hereunder).  All fees and expenses of the Accounting Firm shall be borne solely
by  the Company.  The Company shall indemnify and hold harmless the Employee,
on an after-tax basis,  for any Excise Tax or  income tax (including interest
and  penalties with respect thereto) imposed on  the Employee as a result  of
such payment of  fees and expenses.  Any Gross-Up  Payment with respect  to the
respective Payment,  as determined  pursuant to  this Section 5,  shall be
paid by  the Company  to the Employee within five days of the receipt of the
Accounting Firm's  determination.  If the Accounting Firm determines that no
Excise Tax is  payable by the Employee with  respect to the respective
Payment, it shall furnish the Employee  with a written opinion that  failure to
report the Excise Tax  on the Employee's applicable federal income  tax return
would not result in the imposition of a  negligence or similar penalty.  Any
determination by the Accounting  Firm shall be binding on the Company and  the
Employee.  As a result of uncertainty in the application of  Section 4999 of
the Code at the time of the initial  determination by the Accounting Firm
hereunder,  it is possible that Gross-Up Payments  may not have been made by
the Company which should have been made ("UNDERPAYMENT"), consistent with the





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<PAGE>   9
calculations required to be made  hereunder.  If the Company exhausts its
remedies pursuant to  Section 5.4 below and the Employee thereafter is required
to make a payment of any  Excise Tax, the Accounting Firm shall determine  the
amount of the Underpayment that has occurred  and any such Underpayment shall
be promptly paid by the Company to or for the benefit of the Employee.

         5.4     The  Employee shall  notify the  Company in  writing of  any
claim (including  any threatened  tax lien related to or based on  any such
claim) by the Internal Revenue Service that, if successful, would require the
payment by the  Company of the  Gross-Up Payment.   Such notification  shall be
given  as soon as  practicable but no  later than 10 business days after the
Employee is informed in writing of such claim (or threatened lien) and  shall
apprise the Company of the nature of  such claim and the date on which such
claim is requested to be paid.  The  Employee shall not pay such claim prior
to the expiration of  the 30-day period following  the date on which  the
Employee gives such  notice to the Company (or such shorter period ending on
the  date that any payment of taxes with  respect to such claim is due or  such
tax lien would be imposed).   If the Company notifies the Employee in writing
prior to the expiration of such period that it desires to contest such claim
(or threatened lien), the Employee shall:

                 (a)      give the Company any information reasonably requested
         by the Company relating to  such claim (or threatened lien);

                 (b)      take  such action in connection with  contesting such
         claim (or threatened lien)  as the Company shall  reasonably request
         in  writing  from  time  to  time,  including,  without  limitation,
         accepting  legal representation with respect to such claim by an
         attorney reasonably selected by the Company;

                 (c)      cooperate  with the  Company in  good  faith in
         order  effectively to  contest such  claim  (or threatened lien); and

                 (d)      permit  the Company  to participate  in any
         proceedings relating to  such claim  (or threatened lien);

provided, however,  that the Company shall  bear and pay directly  all costs
and expenses  (including additional interest and penalties) incurred in
connection  with such contest and shall indemnify and hold the Employee
harmless, on an after- tax basis, for any Excise  Tax or income tax (including
interest and penalties with  respect thereto) imposed as a result of  such
representation  and payment  of costs  and expenses.   Without  limitation on
the  foregoing provisions  of this Subsection 5.4, the Company shall control
all proceedings taken in connection  with such contest and, at its sole option,
may pursue or forego any and all administrative  appeals, proceedings, hearings
and conferences with the taxing authority in respect of such  claim and may, at
its sole  option, either direct the Employee to  pay the tax claimed and sue
for a refund or  contest  the claim  in  any permissible  manner,  and the
Employee  agrees to  prosecute  such contest  to  a determination  before any
administrative tribunal,  in a  court of  initial jurisdiction  and in  one or
more appellate courts, as  the Employee shall determine (but in no event shall
the  Company permit or direct the Employee to allow a tax lien to be imposed on
the Employee's property);  provided, further, that if the Company directs the
Employee  to pay such claim and sue for a refund, the Company shall advance the
amount of such payment to the





                                      -9-
<PAGE>   10
Employee, on an interest-free basis,  and shall indemnify and hold the Employee
harmless on an  after-tax basis, from any Excise Tax or income tax (including
interest  or penalties with respect thereto) imposed with respect to such
advance or with respect  to any  imputed income  with respect to  such advance;
and further,  provided, that any  extension of  the statute of limitations
relating to payment  of taxes for  the taxable year of  the Employee with
respect to which  such contested amount is claimed to  be due is limited solely
to such contested amount.  In addition, the Company's control of the  contest
shall be  limited to issues  with respect to  which a Gross-Up Payment  would
be payable  hereunder, and the Employee  shall be entitled to  settle or
contest,  as the case  may be, any  other issue raised by  the Internal Revenue
Service or any other taxing authority.

         5.5     If, after the receipt by the  Employee of an amount advanced
by the Company pursuant to Section 5.2, 5.3 or 5.4, the  Employee becomes
entitled to receive any refund with respect to  such amount, the Employee shall
(subject to the  Company's complying with  the requirements  of Section 5.4
above)  promptly pay  to the  Company the amount  of such refund  (together
with any interest  paid or credited thereon  after taxes applicable thereto).
If after the receipt by the Employee  of an amount advanced  by the Company
pursuant  to Section 5.2, 5.3  or 5.4 above, a  determination is made that the
Employee shall  not be entitled to any  refund with respect to such  amount and
the Company does not  notify the Employee in  writing of  its intent  to
contest such  denial of  refund prior  to the  expiration of 30  days after
such determination, then such advance shall  be forgiven and shall not be
required to be repaid and the amount of such advance shall offset, to the
extent thereof, the amount of Gross-Up Payment required to be paid.

         SECTION 6.       NO MITIGATION OF DAMAGES.  The provisions of this
Agreement are not intended  to, nor shall they be construed to,  require that
the Employee seek  or accept other employment  following a termination of
employment and, amounts payable and  benefits provided  under this  Agreement
to  the Employee  shall not  be reduced  by the  Employee's acceptance of  (or
failure to  seek or accept)  employment with another  person.  The  Company's
obligations to  make the payments and  provide the  benefits required for  in
this Agreement  and otherwise  to perform its  obligations hereunder shall  not
be  affected by any  set off,  counterclaim, recoupment,  defense or  other
claim,  rights or action  that the Company may have against the Employee or
others.

         SECTION 7.       SUCCESSORS; BINDING AGREEMENT.

         7.1     The Company will require any  successor, whether direct or
indirect, by purchase,  merger, consolidation or otherwise, of all or
substantially all of the business and/or assets of the Company, expressly to
assume and agree to perform this Agreement  in the same  manner and to the
same extent as  the Company would have  been required if no  such succession
had  taken place.   Failure of the  Company to obtain  such agreement prior  to
the effectiveness of  any such succession shall be  a breach of this Agreement
and shall entitle the Employee  to compensation from the  Company in the same
amount and on the same  terms as the Employee would be entitled hereunder if
the Employee terminated the Employee's employment for  Good  Reason, except
that  for purposes  of  implementing the  foregoing, the  date  on which  any
such succession  becomes effective shall be deemed the  Date of Termination.
As used  in this Agreement, "COMPANY" shall mean the Company  as hereinbefore
defined and any  successor to  its business  and/or assets as  aforesaid that
executes and delivers the agreement provided for in





                                      -10-
<PAGE>   11
this Section 7.1 or which otherwise becomes bound by all the terms and
provisions of this Agreement by operation of law.

         7.2     This Agreement shall  inure to the benefit  of and be
enforceable by the  Employee's personal or  legal representatives,  executors,
administrators,  successors, heirs, distributees,  devisees and  legatees.   If
the Employee should die while any amounts  would still be payable to the
Employee hereunder if the Employee had continued to live, all such  amounts,
unless otherwise  provided herein, shall  be paid in  accordance with the
terms of this  Agreement to the Employee's devisee, legatee or other designee
or, if none, to the Employee's estate.

         SECTION 8.       NOTICE.  For  the purpose of this Agreement,  notices
and all other communications provided  for herein shall be in writing and
shall be deemed to have been duly given when delivered  or five days after
deposit in the United States  mail, registered and return receipt requested,
postage prepaid,  addressed to the respective addresses set forth  below or  to
such  other address  as either  party shall  have furnished  to the  other  in
writing  in accordance herewith, except that notices of change of address shall
be effective only on receipt.

                          If to the Company:

                          Allwaste, Inc.
                          5151 San Felipe, Suite 1600
                          Houston, Texas  77056
                          Attention:  Chairman of the Compensation
                          Committee of the Board of Directors

                          If to Employee:

                          T. Wayne Wren, Jr.
                          11311 Williamsburg
                          Houston, Texas  77024

         SECTION 9.       CHANGE IN CONTROL.   For purposes of this  Agreement,
a "CHANGE  IN CONTROL" shall be  deemed to have  occurred upon the consummation
of  the transactions contemplated by  the Merger Agreement at  the Effective
Time of the Merger (as defined in the Merger Agreement).

         SECTION 10.      EMPLOYMENT WITH  SUBSIDIARIES AND PARENTS.
Employment  with the Company  for purposes  of this Agreement includes
employment with any entity (a "PARENT") which  owns, directly or indirectly,
50% or more of  the total combined voting power of  the Company's outstanding
equity interests and employment with  any entity in which the Company or  the
Parent has  a direct or  indirect ownership interest  of 50% or  more of the
total combined voting  power of all outstanding equity interests, it being
understood that for purposes of clause  (a) of Section 2.4 hereof, "GOOD
REASON" shall be construed to refer to each of  the Employee's positions,
duties, responsibilities (reporting and other), status, titles and offices with
the Company and each of its subsidiaries and parents.





                                      -11-
<PAGE>   12
         SECTION 11.      MISCELLANEOUS.   No  provision of this  Agreement may
be modified, waived  or discharged unless such waiver,  modification or
discharge is  agreed to  in writing  signed by  the Employee and  by the
Chairman of  the Compensation Committee of the Board  or other authorized
officer of the Company.  No waiver by either party hereto at any time of any
breach by the  other party hereto of, or compliance with, any condition or
provision of this Agreement to be performed  by such other party shall be
deemed a waiver of  similar or dissimilar provisions or conditions at the same
or at any prior  or subsequent time.  Any  payments provided for hereunder
shall  be paid net of any  applicable withholding required under federal, state
or local law and any additional withholding to which the Employee has agreed.

         SECTION 12.      VALIDITY.  THE INTERPRETATION, CONSTRUCTION AND
PERFORMANCE OF THIS AGREEMENT SHALL BE GOVERNED BY  AND CONSTRUED AND  ENFORCED
IN  ACCORDANCE WITH THE  LAWS OF THE  STATE OF TEXAS  WITHOUT REGARD TO  THE
PRINCIPLE OF CONFLICTS OF LAWS.   The invalidity or unenforceability of any
provisions of this Agreement shall not affect the validity or enforceability of
any other provision of this Agreement, each of which shall remain in full force
and effect.

         SECTION 13.      COUNTERPARTS.  This Agreement may  be executed in one
or more  counterparts, each of which shall be deemed to be an original but all
of which together shall constitute one and the same instrument.

         SECTION 14.      DESCRIPTIVE HEADINGS.   Descriptive headings are for
convenience  only and shall  not control or affect the meaning or construction
of any provision of this Agreement.

         SECTION 15.      CORPORATE APPROVAL.  This Agreement has  been
approved by  the Board of Directors, and has  been duly executed and delivered
by Employee and on behalf of the Company by its duly authorized representative.

         SECTION 16.      DISPUTE RESOLUTION.

         16.1    In the event  a dispute shall arise between the  parties as to
whether the provisions  of this Agreement have  been complied  with (a
"DISPUTE") the  parties agree  to resolve  such Dispute  in accordance  with
the following procedure:

                 (a)      A meeting shall be held promptly between  the
         parties, attended by (in the  case of the Company) one  or more
         individuals with  decision-making authority  regarding the  Dispute,
         to  attempt  in good  faith to negotiate a resolution of the Dispute.

                 (b)      If,  within  10 days  after  such  meeting, the
         parties  have not  succeeded  in  negotiating a resolution  of the
         Dispute,  the parties  agree  to submit  the  Dispute to  mediation
         in accordance  with  the Commercial Mediation Rules of the American
         Arbitration Association.

                 (c)      The parties  will jointly  appoint a  mutually
         acceptable  mediator, seeking assistance  in such regard from the
         American Arbitration Association if they





                                      -12-
<PAGE>   13
         have been unable  to agree on such appointment within 10  days
         following the 10-day  period referred to in clause (b) above.

                 (d)      On appointment of the mediator, the parties agree to
         participate in good faith in  the mediation and negotiations relating
         thereto for 15 days.

                 (e)      If the parties are  not successful in resolving the
         Dispute through mediation within such 15-day period, the  parties
         agree that the  Dispute shall be  settled by arbitration in
         accordance with the  Commercial Arbitration Rules of the American
         Arbitration Association.

                 (f)      The fees and expenses  of the mediator/arbitrators
         shall be borne solely by  the non-prevailing party or, in the event
         there is no clear prevailing party, shall be borne by the Company.

                 (g)      If  any dispute  shall  arise  under this  Agreement
         involving termination  of  the  Employee's employment with the
         Company or involving the  failure or refusal of the  Company to fully
         perform in accordance with  the terms hereof,  the Company  shall
         reimburse the  Employee, on a current  basis, for all  legal fees and
         expenses, if any, incurred  by the Employee in  connection with such
         dispute, together with interest  thereon at the prevailing legal  rate
         of interest, such interest  to accrue from the  date of Notice of
         Termination  through the date of payment thereof; provided,  however,
         that in the event the resolution  of such dispute in  accordance with
         this Section 16 includes  a finding denying, in total, the  Employee's
         claims in such dispute, the  Employee shall be  required to reimburse
         the Company,  over a  period determined by  the Employee  but not  to
         exceed  12 months from the  date of such resolution,  for all sums
         advanced to the  Employee with respect  to such  dispute pursuant to
         this clause (g).

                 (h)      Except as  provided above, each party shall pay  its
         own costs  and expenses (including, without limitation, reasonable
         attorneys' fees) relating  to any mediation/arbitration  proceeding
         conducted under  this Section 16.

                 (i)      All mediation/arbitration conferences and hearings
         will be held in Houston, Texas.

         16.2    In the event there  is any disputed question of law involved
in  any arbitration proceeding, such as the proper  legal  interpretation of
any  provision of  this Agreement,  the arbitrators  shall  make separate  and
distinct findings of all facts material  to the disputed question of law  to be
decided and, on  the basis of the facts  so found, express their conclusion of
the  question of law.  The facts so found shall be conclusive and binding on
the parties, but any legal  conclusion reached by the arbitrators from such
facts  may be submitted by either party to  a court of law for final
determination  by initiation  of a civil  action in the  proper state  or
Federal court  sitting in  Harris County, Texas.  Such action,  to be valid,
must be commenced  within 20 days after receipt  of the arbitrators' decision.
If no such civil  action is  commenced within such  20-day period,  the legal
conclusion reached by  the arbitrators  shall be conclusive  and binding on the
parties.  Any such  civil action shall be  submitted, heard and  determined
solely on the basis of the facts found by the arbitrators.  Neither of the
parties shall, or shall be entitled to, submit





                                      -13-
<PAGE>   14
any additional or different facts  for consideration by the court.  In the
event any civil action is commenced under this Section 16.2, the party who
prevails  or substantially prevails (as determined  by the court) in such civil
action shall be entitled to  recover from the other  party all costs, expenses
and  reasonable attorneys' fees incurred  in connection with such action and on
appeal.

         16.3    Except as limited  by Section 16.2 above, the parties  agree
that judgment on the  award rendered by the arbitrators may be  entered in any
court of competent  jurisdiction.  In  the event legal  proceedings are
commenced  to enforce  the rights awarded in an arbitration proceeding, the
party  who prevails or substantially prevails in such legal proceeding shall be
entitled to recover from the other party  all costs, expenses and reasonable
attorneys' fees incurred in connection with such legal proceeding and on
appeal.

         16.4    Except as provided above,  no legal action may be brought  by
either party with respect to  any Dispute.  All Disputes shall be determined
only in accordance with the procedures set forth above.

         SECTION 17.      NO  OTHER SEVERANCE BENEFITS.  In the event the
Employee becomes entitled to severance payments under Section 3.3 or 3.4  of
this Agreement, then  the amounts payable under this  Agreement to the Employee
shall  be in lieu of, and not in addition  to, any similar severance amounts to
which  the Employee may otherwise be entitled under  a severance plan or
program of the Company or any employment contract or agreement with the
Company.

         IN WITNESS WHEREOF,  the Company and the  Employee have entered into
this Agreement as  of the day and year first above written.

                                  ALLWASTE, INC.


                                  By: /s/ Robert M. Chiste                    
                                      ----------------------------------------
                                           Robert M. Chiste



                                  EMPLOYEE


                                  /s/ T. Wayne Wren, Jr.                       
                                  --------------------------------------------
                                  T. Wayne Wren, Jr.





                                      -14-
