Document:

FOURTH AMENDMENT

                  FOURTH  AMENDMENT  (this  "AMENDMENT"),  dated as of March 13,
2000, to the Amended and Restated  Credit  Agreement,  dated as of April 3, 1998
(as amended,  supplemented or otherwise  modified from time to time, the "CREDIT
AGREEMENT"),  among SAFETY-KLEEN SERVICES, INC. (formerly known as LES, Inc.), a
Delaware   corporation  (the  "COMPANY"),   SAFETY-KLEEN   LTD.   (successor  to
Safety-Kleen  (Canada) Ltd.,  which was formerly known as Laidlaw  Environmental
Services (Canada) Ltd.), a Canadian corporation and a wholly owned subsidiary of
the Company (together with the Company, the "BORROWERS"),  the several banks and
other financial  institutions or entities from time to time parties thereto (the
"LENDERS"),  TORONTO DOMINION (TEXAS), INC., as general administrative agent (in
such capacity, the "GENERAL  ADMINISTRATIVE  AGENT"), THE TORONTO-DOMINION BANK,
as Canadian  administrative  agent, TD SECURITIES  (USA) INC., as advisor to the
Borrowers and arranger of the commitments described in the Credit Agreement, THE
BANK OF NOVA SCOTIA, BANK OF AMERICA (formerly known as Nationsbank,  N.A.), THE
FIRST NATIONAL BANK OF CHICAGO and WACHOVIA BANK, N.A., as managing agents,  THE
BANK OF NOVA SCOTIA and THE FIRST NATIONAL BANK OF CHICAGO,  as co-documentation
agent, and BANK OF AMERICA (formerly known as Nationsbank, N.A.), as syndication
agent.

                              W I T N E S S E T H:
                              - - - - - - - - - -

                  WHEREAS,  the Borrowers have requested that the Administrative
Agents and the Lenders agree to amend certain provisions of the Credit Agreement
upon the terms and subject to the conditions set forth herein; and

                  WHEREAS, the Administrative Agents and the Lenders have agreed
to such  amendments  only upon the terms and subject to the conditions set forth
herein;

                  NOW,  THEREFORE,  in  consideration  of the  premises  and the
mutual  covenants   contained  herein  and  in  the  Credit  Agreement  and  the
Supplement, the parties hereto hereby agree as follows:

                  1.  Defined  Terms.   Unless  otherwise  defined  herein,  all
                      -------------
capitalized  terms  used  herein  shall have the  meanings  given to them in the
Credit Agreement.

                  2.  Amendment  to  Section  10.2.  Section  10.2 of the Credit
                      ----------------------------
Agreement  is hereby  amended by adding at the end  thereof  the  following  new
paragraph:

                  (k)   Indebtedness   incurred  on  or  after  March  13,  2000
         represented  by loans  (which  may be  secured  by Liens  permitted  by
         Section  10.3(m))  in  an  aggregate  principal  amount  not  exceeding
         $20,000,000.

093110-0154-01964-A03AFJN9-WAI
<PAGE>

                                                                               2

                  3.  Amendment  to  Section  10.3.  Section  10.3 of the Credit
                      ----------------------------
Agreement  is hereby  amended by adding at the end  thereof  the  following  new
paragraph:

                  (m) Liens on real  property of the Company or a Subsidiary  of
         the  Company  located  in Elgin,  Illinois,  and on other  unencumbered
         assets of the  Company  and its  Subsidiaries,  in each  case  securing
         Indebtedness permitted by Section 10.2(k).

                  4.  Amendment  to  Section  10.6.  Section  10.6 of the Credit
                      ----------------------------
Agreement  is hereby  amended by adding at the end  thereof  the  following  new
paragraph:

                  (h) the sale or other  Disposition  of assets  subject  to the
         Liens permitted by Section 10.3(m), provided that the Net Cash Proceeds
         of such sale or other  Disposition  shall be applied in accordance with
         this Agreement.

                  5.  Conditions to  Effectiveness.  This Amendment shall become
                      ----------------------------
effective  as of the date  first  above  written  when (i) each of the  Required
Lenders, the General  Administrative Agent and the Borrowers shall have executed
and delivered this Amendment and (ii) each Guarantor shall have acknowledged and
agreed to this Amendment.

                  6. Continuing  Effects.  Except as expressly waived or amended
                     -------------------
hereby,  the Credit  Agreement and the Supplement shall continue to be and shall
remain in full force and effect in accordance with their respective terms.

                  7.  Expenses.  The  Company  agrees to pay and  reimburse  the
                      --------
General  Administrative Agent for all of its reasonable  out-of-pocket costs and
expenses  incurred in connection with the negotiation,  preparation,  execution,
and delivery of this  Amendment,  including the reasonable  fees and expenses of
counsel.

                  8. Counterparts.  This Amendment may be executed on any number
                     ------------
of separate  counterparts and all of said  counterparts  taken together shall be
deemed to constitute one and the same instrument.

                  9.  GOVERNING  LAW. THIS  AMENDMENT  SHALL BE GOVERNED BY, AND
                      --------------
CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAW  OF THE STATE OF NEW YORK.

<PAGE>
                                                                               3

                  IN WITNESS  WHEREOF,  the  parties  hereto  have  caused  this
Amendment to be duly executed and delivered by their proper and duly  authorized
officers as of the day and year first above written.

                                  SAFETY-KLEEN SERVICES, INC. (formerly
                                    known as LES, Inc.)

                                  By:  /s/ Henry H. Taylor
                                      -----------------------------
                                       Name:  Henry H. Taylor
                                       Title: Secretary

                                  SAFETY-KLEEN (CANADA) LTD. (formerly
                                    known as Laidlaw Environmental Services
                                    (Canada) Ltd.)

                                  By:  /s/ Henry H. Taylor
                                      -----------------------------
                                       Name:  Henry H. Taylor
                                       Title: Secretary

                                  TORONTO DOMINION (TEXAS), INC., as
                                    General Administrative Agent and Lender

                                  By:  /s/ Warren Finlay
                                      -----------------------------
                                       Name:  Warren Finlay
                                       Title: President

                                  THE TORONTO-DOMINION BANK,
                                    as Canadian Administrative Agent

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  THE TORONTO-DOMINION BANK, as a Lender

                                  By:  /s/ Warren Finlay
                                      -----------------------------
                                       Name:  Warren Finlay
                                       Title: President

<PAGE>
                                                                               4
                                 TD SECURITIES (USA) INC., as Arranger

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  THE BANK OF NOVA SCOTIA, as Managing
                                    Agent, Co-Documentation Agent and Lender

                                  By:  /s/ William E. Zarrett
                                      -----------------------
                                       Name:  William E. Zarrett
                                       Title: Managing Director

                                  THE FIRST NATIONAL BANK OF CHICAGO,
                                    n/k/a BankOne, NA, as Managing Agent,
                                    Co-Documentation Agent and Lender

                                  By:  /s/ Richard Babcock
                                      -----------------------------
                                       Name:  Richard Babcock
                                       Title: Vice President

                                  BANK OF AMERICA (formerly known as
                                    Nationsbank, N.A.), as Syndication Agent,
                                    Managing Agent and Lender

                                  By:  /s/ Richard M. Starke
                                      -----------------------------
                                       Name:  Richard M. Starke
                                       Title: Managing Director

                                  WACHOVIA BANK, N.A., as Managing Agent
                                    and Lender

                                  By:  /s/ Donald E. Sellers, Jr.
                                      -----------------------------
                                       Name:  Donald E. Sellers, Jr.
                                       Title: Vice President

                                  THE CIT GROUP/BUSINESS CREDIT, INC.

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

<PAGE>
                                                                               5

                                  GENERAL ELECTRIC CAPITAL
                                    CORPORATION

                                  By:  /s/ Karl Kieffer
                                      -----------------------------
                                       Name:  Karl Kieffer
                                       Title: Duly Authorized Signatory

                                  COMERICA BANK

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  FLEET NATIONAL BANK

                                  By:  /s/ T. D. Opie
                                        ---------------------------
                                       Name:  Thomas D. Opie
                                       Title: VP

                                  ROYAL BANK OF CANADA

                                  By:
                                           Name:
                                           Title:

                                  CREDIT INDUSTRIEL ET COMMERCIAL

                                  By:  /s/ Brian O'Leary
                                      -----------------------------
                                       Name:  Brian O'Leary
                                       Title: Vice President

                                  By:  /s/ Anthony Rock
                                      -----------------------------
                                       Name:  Anthony Rock
                                       Title: Vice President
<PAGE>
                                                                               6

                                  HSBC BANK USA (formerly Marine Midland
                                    Bank)

                                  By:  /s/ Stephen V. Proctor
                                      ----------------------
                                       Name:  Stephen V. Proctor
                                       Title: Authorized Signatory

                                  THE LONG-TERM CREDIT BANK OF JAPAN,
                                    LTD.

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  THE MITSUBISHI TRUST AND BANKING
                                    CORPORATION

                                  By:  /s/ Toshihiro Hayashi
                                       ----------------------------
                                       Name:  Toshihiro Hayashi
                                       Title: Senior Vice President

                                  FLEET BUSINESS CREDIT CORPORATION
                                    (formerly Sanwa Business Credit Corporation)

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  SOCIETE GENERALE

                                  By:  /s/ Robert Petersen
                                      -----------------------------
                                       Name:  Robert Petersen
                                       Title: Director

                                  SOUTHERN PACIFIC BANK

                                  By::
                                      -----------------------------
                                       Name:
                                       Title:

<PAGE>
                                                                               7

                                  CREDIT LYONNAIS ATLANTA AGENCY

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  COOPERATIEVE CENTRALE RAIFEISEN-
                                    BOERENLEENBANK B.A., "RABOBANK
                                    NEDERLAND" NEW YORK BRANCH

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  COMMERCIAL LOAN FUNDING TRUST I

                                  By: Lehman Commercial Paper Inc., not in its
                                      individual capacity but solely as
                                      administrative agent

                                  By:  /s/ Michele Swanson
                                      -----------------------------
                                       Name:  Michele Swanson
                                       Title: Authorized Signatory

                                  CREDIT SUISSE FIRST BOSTON

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  THE SAKURA BANK, LTD.

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

<PAGE>
                                                                               8
                                  FIRSTAR BANK, N.A.

                                  By:  /s/ Mark A. Whitson
                                      -------------------
                                       Name:  Mark A. Whitson
                                       Title: Vice President

                                  BANK OF HAWAII

                                  By:
                                      -----------------------------
                                       Name:
                                       Title: t

                                  CITIBANK, N.A.

                                  By:  /s/
                                       ----------------------------
                                       Name:
                                       Title:

                                  THE DAI-ICHI KANGYO BANK, LTD.

                                  By:
                                      -----------------------------
                                       Name:
                                       Title

                                  SKANDINAVISKA ENSKILDA BANKEN AS
                                  (PUBL.) NY BRANCH

                                  By:
                                      -----------------------------
                                       Name:
                                       Title

                                  THE SUMITOMO BANK, LTD.

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

<PAGE>
                                                                               9

                                  THE SUMITOMO TRUST & BANKING CO.,
                                    LTD., NEW YORK BRANCH

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  NATIONAL CITY BANK

                                  By:  /s/ Lisa B. Lisi
                                      -----------------------------
                                       Name:  Lisa B. Lisi
                                       Title: Vice President

                                  BHF-BANK AKTIENGESELLSCHAFT

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  THE FUJI BANK, LIMITED

                                  By:  /s/ John D. Doyle
                                      -----------------------------
                                       Name:  John D. Doyle
                                       Title: Vice President & Manager

                                  CAISSE DE DEPOT ET PLACEMENT DU
                                    QUEBEC

                                  By:  /s/ Luis Lavoie
                                      -----------------------------
                                       Name:  Louis Lavoie
                                       Title: Vice President

                                  By:  /s/ Lucie Rousseau
                                      -----------------------------
                                       Name:  Lucie Rousseau
                                       Title: Vice-President
<PAGE>
                                                                              10

                                  KZH PONDVIEW LLC

                                  By:  /s/ Susan Lee
                                      -----------------------------
                                       Name:  Susan Lee
                                       Title: Authorized Agent

                                  WEBSTER BANK

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  BANQUE WORMS CAPITAL CORPORATION

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  IMPERIAL BANK

                                  By:  /s/ Ray Vadalma
                                      -----------------------------
                                           Name:  Ray Vadalma
                                           Title:   Senior Managing Director

                                  THE PRUDENTIAL INSURANCE COMPANY
                                           OF AMERICA

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  GPSF SECURITIES, INC.

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:
<PAGE>
                                                                              11

                                  KZH CNC LLC

                                  By:   /s/ Susan Lee
                                      -----------------------------
                                       Name:  Susan Lee
                                       Title: Authorized Agent

                                  SUMMIT BANK

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  METROPOLITAN LIFE INSURANCE
                                           COMPANY

                                  By:  /s/ James R. Dingler
                                      -----------------------------
                                       Name:  James R. Dingler
                                       Title: Director

                                  FIRST TRUST BANK

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  BANCO ESPIRITO SANTO

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  THE CITY NATIONAL BANK

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:
<PAGE>
                                                                              12

                                  VAN KAMPEN PRIME RATE INCOME TRUST
                                  By:  Van Kampen Investment Advisory Corp.

                                  By:  /s/ Douglas J. Smith
                                      -----------------------------
                                       Name:  Douglas J. Smith
                                       Title: Vice President

                                  OAK HILL SECURITIES FUND, L.P.

                                  By:  OAK HILL SECURITIES GENPAR, L.P.,
                                       its General Partner

                                  By:  OAK HILL SECURITIES MGP, INC., its
                                       General Partner

                                  By:    /s/ William H. Bohnsack
                                        -----------------------------
                                  Name:  William H. Bohnsack, Jr.
                                  Title: V.P.

                                  SENIOR DEBT PORTFOLIO

                                  By: BOSTON MANAGEMENT AND
                                      RESEARCH, as Investment Advisor

                                  By:  /s/ Payson F. Swaffield
                                      -----------------------------
                                       Name:  Payson F. Swaffield
                                       Title: Vice President

                                  VAN KAMPEN CLO I, LIMITED

                                  By:  VAN KAMPEN MANAGEMENT INC.,
                                       as Collateral Manager

                                  By:  /s/ Douglas J. Smith
                                      -----------------------------
                                       Name:  Douglas J. Smith
                                       Title: Vice President
<PAGE>
                                                                              13

                                  OCTAGON LOAN TRUST

                                  By:  OCTAGON CREDIT INVESTORS, as
                                       Manager

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  FRANKLIN FLOATING RATE TRUST

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                             AG CAPITAL FUNDING PARTNERS, L.P.

                                  By: ANGELO, GORDON & CO., L.P.,
                                      as Investment Advisor

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  FIRST DOMINION FUNDING I

                                  By:  /s/ Andrew H. Marshak
                                       -----------------------------
                                       Name:  Andrew H. Marshak
                                       Title: Authorized Signatory

                                  JACKSON NATIONAL LIFE INSURANCE
                                    COMPANY

                                  By: PPM AMERICA, INC., as attorney in fact on
                                      behalf of Jackson National Life Insurance
                                       Company

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:
<PAGE>
                                                                              14

                                  ELC (CAYMAN) LTD.

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  AMERICAN GENERAL ANNUITY
                                    INSURANCE COMPANY, formerly
                                    WESTERN NATIONAL LIFE
                                    INSURANCE COMPANY

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  KZH CRESCENT LLC

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  KZH CRESCENT-2 LLC

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  CRESCENT/MACH I PARTNERS, L.P.

                                  By: TCW ASSET MANAGEMENT
                                      COMPANY, as its Investment Manager

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:
<PAGE>
                                                                              15

                                  PAM CAPITAL FUNDING LP

                                  By: HIGHLAND CAPITAL MANAGEMENT,
                                      L.P., as Collateral Manager

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  KZH CYPRESSTREE-1 LLC

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  PAMCO CAYMAN LTD.

                                  By: HIGHLAND CAPITAL MANAGEMENT,
                                      L.P., as Collateral Manager

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  ARCHIMEDES FUNDING, LLC

                                  By:  ING CAPITAL ADVISORS, LLC. as
                                       Collateral Manager

                                  By:  /s/ Michael J. Campbell
                                      ------------------------
                                       Name:  Michael J. Campbell
                                       Title: Senior Vice President &
                                              Portfolio Manager
<PAGE>
                                                                              16

                                  ING HIGH INCOME PRINCIPAL
                                    PRESERVATION FUND HOLDINGS, LDC

                                  By:  ING CAPITAL ADVISORS, INC., as
                                       Investment Advisor

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  KZH SHOSHONE LLC

                                  By:  /s/ Susan Lee
                                      -----------------------------
                                       Name:  Susan Lee
                                       Title: Authorized Agent

                                  KZH ING-1 LLC

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  KZH PAMCO LLC

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  PACIFICA PARTNERS I, L.P.

                                  By:  IMPERIAL CREDIT ASSET
                                       MANAGEMENT, as its Investment Manager

                                  By:  /s/ Tom Colwell
                                      -----------------------------
                                       Name:  Tom Colwell
                                       Title: VP
<PAGE>
                                                                              17

                                  KZH RIVERSIDE LLC

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  PILGRIM AMERICAN HIGH INCOME
                                    INVESTMENTS LTD.

                                  By:  PILGRIM INVESTMENTS, INC.,
                                       as its Investment Manager

                                  By:  /s/ Charles E. LeMieux
                                      -----------------------------
                                       Name:  Charles E. LeMieux, CFA
                                       Title: Assistant Vice President

                                  KZH ING-2 LLC

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  INDOSUEZ CAPITAL FUNDING IIA, LIMITED

                                  By:  Indosuez Capital as Portfolio
                                       Advisor

                                  By:  /s/ Melissa Marano
                                      -----------------------------
                                       Name:  Melissa Marano
                                       Title: Vice President

                                  INDOSUEZ CAPITAL FUNDING IIA, LIMITED

                                  By:  INDOSUEZ CAPITAL LUXEMBOURG, a
                                       Collateral Manager

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:
<PAGE>
                                                                              18

                                  DELANO COMPANY

                                  By:  PACIFIC INVESTMENT MANAGEMENT
                                       COMPANY, as its Investment Advisor

                                  By:  PIMCO MANAGEMENT INC., a General
                                       Partner

                                  By:  /s/ Mohan V. Phansalkar
                                      -----------------------------
                                       Name:  Mohan V. Phansalkar
                                       Title: Senior Vice President

                                  KZH CRESCENT-3 LLC

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  BALANCED HIGH-YIELD FUND I LTD.

                                  By:  BHF-BANK AKTIENGESELLSCHAFT
                                       acting through its New York Branch, as
                                       its attorney-in-fact

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  STATE STREET BANK AND TRUST
                                    COMPANY, as Trustee for GENERAL
                                    MOTORS EMPLOYEES GLOBAL GROUP
                                    PENSION TRUST

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:
<PAGE>
                                                                              19

                                  INDOSUEZ CAPITAL FUNDING III, LIMITED
                                  By:  Indosuez Capital as Portfolio Advisor

                                  By:  /s/ Melissa Marano
                                      -----------------------------
                                       Name:  Melissa Marano
                                       Title: Vice President

                                  KZH SOLEIL LLC

                                  By:  ----------------------------
                                       Name:
                                       Title:

                                  ML CLO XII PILGRIM AMERICA (CAYMAN)
                                       LTD.

                                  By:  PILGRIM INVESTMENTS, INC., as its
                                       Investment Manager

                                  By:  /s/ Charles E. LeMieux
                                      -----------------------------
                                       Name:  Charles E. LeMieux, CFA
                                       Title: Assistant Vice President

                                  MLCLO XV PILGRIM AMERICA (CAYMAN)
                                    LTD.

                                  By:  PILGRIM INVESTMENTS, INC., as its
                                       Investment Manager

                                  By:  /s/ Charles E. LeMieux
                                      -----------------------
                                       Name:  Charles E. LeMieux, CFA
                                       Title: Assistant Vice President

                                  MOUNTAIN CAPITAL CLO I LTD.

                                  By:  /s/ Darren P. Riley
                                      -----------------------------
                                       Name:  Darren P. Riley
                                       Title: Director
<PAGE>
                                                                              20

                                  CERES FINANCE LTD.

                                  By:  ---------------------------
                                       Name:
                                       Title:

                                  OASIS COLLATERALIZED HIGH INCOME
                                    PORTFOLIO I LTD

                                  By:  INVESCO Senior Secured Management, Inc.
                                       as Sub-Advisor

                                  By:  /s/ Gregory Stoeckle
                                      -----------------------------
                                       Name:  Gregory Stoeckle
                                       Title: Authorized Signatory

                                  BALANCED HIGH-YIELD FUND II LTD.

                                  By:  BHF-BANK AKTIENGESELLSCHAFT
                                       acting through its New York Branch, as
                                       its attorney-in-fact

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  CAPTIVA III FINANCE, LTD. as advised by,
                                    PACIFIC INVESTMENT MANAGAGEMENT
                                    COMPANY

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  EATON VANCE SENIOR INCOME TRUST

                                  By:  EATON VANCE MANAGEMENT, as
                                       Investment Advisor

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:
<PAGE>
                                                                              21

                                  BLACK DIAMOND CLO 1998-1 LTD

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  KZH LANGDALE LLC

                                  By:   /s/ Susan Lee
                                      -----------------------------
                                       Name:  Susan Lee
                                       Title: Authorized Agent

                                  ARCHIMEDES FUNDING II, LTD.

                                  By:  ING CAPITAL ADVISORS, INC., as
                                       Collateral Manager

                                  By:  /s/ Michael J. Campbell
                                      -----------------------------
                                       Name:  Michael J. Campbell
                                       Title: Senior Vice President &
                                              Portfolio Manager

                                  ALLIANCE CAPITAL FUNDING, L.L.C.

                                  By:  ALLIANCE CAPITAL MANAGEMENT
                                       L.P., as Manager on behalf of ALLIANCE
                                       CAPITAL FUNDING, L.L.L.

                                  By:  ALLIANCE CAPITAL MANAGEMENT
                                       CORPORATION, General Partner of Alliance
                                       Capital Management, L.P.

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:
<PAGE>
                                                                              22

                                  BATTERSON PARK CBO I

                                  By:  General Re-New England Asset Management,
                                       Inc., as Collateral Manager

                                       By: /s/ Theodore M. Haag
                                           -----------------------------
                                           Name:  Theodore M. Haag
                                           Title: V.P.

                                  ATHENA CDO, LTD.

                                  By: Pacific Investment Management Company as
                                       its investment advisor

                                  By:  PIMCO Management Inc., a general partner

                                  By:  /s/ Mohan V. Phansalkar
                                      -----------------------------
                                       Name:  Mohan V. Phansalkar
                                       Title: Senior Vice President

                                  CAPTIVA II FINANCE LTD.

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  STRATA FUNDING LTD.

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:
<PAGE>
                                                                              23

                                  ALLIANCE CAPITAL FUNDING, L.L.C.

                                  By:  ALLIANCE CAPITAL MANAGEMENT
                                       L.P., as Manager on behalf of ALLIANCE
                                       CAPITAL FUNDING, L.L.L.

                                  By:  ALLIANCE CAPITAL MANAGEMENT
                                       CORPORATION, General Partner of Alliance
                                       Capital Management, L.P.

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  VAN KAMPEN SENIOR FLOATING RATE
                                    FUND
                                  By:  Van Kampen Investment Advisory Corp.

                                  By:  /s/ Douglas J. Smith
                                      -----------------------------
                                       Name:  Douglas J. Smith
                                       Title: Vice President

                                  CONTINENTAL ASSURANCE COMPANY
                                    SEPARATE ACCOUNT (E)

                                  By:  TCW ASSET MANAGEMENT COMPANY,
                                       as Attorney-in-Fact

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:
<PAGE>
                                                                              24

                                  AMARA 2 - FINANCE LTD

                                  By:  INVESCO Senior Secured Management,
                                       as Sub-Advisor

                                       By:  /s/ Gregory Stoeckle
                                           -----------------------------
                                            Name:  Gregory Stoeckle
                                            Title: Authorized Signatory

                                  ROYALTON COMPANY

                                  By:  PACIFIC INVESTMENT MANAGEMENT
                                        COMPANY, as its Investment Advisor

                                  By:  PIMCO MANAGEMENT INC.,
                                       a General Partner

                                  By:  /s/ Mohan V. Phansalkar
                                      -----------------------------
                                       Name:  Mohan V. Phansalkar
                                       Title: Senior Vice President

                                  FLOATING RATE PORTFOLIO

                                  By:  INVESCO Senior Secured
                                       Management Inc., as attorney in fact

                                  By:  /s/ Gregory Stoeckle
                                      -----------------------------
                                       Name:  Gregory Stoeckle
                                       Title: Authorized Signatory

                                  AMARA-1 FINANCE LTD.

                                  By:  INVESCO Senior Secured Management
                                       Inc., as Sub-Advisor

                                  By:  /s/ Gregory Stoeckle
                                      -----------------------------
                                       Name:  Gregory Stoeckle
                                       Title: Authorized Signatory
<PAGE>
                                                                              25

                                  KISLAK NATIONAL BANK

                                  By:  ING CAPITAL ADVISORS LLC., as
                                       Investment Advisor

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  STB DELAWARE FUNDING TRUST I

                                  By:  /s/ Donald C. Hargadon
                                      -----------------------------
                                       Name:  Donald C. Hargadon
                                       Title: Assistant Vice President

                                  STATE STREET BANK AND TRUST
                                    COMPANY, as Trustee for GENERAL
                                    MOTORS WELFARE BENEFITS TRUST

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  NORTH AMERICAN SENIOR FLOATING RATE
                                    FUND

                                  By:  CYPRESSTREE INVESTMENT
                                       MANAGEMENT COMPANY, INC., as Portfolio
                                       Manager

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:
<PAGE>
                                                                              26

                                  CYPRESSTREE INSTITUTIONAL FUND, LLC

                                  By:  CYPRESSTREE INVESTMENT
                                       MANAGEMENT COMPANY, INC., its
                                       Managing Member

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  CYPRESSTREE INVESTMENT PARTNERS II,
                                    LTD

                                  By:  CYPRESSTREE INVESTMENT
                                       MANAGEMENT COMPANY, INC., as
                                       Portfolio Manager

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  KZH III LLC

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  North American Senior Floating Rate Fund
                                  By:  Cypress Tree Investment Management
                                  Company, Inc. as Portfolio Manager

                                  By:  /s/ Jonathan D. Sharkey
                                      -----------------------------
                                       Name:  Jonathan D. Sharkey
                                       Title: Principal

                                  Cypress Tree Senior Floating Rate Fund
                                  By:  Cypress Tree Investment Management
                                  Company, Inc. as Portfolio Manager

                                  By:  /s/ Jonathan D. Sharkey
                                      -----------------------------
                                       Name:  Jonathan D. Sharkey
                                       Title: Principal
<PAGE>
                                                                              27

                                  Cypress Tree Investment Partners I, Ltd.
                                  By:  Cypress Tree Investment Management
                                  Company, Inc. as Portfolio Manager

                                  By:  /s/ Jonathan D. Sharkey
                                      -------------------------
                                       Name:  Jonathan D. Sharkey
                                       Title: Principal

                                  Cypress Tree Investment Fund LLC
                                  By:  Cypress Tree Investment Management
                                  Company, Inc. as its Managing Member

                                  By:  /s/ Jonathan D. Sharkey
                                      -----------------------------
                                       Name:  Jonathan D. Sharkey
                                       Title: Principal

                                  Cypress Tree Institutional Fund, LLC
                                  By:  Cypress Tree Investment Management
                                  Company, Inc. as its Managing Member

                                  By:   /s/ Jonathan D. Sharkey
                                      -----------------------------
                                       Name:  Jonathan D. Sharkey
                                       Title: Principal

                                  Cypress Tree Investment Management Company,
                                  Inc.
                                  As:  Attorney-in-Fact and on behalf of First
                                  Allmerica Financial Life Insurance Company as
                                  Portfolio
                                  Manager

                                  By:  /s/ Jonathan D. Sharkey
                                      -----------------------------
                                       Name: Jonathan D. Sharkey
                                       Title:   Principal

                                  Cypress Tree Investment Partners II, Ltd.
                                  By:  Cypress Tree Investment Management
                                  Company, Inc. as Portfolio Manager

                                  By:  /s/ Jonathan D. Sharkey
                                      -------------------------
                                       Name:  Jonathan D. Sharkey
                                       Title: Principal
<PAGE>
                                                                              28

                                  KZH HIGHLAND-2 LLC

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  KZH IV LLC

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  FIRST UNION NATIONAL BANK

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  CYPRESSTREE INVESTMENT FUND, LLC

                                  By:  CYPRESSTREE INVESTMENT
                                       MANAGEMENT COMPANY, INC., its
                                       Managing Member

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  RABOBANK CANADA

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:
<PAGE>
                                                                              29

                                  CREDIT LYONNAIS CANADA

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  FIRST DOMINION FUNDING III

                                  By:  /s/ Andrew H. Marshak
                                      -----------------------------
                                       Name:  Andrew H. Marshak
                                       Title: Authorized Signatory

                                  FIRST DOMINION FUNDING II

                                  By:  /s/ Andrew H. Marshak
                                      -----------------------------
                                       Name:  Andrew H. Marshak
                                       Title: Authorized Signatory

                                  LEHMAN COMMERCIAL PAPER INC.

                                  By:
                                      -----------------------------
                                       Name:
                                       Title:

                                  VAN KAMPEN CLO II, LIMITED

                                  By:  VAN KAMPOEN MANAGEMENT INC.,
                                       as Collateral Manager

                                  By:  /s/ Douglas J. Smith
                                      -----------------------------
                                      Name:  Douglas J. Smith
                                      Title: Vice President

<PAGE>
                                                                              30

                                  ARIES FINANCE LIMITED

                                  By:  INVESCO Senior Secured
                                        Management Inc., as Sub-Managing Agent

                                       By:  /s/ Gregory Stoeckle
                                           -----------------------------
                                       Name:  Gregory Stoeckle
                                       Title: Authorized Signatory

                                  AVALON CAPITAL LTD.

                                  By:  INVESCO Senior Secured
                                       Management Inc., as Portfolio Advisor

                                       By:  /s/ Gregory Stoeckle
                                          -----------------------------
                                       Name:  Gregory Stoeckle
                                       Title: Authorized Signatory

                                  STRATA FUNDING LTD.

                                  By:  INVESCO Senior Secured Management Inc.,
                                       as Sub-Managing Agent

                                  By:  /s/ Gregory Stoeckle
                                      -----------------------------
                                       Name:  Gregory Stoeckle
                                       Title: Authorized Signatory

                                  CERES FINANCE LTD.

                                  By:  INVESCO Senior Secured Management,
                                       Inc. as Sub-Managing Agent

                                       By:  /s/ Gregory Stoeckle
                                           -----------------------------
                                       Name:  Gregory Stoeckle
                                       Title: Authorized Signatory

<PAGE>
                                                                              31

                                  TRITON CDO IV, LIMITED

                                  By:  INVESCO Senior Secured Management Inc.,
                                       as Investment Advisor

                                       By: /s/ Gregory Stoeckle
                                      -----------------------------
                                       Name: Gregory Stoeckle
                                       Title:   Authorized Signatory

                                  KEMPER FLOATING RATE FUND

                                  By:   /s/ Mark E. Wittnebel
                                      -----------------------------
                                         Name:  Mark E. Wittnebel
                                         Title: Senior Vice President

                                  Indosuez Capital Funding IV, L.P.

                                  By:  Indosuez Capital, as Portfolio Advisor

                                  By:  /s/ Melissa Marano
                                      -----------------------------
                                       Name:  Melissa Marano
                                       Title: Vice President

                                  BHF (USA) CAPITAL CORPORATION

                                  By:  /s/ Richard Cameron
                                      -----------------------------
                                       Name:  Richard Cameron
                                       Title: Associate

                                  By:  /s/ Dana L. McDougall
                                       ----------------------
                                       Name:  Dana L. McDougall
                                       Title: Vice President

<PAGE>
                                                                              32

                                  Balanced High-Yeld Fund I LTD.
                                  By:  BHF (USA) Capital Corporation,
                                  as Attorney-In-Fact

                                  By:  /s/ Richard Cameron
                                      -----------------------------
                                       Name:  Richard Cameron
                                       Title: Associate

                                  By:  /s/ Dana L. McDougall
                                      -----------------------------
                                       Name:  Dana L. McDougall
                                       Title: Vice President

                                  Balanced High-Yeld Fund II LTD.
                                  By:  BHF (USA) Capital Corporation,
                                  as Attorney-In-Fact
                                  By:  /s/ Richard Cameron
                                      -----------------------------
                                       Name:  Richard Cameron
                                       Title: Associate

                                  By:   /s/ Dana L. McDougall
                                      -----------------------------
                                       Name:  Dana L. McDougall
                                       Title: Vice President

                                  OCTAGON INVESTMENT PARTNERS II, LLC
                                  By:  Octagon Credit Investors, LLC,
                                       as sub-investment manager

                                  By:  /s/ Michael Nechamkin
                                      -----------------------------
                                       Name:  Michael Nechamkin
                                       Title: Portfolio Manager

                                  OCTAGON INVESTMENT PARTNERS III, LLC
                                  By:  Octagon Credit Investors, LLC,
                                       as Portfolio Manager

                                  By:  /s/ Michael Nechamkin
                                      -----------------------------
                                       Name:  Michael Nechamkin
                                       Title: Portfolio Manager

<PAGE>
                                                                              33

                                  TEXTRON FINANCIAL CORP.

                                  By:  /s/ R. Rodney Weaver
                                      -----------------------------
                                       Name:  R. Rodney Weaver
                                       Title: Vice President

<PAGE>

                           ACKNOWLEDGMENT AND CONSENT

                  The  undersigned  does hereby  acknowledge  and consent to the
foregoing  Amendment The undersigned  does hereby confirm and agree that,  after
giving effect to such Amendment,  the Guarantee and Collateral  Agreement is and
shall  continue  to be in full  force and  effect  and is hereby  confirmed  and
ratified in all respects.

                                SAFETY-KLEEN SERVICES, INC. (formerly
                                  known as LES, Inc.)
                                SAFETY-KLEEN CORP. (formerly known as
                                  Laidlaw Environmental Services, Inc.)
                                SAFETY-KLEEN (PECATONICA), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services of Illinois, Inc.)
                                GSX CHEMICAL SERVICES OF OHIO, INC.
                                SAFETY-KLEEN (BDT), INC. (formerly known
                                  as Laidlaw Environmental Services (BDT), Inc.)
                                SAFETY-KLEEN (FS), INC. (formerly known as
                                   Laidlaw Environmental Services (FS), Inc.)
                                SAFETY-KLEEN (GS), INC. (formerly known as
                                   Laidlaw Environmental Services (GS), Inc.)
                                SAFETY-KLEEN (CHATTANOOGA), INC.
                                   (formerly known as Laidlaw Environmental
                                   Services of Chattanooga, Inc.)
                                SAFETY-KLEEN (WHITE CASTLE), INC.
                                   (formerly known as Laidlaw Environmental
                                   Services of White Castle, Inc.)
                                SAFETY-KLEEN (CROWLEY), INC. (formerly
                                   known as Laidlaw Environmental Services
                                   (Recovery), Inc.)
                                SAFETY-KLEEN (TS), INC. (formerly known as
                                   Laidlaw Environmental Services (TS), Inc.)
                                SAFETY-KLEEN (WESTMORLAND), INC.
                                   (formerly known as Laidlaw Environmental
                                   Services (Imperial Valley), Inc.)
                                SAFETY-KLEEN (BUTTONWILLOW), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services (Lokern), Inc.)
                                SAFETY-KLEEN (CALIFORNIA), INC.
                                  (formerly known as Laidlaw Environmental
                                  of California, Inc.)

<PAGE>
                                                                               2

                                SAFETY-KLEEN (PINEWOOD),INC.(formerly
                                  known as Laidlaw Environmental Services of
                                  SouthCarolina, Inc.)
                                SAFETY-KLEEN (NE), INC.(formerly known as
                                  Laidlaw Environmental Services
                                  (North  East), Inc.)
                                SAFETY-KLEEN (LAPORTE), INC. (formerly
                                  known as Laidlaw Environmental Services
                                  (TES), Inc.)
                                SAFETY-KLEEN CHEMICAL SERVICES, INC.
                                  (formerly known as Laidlaw Chemical Services,
                                  Inc.)
                                SAFETY-KLEEN (ROEBUCK), INC.(formerly
                                  known as Laidlaw Environmental Services
                                   (TOC), Inc.)
                                SAFETY-KLEEN (TG), INC. (formerly known as
                                  Laidlaw Environmental Services (TG), Inc.)
                                SAFETY-KLEEN (ALTAIR), INC. (formerly
                                  known as Laidlaw Environmental Services
                                  (Altair), Inc.)
                                SAFETY-KLEEN (WT), INC. (formerly known as
                                  Laidlaw Environmental Services (WT), Inc.)
                                SAFETY-KLEEN (BARTOW), INC. (formerly
                                  known as Laidlaw Environmental Services of
                                  Bartow, Inc.)
                                SAFETY-KLEEN (COLFAX), INC. (formerly
                                  known as Laidlaw Environmental Services
                                  (Thermal Treatment), Inc.)
                                LEMC, INC.
                                SAFETY-KLEEN OSCO HOLDINGS, INC.
                                  (formerly known as Laidlaw OSCO Holdings,
                                  Inc.)
                                SAFETY-KLEEN (NASHVILLE), INC. (formerly
                                  known as Laidlaw Environmental Services of
                                  Nashville, Inc.)
                                SAFETY-KLEEN (CLIVE), INC. (formerly
                                  known as Laidlaw Environmental Services
                                  (Clive), Inc.)
                                SAFETY-KLEEN (LONE AND GRASSY
                                  MOUNTAIN), INC. (formerly known as
                                  Laidlaw Environmental Services
                                  (Lone and Grassy Mountain), Inc.)
                                SAFETY-KLEEN (TULSA), INC. (formerly
                                  known as Laidlaw Environmental Services
                                  (Tulsa), Inc.)
                                SAFETY-KLEEN (SAN ANTONIO), INC.

<PAGE>
                                                                               3

                                  (formerly known as Laidlaw Environmental
                                  Services (San Antonio), Inc.)
                                SAFETY-KLEEN (WICHITA), INC. (formerly
                                  known as Laidlaw Environmental Services
                                  (Wichita), Inc.)
                                SAFETY-KLEEN (DELAWARE), INC. (formerly
                                  known as Laidlaw Environmental Services of
                                  Delaware, Inc.)
                                USPCI, INC. OF GEORGIA
                                SAFETY-KLEEN (SAN JOSE), INC. (formerly
                                  known as Laidlaw Environmental Services
                                  (San Jose), Inc.)
                                SAFETY-KLEEN (SAWYER), INC. (formerly
                                  known as Laidlaw Environmental Services
                                  (Sawyer), Inc.)
                                CHEMCLEAR, INC. OF LOS ANGELES
                                SAFETY-KLEEN (ROSEMOUNT), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services (Rosemount), Inc.)
                                SAFETY-KLEEN HOLDING'S, INC. (formerly
                                  known as LES Holding's, Inc.)
                                SAFETY-KLEEN (PPM), INC. (formerly known
                                  as Laidlaw Environmental Services (Tucker),
                                  Inc.)
                                NINTH STREET PROPERTIES, INC.
                                SAFETY-KLEEN (MT. PLEASANT), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services (Mt. Pleasant), Inc.)
                                SAFETY-KLEEN (DEER TRAIL), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services (Deer Trail), Inc.)
                                SAFETY-KLEEN (MINNEAPOLIS), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services (Minneapolis), Inc.)
                                SAFETY-KLEEN (LOS ANGELES), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services (Los Angeles), Inc.)
                                SAFETY-KLEEN (BATON ROUGE), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services (Baton Rouge), Inc.)
                                SAFETY-KLEEN (PLAQUEMINE), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services (Plaquemine), Inc.)
                                SAFETY-KLEEN (BRIDGEPORT), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services (Bridgeport), Inc.)

<PAGE>
                                                                               4

                                SAFETY-KLEEN (DEER PARK), INC. (formerly
                                  known as Laidlaw Environmental Services
                                  (Deer Park), Inc.)
                                SAFETY-KLEEN (TIPTON), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services (Tipton), Inc.)
                                SAFETY-KLEEN (SUSSEX), INC. (formerly
                                  known as Laidlaw Environmental Services
                                  (Sussex), Inc.)
                                SAFETY-KLEEN (GLOUCESTER), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services (Gloucester), Inc.)
                                SAFETY-KLEEN (CUSTOM TRANSPORT),
                                  INC. (formerly known as Laidlaw Environmental
                                  Services (Custom Transport), Inc.)
                                SAFETY-KLEEN (ARAGONITE), INC. (formerly
                                  known as Laidlaw Environmental Services
                                  (Aragonite), Inc.)
                                SAFETY-KLEEN (PUERTO RICO), INC.
                                  (formerly known as Laidlaw Environmental
                                  Services (Puerto Rico), Inc.)
                                SAFETY-KLEEN SYSTEMS, INC. (formerly
                                  known as Safety-Kleen Corp.)
                                DIRT MAGNET, INC.
                                THE MIDWAY GAS & OIL CO.
                                ELGINT CORP.
                                SAFETY-KLEEN ENVIROSYSTEMS
                                  COMPANY
                                SAFETY-KLEEN ENVIROSYSTEMS
                                  COMPANY OF PUERTO RICO, INC.
                                PETROCON, INC.
                                PHILLIPS ACQUISITION CORP.
                                VIROGROUP, INC.), Inc.(formerly known as Safety-
                                  Kleen Aviation, Inc.)
                                SK REAL ESTATE, INC.
                                SAFETY-KLEEN INTERNATIONAL, INC.
                                SAFETY-KLEEN OIL RECOVERY CO.
                                SAFETY-KLEEN OIL SERVICES, INC.

<PAGE>
                                                                               5

                                THE SOLVENTS RECOVERY SERVICE OF
                                   NEW JERSEY, INC.
                                SK EUROPE, INC.

                                By:  /s/ Henry H. Taylor
                                     -------------------
                                     Name:  Henry H. Taylor
                                     Title: Secretary

                                3E COMPANY ENVIRONMENTAL,
                                  ECOLOGICAL AND ENGINEERING

                                By:  /s/ Henry H. Taylor
                                    --------------------
                                     Name:  Henry H. Taylor
                                     Title: Assistant Secretary

                                SK INSURANCE COMPANY

                                By:  /s/ A. John Guignion
                                    ------------------
                                Name:  A. John Guignion
                                Title: Vice President, DirectorCONSENT

         CONSENT  (this  "CONSENT"),  dated as of March 16, 2000, to the Amended
and  Restated  Credit  Agreement,  dated  as  of  April  3,  1998  (as  amended,
supplemented or otherwise  modified from time to time, the "CREDIT  AGREEMENT"),
among  SAFETY-KLEEN  SERVICES,  INC.  (formerly  known as LES, Inc.), a Delaware
corporation  (the  "COMPANY"),  SAFETY-KLEEN  LTD.  (successor  to  Safety-Kleen
(Canada)  Ltd.,  which was  formerly  known as  Laidlaw  Environmental  Services
(Canada)  Ltd.),  a Canadian  corporation  and a wholly owned  subsidiary of the
Company  (together  with the Company,  the  "BORROWERS"),  the several banks and
other financial  institutions or entities from time to time parties thereto (the
"LENDERS"),  TORONTO DOMINION (TEXAS), INC., as general administrative agent (in
such capacity, the "GENERAL  ADMINISTRATIVE  AGENT"), THE TORONTO-DOMINION BANK,
as Canadian  administrative  agent, TD SECURITIES  (USA) INC., as advisor to the
Borrowers and arranger of the commitments described in the Credit Agreement, THE
BANK OF NOVA SCOTIA, BANK OF AMERICA (formerly known as Nationsbank, N.A.), BANK
ONE, N.A.  (formerly  known as The First  National Bank of Chicago) and WACHOVIA
BANK, N.A., as managing  agents,  THE BANK OF NOVA SCOTIA and THE FIRST NATIONAL
BANK OF CHICAGO, as co-documentation  agent, and BANK OF AMERICA (formerly known
as Nationsbank, N.A.), as syndication agent.

                              W I T N E S S E T H:
                              - - - - - - - - - -

         WHEREAS,  the  Borrowers,  the  General  Administrative  Agent  and the
Lenders have entered into the Fourth  Amendment,  dated as of March 13, 2000, to
the Credit Agreement (the "Fourth Amendment"); and

         WHEREAS,  the Company has requested that the Lenders consent to certain
actions in furtherance of the transactions set forth in the Fourth Amendment.

         NOW,  THEREFORE,  in  consideration  of the  premises  and  the  mutual
covenants  contained  herein and in the Credit  Agreement,  the  parties  hereto
hereby agree as follows:

         1. Defined Terms.  Unless  otherwise  defined  herein,  all capitalized
            -------------
terms used herein shall have the meanings given to them in the Credit Agreement.

         2. Consent. The Lenders hereby consent to the execution and delivery by
            -------
the  General  Administrative  Agent of a  subordination  agreement,  whereby the
Mortgage on the real property of Safety-Kleen  Systems,  Inc.  located in Elgin,
Illinois,   shall  be  subordinated  to  the  liens  and  mortgage   granted  by
Safety-Kleen Systems, Inc. on such property pursuant to Section 10.3(m).

         3. Representation and Warranty.  The Company represents and warrants to
            ---------------------------
each  Administrative   Agent  and  Lender  that,  after  giving  effect  to  the
transactions  contemplated

093110-0154-01964-A03FN00L-CST

<PAGE>
                                                                               2

hereby,  on the date  hereof,  the fair value of the  Collateral  is equal to or
greater than the  aggregate  amount of the  Obligations  taking into account all
prior Liens on the Collateral securing other Indebtedness.

         4. Conditions to Effectiveness.  This Consent shall become effective as
            ---------------------------
of the date first  above  written  when (i) each of the  Required  Lenders,  the
General Administrative Agent and the Borrowers shall have executed and delivered
this Consent and (ii) each Guarantor shall have  acknowledged and agreed to this
Consent.

         5. Continuing Effects.  Except as expressly modified hereby, the Credit
            ------------------
Agreement and the Supplement shall continue to be and shall remain in full force
and effect in accordance with their respective terms.

         6.  Expenses.  The  Company  agrees to pay and  reimburse  the  General
             --------
Administrative Agent for all of its reasonable  out-of-pocket costs and expenses
incurred  in  connection  with  the  negotiation,  preparation,  execution,  and
delivery of this Consent, including the reasonable fees and expenses of counsel.

         7. Counterparts. This Consent may be executed on any number of separate
            ------------
counterparts  and all of said  counterparts  taken  together  shall be deemed to
constitute one and the same instrument.

         8.  GOVERNING LAW. THIS CONSENT SHALL BE GOVERNED BY, AND CONSTRUED AND
             -------------
INTERPRETED IN ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK.

<PAGE>

                                                                             3

                 IN WITNESS  WHEREOF,  the  parties  hereto  have  caused  this
Amendment to be duly executed and delivered by their proper and duly  authorized
officers as of the day and year first above written.

                            SAFETY-KLEEN SERVICES, INC. (formerly
                               known as LES, Inc.)

                               By:   /s/ Henry H. Taylor
                                     --------------------------
                                     Name:  Henry H. Taylor
                                     Title: Secretary

                            SAFETY-KLEEN LTD. (successor to Safety-Kleen
                              Services (Canada) Ltd., which was formerly
                              known as Laidlaw Environmental Services
                              (Canada) Ltd.)

                              By:  /s/ Henry H. Taylor
                                   ----------------------------
                                   Name:  Henry H. Taylor
                                   Title: Secretary

                            TORONTO DOMINION (TEXAS), INC., as
                              General Administrative Agent and Lender

                              By:  /s/ Warren Finlay
                                   ----------------------------
                                   Name:  Warren Finlay
                                   Title: President

                            THE TORONTO-DOMINION BANK, as Canadian
                              Administrative Agent

                              By:  /s/ Wagner M. Shiplo
                                   ----------------------------
                                   Name:  Wagner M. Shiplo
                                   Title: Manager, Syndicated Loans Agency

                            TD SECURITIES (USA) INC., as Arranger

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

          <PAGE>

                                                                               4

                            THE TORONTO-DOMINION BANK, as a Lender

                              By:  /s/ Warren Finlay
                                   ----------------------------
                                   Name:  Warren Finlay
                                   Title: President:

                            THE  BANK  OF  NOVA  SCOTIA,  as  Managing
                              Agent, Co-Documentation Agent and Lender

                              By:  /s/ William E. Zarrett
                                   ----------------------------
                                   Name:  William E. Zarrett
                                   Title: Managing Director

                            THE FIRST NATIONAL BANK OF CHICAGO,
                              n/k/a BankOne, NA, as Managing Agent,  Co-
                              Documentation Agent and Lender

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            BANK OF AMERICA (formerly known as
                              Nationsbank, N.A.), as Syndication Agent,
                              Managing Agent and Lender

                              By:  /s/ William Crawford
                                   ----------------------------
                                   Name:  William Crawford
                                   Title: Managing Director

                            WACHOVIA BANK, N.A., as Managing Agent
                              and Lender

                              By:  /s/ Donald E. Sellers, Jr.
                                   ---------------------------
                                   Name:  Donald E. Sellers, Jr.
                                   Title: Vice President

<PAGE>
                                                                               5

                            THE CIT GROUP/BUSINESS CREDIT, INC.

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            GENERAL ELECTRIC CAPITAL
                              CORPORATION

                              By:  /s/ Karl Kiefer
                                   ----------------------------
                                   Name:  Karl Kiefer
                                   Title: Duly Authorized Signatory

                            COMERICA BANK

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            FLEET NATIONAL BANK

                              By:  /s/ Thomas D. Opie
                                   ----------------------------
                                   Name:  Thomas D. Opie
                                   Title: VP

                            ROYAL BANK OF CANADA

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            CREDIT INDUSTRIEL ET COMMERCIAL

                              By:  /s/ Sean Mounier
                                   ----------------------------
                                   Name:  Sean Mounier
                                   Title: First Vice President

                              By:  /s/ Brian O'Leary
                                   ----------------------------
                                   Name:  Brian O'Leary
                                   Title: Vice President

<PAGE>
                                                                               6

                            HSBC BANK USA (formerly Marine Midland
                              Bank)

                              By:  /s/ Kevin J. Ayers
                                   ------------------
                                   Name:  Kevin J. Ayers
                                   Title: V. P.

                            THE LONG-TERM CREDIT BANK OF JAPAN,
                              LTD.

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            THE MITSUBISHI TRUST AND BANKING
                              CORPORATION

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            FLEET BUSINESS CREDIT CORPORATION
                              (formerly Sanwa Business Credit Corporation)

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            SOCIETE GENERALE

                              By:  /s/ Robert Petersen
                                   ----------------------------
                                   Name:  Robert Petersen
                                   Title: Director

                            SOUTHERN PACIFIC BANK

                              By: /s/ Mun Young Kim
                                   ----------------------------
                                   Name:  Mun Young Kim
                                   Title: Vice President

<PAGE>
                                                                               7

                            CREDIT LYONNAIS ATLANTA AGENCY

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            COOPERATIEVE CENTRALE RAIFEISEN-
                              BOERENLEENBANK B.A., "RABOBANK
                              NEDERLAND" NEW YORK BRANCH

                              By:  /s/ Ian Reece
                                   ----------------------------
                                   Name:  Ian Reece
                                   Title: Senior Vice President

                              By:  /s/ Olietier B. Turnbull
                                   ----------------------------
                                   Name:  Olietier B. Turnbull
                                   Title: Vice President

                            COMMERCIAL LOAN FUNDING TRUST I

                              By:  Lehman Commercial Paper Inc., not in its
                                   individual capacity but solely as
                                   administrative agent

                                   By:
                                        -----------------------
                                        Name:
                                        Title:

                            CREDIT SUISSE FIRST BOSTON

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                              By:
                                   ----------------------------
                                   Name:
                                   Title:e:
<PAGE>
                                                                               8

                            THE SAKURA BANK, LTD.

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            FIRSTAR BANK, N.A.

                              By:  /s/ Mark A. Whitson
                                   -------------------
                                   Name:  Mark A. Whitson
                                   Title: Vice President

                            BANK OF HAWAII

                              By:  /s/ Patricia Rohifing
                                   ----------------------------
                                   Name:  Patricia Rohifing
                                   Title: Vice President

                            CITIBANK, N.A.

                              By:  /s/ Bradley Dietz
                                   ----------------------------
                                   Name:  Bradley Dietz
                                   Title  Managing Director

                            THE SUMITOMO TRUST & BANKING CO.,
                              LTD., NEW YORK BRANCH

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            NATIONAL CITY BANK

                              By:  /s/ Robert C. Rowe
                                   ----------------------------
                                   Name:  Robert C. Rowe
                                   Title: Senior VP
<PAGE>
                                                                               9

                            BHF-BANK AKTIENGESELLSCHAFT

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            THE FUJI BANK, LIMITED

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            CAISSE DE DEPOT ET PLACEMENT DU QUEBEC

                              By:  /s/ Luis Lavoie
                                   ----------------------------
                                   Name:  Louis Lavoie
                                   Title: Vice President

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            KZH PONDVIEW LLC

                              By:  /s/ Peter Chin
                                   ----------------------------
                                   Name:  Peter Chin
                                   Title: Authorized Agent

                            WEBSTER BANK

                              By:  /s/ Richard F. DiLorenzo
                                   -------------------------
                                   Name:  Richard F. DiLorenzo
                                   Title:    Sr. V.P.
<PAGE>
                                                                              10

                            BANQUE WORMS CAPITAL CORPORATION

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            IMPERIAL BANK

                              By:  /s/ Ray Vadalma
                                   ----------------------------
                                   Name:  Ray Vadalma
                                   Title: Senior Managing Director

                            THE PRUDENTIAL INSURANCE COMPANY
                              OF AMERICA

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            GPSF SECURITIES, INC.

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            KZH CNC LLC

                              By:  /s/ Peter Chin
                                   ----------------------------
                                   Name:  Peter Chin
                                   Title: Authorized Agent

                            SUMMIT BANK

                              By:  /s/ Robert L. Turnipseed
                                   ------------------------
                                   Name:  Robert L. Turnipseed
                                   Title: Vice president
<PAGE>
                                                                              11

                            METROPOLITAN LIFE INSURANCE
                              COMPANY

                              By:  /s/ Claudia Cromie
                                   ----------------------------
                                   Name:  Claudie Cromie
                                   Title: Director

                            FIRSTRUST BANK

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            BANCO ESPIRITO SANTO

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            THE CITY NATIONAL BANK

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            VAN KAMPEN PRIME RATE INCOME TRUST

                              By:  /s/ Darvin D. Pierce
                                   ----------------------------
                                   Name:  Darvin D. Pierce
                                   Title: Vice President
<PAGE>
                                                                              12

                            OAK HILL SECURITIES FUND, L.P.

                              By: OAK HILL SECURITIES GENPAR, L.P.,
                                   its General Partner

                              By: OAK HILL SECURITIES MGP, INC., its
                                   General Partner

                              By:  /s/ William H. Bomsack, Jr.
                                   ----------------------------
                                   Name:  William H. Bomsack
                                   Title: V.P.

                            SENIOR DEBT PORTFOLIO

                              By:  BOSTON MANAGEMENT AND
                                   RESEARCH, as Investment Advisor

                                   By:  /S/ Payson F. Swaffield
                                        ------------------------
                                        Name:  Payson F. Swaffield
                                        Title: Vice President

                            VAN KAMPEN CLO I, LIMITED

                              BY:  VAN KAMPEN MANAGEMENT INC.,
                                   as Collateral Manager

                                   By:  /s/ Darvin D. Pierce
                                        ------------------------
                                        Name:  Darvin D. Pierce
                                        Title: Vice President

                            OCTAGON LOAN TRUST

                              By:  OCTAGON CREDIT INVESTORS, as
                                   Manager

                                   By:
                                        ----------------------------
                                        Name:
                                        Title:
<PAGE>
                                                                              13

                            FRANKLIN FLOATING RATE TRUST

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            AG CAPITAL FUNDING PARTNERS, L.P.

                              By:  ANGELO, GORDON & CO., L.P.,
                                   as Investment Advisor

                                   By:
                                        ----------------------------
                                        Name:
                                        Title:

                            FIRST DOMINION FUNDING I

                              By:  /s/ Andrew H. Marshak
                                   ----------------------------
                                   Name:  Andrew H. Marshak
                                   Title: Authorized Signatory

                            JACKSON NATIONAL LIFE INSURANCE
                              COMPANY

                              By:  PPM AMERICA, INC., as attorney in fact on
                                   behalf of Jackson National Life Insurance
                                   Company

                                   By:  /s/ John (illegible)
                                        ------------------------
                                        Name:  John (illegible)
                                        Title: Managing Director

                            ELC (CAYMAN) LTD.

                              By:
                                   ----------------------------
                                   Name:
                                   Title:
<PAGE>
                                                                              14

                            AMERICAN GENERAL ANNUITY
                              INSURANCE COMPANY, formerly
                              WESTERN NATIONAL LIFE INSURANCE
                              COMPANY

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            KZH CRESCENT LLC

                              By:  /s/ Peter Chin
                                   ----------------------------
                                   Name:  Peter Chin
                                   Title: Authorized Agent

                            KZH CRESCENT-2 LLC

                              By:  /s/ Peter Chin
                                   ----------------------------
                              Name:  Peter Chin
                              Title: Authorized Agent

                            CRESCENT/MACH I PARTNERS, L.P.

                              By:  TCW ASSET MANAGEMENT
                                   COMPANY, as its Investment Manager

                                   By:  /s/ Mark L. Gold
                                        ------------------------
                                        Name:  Mark L. Gold
                                        Title: Managing Director

                            PAM CAPITAL FUNDING LP

                              By:  HIGHLAND CAPITAL MANAGEMENT,
                                   L.P., as Collateral Manager

                                    By:
                                        ----------------------------
                                        Name:
                                        Title:
<PAGE>
                                                                              15

                            KZH CYPRESSTREE-1 LLC

                              By:  /s/ Peter Chin
                                   ----------------------------
                                   Name:  Peter Chin
                                   Title: Authorized Agent

                            PAMCO CAYMAN LTD.

                              By:  HIGHLAND CAPITAL MANAGEMENT,
                                   L.P., as Collateral Manager

                                   By:
                                        ------------------------
                                        Name:
                                        Title:

                            ARCHIMEDES FUNDING, LLC

                              BY:  ING CAPITAL ADVISORS, INC. as
                                   Collateral Manager

                                   By:  /s/ Kurt Wegleitner
                                        ------------------------
                                        Name:  Kurt Wegleitner
                                        Title: Vice President

                            ING HIGH INCOME PRINCIPAL
                              PRESERVATION FUND HOLDINGS, LDC

                              BY:  ING CAPITAL ADVISORS, INC., as
                                   Investment Advisor

                                   By:  /s/ Kurt Wegleitner
                                        ------------------------
                                        Name:  Kurt Wegleitner
                                        Title: Vice President

                            KZH SHOSHONE LLC

                              By:  /s/ Peter Chin
                                   ----------------------------
                                   Name:  Peter Chin
                                   Title: Authorized Agent
<PAGE>
                                                                              16

                            KZH ING-1 LLC

                              By:  /s/ Peter Chin
                                   ----------------------------
                                   Name:  Peter Chin
                                   Title:   Authorized Agent

                            KZH PAMCO LLC

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            PACIFICA PARTNERS I, L.P.

                              By:  IMPERIAL CREDIT ASSET
                                   MANAGEMENT, as its Investment Manager

                                   By:  /s/ Dean K. Kawai
                                        ------------------------
                                        Name:  Dean K. Kawai
                                        Title: Vice President

                            KZH RIVERSIDE LLC

                              By:  /s/ Peter Chin
                                   ----------------------------
                                   Name:  Peter Chin
                                   Title: Authorized Agent

                            PILGRIM AMERICAN HIGH INCOME
                              INVESTMENTS LTD.

                              By:  PILGRIM INVESTMENTS, INC.,
                                   as its Investment Manager

                                   By:  /s/ Charles E. LeMieux
                                        -----------------------
                                        Name:  Charles E. LeMieux, CFA
                                        Title: Assistant Vice President
<PAGE>
                                                                              17

                            KZH ING-2 LLC

                              By:  /s/ Peter Chin
                                   ----------------------------
                                   Name:  Peter Chin
                                   Title: Authorized Agent

                            INDOSUEZ CAPITAL FUNDING IIA, LIMITED

                              BY:  INDOSUEZ CAPITAL as Portfolio
                                   Manager

                                   By:  /s/ Melissa Marano
                                        ------------------------
                                        Name:  Melissa Marano
                                        Title: Vice President

                            DELANO COMPANY

                              By:  PACIFIC INVESTMENT MANAGEMENT
                                   COMPANY, as its Investment Advisor

                              By:  PIMCO MANAGEMENT INC., a General
                                   Partner

                                   By:  /s/ John S. Loftus
                                        ------------------------
                                        Name:  John S. Loftus
                                        Title: Managing Director

                            KZH CRESCENT-3 LLC

                              By:  /s/ Peter Chin
                                   ----------------------------
                                   Name:  Peter Chin
                                   Title: Authorized Agent

                            BALANCED HIGH-YIELD FUND I LTD.

                              By:  BHF-BANK AKTIENGESELLSCHAFT
                                   acting through its New York Branch, as its
                                   attorney-in-fact

                                   By:
                                        ----------------------------
                                        Name:
                                        Title:
<PAGE>
                                                                              18

                            STATE STREET BANK AND TRUST
                              COMPANY, as Trustee for GENERAL
                              MOTORS EMPLOYEES GLOBAL GROUP
                              PENSION TRUST

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            INDOSUEZ CAPITAL FUNDING III, LIMITED

                              By:  Indosuez Capital as Portfolio Advisor

                                   By:  /s/ Melissa Marano
                                        ------------------------
                                        Name:  Melissa Marano
                                        Title: Vice President

                            KZH SOLEIL LLC

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            ML CLO XII PILGRIM AMERICA (CAYMAN)
                              LTD.

                              By:  PILGRIM INVESTMENTS, INC., as its
                                   Investment Manager

                                   By:  /s/ Charles E. LeMieux
                                        ------------------------
                                        Name:  Charles E. LeMieux, CFA
                                        Title: Assistant Vice President

<PAGE>
                                                                              19

                            MLCLO XV PILGRIM AMERICA (CAYMAN)
                              LTD.

                              By:  PILGRIM INVESTMENTS, INC., as its
                                   Investment Manager

                                   By:  /s/ Charles E. LeMieux
                                        ------------------------
                                        Name:  Charles E. LeMieux, CFA
                                        Title: Assistant Vice President

                            MOUNTAIN CAPITAL CLO I LTD.

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            CERES FINANCE LTD.

                              By:  /s/ Gregory Stoeckle
                                   -------------------
                                   Name:
                                   Title:

                            OASIS COLLATERALIZED HIGH INCOME
                              PORTFOLIO I LTD

                              By:  INVESCO SENIOR SECURED
                                   MANAGEMENT, INC.

                                   By:  /s/ Gregory Stoeckle
                                        ------------------------
                                        Name:
                                        Title:

                            BALANCED HIGH-YIELD FUND II LTD.

                              By: BHF-BANK AKTIENGESELLSCHAFT
                                   acting through its New York Branch, as its
                                   attorney-in-fact

                                   By:
                                        ------------------------
                                        Name:
                                        Title:
<PAGE>
                                                                              20

                            CAPTIVA III FINANCE, LTD. as advised by,
                              PACIFIC INVESTMENT MANAGAGEMENT
                              COMPANY

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            EATON VANCE SENIOR INCOME TRUST

                              By:  EATON VANCE MANAGEMENT, as
                                   Investment Advisor

                                   By:  /s/ Payson F. Swaffield
                                        ------------------------
                                        Name:  Payson F. Swaffield
                                        Title: Vice President

                            BLACK DIAMOND CLO 1998-1 LTD

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            KZH LANGDALE LLC

                              By:  /s/ Peter Chin
                                   ----------------------------
                                   Name:  Peter Chin
                                   Title: Authorized Agent

                            ARCHIMEDES FUNDING II, LTD.

                              BY:  ING CAPITAL ADVISORS, INC., as
                                   Collateral Manager

                                   By:  /s/ Kurt Wegleitner
                                        ------------------------
                                        Name:  Kurt Wegleitner
                                        Title: Vice President
<PAGE>
                                                                              21

                            ARCHIMEDES FUNDING III, LTD.

                              BY:  ING CAPITAL ADVISORS, LLC., as
                                   Collateral Manager

                                   By:  /s/ Kurt Wegleitner
                                        ------------------------
                                        Name:  Kurt Wegleitner
                                        Title: Vice President

                            SEQUILS-ING I (HBDGM), LTD.

                              BY:  ING CAPITAL ADVISORS, LLC., as
                                   Collateral Manager

                                   By:  /s/ Kurt Wegleitner
                                        ------------------------
                                        Name:  Kurt Wegleitner
                                        Title: Vice President

                            ALLIANCE CAPITAL FUNDING, L.L.C.

                                   By:  ALLIANCE CAPITAL MANAGEMENT
                                        L.P., as Manager on behalf of ALLIANCE
                                        CAPITAL FUNDING, L.L.L.

                                        By:  ALLIANCE CAPITAL
                                             MANAGEMENT CORPORATION,
                                             General Partner of Alliance Capital
                                             Management, L.P.

                                             By:
                                                  ------------------------
                                                  Name:
                                                  Title:

                            BATTERSON PARK CBO I

                              By:  GENERAL RE-NEW ENGLAND ASSET
                                   MANAGEMENT, INC., as Collateral Manager

                                   By:
                                        ------------------------
                                        Name:
                                        Title:

<PAGE>
                                                                              22

                            ATHENA CDO, LTD.

                              By:  PACIFIC INVESTMENT MANAGEMENT
                                   COMPANY as its investment advisor

                                   By:  PIMCO MANAGEMENT INC., a
                                        general partner

                                        By:  /s/ John S. Loftus
                                             -------------------
                                             Name:  John S. Loftus
                                             Title: Managing Director

                            SEQUILS I, LTD.

                              By:  TWC Advisors, Inc. as its
                                   Collateral Manager

                                   By:  /s/ Mark L. Gold
                                        ------------------------
                                        Name:  Mark L. Gold
                                        Title: Managing Director

                                   By:  /s/ Jonathan R. Insull
                                        ------------------------
                                        Name:  Jonathan R. Insull
                                        Title: Vice President

                            CAPTIVA II FINANCE LTD.

                              By:  /s/ (illegible)
                                   ----------------------------
                                   Name:  (illegible)
                                   Title: Director

                            STRATA FUNDING LTD.

                              By:  /s/ Gregory Stoeckle
                                   ----------------------------
                                   Name:
                                   Title:
<PAGE>
                                                                              23

                            ALLIANCE CAPITAL FUNDING, L.L.C.

                              By:  ALLIANCE CAPITAL MANAGEMENT
                                   L.P., as Manager on behalf of ALLIANCE
                                   CAPITAL FUNDING, L.L.L.

                              By:  ALLIANCE CAPITAL
                                   MANAGEMENT CORPORATION,
                                   General Partner of Alliance
                                   Capital Management, L.P.

                                   By:
                                        ------------------------
                                        Name:
                                        Title:

                            VAN KAMPEN SENIOR FLOATING RATE
                              FUND

                              By:  /s/ Darvin D. Pierce
                                   ----------------------------
                                   Name:  Darvin D. Pierce
                                   Title: Vice President

                            CONTINENTAL ASSURANCE COMPANY
                              SEPARATE ACCOUNT (E)

                              By:  TCW ASSET MANAGEMENT
                                   COMPANY, as Attorney-in-Fact

                                   By:  /s/ Mark L. Gold
                                        ------------------------
                                        Name:  Mark L. Gold
                                        Title: Managing Director

                                   By:  /s/ Jonathan R. Insull
                                        ------------------------
                                        Name:  Jonathan R. Insull
                                        Title  Vice President

                            AMARA 2 - FINANCE LTD

                              By:  INVESCO SENIOR SECURED
                                   MANAGEMENT, INC., as Sub-Advisor

                                   By:  /s/ Gregory Stoeckle
                                        ------------------------
                                        Name:
                                        Title:
<PAGE>
                                                                              24

                            ROYALTON COMPANY

                              By:  PACIFIC INVESTMENT MANAGEMENT
                                   COMPANY, as its Investment Advisor

                                   By:  PIMCO MANAGEMENT INC.,
                                        a General Partner

                                        By:  /s/ John S. Loftus
                                             ----------------------------
                                             Name:  John S. Loftus
                                             Title: Managing Director

                            FLOATING RATE PORTFOLIO

                              By:  INVESCO SENIOR SECURED
                                   MANAGEMENT INC., as attorney in fact

                                   By:  /s/ Gregory Stoeckle
                                        ---------------------------------
                                        Name:
                                        Title:

                            AERIES FINANCIE-II LIMITED

                              By:  INVESCO SENIOR SECURED
                                   MANAGEMENT INC., as Sub-Managing Agent

                                   By:  /s/ Gregory Stoeckle
                                        ---------------------------------
                                        Name:
                                        Title:

                            AVALON CAPITAL LTD.

                              By:  INVESCO SENIOR SECURED
                                   MANAGEMENT INC., as Portfolio Advisor

                                   By:  /s/ Gregory Stoeckle
                                        ---------------------------------
                                        Name:
                                        Title:
<PAGE>
                                                                              25

                            STRATA FUNDING LTD.

                              By:  INVESCO SENIOR SECURED
                                   MANAGEMENT INC., as Sub-Managing Agent

                                   By:  /s/ Gregory Stoeckle
                                        ---------------------------------
                                        Name:
                                        Title:

                            CERES FINANCE LTD.

                              By:  INVESCO SENIOR SECURED
                                   MANAGEMENT INC., as Sub-Managing Agent

                                   By:  /s/ Gregory Stoeckle
                                        ---------------------------------
                                        Name:
                                        Title:

                            TRITON CDO IV, LIMITED

                              By:  INVESCO SENIOR SECURED
                                   MANAGEMENT INC., as Investment Advisor

                                   By:  /s/ Gregory Stoeckle
                                        ------------------------
                                        Name:
                                        Title:

                            KISLAK NATIONAL BANK

                              By:  ING CAPITAL ADVISORS LLC., as
                                   Investment Advisor

                                   By:
                                        ------------------------
                                        Name:
                                        Title:
<PAGE>
                                                                              26

                            STB DELAWARE FUNDING TRUST I

                              By:  /s/ Donald C. Hargadon
                                   ----------------------------
                                   Name:  Donald C. Hargadon
                                   Title: Assistant Vice President

                            STATE STREET BANK AND TRUST
                              COMPANY, as Trustee for GENERAL
                              MOTORS WELFARE BENEFITS TRUST

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            NORTH AMERICAN SENIOR FLOATING RATE
                              FUND

                              By:  CYPRESSTREE INVESTMENT
                                   MANAGEMENT COMPANY, INC.,
                                   as Portfolio Manager

                                   By:  /s/ illegible
                                        ----------------------------
                                        Name:
                                        Title

                            CYPRESSTREE SENIOR FLOATING RATE
                              FUND

                              By:  CYPRESSTREE INVESTMENT
                                   MANAGEMENT COMPANY, INC., its
                                   Portfolio Manager

                                   By:  /s/ illegible
                                        -----------------------------
                                        Name:
                                        Title:
<PAGE>
                                                                              27

                            CYPRESSTREE INVESTMENT PARTNERS I,
                              LTD

                              By:  CYPRESSTREE INVESTMENT
                                   MANAGEMENT COMPANY, INC., as
                                   Portfolio Manager

                                   By:  /s/ illegible
                                        -----------------------------
                                        Name:
                                        Title:

                            CYPRESSTREE INVESTMENT FUND, LLC

                              By:  CYPRESSTREE INVESTMENT
                                   MANAGEMENT COMPANY, INC., its
                                   Managing Member

                                   By:  /s/ illegible
                                        -----------------------------
                                        Name:
                                        Title:

                            CYPRESSTREE INSTITUTIONAL FUND, LLC

                              By:  CYPRESSTREE INVESTMENT
                                   MANAGEMENT COMPANY, INC., its
                                   Managing Member

                                   By:  /s/ illegible
                                        -----------------------------
                                        Name:
                                        Title:

                            CYPRESSTREE INVESTMENT MANAGEMENT
                              COMPANY, INC. AS: Attorney-in-Fact and on
                              Behalf of First Allmerica Financial Life
                              Insurance Company, as Portfolio Manager

                              By:  /s/ illegible
                                   ----------------------------
                                   Name:
                                   Title:
<PAGE>
                                                                              28

                            CYPRESSTREE INVESTMENT PARTNERS II,
                              LTD.

                              By:  CYPRESSTREE INVESTMENT
                                   MANAGEMENT COMPANY, INC., as
                                   Portfolio Manager

                                   By:  /s/ illegible
                                        --------------------------
                                        Name:
                                        Title:

                            KZH III LLC

                              By:
                                   ----------------------------
                                   Name
                                   Title:

                            KZH HIGHLAND-2 LLC

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            KZH IV LLC

                              By:
                                   ----------------------------
                                   Name:
                                   Title:

                            FIRST UNION NATIONAL BANK

                              By:
                                   ----------------------------
                                   Name:
                                   Title
<PAGE>
                                                                              29

                            CYPRESSTREE INVESTMENT FUND, LLC

                              BY:  CYPRESSTREE INVESTMENT
                                   MANAGEMENT COMPANY, INC., its
                                   Managing Member

                                   By:  /s/ illegible
                                        -----------------------------
                                        Name:
                                        Title:

                            RABOBANK CANADA

                              By:
                                   ----------------------------
                                   Name:
                                   Title

                            CREDIT LYONNAIS CANADA

                              By:
                                   ----------------------------
                                   Name:
                                   Title

                            FIRST DOMINION FUNDING III

                              By:  /s/ Andrew H. Marshak
                                   ----------------------------
                                   Name:  Andrew H. Marshak
                                   Title: Authorized Signatory

                            FIRST DOMINION FUNDING II

                              By:  /s/ Andrew H. Marshak
                                   ----------------------------
                                   Name:  Andrew H. Marshak
                                   Title: Authorized Signatory

                            LEHMAN COMMERCIAL PAPER INC.

                              By:  /s/ Michael E. O'Brien
                                   ----------------------------
                                   Name:  Michael E. O'Brien
                                   Title: Authorized Signatory
<PAGE>
                                                                              30

                            VAN KAMPEN CLO II, LIMITED

                              By:  VAN KAMPEN MANAGEMENT INC., as
                                   Collateral Manager

                                   By:  /s/ Darvin D. Pierce
                                        -----------------------------
                                        Name:  Darvin D. Pierce
                                        Title: Vice President

                            KEMPER FLOATING RATE FUND

                              By:  /s/ Jonathan W. Trutter
                                   ----------------------------
                                   Name:
                                   Title:

                            INDOSUEZ CAPITAL FUNDING IV, L.P.

                              By:  INDOSUEZ CAPITAL, as Portfolio
                                   Advisor

                                   By:  /s/ Melissa Marano
                                        -----------------------------
                                        Name:  Melissa Marano
                                        Title: Vice President

                            BHF (USA) CAPITAL CORPORATION

                              By:  /s/ Richard Cameron
                                   ----------------------------
                                   Name:  Richard Cameron
                                   Title: Associate

                                   By:  /s/ Dana L. McDougall
                                        -----------------------------
                                        Name:  Dana L. McDougall
                                        Title: Vice President

<PAGE>
                                                                              31

                            BALANCED HIGH-YELD FUND I LTD.

                              By:  BHF (USA) CAPITAL CORPORATION,
                                   as Attorney-In-Fact

                                   By:  /s/ Richard Cameron
                                        -----------------------------
                                        Name:  Richard Cameron
                                        Title: Associate

                                   By:  /s/ Dana L. McDougall
                                        -----------------------------
                                        Name:  Dana L. McDougall
                                        Title: Vice President

                            BALANCED HIGH-YELD FUND II LTD.

                              By:  BHF (USA) CAPITAL CORPORATION,
                                   as Attorney-In-Fact

                                   By:  /s/ Richard Cameron
                                        -----------------------------
                                        Name:  Richard Cameron
                                        Title:  Associate

                                   By:  /s/ Dana L. McDougall
                                        -----------------------------
                                        Name:  Dana L. McDougall
                                        Title: Vice President

                            NOMURA BOND AND LOAN FUND

                              By:  NOMURA CORPORATE RESEARCH
                                   AND ASSET MANAGEMENT INC.
                                             AS
                                     INVESTMENT ADVISOR

                                   By:  /s/ Richard W. Stewart
                                        -----------------------------
                                        Name:  Richard W. Stewart
                                        Title: Director
<PAGE>
                                                                              32

                            OCTAGON INVESTMENT PARTNERS II, LLC

                              By:  OCTAGON CREDIT INVESTORS, LLC,
                                   as sub-investment manager

                                   By:
                                        -----------------------------
                                        Name:
                                        Title:

                            OCTAGON INVESTMENT PARTNERS III, LLC

                              By:  OCTAGON CREDIT INVESTORS, LLC,
                                   as sub-investment manager

                                   By:
                                        -----------------------------
                                        Name:
                                        Title:

                            TEXTRON FINANCIAL CORP.

                                   By:  /s/ R. Rodney Weaver
                                        -----------------------------
                                        Name:  R. Rodney Weaver
                                        Title: Vice President

                            OLYMPIC FUNDING TRUST, Series 1999-1

                              By:  /s/ Kelly C. Walker
                                   ----------------------------
                                   Name:  Kelly C. Walker
                                   Title: Authorized Agent

                            PPM SPYGLASS FUNDING TRUST

                                   By:  /s/ Kelly C. Walker
                                        -----------------------------
                                        Name:  Kelly C. Walker
                                        Title: Authorized Agent

                            WINGED FOOT FUNDING TRUST

                                   By:  /s/ Kelly C. Walker
                                        -----------------------------
                                        Name:  Kelly C. Walker
                                        Title: Authorized Agent
<PAGE>
                                                                              33

                            Zematt CBO, LTD.

                              By:  /s/ James Duplessie
                                   ----------------------------
                                   Name:  James Duplessie
                                   Title: Executive Director
                                          UBS AG, New York Branch

                            Bayerische Hypo-und Vereinsbank AG,
                              New York Branch

                              By:  /s/ Timothy Harrod
                                   ----------------------------
                                   Name:  Timothy Harrod
                                   Title:    Director

                              By:  /s/ Steven Simons
                                   ----------------------------
                                   Name:  Steven Simons
                                   Title: Associate Director

<PAGE>

                           ACKNOWLEDGMENT AND CONSENT

         The  undersigned  does hereby  acknowledge and consent to the foregoing
Consent. The undersigned does hereby confirm and agree that, after giving effect
to such Consent, the Guarantee and Collateral Agreement is and shall continue to
be in full  force  and  effect  and is  hereby  confirmed  and  ratified  in all
respects.

                              SAFETY-KLEEN CORP. (formerly known as
                                Laidlaw Environmental Services, Inc.)

                                By:  /s/ Henry H. Taylor
                                     -----------------------------
                                     Name:  Henry H. Taylor
                                     Title: Secretary

                              SAFETY-KLEEN SERVICES, INC. (formerly
                                known as LES, Inc.)
                              SAFETY-KLEEN (PECATONICA), INC.
                                (formerly known as Laidlaw Environmental
                                Services of Illinois, Inc.)
                              GSX CHEMICAL SERVICES OF OHIO, INC.
                              SAFETY-KLEEN (BDT), INC. (formerly known
                                as Laidlaw Environmental Services (BDT), Inc.)
                              SAFETY-KLEEN (FS), INC. (formerly known as
                                 Laidlaw Environmental Services (FS), Inc.)
                              SAFETY-KLEEN (GS), INC. (formerly known as
                                 Laidlaw Environmental Services (GS), Inc.)
                              SAFETY-KLEEN (CHATTANOOGA), INC.
                                 (formerly known as Laidlaw Environmental
                                 Services of Chattanooga, Inc.)
                              SAFETY-KLEEN (WHITE CASTLE), INC.
                                 (formerly known as Laidlaw Environmental
                                 Services of White Castle, Inc.)
                              SAFETY-KLEEN (CROWLEY), INC. (formerly
                                 known as Laidlaw Environmental Services
                                 (Recovery), Inc.)
                              SAFETY-KLEEN (TS), INC. (formerly known as
                                 Laidlaw Environmental Services (TS), Inc.)
                              SAFETY-KLEEN (WESTMORLAND), INC.
                                 (formerly known as Laidlaw Environmental
                                 Services (Imperial Valley), Inc.)

<PAGE>

                                                                               2

                              SAFETY-KLEEN (BUTTONWILLOW), INC.
                                (formerly known as Laidlaw Environmental
                                Services (Lokern), Inc.)
                              SAFETY-KLEEN (CALIFORNIA), INC.
                                (formerly known as Laidlaw Environmental
                                of California, Inc.)
                              SAFETY-KLEEN (PINEWOOD), INC.(formerly
                                known as Laidlaw Environmental Services of
                                South Carolina, Inc.)
                              SAFETY-KLEEN (NE), INC.(formerly known as
                                Laidlaw Environmental Services
                                (North   East), Inc.)
                              SAFETY-KLEEN (LAPORTE), INC. (formerly
                                known as Laidlaw Environmental Services
                                (TES), Inc.)
                              SAFETY-KLEEN CHEMICAL SERVICES, INC.
                                (formerly known as Laidlaw Chemical Services,
                                Inc.)
                              SAFETY-KLEEN (ROEBUCK), INC.(formerly
                                known as Laidlaw Environmental Services
                                (TOC), Inc.)
                              SAFETY-KLEEN (TG), INC. (formerly known as
                                Laidlaw Environmental Services (TG), Inc.)
                              SAFETY-KLEEN (ALTAIR), INC. (formerly
                                known as Laidlaw Environmental Services
                                (Altair), Inc.)
                              SAFETY-KLEEN (WT), INC. (formerly known as
                                Laidlaw Environmental Services (WT), Inc.)
                              SAFETY-KLEEN (BARTOW), INC. (formerly
                                known as Laidlaw Environmental Services of
                                Bartow, Inc.)
                              SAFETY-KLEEN (COLFAX), INC. (formerly
                                known as Laidlaw Environmental Services
                                (Thermal Treatment), Inc.)
                              LEMC, INC.
                              SAFETY-KLEEN OSCO HOLDINGS, INC.
                                (formerly known as Laidlaw OSCO Holdings,
                                Inc.)
                              SAFETY-KLEEN (NASHVILLE), INC. (formerly
                                known as Laidlaw Environmental Services of
                                Nashville, Inc.)
                              SAFETY-KLEEN (CLIVE), INC. (formerly
                                known as Laidlaw Environmental Services
                                (Clive), Inc.)

<PAGE>
                                                                               3
                              SAFETY-KLEEN (LONE AND GRASSY
                                MOUNTAIN), INC. (formerly known as
                                Laidlaw Environmental Services
                                (Lone and Grassy Mountain), Inc.)
                              SAFETY-KLEEN (TULSA), INC. (formerly
                                known as Laidlaw Environmental Services
                                (Tulsa), Inc.)
                              SAFETY-KLEEN (SAN ANTONIO), INC.
                                  (formerly known as Laidlaw Environmental
                                Services (San Antonio), Inc.)
                              SAFETY-KLEEN (WICHITA), INC. (formerly
                                known as Laidlaw Environmental Services
                                (Wichita), Inc.)
                              SAFETY-KLEEN (DELAWARE), INC. (formerly
                                known as Laidlaw Environmental Services of
                                Delaware, Inc.)
                              USPCI, INC. OF GEORGIA
                              SAFETY-KLEEN (SAN JOSE), INC. (formerly
                                known as Laidlaw Environmental Services
                                (San Jose), Inc.)
                              SAFETY-KLEEN (SAWYER), INC. (formerly
                                known as Laidlaw Environmental Services
                                (Sawyer), Inc.)
                              CHEMCLEAR, INC. OF LOS ANGELES
                              SAFETY-KLEEN (ROSEMOUNT), INC.
                                (formerly known as Laidlaw Environmental
                                Services (Rosemount), Inc.)
                              SAFETY-KLEEN HOLDING'S, INC. (formerly
                                known as LES Holding's, Inc.)
                              SAFETY-KLEEN (PPM), INC. (formerly known
                                as Laidlaw Environmental Services (Tucker),
                                Inc.)
                              NINTH STREET PROPERTIES, INC.
                              SAFETY-KLEEN (MT. PLEASANT), INC.
                                (formerly known as Laidlaw Environmental
                                Services (Mt. Pleasant), Inc.)
                              SAFETY-KLEEN (DEER TRAIL), INC.
                                (formerly known as Laidlaw Environmental
                                Services (Deer Trail), Inc.)
                              SAFETY-KLEEN (MINNEAPOLIS), INC.
                                (formerly known as Laidlaw Environmental
                                Services (Minneapolis), Inc.)
                              SAFETY-KLEEN (LOS ANGELES), INC.
                                (formerly known as Laidlaw Environmental
                                Services (Los Angeles), Inc.)

<PAGE>
                                                                               4

                              SAFETY-KLEEN (BATON ROUGE), INC.
                                (formerly known as Laidlaw Environmental
                                Services (Baton Rouge), Inc.)
                              SAFETY-KLEEN (PLAQUEMINE), INC.
                                (formerly known as Laidlaw Environmental
                                Services (Plaquemine), Inc.)
                              SAFETY-KLEEN (BRIDGEPORT), INC.
                                (formerly known as Laidlaw Environmental
                                Services (Bridgeport), Inc.)
                              SAFETY-KLEEN (DEER PARK), INC. (formerly
                                known as Laidlaw Environmental Services
                                (Deer Park), Inc.)
                              SAFETY-KLEEN (TIPTON), INC.
                                (formerly known as Laidlaw Environmental
                                Services (Tipton), Inc.)
                              SAFETY-KLEEN (SUSSEX), INC. (formerly
                                known as Laidlaw Environmental Services
                                (Sussex), Inc.)
                              SAFETY-KLEEN (GLOUCESTER), INC.
                                (formerly known as Laidlaw Environmental
                                Services (Gloucester), Inc.)
                              SAFETY-KLEEN (CUSTOM TRANSPORT),
                                INC. (formerly known as Laidlaw Environmental
                                Services (Custom Transport), Inc.)
                              SAFETY-KLEEN (ARAGONITE), INC. (formerly
                                known as Laidlaw Environmental Services
                                (Aragonite), Inc.)
                              SAFETY-KLEEN (PUERTO RICO), INC.
                                (formerly known as Laidlaw Environmental
                                Services (Puerto Rico), Inc.)
                              SAFETY-KLEEN SYSTEMS, INC. (formerly
                                known as Safety-Kleen Corp.)
                              DIRT MAGNET, INC.
                              THE MIDWAY GAS & OIL CO.
                              ELGINT CORP.
                              SAFETY-KLEEN ENVIROSYSTEMS
                                COMPANY
                              SAFETY-KLEEN ENVIROSYSTEMS
                                COMPANY OF PUERTO RICO, INC.
                              PETROCON, INC.
                              PHILLIPS ACQUISITION CORP.
                              SAFETY-KLEEN (CONSULTING), Inc. (formerly
                                 known as Virogroup, Inc., which was formerly
                                 known as Safety-Kleen Aviation, Inc.)
                              SK REAL ESTATE, INC.
                              SAFETY-KLEEN INTERNATIONAL, INC.

<PAGE>
                                                                               5

                              SAFETY-KLEEN OIL RECOVERY CO.
                              SAFETY-KLEEN OIL SERVICES, INC.
                              THE SOLVENTS RECOVERY SERVICE OF
                                 NEW JERSEY, INC.

                                  By: /s/ Henry H. Taylor
                                      ------------------------------
                                      Name:  Henry H. Taylor
                                      Title: Secretary

                              3E COMPANY ENVIRONMENTAL,
                                ECOLOGICAL AND ENGINEERING

                                  By: /s/ Henry H. Taylor
                                      ------------------------------
                                      Name:  Henry H. Taylor
                                      Title: Assistant Secretary

                              SK INSURANCE COMPANY

                                  By: /s/ A. John Guignion
                                      ------------------------------
                                      Name:  A. John Guignion
                                      Title: Vice President & Director

                              SK EUROPE, INC.

                                  By: /s/ Henry H. Taylor
                                      ------------------------------
                                      Name:  Henry H. Taylor
                                      Title: Secretary

                              SAFETY-KLEEN (ENCOTEC), INC. (formerly
                                known as Laidlaw Environmental, Inc.)

                                  By: /s/ William D. Ridings
                                      ------------------------------
                                      Name:  William D. Ridings
                                      Title: Vice President of Finance and
                                             Treasurer
<PAGE>

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