EXHIBIT 4.15


                                 March 28, 2000

CLEAN HARBORS ENVIRONMENTAL
  SERVICES, INC.

CLEAN HARBORS KINGSTON FACILITY
  CORPORATION
CLEAN HARBORS OF BRAINTREE, INC.
CLEAN HARBORS SERVICES, INC.
CLEAN HARBORS OF NATICK, INC.
CLEAN HARBORS OF CONNECTICUT, INC.
MURPHY'S WASTE OIL SERVICE, INC.
MR. FRANK, INC.
SPRING GROVE RESOURCE RECOVERY, INC.
HARBOR MANAGEMENT CONSULTANTS, INC.

     Re:  EIGHTH AMENDMENT TO FINANCING AGREEMENTS ("EIGHTH AMENDMENT")

Gentlemen:

         Reference is made to the Loan and Security Agreement dated May 8, 1995,
as amended, between you and the undersigned (the "Loan Agreement"). All
capitalized terms not otherwise defined herein shall have the meanings given
such terms in the Loan Agreement. This Agreement is referred to as the "Eighth
Amendment".

         Borrowers have requested that the Lender consent to the acquisition by
CHES of certain motor vehicles and rolling stock (as hereinafter defined, the
"Acquired Vehicles") that have been subject to leases as described on Exhibit A
hereto. In addition, Borrowers have requested that Lender agree to advance an
additional term loan (the "2000 Term Loan") in the original principal amount of
$3,000,000, to a change in the definition of "Working Capital," to a change in
the Adjusted Net Worth covenant and to an extension of the term of the Financing
Agreements to May 8, 2003. Subject to the terms and conditions hereof and
effective on the Eighth Amendment Effective Date (as defined herein), the Lender
agrees with the Borrowers as follows:

         (1) Subject to the conditions, representations, acknowledgements and
affirmations set forth in this Eighth Amendment, Lender hereby consents to the
acquisition of the Acquired Vehicles (the "Acquisition"), and waives Section
9.10 of the Loan Agreement with respect to the Acquisition, PROVIDED that the
aggregate purchase price of the Acquisition (after rental rebates) does not
exceed $3,500,000.00. Lender's




March 28, 2000
Page 2


consent given herein is limited strictly to its terms and shall apply only to
the specific provisions described herein. The consent contained herein shall not
extend to or affect any other Obligations of the Borrowers or the Obligors and
shall not impair or prejudice any rights consequent thereon.

         (2) The Loan Agreement is amended to delete Section 1.53 and to
substitute the following in place thereof:

                  "1.53 "Working Capital" shall mean as to any Person, at any
                  time, in accordance with GAAP, on a consolidated basis for
                  such Person and its subsidiaries (if any), the amount equal to
                  the difference between: (a) the aggregate net book value of
                  all current assets of such Person and its subsidiaries (as
                  determined in accordance with GAAP), and (b) all current
                  liabilities of such Person and its subsidiaries (as determined
                  in accordance with GAAP), PROVIDED, THAT, as to Borrowers, for
                  purposes of Section 9.13, the liabilities of Borrowers and
                  their subsidiaries to Lender under this Agreement shall not be
                  considered current liabilities (whether or not classified as
                  current liabilities in accordance with GAAP) and, as to
                  Parent, for purposes of Section 9.13, the liabilities of
                  Parent (as issuer) and its subsidiaries (as guarantors) on the
                  Senior Unsecured Notes shall not be considered current
                  liabilities (whether or not classified as current liabilities
                  in accordance with GAAP)."

         (3) The Loan Agreement is amended to add the following Section 2.3A
thereto, immediately following Section 2.3:

                  2.3A 2000 TERM LOAN. On the Eighth Amendment Effective Date
                  (as defined in the Eighth Amendment), Lender is making the
                  2000 Term Loan to Borrowers in the original principal amount
                  of $3,000,000. The 2000 Term Loan (a) is evidenced by a 2000
                  Term Promissory Note (the "2000 Term Promissory Note" and
                  together with the existing Term Promissory Note, the "Term
                  Note") in such original principal amount duly executed and
                  delivered by the Borrowers to Lender concurrently with the
                  Eighth Amendment; (b) is to be repaid, together with interest
                  and other amounts, in accordance with this Agreement, the 2000
                  Term Promissory Note, and other Financing Agreements; (c) is
                  secured by all of the Collateral; and (d) the proceeds of the
                  2000 Term Loan shall be used to purchase the Acquired
                  Vehicles."

         (4) Section 9.14 of the Loan Agreement is deleted and the following is
substituted in the place thereof:

                  "9.14 ADJUSTED NET WORTH. Parent shall, at all times, maintain
                  an Adjusted Net Worth of not less than $30,000,000."




March 28, 2000
Page 3

         (5) The first sentence of Section 12.1(a) of the Loan Agreement is
deleted and replaced with the following sentence:

                  "This Agreement and the other Financing Agreements shall
                  become effective as of the date set forth on the first page
                  hereof and shall continue in full force and effect for a term
                  ending on the date eight (8) years from the date hereof (the
                  "Renewal Date"), and from year to year thereafter, unless
                  sooner terminated pursuant to the terms hereof; PROVIDED,
                  THAT, Lender may, at its option, extend the Renewal Date to
                  the date nine (9) years from the date hereof by giving
                  Borrowers notice at least one hundred twenty (120) days prior
                  to the eighth anniversary of this Agreement."

         (6) Section 12.1(c) of the Loan Agreement is deleted in its entirety
and replaced with the following:

                  "If for any reason this Agreement is terminated prior to the
                  end of the then current term or renewal term of this
                  Agreement, in view of the impracticality and extreme
                  difficulty of ascertaining actual damages and by mutual
                  agreement of the parties as to a reasonable calculation of
                  Lender's lost profits as a result thereof, Borrowers agree to
                  pay to Lender, upon the effective date of such termination, an
                  early termination fee in the amount of: 1 1/2% of the
                  Revolving Credit Limit if such termination is effective in the
                  period from the date of the Eighth Amendment to and including
                  May 8, 2001; 1% of the Revolving Credit Limit if such
                  termination is effective in the period from May 9, 2001 to and
                  including May 8, 2002; and 1/2% of the Revolving Credit Limit
                  if such termination is effective in the period from May 9,
                  2002 to and including May 8, 2003. Such early termination fee
                  shall be presumed to be the amount of damages sustained by
                  Lender as a result of such early termination and Borrowers
                  agree that it is reasonable under the circumstances currently
                  existing. The refinancing and repayment of the Term Loan
                  through the issuance of pollution control authority industrial
                  revenue bonds shall not trigger the payment of the early
                  termination fee. The early termination fee provided for in
                  this Section 12.1 shall be deemed included in the
                  Obligations."

         (7) This Eighth Amendment and the Lender's obligations hereunder shall
not be effective until each of the following conditions are satisfied (the
"Eighth Amendment Effective Date"):

                  (a) Borrowers shall have duly executed and delivered this
Eighth Amendment, the 2000 Term Promissory Note and all other instruments,
documents and agreements required by Lender;

                  (b) Borrowers shall have furnished (i) a complete list of all
the Borrowers' motor vehicles and of the Acquired Vehicles to be acquired by the
Borrowers




March 28, 2000
Page 4

in connection with the Acquisition, (ii) certificates of title for all motor
vehicles now owned by Borrowers with Lender's lien noted thereon, and (iii)
evidence satisfactory to Lender that certificates of title for all of the
Acquired Vehicles will be delivered to Lender within thirty (30) days of the
date hereof; and Borrowers shall have executed and delivered (or in the case of
certificates of title for the Acquired Vehicles, shall concurrently with the
delivery thereof to Lender execute and deliver) to Lender all documents that are
necessary for the Lender's lien to be noted thereon at the appropriate state
departments and agencies for the registration of motor vehicles so that Lender
shall have valid and perfected first priority security interests in and liens
upon all of the Borrowers' motor vehicles and rolling stock, subject only to
security interests and liens permitted under the Agreement and other Loan
Documents;

                  (c) all requisite corporate action and proceedings of the
Borrowers in connection with this Eighth Amendment shall be satisfactory in form
and substance to Lender and Lender shall receive certified copies of such
corporate action and proceedings and a legal opinion of counsel to the Borrowers
as to the due authorization and enforceability of this Amendment and the
Financing Agreements entered into pursuant hereto;

                  (d) no material adverse change shall have occurred in the
assets (including the Acquired Vehicles), business or prospects of any Borrower
since the date of the most recent financial statements furnished to Lender
pursuant to the Loan Agreement and no change or event shall have occurred which
would impair the ability of any Borrower or any Obligor to perform its
obligations under the Loan Agreement or any of the other Financing Agreements or
of Lender to enforce the Obligations or to realize upon the Collateral;

                  (e) Borrowers shall pay to Lender, and hereby direct Lender to
debit their loan account for, an additional facility fee equal to $50,000.00,
which fee shall be fully earned and non-refundable on the date hereof;

                  (f) Lender shall have received, in form and substance
satisfactory to Lender, evidence that all instruments, documents and agreements
entered into pursuant to the Acquisition or relating thereto (the "Purchase
Agreements") have been duly executed and delivered by and to the appropriate
parties thereto and the transactions contemplated under the terms of the
Purchase Agreements have been consummated prior to or contemporaneously with the
execution of the Eighth Amendment (except for the execution and delivery of
certain documents within 30 days of the date hereof as described in clause (b)
above); and

                  (f) Lender shall have received the consent of its Participant,
Pilgrim America Prime Rate Trust to this Eighth Amendment.

         (8) Each Borrower represents and warrants to Lender the following:




March 28, 2000
Page 5

                  (a) The Purchase Agreements and the transactions contemplated
thereunder have been duly executed, delivered and performed in accordance with
their terms by the respective parties thereto in all respects, including the
fulfillment (not merely the waiver, except as may be disclosed to Lender and
consented to in writing by Lender) of all conditions precedent set forth therein
and giving effect to the terms of the Purchase Agreements and the assignments to
be executed and delivered thereunder, CHES has acquired and has good and
marketable title to the Acquired Vehicles, free and clear of all claims, liens,
pledges and encumbrances of any kind, except as permitted hereunder;

                  (b) All actions and proceedings required by the Purchase
Agreements or applicable law or regulation have been taken and the transactions
required thereunder have been duly and validly taken and consummated;

                  (c) No court of competent jurisdiction has issued any
injunction, restraining order or other order which prohibits consummation of the
transactions described in the Purchase Agreements and no governmental or other
action or proceeding has been threatened or commenced, seeking any injunction,
restraining order or other order which seeks to void or otherwise modify the
transactions described in the Purchase Agreements; and

                  (d) Borrowers have delivered, or caused to be delivered, to
Lender, true, correct and complete copies of the Purchase Agreements.

         (9) Each Borrower confirms and agrees that (a) all representations and
warranties contained in the Loan Agreement and in the other Financing Agreements
are on the date hereof true and correct in all material respects (except for
changes that have occurred as permitted by the covenants in Section 9 of the
Loan Agreement), (b) it is unconditionally and jointly and severally liable for
the punctual and full payment of all Obligations, including, without limitation,
all charges, fees, expenses and costs (including attorneys' fees and expenses)
under the Financing Agreements, and that no Borrower has any defenses,
counterclaims or setoffs with respect to full, complete and timely payment of
all Obligations and (c) that all certificates of title and documents necessary
to note Lender's first priority lien thereon duly executed by Borrowers and
satisfactory to Lender shall be delivered to Lender within thirty (30 days of
the date hereof.

         (10) Each Obligor, for value received, hereby assents to the Borrowers'
execution and delivery of this Amendment, and to the performance by the
Borrowers of their respective agreements and obligations hereunder. This
Amendment and the performance or consummation of any transaction or matter
contemplated under this Amendment, shall not limit, restrict, extinguish or
otherwise impair any of the Obligor's liability to Lender with respect to the
payment and other performance obligations of the Obligors pursuant to the
Guarantees, dated May 8, 1995 executed for the benefit of Lender. Each Obligor
acknowledges that it is unconditionally liable to Lender for the full and
complete payment of all Obligations including, without limitation, all charges,
fees, expenses and costs (including attorney's fees and expenses) under the
Financing




March 28, 2000
Page 6

Agreements and that such Obligor has no defenses, counterclaims or setoffs with
respect to full, complete and timely payment of any and all Obligations.

         (11) Borrowers hereby agree to pay to Lender all reasonable attorney's
fees and costs which have been incurred or may in the future be incurred by
Lender in connection with the negotiation and preparation of this Amendment and
any other documents and agreements prepared in connection with this Amendment.
The undersigned confirm that the Financing Agreements remain in full force and
effect without amendment or modification of any kind, except for the amendments
explicitly set forth herein. The undersigned further confirm that no Event of
Default or events which with notice or the passage of time or both would
constitute an Event of Default have occurred and are continuing. The execution
and delivery of this Amendment by Lender shall not be construed as a waiver by
Lender of any Event of Default under the Financing Agreements. This Amendment
shall be deemed to be a Financing Agreement and, together with the other
Financing Agreements, constitute the entire agreement between the parties with
respect to the subject matter hereof and supersedes all prior dealings,
correspondence, conversations or communications between the parties with respect
to the subject matter hereof.

                  [Remainder of Page Intentionally Left Blank]




March 28, 2000
Page 7

         If you accept and agree to the foregoing please sign and return the
enclosed copy of this letter. Thank you.

                                       Very truly yours,

                                       CONGRESS FINANCIAL CORPORATION
                                       (NEW ENGLAND)

                                       By:  /s/ MARK E. SWARTZ
                                           --------------------------------
                                           Name: Mark E. Swartz
                                           Title: Sr. Vice President

AGREED:

CLEAN HARBORS ENVIRONMENTAL
  SERVICES, INC.

By:  /s/ STEPHEN MOYNIHAN
    ----------------------------------
     Name: Stephen Moynihan
     Title: Sr. Vice President


CLEAN HARBORS KINGSTON FACILITY

     CORPORATION

By:  /s/ STEPHEN MOYNIHAN
    ----------------------------------
     Name: Stephen Moynihan
     Title: Sr. Vice President


CLEAN HARBORS OF BRAINTREE, INC.

By:  /s/ STEPHEN MOYNIHAN
    ----------------------------------
     Name: Stephen Moynihan
     Title: Sr. Vice President





March 28, 2000
Page 8

CLEAN HARBORS SERVICES, INC.

By:  /s/ STEPHEN MOYNIHAN
    ----------------------------------
     Name: Stephen Moynihan
     Title: Sr. Vice President


CLEAN HARBORS OF NATICK, INC.

By:  /s/ STEPHEN MOYNIHAN
    ----------------------------------
     Name: Stephen Moynihan
     Title: Sr. Vice President


CLEAN HARBORS OF CONNECTICUT, INC.

By:  /s/ STEPHEN MOYNIHAN
    ----------------------------------
     Name: Stephen Moynihan
     Title: Sr. Vice President


MURPHY'S WASTE OIL SERVICE, INC.

By:  /s/ STEPHEN MOYNIHAN
    ----------------------------------
     Name: Stephen Moynihan
     Title: Sr. Vice President


MR. FRANK, INC.

By:  /s/ STEPHEN MOYNIHAN
    ----------------------------------
     Name: Stephen Moynihan
     Title: Sr. Vice President


SPRING GROVE RESOURCE RECOVERY, INC.

By:  /s/ STEPHEN MOYNIHAN
    ----------------------------------
     Name: Stephen Moynihan
     Title: Sr. Vice President





March 28, 2000
Page 9

HARBOR MANAGEMENT CONSULTANTS, INC.

By:  /s/ STEPHEN MOYNIHAN
    ----------------------------------
     Name: Stephen Moynihan
     Title: Sr. Vice President


OBLIGORS:

CLEAN HARBORS, INC.

By:  /s/ STEPHEN MOYNIHAN
    ----------------------------------
     Name: Stephen Moynihan
     Title: Sr. Vice President


CLEAN HARBORS OF BALTIMORE, INC.

By:  /s/ STEPHEN MOYNIHAN
    ----------------------------------
     Name: Stephen Moynihan
     Title: Sr. Vice President