Document:

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                           MENTOR GRAPHICS CORPORATION

                             1982 STOCK OPTION PLAN

Mentor Graphics recognizes that its continuing success depends upon the
initiative, ability and significant contributions of officers and key employees.
Mentor Graphics believes that by affording such employees the opportunity to
purchase shares in Mentor Graphics it will enhance its ability to attract and
retain such employees and will provide an incentive for them to exert their best
efforts on its behalf.

         The Plan is as follows:

1.       SHARES SUBJECT TO OPTION.

         1.1 Options granted under this Plan shall be for authorized but
unissued or reacquired common stock of Mentor Graphics.

         1.2 Options may be granted under paragraph 4 of the Plan and stock
appreciation rights may be granted under paragraph 8.2 of the Plan for a total
of not more than 21,670,000 shares of common stock, subject to adjustment under
paragraph 9. Shares subject to options and to stock appreciation rights granted
under paragraph 8.2 that are terminated or expire without being exercised, other
than options that are surrendered on exercise of a stock appreciation right
granted under paragraph 8.1, shall be added to the shares remaining for future
options and stock appreciation rights.

         1.3 No employee may be granted options or stock appreciation rights
under the Plan for more than an aggregate of 500,000 shares of Common Stock in
any calendar year.

2.       EFFECTIVE DATE; DURATION.

         This Plan shall be effective January 1, 1982 and shall continue until
all shares available for issuance under the Plan have been issued, unless sooner
terminated by the Board of Directors of Mentor Graphics (Board of Directors).
Expiration or termination of the Plan shall not affect outstanding options,
bonus rights or stock appreciation rights.

3.       ADMINISTRATION.

         3.1 The Plan shall be administered by a compensation committee
appointed by the Board of Directors (Committee). The Committee may delegate any
of its administrative duties to one or more agents and may retain advisors to
assist it.

         3.2 The Committee shall have general responsibility to interpret and
administer the Plan. Any decision by the Committee shall be final and bind all
parties. Notwithstanding the foregoing, the Committee's exclusive power to make
final and binding interpretations of the Plan shall immediately terminate upon
the occurrence of a Change in Control (as defined in paragraph 7.2). The
Committee shall keep adequate records of options, bonus rights and stock
appreciation rights granted under the Plan and shall be responsible for
communication with optionees.

         3.3 No Committee member shall participate in the decision of any
question relating exclusively to an option, bonus right or stock appreciation
right granted to the member.

4.       GRANT OF OPTIONS.

         4.1 Options granted under the Plan may be either incentive stock
options within the meaning of Section 422 of the Internal Revenue Code of 1986,
as amended (the Code), or options other than incentive stock options
(nonqualified stock options). No incentive stock options may be granted under
the Plan on or after the tenth anniversary of the last action by the Board of
Directors approving an increase in the number of shares available for issuance
under the Plan, which action was subsequently approved within 12 months by the
shareholders.

         4.2 Options may be granted to any officer or key employee of Mentor
Graphics and any subsidiary of Mentor Graphics and may be granted in
substitution for outstanding options of another corporation by reason of merger,
consolidation, acquisition of property or stock, or other reorganization between
such other corporation and Mentor Graphics or any subsidiary of Mentor Graphics.
Additional options may be granted to existing optionees and may be granted in
exchange for outstanding options.

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         4.3 The Committee shall designate persons to receive grants, and as to
each option shall specify the number of shares, the option price and term, the
time or times at which the option may be exercised, whether the option is an
incentive stock option or a nonqualified stock option and all other terms and
conditions of the option.

         4.4 No employee may be granted incentive stock options under the Plan
such that the aggregate fair market value, on the date of grant, of the shares
with regard to which incentive stock options are exercisable for the first time
by that employee during any calendar year under the Plan and under any other
stock option plan of Mentor Graphics or any parent or subsidiary of Mentor
Graphics exceeds $100,000. Fair market value shall be determined under
subparagraph 5.1(c) as of the date of each grant.

5.       OPTION TERMS.

         5.1 The option price shall be fixed by the Committee as follows:

                  (a) Subject to (b) the option price for an incentive stock
option shall be not less than the fair market value of the shares on the date of
grant. The option price for a nonqualified stock option shall be not less than
50% of the fair market value of the shares on the date of grant.

                  (b) If the optionee at the time of grant owns stock possessing
more than 10 percent of the combined voting power of all classes of stock of
Mentor Graphics, the option price for an incentive stock option shall be not
less than 110 percent of the fair market value of the shares on the date of
grant. Stock owned by the optionee shall include for this purpose, and for
purposes of paragraph 5.2, stock attributed to the optionee pursuant to
applicable provisions of the Code.

                  (c) "Fair market value" means an amount determined by, or in
an manner approved by, the Committee. The Committee may appoint and rely on one
or more qualified independent appraisers to value the stock or use such other
evaluation as it considers appropriate.

         5.2 The Committee shall fix a time limit of not over 10 years after the
date of grant for exercise of an incentive stock option. The Committee shall fix
a time limit of not over 10 years plus seven days after the date of grant for
exercise of a nonqualified stock option. For a more than 10 percent shareholder
the maximum limit for exercise of an incentive stock option shall be 5 years.
The Committee may make the option exercisable in full immediately or in
graduated amounts over the option term.

         5.3 The option shall be evidenced by a stock option agreement executed
by Mentor Graphics and the optionee in a form prescribed by the Committee.

         5.4 The option may not be assigned or transferred except on death, by
will or operation of law, or pursuant to a qualified domestic relations order as
defined under the Code or Title I of the Employee Retirement Income Security
Act. The option may be exercised only by the optionee or by a successor or
representative after death.

         5.5 Unless otherwise determined by the Committee, if an officer of
Mentor Graphics subject to Section 16 of the Securities Exchange Act of 1934
(1934 Act) exercises an option within six months of the grant of the option, the
shares acquired upon exercise of the option may not be sold until six months
after the date of grant of the option.

6.       BONUS RIGHTS.

         6.1 The Committee may grant bonus rights in connection with
nonqualified stock options granted under the Plan. Bonus rights may be granted
with the related option or at a later time. A bonus right may not be assigned or
transferred except on death, by will or operation of law, or pursuant to a
qualified domestic relations order as defined under the Code or Title I of the
Employee Retirement Income Security Act. Bonus rights will be subject to such
rules, terms, and conditions as the Committee may prescribe.

         6.2 A bonus right will entitle an optionee to a cash bonus in
connection with the exercise in whole or in part of the related option. Subject
to paragraph 6.3, the amount of the bonus shall be determined by multiplying the
applicable bonus percentage by the amount by which the fair market value, on the
exercise date, of the shares received on exercise of the related option exceeds
the option price. The cash bonus will be payable within 30 days following the
date as of which its amount is determined. For the purpose of this paragraph,
fair market value shall be determined according to subparagraph 5.1(c). The
bonus percentage applicable to a bonus right shall be determined by the
Committee, but shall in no event exceed 100 percent.

         6.3 The Committee may set a maximum dollar limit on the amount of cash
to be paid under any bonus right.

7.       ACCELERATION UPON CHANGE IN CONTROL.

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         7.1 The Committee may grant acceleration rights to holders of options
or stock appreciation rights which will provide that the options or stock
appreciation rights will become exercisable in full for the remainder of their
terms upon the occurrence of a Change in Control. Acceleration rights may be
granted with an option or stock appreciation right or at a later time by
amendment of outstanding options or stock appreciation rights.

         7.2 "Change in Control" means the occurrence of any of the following
events, unless prior to the occurrence of the event, the Committee determines
that the specific event shall not be considered a Change in Control:

                  (a)      the shareholders of Mentor Graphics shall approve:

                           (i) any consolidation, merger or plan of share
         exchange involving Mentor Graphics (Merger) in which Mentor Graphics is
         not the continuing or surviving corporation or pursuant to which shares
         of common stock would be converted into cash, securities or other
         property, other than a Merger involving Mentor Graphics in which the
         holders of Mentor Graphics' common stock immediately prior to the
         Merger have the same proportionate ownership of common stock of the
         surviving corporation immediately after the Merger;

                           (ii) any sale, lease, exchange or other transfer (in
         one transaction or a series of related transactions) of all, or
         substantially all, the assets of Mentor Graphics; or

                           (iii) the adoption of any plan or proposal for the
         liquidation or dissolution of Mentor Graphics;

                  (b) at any time during a period of two consecutive years,
individuals who at the beginning of such period constituted the Board of
Directors (Incumbent Directors) shall cease for any reason to constitute at
least a majority thereof, unless each new director elected during such two-year
period was nominated or elected by two-thirds of the Incumbent Directors then in
office and voting (new directors nominated or elected by two-thirds of the
Incumbent Directors shall also be deemed to be Incumbent Directors); or

                  (c) any person (as such term is used in Section 13(d) of the
1934 Act) shall, as a result of a tender or exchange offer, open market
purchases, privately negotiated purchases or otherwise, have become the
beneficial owner (within the meaning of Rule 13d-3 under the 1934 Act), directly
or indirectly, of securities of Mentor Graphics ordinarily having the right to
vote in the election of directors (Voting Securities) representing twenty
percent (20%) or more of the combined voting power of the then outstanding
Voting Securities.

8.       STOCK APPRECIATION RIGHTS.

         8.1      (a) The Committee, in its sole discretion, may grant both
"general" and "limited" stock appreciation rights with all or any part of an
incentive stock option or a nonqualified stock option granted under the Plan.
Stock appreciation rights may be granted with the related option or at any later
time during the term of the option.

                  (b) A general stock appreciation right granted with all or any
part of an option shall be exercisable only at the time or times established by
the Committee and only to the extent that the related option could be exercised.
A limited stock appreciation right shall be exercisable only during the 60
calendar days immediately following a Change in Control and only if the
immediate resale of shares acquired upon exercise of the related option would
subject the optionee to liability under Section 16(b) of the 1934 Act; provided,
however, that a limited stock appreciation right may not be exercised within six
months of its date of grant. Upon exercise of a stock appreciation right, the
option or portion thereof to which the stock appreciation right relates must be
surrendered. The shares subject to an option or portion thereof that is
surrendered upon exercise of a stock appreciation right shall not be available
for future option or stock appreciation right grants under the Plan.

                  (c) Each stock appreciation right granted with all or any part
of an option shall entitle the holder to receive from Mentor Graphics an amount
equal to the excess of the fair market value at the time of exercise of one
share of Mentor Graphics common stock over the option price per share under the
related option, multiplied by the number of shares covered by the related option
or portion of the related option.

                  (d) The terms of a limited stock appreciation right granted
with a nonqualified stock option may provide, if so determined by the Committee,
that the fair market value of the common stock for purposes of subparagraph
8.1(c) shall be equal to the higher of:

                           (i) the highest reported sales price of the common
         stock during the 60-day period ending on the date the limited stock
         appreciation right is exercised;

                           (ii) the highest per share price paid for shares of
         common stock purchased in any tender or exchange offer during the 60
         calendar days preceding the exercise of the limited stock appreciation
         right;

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                           (iii) the fixed or formula price to be received by
         holders of shares of common stock in or as a result of any transaction
         described in subparagraph 7.2(a) if such price is determinable on the
         date of exercise, provided that any securities or other property that
         are part of the fixed or formula price shall be valued at the highest
         valuation placed on the securities or property in any communication to
         the shareholders of Mentor Graphics by any party to the transaction;
         and

                           (iv) the highest price per share shown on a Schedule
         13D, or any amendment thereto, filed by the holder or holders of the
         specified percentage of common stock whose acquisition gives rise to
         the exercisability of the limited stock appreciation right.

         8.2      (a) The Committee may grant general stock appreciation rights
without related options under the Plan to any officer or key employee of Mentor
Graphics and any subsidiary of Mentor Graphics. Such stock appreciation rights
may be granted in substitution for outstanding stock appreciation rights of
another corporation by reason of merger, consolidation, acquisition of property
or stock, or other reorganization between such other corporation and Mentor
Graphics or any subsidiary of Mentor Graphics. Additional stock appreciation
rights may be granted to existing holders of stock appreciation rights and may
be granted in exchange for outstanding stock appreciation rights.

                  (b) The Committee shall designate persons to receive grants of
stock appreciation rights, and as to each stock appreciation right shall specify
the number of shares, the stock appreciation right price, the term, the time or
times at which the stock appreciation right may be exercised and all other terms
and conditions of the stock appreciation right. The stock appreciation right
price shall not be less than 50% of the fair market value of the shares on the
date of grant.

                  (c) Each stock appreciation right granted without a related
option shall entitle the holder to receive from Mentor Graphics an amount equal
to the excess of the fair market value at the time of exercise of one share of
Mentor Graphics common stock over the stock appreciation right price, multiplied
by the number of shares covered by the stock appreciation right or portion
thereof that is exercised. The shares subject to a stock appreciation right or
portion thereof that is exercised shall not be available for future option or
stock appreciation right grants under the Plan.

         8.3      (a) Payment upon exercise of a general stock appreciation
right by Mentor Graphics may be made in shares of Mentor Graphics common
stock valued at fair market value, or in cash, or partly in shares and partly
in cash. The Committee shall either specify the form of payment or retain the
power to disapprove any election by a holder to receive cash on exercise of a
stock appreciation right. For the purpose of this paragraph, fair market
value shall be determined according to subparagraph 5.1(c).

                  (b) Payment upon exercise of a limited stock  appreciation
right by Mentor Graphics may be made only in cash.

         8.4       No fractional shares shall be issued upon exercise of a stock
appreciation right. In lieu thereof, cash may be paid in an amount equal to the
value of the fraction or, in the discretion of the Committee, the number of
shares may be rounded to the next whole share.

         8.5       Stock appreciation rights will be subject to such rules,
terms, and conditions, and shall be evidenced by an agreement in such form, as
the Committee may prescribe prior to the occurrence of a Change in Control.

         8.6       Stock appreciation rights may not be assigned or transferred
except on death, by will or operation of law, or pursuant to a qualified
domestic relations order as defined under the Code or Title I of the Employee
Retirement Income Security Act. Stock appreciation rights may be exercised only
by the holder or by a successor or representative after death.

         8.7       Unless otherwise determined by the Committee, no stock
appreciation right may be exercised by an officer of Mentor Graphics subject to
Section 16 of the 1934 Act during the first six months following the date of
grant.

9.       CHANGES IN CAPITAL STRUCTURE.

         If any change is made in the outstanding common stock without Mentor
Graphics' receiving any consideration, such as a stock split, reverse stock
split, stock dividend, or combination or reclassification of the common stock, a
corresponding change shall be made in the number of shares remaining available
for grants of options or stock appreciation rights under paragraph 1,
disregarding fractional shares, without any further approval of the
shareholders. The adjustment shall be made by the Committee whose determination
shall be conclusive.

10.      AMENDMENT OR TERMINATION OF THE PLAN.

         10.1     The Board of Directors may amend or terminate this Plan at any
                  time subject to paragraph 10.2.

         10.2     Unless the amendment is approved by the shareholders, no
                  amendment shall be made in the Plan that would:

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                  (a)    Increase the total number of shares available for
                         options or stock appreciation rights;

                  (b)    Increase the maximum option term; or

                  (c)    Modify the requirements for eligibility under the Plan.<PAGE>

                                                                    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

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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."

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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

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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:

<PAGE>

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

<PAGE>

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]

<PAGE>

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

<PAGE>

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

<PAGE>

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

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00005-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00005-of-00352.parquet"}]]