<PAGE>

                                                                    EXHIBIT 4.22


                              CLEAN HARBORS, INC.

                               WARRANT AGREEMENT
                               -----------------


     THIS WARRANT AGREEMENT is made as of April 30, 2001 among Clean Harbors,
Inc., a Massachusetts corporation (the "Company"), and the institutional
investors party hereto (collectively, "Purchasers").

                                    RECITAL
                                    -------

     The parties to this Warrant Agreement are also parties to a Securities
Purchase Agreement dated April 12, 2001 among the Company and the Purchasers
(the "Securities Purchase Agreement") pursuant to which the Purchasers have
agreed to purchase and the Company has agreed to sell Senior Subordinated Notes
in the aggregate principal amount of $35,000,000 and warrants to purchase, in
the aggregate, 1,519,020 shares of Common Stock of the Company at the time of
issuance (the "Warrants").  Under the Securities Purchase Agreement the Warrants
are required to be issued pursuant to this Warrant Agreement.  Certain terms
used in this Warrant Agreement are defined in Section 8.  Capitalized terms not
otherwise defined in this Warrant Agreement have the meanings given therefor in
the Securities Purchase Agreement.

     NOW, THEREFORE, the parties agree:

     1.   Purchase and Sale of the Warrants.
          ---------------------------------

          (i)  Authorization and Issuance of Shares and Warrants. The Company
               -------------------------------------------------
has authorized the issuance of (a) the Warrants to the Purchasers pursuant to
this Warrant Agreement, and (b) such number of shares of Common Stock as shall
be necessary to permit the Company to comply with its obligations to issue
Warrant Shares pursuant to the Warrants.

          (ii) Issuance of Warrants.  On the Issue Date, the Company shall (a)
               --------------------
issue to the Purchasers an aggregate of 1,519,020 Warrants to purchase shares of
Common Stock as of the Issue Date, allocated among the Purchasers in accordance
with Annex 1 to the Securities Purchase Agreement and (b) deliver to each
     -------
Purchaser a Warrant Certificate for the Warrants to be acquired by such
Purchaser pursuant to this Section 1, registered in the name of such Purchaser,
except that if such Purchaser shall notify the Company in writing prior to such
issuance that it desires its Warrant Certificates to be issued in other
denominations or registered in the name or names of any Affiliate, nominee or
nominees of such Purchaser for its or their benefit, then the Warrant
Certificates for such Warrants shall be issued in the denominations and
registered in the name or names specified in such notice, provided that such
                                                          --------
Affiliate, nominee or nominees (other than an institutional nominee) agrees to
be bound by the terms of this Agreement. Each Warrant shall initially entitle
the Warrantholder thereof to purchase one share of Common Stock, provided the
                                                                 --------
number of shares of Common Stock for which a Warrant is exercisable shall be
subject to adjustment from time to time as provided in Section 13.
<PAGE>

     2.   Warrant Certificates.
          --------------------

          (i)    The certificates evidencing the Warrants (the "Warrant
Certificates") to be delivered pursuant to this Warrant Agreement shall be in
registered form and in the form of Exhibit A.

          (ii)   Warrant Certificates shall be signed on behalf of the Company
by its Chairman of the Board or its President or any Vice President and by its
Clerk or an Assistant Clerk under its corporate seal. Each such signature upon
the Warrant Certificates may be in the form of a facsimile signature and may be
imprinted or otherwise reproduced on the Warrant Certificates. The seal of the
Company may be in the form of a facsimile thereof and may be impressed, affixed,
imprinted or otherwise reproduced on the Warrant Certificates.

          (iii)  In case any officer of the Company who shall have signed any of
the Warrant Certificates shall cease to be such officer before the Warrant
Certificates so signed shall have been disposed of by the Company, such Warrant
Certificates nevertheless may be disposed of as though such individual had not
ceased to be such officer of the Company; and any Warrant Certificate may be
signed on behalf of the Company by any individual who, at the actual date of the
execution of such Warrant Certificate, shall be a proper officer of the Company
to sign such Warrant Certificate, although at the date of the execution of this
Warrant Agreement any such individual was not such an officer.

     3.   Registration.  The Company shall keep at its principal office in the
          ------------
continental United States, a register (the "Warrant Register") in which the
Company shall record the registrations of the Warrants and the names and
addresses of the Warrantholders thereof from time to time and all transfers
thereof.  The Company shall number and register the Warrant Certificates in the
Warrant Register as they are issued by the Company and shall give the
Warrantholders prior written notice of any change of the address at which such
register is kept.  The office of the Company at which the Warrant Register is
maintained is referred to as the "Principal Office."

     The Company may deem and treat the registered Warrantholders of the Warrant
Certificates as the absolute owners of the Warrants represented thereby for all
purposes and the Company shall not be affected by any notice to the contrary.

     4.   Registration of Transfers, Exchanges or Assignments of Warrants.
          ---------------------------------------------------------------

          (i)    Subject to the limitations of this Section 4, a Warrantholder
shall be entitled to assign its Warrants or Warrant Shares in whole or in part
to any Person.

          (ii)   The Company shall, from time to time, register the transfer of
any outstanding Warrants upon the Warrant Register, upon surrender of the
Warrant Certificate representing such Warrants at the Principal Office
accompanied by a written instrument or instruments of transfer in the form of
the Assignment attached to the Warrant Certificate (an "Assignment") duly
executed by the Warrantholder thereof or its duly appointed legal
representative.

          (iii)  If a transfer is not made pursuant to an effective registration
statement under the Securities Act or Rule 144 or Rule 144A of the Securities
Act, the Company may require the transferor to deliver, prior to such transfer,
an opinion of counsel, which may be

                                      -2-
<PAGE>

counsel to such transferor, reasonably satisfactory to the Company, that the
Warrants or Warrant Shares may be so transferred without registration under the
Securities Act. In such event, regardless of whether the Company requires
delivery of an opinion of counsel, the Company may also require that the
transferee provide, prior to such transfer:

                 (1)   a written representation, signed by the proposed
          transferee, that such transferee is purchasing such Warrants or
          Warrant Shares for investment and not with a view toward distribution;

                 (2)   an agreement by such transferee to the placement of the
          restrictive legends set forth in Section 5 on such Warrant or Warrant
          Shares;

                 (3)   an agreement by such transferee that the Company may
          place a notation in the Warrant Register and stock records of the
          Company in respect of the restrictions on transfer described in the
          legends set forth in Section 5; and

                 (4)   an agreement by such transferee to be bound by the
          provisions of this Section 4 relating to the restrictions on transfer
          of such Warrant or Warrant Shares.

          (iv)   Warrant Certificates may be exchanged or combined at the option
of the Warrantholder thereof for another Warrant Certificate or other Warrant
Certificates of like tenor and representing in the aggregate a like number of
Warrants upon presentation thereof to the Company at the Principal Office,
together with a written notice signed by the Warrantholder specifying the
denominations in which the new Warrant Certificates are to be issued.

          (v)    Upon surrender of a Warrant Certificate for transfer in
accordance with this Section 4, the Company shall, without charge, execute and
deliver a new Warrant Certificate of like tenor and representing in the
aggregate a like number of Warrants in the name of the transferee named in such
Assignment and, if all of the Warrants represented by such Warrant Certificate
are not being transferred, in the name of the Warrantholder with respect to the
Warrants not transferred, and the Warrant Certificate so surrendered shall
promptly be canceled.

     5.   Restrictive Legends. (i)  Each Warrant Certificate shall, until the
          -------------------
Warrants represented by such certificate have been distributed to the public
pursuant to a public offering pursuant to an effective registration statement
under the Securities Act, or the Company has received an opinion of counsel
(which opinion shall be satisfactory in form and substance to the Company),
which may be counsel to the holder of such certificate, that such legend is not
required under the Securities Act, bear the following legend:

     THIS SECURITY WAS ORIGINALLY ISSUED IN A TRANSACTION EXEMPT FROM
     REGISTRATION UNDER SECTION 5 OF THE UNITED STATES SECURITIES ACT OF 1933,
     AS AMENDED, AND THIS SECURITY MAY NOT BE OFFERED, SOLD OR OTHERWISE
     TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN APPLICABLE EXEMPTION
     THEREFROM.

     (ii)  Each Warrant Certificate shall also bear the following legend:

                                      -3-
<PAGE>

     THE TRANSFER OF THE SECURITY REPRESENTED BY THIS CERTIFICATE IS ALSO
     SUBJECT TO THE CONDITIONS SPECIFIED IN (AND THE HOLDER HEREOF IS ENTITLED
     TO THE BENEFITS OF) THAT CERTAIN WARRANT AGREEMENT DATED AS OF APRIL 30,
     2001 (THE "WARRANT AGREEMENT") AMONG THE ISSUER AND THE INSTITUTIONAL
                -----------------
     INVESTORS A PARTY THERETO (THE "PURCHASERS") AND THE BENEFITS OF THE
                                     ----------
     REGISTRATION RIGHTS AGREEMENT DATED AS OF APRIL 30, 2001 (THE "REGISTRATION
                                                                    ------------
     AGREEMENT") AMONG THE ISSUER AND THE PURCHASERS, AS EACH OF THE WARRANT
     ---------
     AGREEMENT AND THE REGISTRATION AGREEMENT MAY BE AMENDED, MODIFIED AND
     SUPPLEMENTED AND IN EFFECT FROM TIME TO TIME IN ACCORDANCE WITH THE TERMS
     THEREOF.  A COPY OF THE WARRANT AGREEMENT AND THE REGISTRATION AGREEMENT
     WILL BE FURNISHED BY THE ISSUER UPON REQUEST.  THE HOLDER OF THIS
     CERTIFICATE, BY ACCEPTANCE OF THIS CERTIFICATE, AGREES TO BE BOUND BY THE
     PROVISIONS OF THE WARRANT AGREEMENT AND THE REGISTRATION AGREEMENT.

     6.   Terms of Warrants; Exercise of Warrants.
          ---------------------------------------

          (i)   Subject to the terms of this Warrant Agreement, each
Warrantholder shall have the right during the Exercise Period to exercise, at
any time and from time to time, in full or in part, its Warrants. The "Exercise
Period" shall mean the period from (and including) the Issue Date and until 5:00
p.m., Boston, Massachusetts local time, on April 30, 2008 (the "Expiration
Date") provided that, if the Warrantholder shall have given the Company
       --------
written notice of its intention to exercise its Warrants on or before 5:00 p.m.,
Boston, Massachusetts local time, on the Expiration Date, such Warrantholder may
exercise its Warrants at any time through (and including) the Business Day next
following the date that all applicable required regulatory holding periods have
expired and all applicable required governmental approvals have been obtained in
connection with such exercise of Warrants by such Warrantholder, if such
Business Day is later than on the Expiration Date. Each Warrant not exercised
prior to the expiration of the Exercise Period shall become void and all rights
thereunder and all rights in respect thereof under this Warrant Agreement shall
cease as of such time.

          (ii)  A Warrantholder may exercise some or all of its Warrants by (a)
delivering to the Company at the Principal Office the Warrant Certificate
representing such Warrants and a completed Election to Purchase in the form
attached to the Warrant Certificate (an "Exercise Notice") and (b) paying to the
Company the Exercise Price for the number of Warrant Shares in respect of which
such Warrants are then being exercised. The Warrant Shares in respect of which
the Warrants are exercised shall be deemed issued on the date that the
requirements set forth in clause (a) and (b) above are first satisfied, and the
Person in whose name the certificate representing the Warrant Shares is to be
issued shall be deemed the holder of such Warrant Shares as of that date for all
purposes, with, to the extent permitted by law, the right to vote such Warrant
Shares at any meeting of the Company's Shareholders from and after such date.

          (iii) Upon the exercise of any Warrants, the Company shall issue, at
the Company's expense, and cause to be delivered with all reasonable dispatch,
but in any event within 5 Business Days, a certificate or certificates for the
aggregate number of Warrant Shares to be issued upon the exercise of such
Warrants together with such other property, including cash, which may be
deliverable upon such exercise pursuant to the terms of this Warrant

                                      -4-
<PAGE>

Agreement. The certificates for Warrant Shares so delivered shall be in such
denominations as may be specified in the Exercise Notice and shall be registered
in the name of the Warrantholder or, subject to compliance with Section 4, such
other name or names as shall be designated by such Warrantholder in such
Exercise Notice.

          (iv)   If fewer than all of the Warrants represented by a Warrant
Certificate surrendered are exercised, a new Warrant Certificate evidencing the
Warrants not exercised will be issued by the Company at the Company's expense,
to the Warrantholder of such Warrants with all reasonable dispatch, but in any
event within 5 Business Days, or, at the request of the Warrantholder,
appropriate notation may be made on the Warrant Certificate surrendered and the
same returned to the Warrantholder. All Warrant Certificates surrendered upon
exercise of Warrants and not so returned shall be canceled by the Company.

          (v)    All Warrant Shares issued upon the exercise of any Warrant
shall be duly and validly issued, fully paid and nonassessable and free and
clear of any Liens or preemptive rights.

          (vi)   Notwithstanding the foregoing, the Company shall not be
required to issue a fractional Warrant Share upon exercise of any Warrant. If
more than one Warrant Certificate shall be presented for exercise at the same
time by the same Warrantholder, the number of full Warrant Shares which shall be
issuable upon the exercise thereof shall be computed on the basis of the
aggregate number of Warrant Shares purchasable on exercise of the Warrants
represented by the Warrant Certificates so presented. If any fraction of a
Warrant Share would, except for the provisions of this clause (vi), be issuable
on the exercise of any Warrants (or specified portion thereof), the Company
shall pay cash to the Warrantholder in respect of such fraction equal to the
same fraction of the Market Price per Warrant Share on the Business Day next
preceding the date of such exercise.

     7.   Payment of Exercise Price. The Exercise Price may be paid by any (or
          -------------------------
any combination) of the following as elected by the Warrantholder: (a) cash or
certified bank check, (b) cancellation of Warrants exercisable for such number
of Warrant Shares which, when multiplied by the Market Price for such Warrant
Shares on the date of such exercise, less the Exercise Price, equals the
Exercise Price, or (c) cancellation of a principal amount of any Senior
Subordinated Note or other debt instrument of the Company then held by the
Warrantholder equal to the Exercise Price.

     8.   Payment of Taxes.  The Company will pay all documentary stamp taxes
          ----------------
attributable to the initial issuance of the Warrants and Warrant Shares upon the
exercise of Warrants; provided that the Company shall not be required to pay any
                      --------
taxes generally levied on such Warrantholders' investment income, any transfer
tax or taxes which may be payable in respect of any transfer involved in the
issue of any Warrant Certificates or any certificates for Warrant Shares in a
name other than that of the Warrantholder of the Warrant Certificate surrendered
for exercise or transfer.

     9.   Mutilated or Missing Warrant Certificates.  Upon receipt of evidence
          -----------------------------------------
satisfactory to the Company of the loss, theft or destruction of a Warrant
Certificate, the Company shall issue in exchange and substitution for, upon
surrender of the mutilated Warrant Certificate at the Principal Office, or in
lieu of and substitution for the Warrant Certificate lost, stolen or destroyed,
a new Warrant Certificate of like tenor and representing an equivalent number of
Warrants.  The new Warrant Certificate shall be dated the date of issue of the
lost, stolen or

                                      -5-
<PAGE>

destroyed Warrant Certificate. In the case of any loss, theft or destruction of
a Warrant Certificate, the Company may request the Warrantholder provide an
indemnity agreement (and, in the case of a Warrantholder who is not a Purchaser
or an Institutional Investor, with such security therefor and as may be
reasonably requested by the Company and in form and substance, reasonably
acceptable to the Company).

     10.  Reservation of Warrant Shares.  The Company and any transfer agent for
          -----------------------------
the Company will at all times reserve and keep available, free from preemptive
rights and Liens, out of the aggregate of its authorized but unissued Capital
Stock or its authorized and issued Capital Stock held in its treasury, for the
purpose of enabling it to satisfy any obligation to issue Warrant Shares upon
exercise of Warrants, the maximum number of Warrant Shares which may then be
deliverable upon the exercise of all outstanding Warrants.  The Company will
keep a copy of this Warrant Agreement on file with every transfer agent for any
of the Company's Capital Stock.  The Company shall at its expense from time to
time take all action which may be necessary to obtain and keep effective any and
all permits, consents and approvals of Governmental Authorities which may be or
become requisite in connection with the issuance, sale, transfer and delivery of
the Warrants and the exercise of the Warrants and the issuance, sale, transfer
and delivery of the Warrant Shares.

     11.  Indemnification.  The Company shall indemnify and hold harmless each
          ---------------
of the Purchasers and the Warrantholders and each of their respective directors,
officers, employees and Affiliates (and such Affiliates' directors, officers and
employees) and agents (each, an "Indemnified Person") from and against any and
                                 ------------------
all losses, claims, damages, liabilities (or actions or other proceedings
commenced or threatened in respect thereof) and expenses that arise out of or
result from the Company's breach of, or negligence in connection with, this
Warrant Agreement, the Warrants or the Warrant Shares, including any legal or
other expenses reasonably incurred in connection with investigating, defending
or participating in the defense of any such loss, claim, damage, liability,
action or other proceeding (whether or not such Indemnified Person is a party to
any action or proceeding out of which any such expenses arise), except to the
extent incurred by reason of the gross negligence or willful misconduct of such
Indemnified Person or such Indemnified Person's willful and material breach of
this Warrant Agreement or the Warrants.  No Indemnified Person shall be
responsible or liable to the Company for any damages which may be alleged as a
result of or relating to this Warrant Agreement or the Warrants or in connection
with the other transactions contemplated hereby.  The provisions of this Section
11 shall survive any issuance of Warrant Shares and the expiration of the
Exercise Period.

     12.  Other Agreements of the Company.  The Company hereby covenants and
          -------------------------------
agrees that:

          (i)    so long as any of the Warrants are outstanding it (a) will not
take any action which results in the total number of Warrant Shares issuable
upon the exercise of the Warrants to exceed the total number of shares of Common
Stock or other shares of Capital Stock then authorized by the Company and
available for issue upon such exercise, and (b) will, before taking any action
which would result in an adjustment in the number of Warrant Shares issuable
upon exercise of a Warrant, obtain all such authorizations or exemptions
thereof, or consents thereto, as may be necessary from any public regulatory
body or bodies having jurisdiction thereof;

                                      -6-
<PAGE>

          (ii)   it will list and maintain such listing on each national
securities exchange on which any of its Capital Stock may at any time be listed,
subject to official notice of issuance upon exercise of the Warrants, all
Warrant Shares from time to time issuable upon the exercise of the Warrants that
are of the same class of Capital Stock; and

          (iii)  it will deliver to each Warrantholder promptly upon their
becoming available, and in any event within fifteen (15) days thereafter, each
financial statement, report, notice or proxy statement sent by the Company to
stockholders generally.

     13.  Antidilution Provisions.  The number of Warrant Shares receivable on
          -----------------------
exercise of a Warrant and the number of Warrant Shares outstanding shall be
subject to adjustment from time to time as provided in this Section 13.

          (i)    Issuance of Additional Common Stock.  If the Company, at any
                 -----------------------------------
time or from time to time after the Issue Date, shall issue, sell, grant or
shall fix a record date for the determination of holders of any class of
securities entitled to receive Additional Common Stock at a price per share of
Common Stock that is less than the then Market Price for Common Stock a
("Dilutive Issuance") then the number of shares of Common Stock for which each
Warrant is exercisable shall be increased as of the date of such issuance, sale
or grant or, in the case of a record date, the close of business on such record
date, by a fraction, the denominator of which shall be the number of shares of
           --------      -----------
Common Stock actually outstanding immediately prior to the Dilutive Issuance
plus the number of shares of Common Stock that the aggregate consideration to be
paid for the Additional Common Stock in the Dilutive Issuance (determined
pursuant to Section 13(xiv)) would have purchased at the Market Price and the
numerator of which shall be the number of shares of Common Stock actually
---------
outstanding immediately prior to the Dilutive Issuance plus the number of shares
of Additional Common Stock issued (or deemed to be issued pursuant to the other
provisions of this Section 13) in such Dilutive Issuance.

     For the purpose of calculating the number of Warrant Shares issuable upon
any actual exercise of Warrants, if any other Person shall be entitled to
receive Additional Common Stock as a result of such exercise and related
issuance of Warrant Shares (whether before or after the date of such exercise),
an adjustment shall be made in accordance with the provisions of this Section
13(i) as if such issuance of Additional Common Stock had been made immediately
prior to the exercise of Warrants.

          (ii)   Treatment of Options and Convertible Securities.  If the
                 -----------------------------------------------
Company, at any time or from time to time after the Issue Date, shall issue,
sell, grant or assume, or shall fix a record date for the determination of
holders of any class of securities entitled to receive, any Options or
Convertible Securities, then, and in each such case, the maximum number of
shares of Additional Common Stock (as set forth in the instrument relating
thereto, without regard to any provisions contained therein for a subsequent
adjustment of such number and whether or not the right to convert or exchange or
exercise is immediate or conditioned upon the passage of time, the occurrence or
non-occurrence of some event or otherwise) issuable upon the exercise of such
Options or, in the case of Convertible Securities and options therefor, the
conversion or exchange of such Convertible Securities, shall be deemed to be
Additional Common Stock issued as of the time of such issue, sale, grant or
assumption or, in case such a record date shall have been fixed, as of the close
of business on such record date, and if such Additional Common Stock are deemed
to have been issued at a price per share less than the then Market Price (as
determined pursuant to Section 13(xiv)) the number of shares of

                                      -7-
<PAGE>

Common Stock for which each Warrant is then exercisable, shall be adjusted
pursuant to Section 13(i); provided in each such case:
                           --------

                 (a)  if, as a result of provisions for subsequent adjustment
contained in the instrument relating thereto or otherwise, the maximum number of
shares of Additional Common Stock issuable upon exercise or conversion or
exchange of such Options or Convertible Securities shall change, the number of
Warrant Shares issuable upon exercise of a Warrant or the adjustment to the
number of Warrant Shares outstanding, in each case computed upon the original
issue, sale, grant or record date thereof and any subsequent adjustments based
thereon, shall be recomputed as if such changed number was the maximum number of
shares of Additional Common Stock issuable upon exercise or conversion or
exchange thereof on the date of original, issue, sale, grant or record date;

                 (b)  no further adjustment to the number of Warrant Shares
issuable upon exercise of a Warrant or to the number of Warrant Shares then
outstanding shall be made upon the subsequent issue or sale of Additional Common
Stock upon the exercise of such Options or the conversion or exchange of such
Convertible Securities; and

                 (c)  upon the expiration or cancellation of any such Options or
of the rights of conversion or exchange under any such Convertible Securities
which shall not have been exercised, the number of Warrant Shares issuable upon
exercise of a Warrant and any adjustment to the number of Warrant Shares
outstanding, in each case computed upon the original issue, sale, grant or
record date of such expired or canceled Options or Convertible Securities (or
upon the occurrence of the record date with respect thereto), and any subsequent
adjustments based thereon, shall, upon such expiration or cancellation as the
case may be, be recomputed as if:

                 (1)  in the case of Options for Common Stock or of Convertible
          Securities, the only Additional Common Stock issued or sold (or deemed
          issued or sold) was the Additional Common Stock, if any, actually
          issued or sold upon the exercise of such Options or the conversion or
          exchange of such Convertible Securities; and

                 (2)  in the case of Options for Convertible Securities, only
     the Convertible Securities, if any, actually issued or sold upon the
     exercise of such Options were issued at the time of the issue, sale, grant
     or assumption of such Options;

     provided that no such recomputation under this clause (c) shall have the
     --------
effect of decreasing the number of Warrant Shares issuable upon exercise of a
Warrant by an amount in excess of the amount of the adjustment initially made in
respect of such Options or Convertible Securities in such Dilutive Issuance or
the number of Warrant Shares then issued and outstanding.

          (iii)  Treatment of Dividends in Common Stock.  If the Company, at any
                 --------------------------------------
time or from time to time after the date hereof, shall declare or pay any
dividend or other distribution payable in Common Stock, then, and in each such
case, Additional Common Stock shall be deemed to have been issued, immediately
after the close of business on the record date for the determination of holders
of any class of securities entitled to receive such dividend or distribution.
Notwithstanding the above, if the Company shall thereafter legally abandon its
plan

                                      -8-
<PAGE>

to pay such dividend or distribution, then no adjustment under this Section
13(iii) shall be made.

          (iv)   Combinations, etc. If the outstanding Common Stock shall be
                 -----------------
combined or consolidated, by reclassification or otherwise, into a lesser number
of shares of Common Stock, the number of shares of Common Stock for which each
Warrant is exercisable shall, concurrently with the effectiveness of such
combination or consolidation, be proportionately decreased.

          (v)    Stock Splits, etc. If the outstanding Common Stock shall be
                 ------------------
subdivided into greater number of shares of Common Stock, by reclassification or
otherwise, other than by payment of a dividend or distribution in Common Stock,
then the number of shares of Common Stock for which each Warrant is exercisable
shall, concurrently with the effectiveness of such subdivision, be
proportionately increased.

          (vi)   Repricing of Options, Warrants, Convertible Securities or Other
                 ---------------------------------------------------------------
Rights. If the exercise price for any options, warrants or other rights to
------
acquire Common Stock outstanding as of the Issue Date and disclosed on Schedule
8.2 of the Securities Purchase Agreement or the exchange ratio applicable to the
conversion of any securities convertible into Common Stock outstanding as of the
Issue Date and disclosed on Schedule 8.2 of the Securities Purchase Agreement
(all such disclosed options, warrants, other rights and convertible securities,
"Existing Rights") is reset after the Issue Date to a price per share of Common
Stock that is less than the greater of (i) $2.50 per share or (iii) the then
Market Price per share then the Existing Rights benefiting from such reset shall
be deemed to be issued as of such reset date and shall be subject to Sections
13(i) and 13(ii) as an issuance of Options or Convertible Securities.

          (vii)  Dilution in Case of Other Securities. In case any Other
                 ------------------------------------
Securities shall be issued or sold or shall become subject to issue or sale upon
the conversion or exchange of any securities of the Company or to subscription,
purchase or other acquisition pursuant to any Options issued or granted by the
Company such as to dilute, on a basis to which the standards established in the
other provisions of this Section 13 are applicable, then, and in each such case,
the computations, adjustments and readjustments provided for in this Section 13
shall be made as nearly as possible in the manner so provided and applied to
determine the amount of Other Securities from time to time receivable upon the
exercise of the Warrants, so as to protect the Warrantholders against the effect
of such dilution.

          (viii) Changes in Common Stock. If the Company shall be a party to any
                 -----------------------
Significant Corporate Event in which the previously outstanding Common Stock
shall be changed into or exchanged for different securities of the Company or
common stock or other securities or interests in another Person or other
property (including cash) or any combination of any of the foregoing, the
Company (in the case of a Significant Corporate Event in which the Company
retains substantially all of its assets and survives) or such other corporation
or entity (an "Acquiring Company") then, as a condition of the consummation of
such Significant Corporate Event, lawful and adequate provisions shall be made
so that (a) the Warrantholders, upon the exercise of the Warrants at any time on
or after the date such a Significant Corporate Event is consummated (the
"Consummation Date"), but during the Exercise Period, shall be entitled to
receive, and the Warrants shall thereafter represent the right to receive, in
lieu of the Warrant Shares issuable upon such exercise prior to the Consummation
Date, the greatest number of securities or amount of other property to which
such Warrantholder would actually

                                      -9-
<PAGE>

have been entitled as a holder of Common Stock upon the consummation of such a
Significant Corporate Event if such Warrantholder had exercised its Warrants
immediately prior thereto (subject to adjustments from and after the
Consummation Date as nearly equivalent as possible to the adjustments provided
for in this Section 13), or (b) in the case of a Significant Corporate Event in
which the Company is not the survivor, if so elected by the Company, the
Warrantholders shall be entitled to receive on the Consummation Date in
cancellation of their Warrants, the greatest number of securities or amount of
other property to which such Warrantholder would actually have been entitled as
a holder of Common Stock upon consummation of such Significant Corporate Event
if such Warrantholder had exercised its Warrants immediately prior thereto and
had paid the Exercise Price therefore as provided for in clause (b) of Section
7.

     Notwithstanding anything contained herein to the contrary, unless the
Company makes an election under clause (b) above, the Company shall not effect
any Significant Corporate Event unless prior to the consummation thereof each
Acquiring Company which may be required to deliver any securities or other
property upon the exercise of the Warrants shall assume, by written instrument
delivered to the Warrantholders, the obligation to deliver to such
Warrantholders such securities or other property to which, in accordance with
the foregoing provisions, such Warrantholders may be entitled and an opinion of
counsel reasonably satisfactory to the Majority Warrantholders, stating that the
Warrants, including, without limitation, the exercise provisions applicable to
the Warrants, if any, shall thereafter continue in full force and effect and
shall be enforceable against such Acquiring Company in accordance with the terms
hereof.

          (ix)   Other Dividends or Other Distributions. If the Company declares
                 --------------------------------------
a dividend or other distribution upon its Common Stock, other than a dividend
payable in Additional Common Stock, then the Company shall pay over to each
Warrantholder, on the dividend payment date, the cash, stock or Other Securities
and other property which such Warrantholder would have received if such
Warrantholder had exercised its Warrants in full and had been the record holder
of the Warrant Shares represented by its Warrants on the date on which a record
is taken for the purpose of such dividend, or, if a record is not taken, the
date as of which the holders of such Common Stock of record entitled to such
dividend are to be determined, provided, in the case of a dividend consisting of
                               --------
stock or securities (other than Common Stock, Options or Convertible Securities)
or other property (except cash), each Warrantholder may, at its option, elect
that instead, lawful and adequate provisions shall be made whereby each
Warrantholder shall thereafter have the right to receive, upon exercise of its
Warrants on the terms and conditions specified in this Warrant Agreement and in
addition to the Warrant Shares issuable upon such exercise, such shares of
stock, securities or property.

          (x)    Certain Issues Excepted, Treatment of Options and Convertible
                 -------------------------------------------------------------
Securities Outstanding as of the Issue Date. Anything herein to the contrary
-------------------------------------------
notwithstanding, the Company shall not be required to make any adjustment to the
number of Warrant Shares for which the Warrants are exercisable in the case of
(a) the issuance of the Warrants, or (b) the issuance of Warrant Shares upon
exercise of the Warrants, or (c) subject to Section 13(vi), the issuance of
Common Stock upon exercise or conversion of any Existing Rights, or (d) the
issuance of shares of Common Stock or options or other rights relating thereto
after the Issue Date pursuant to the Company's 1992 Equity Incentive Plan, the
Company's 2000 Stock Incentive Plan, or the Company's Employee Stock Purchase
Plan or any other option or bonus plan approved by the Company's Board of
Directors representing up to 3.5% of the Common Stock of the Company on a fully-
diluted basis or (e) the issuance of Common Stock as a

                                      -10-
<PAGE>

dividend upon the 112,000 outstanding shares of the Company's Series B
Convertible Preferred Stock provided that such Common Stock is valued for
purposes of such dividend at the then "Market Value" of the Common Stock (as
such "Market Value" is calculated in accordance with the terms of such Preferred
Stock as in effect as of the Issue Date).

          (xi)   Notice of Adjustment. Whenever the number of Warrant Shares for
                 --------------------
which a Warrant is exercisable or the number of Warrant Shares outstanding shall
be adjusted pursuant to this Section 13, the Company shall deliver a certificate
signed by its chief financial officer to each Warrantholder setting forth, in
reasonable detail, the event requiring the adjustment and the method by which
such adjustment was calculated, specifying the number of Warrant Shares for
which each Warrant is now exercisable, the number of Warrant Shares now
outstanding and describing the number and kind of any Other Securities
comprising a Warrant Share. The Company shall keep at the Principal Office,
copies of all such certificates and cause the same to be available for
inspection at said office during normal business hours by any Warrantholder or
its nominee. All adjustments set forth in such certificates shall be subject to
the reasonable approval of the Majority Warrantholders.

          (xii)  Notice of Certain Corporate Action. In case the Company shall
                 ----------------------------------
propose to (a) pay any dividend or make any other distribution to the holders of
its Capital Stock, (b) offer to the holders of its Capital Stock rights to
subscribe for or to purchase any Additional Common Stock or shares of any other
class of securities, rights or options, (c) effect any reclassification of its
Capital Stock, (d) effect any capital reorganization or (e) effect any
Significant Corporate Event then, in each such case, the Company shall give to
each Warrantholder, in accordance with Section 16, a notice of such proposed
action, which shall specify the date on which a record is to be taken for the
purposes of such dividend, distribution rights or vote, or the date on which
such reclassification, reorganization, or Significant Corporate Event is to take
place and the date of participation therein by the holders of Capital Stock, if
any such date is to be fixed and shall also set forth such facts with respect
thereto as shall be reasonably necessary to indicate the effect of such action
on the Capital Stock, if any, and the number and kind of any other shares of
Capital Stock which will comprise the Warrant Shares, and the Exercise Price or,
after giving effect to any adjustment, if any, which will be required by this
Section 13 as a result of such action. Such notice shall be so given in the case
of any action covered by clause (a) or (b) above at least 20 days prior to the
record date for determining holders of the Capital Stock for purposes of such
action, and in the case of any other such action, at least 30 days prior to the
date of the taking of such proposed action or the date of participation therein
by the holders of Capital Stock, whichever shall be the earlier.

          (xiii) Certain Events. If any event occurs as to which, in the good
                 --------------
faith judgment of the Board of Directors of the Company, the other provisions of
this Section 13 are not strictly applicable or if strictly applicable would not
fairly protect the exercise rights of the Warrantholders in accordance with the
essential intent and principles of this Section 13, then the Board of Directors
of the Company in the good faith, reasonable exercise of its business judgment
shall make an adjustment in the application of such provisions, in accordance
with such essential intent and principles so as to protect such exercise rights
as aforesaid.

          (xiv)  Computation of Consideration. For the purposes of this Section
                 ----------------------------
13:

          (a)  the consideration for any Additional Common Stock or any Options
     or Convertible Securities, irrespective of the accounting treatment of such
     consideration,

                                      -11-
<PAGE>

               (1) insofar as it consists of cash, shall be computed as the
          amount of cash received by the Company, and insofar as it consists of
          securities, the Market Price therefor or insofar as it consists of
          other property, the Fair Market Value thereof, as of the date
          immediately preceding such issue, sale, grant, or the record date
          therefor, in each case without deducting any expenses paid or incurred
          by the Company, any commissions or compensation paid or concessions or
          discounts allowed to underwriters, dealers or others performing
          similar services, and any accrued interest or dividends in connection
          with such issue or sale, and

               (2) in case Additional Common Stock or Options or Convertible
          Securities are or are to be issued, sold or granted together with
          other stock or securities or other assets of the Company for a
          consideration which covers both, shall be the proportion of such
          consideration so received, computed as provided in subdivision (1)
          above, allocable to such Additional Common Stock or Options or
          Convertible Securities, as the case may be, all as determined by the
          Board of Directors of the Company in the good faith reasonable
          exercise of its business judgment;

          (b) all Additional Common Stock and all Options, or Convertible
     Securities issued in payment of any dividend or other distribution on any
     class of stock of the Company shall be deemed to have been issued without
     consideration;

          (c) Additional Common Stock deemed to have been issued upon the issue,
     sale, or grant of Options and Convertible Securities pursuant to Section
     13(ii), shall be deemed to have been issued for a consideration per share
     determined by dividing

               (1) the total amount, if any, received and receivable (or,
          pursuant to this Section 13(xiv), deemed to have been received) by the
          Company as consideration for the issue, sale, or grant of the Options
          or Convertible Securities in question, plus the minimum aggregate
          amount of additional consideration (as set forth in the instruments
          relating thereto, without regard to any provision contained therein
          for a subsequent adjustment of such consideration) payable to the
          Company upon the exercise in full of such Options or the conversion or
          exchange of such Convertible Securities or, in the case of Options for
          Convertible Securities, the exercise of such Options for Convertible
          Securities and the conversion or exchange of such Convertible
          Securities, in each case comprising such consideration as provided in
          the foregoing clause (a) above, by

               (2) the maximum number of shares of Common Stock (as set forth in
          the instruments relating thereto, without regard to any provision
          contained therein for a subsequent adjustment of such number) issuable
          upon the exercise of such Options or the conversion or exchange of
          such Convertible Securities; and

          (d) In case the Company shall issue any Additional Common Stock,
     Options or Convertible Securities in connection with the acquisition by the
     Company of the stock or assets of any other corporation or the merger of
     any other corporation into the Company under circumstances where on the
     date of issue of such Additional Common Stock, Options or Convertible
     Securities the consideration received for such Additional Common Stock or
     deemed to have been received for the Additional Common Stock

                                      -12-
<PAGE>

     deemed to be issued pursuant to Section 13(ii) is less than the Market
     Price of the Common Stock in effect immediately prior to such issue but
     equaled the Market Price on the date the number of Additional Common Stock
     or the amount and the exercise price or conversion price of such Options or
     Convertible Securities to be so issued were set forth in a binding
     agreement between the Company and the other party or parties to such
     transaction and such terms are not amended prior to the date of issue then
     such Additional Common Stock, the consideration received for such
     Additional Common Stock or deemed to have been received for the Additional
     Common Stock deemed to be issued pursuant to Section 13(ii) shall not be
     deemed to have been issued for less than the Market Price.

     14.  Definitions. For the purpose of this Warrant Agreement the following
          -----------
terms shall have the following meanings:

          "Acquisition" means any transaction pursuant to which all or
           -----------
substantially all of the assets of the Company or any Subsidiary of the Company
are sold, transferred or otherwise disposed, or the Company or any Subsidiary of
the Company merges with or into a Person not the Company or another Subsidiary
of the Company or consolidates with another such a Person, or the Company or any
Subsidiary of the Company liquidates or dissolves.

          "Acquiring Company" has the meaning set forth in Section 13(viii).
           -----------------

          "Additional Common Stock" means all Common Stock issued or sold (or,
           -----------------------
pursuant to Section 13 deemed to be issued) by the Company after the date
hereof, whether or not subsequently reacquired or retired by the Company.

          "Common Stock" means the Company's par value Common Stock.
           ------------

          "Company" has the meaning set forth in the first paragraph of this
           -------
Agreement.

          "Consummation Date" has the meaning set forth in Section 13(viii).
           -----------------

          "Convertible Securities" means any evidences of indebtedness, shares
           ----------------------
of stock, or securities directly or indirectly convertible into or exchangeable
for Common Stock.

          "Dilutive Issuance" has the meaning set forth in Section 13(i).
           -----------------

          "Exercise Notice" has the meaning set forth in Section 6.
           ---------------

          "Exercise Period" has the meaning set forth in Section 6.
           ---------------

          "Exercise Price" means $.01 per Warrant Share.
           --------------

          "Existing Rights" has the meaning set forth in Section 13(vi).
           ---------------

          "Fair Market Value" means, on any date specified herein, as to any
           -----------------
property, the fair market value as reasonably determined by the Board of
Directors of the Company unless the Majority Warrantholders have reasonably
objected to such determination of fair market value within 10 Business Days of
the date notice of such determination by the Board of Directors is delivered to
the Warrantholders, in which case, if the Majority Warrantholders and

                                      -13-
<PAGE>

the Company cannot agree on the Fair Market Value within 10 Business Days of the
date a timely objection is delivered by the Majority Warrantholders, then as
determined by an independent investment banking firm mutually acceptable to the
Majority Warrantholders and the Company (the cost of the engagement of such
investment banking firm to be borne by the Company).

          "fully diluted basis" means, with reference to the determination of
           --------------------
Common Stock or Other Securities deemed outstanding at any time, the number of
Common Stock or Other Securities then issued and outstanding, assuming full
conversion, exercise and exchange of all Warrants, Convertible Securities and
Options that are (or may become) exchangeable for, or exercisable or convertible
into, Common Stock.

          "Indemnified Person" has the meaning set forth in Section 11.
           ------------------

          "Issue Date" means April 30, 2001.
           ----------

          "Liquidation" means any voluntary or involuntary dissolution,
           -----------
liquidation or winding up of the Company.

          "Majority Warrantholders" means the holders of at least 51% of the
           -----------------------
Warrants at the time outstanding.

          "Market Price" means, as to any security on any date specified herein,
           ------------
the Fair Market Value per share of such security, or if there shall be a public
market for such security, the average of the daily closing prices for the twenty
(20) consecutive trading days before such date excluding any trades which are
not bona fide arm's length transactions. The closing price for each day shall be
(a) if any such security is listed or admitted for trading on any national
securities exchange, the last sale price of any such security, regular way, or
the mean of the closing bid and asked prices thereof if no such sale occurred,
in each case as officially reported on the principal securities exchange on
which any such security is listed, or (b) if quoted on NASDAQ or any similar
system of automated dissemination of quotations of securities prices then in
common use, the mean between the closing high bid and low asked quotations of
any such security in the over-the-counter market as shown by NASDAQ or such
similar system of automated dissemination of quotations of securities prices, as
reported by any member firm of the New York Stock Exchange selected by the
Company, or (c) if not quoted as described in clause (b), the mean between the
high bid and low asked quotations for any such security as reported by NASDAQ or
any similar successor organization, as reported by any member firm of the New
York Stock Exchange selected by the Company.  If any such security is quoted on
a national securities or central market system in lieu of a market or quotation
system described above, the closing price shall be determined in the manner set
forth in clause (a) of the preceding sentence if bid and asked quotations are
reported but actual transactions are not, and in the manner set forth in clause
(b) of the preceding sentence if actual transactions are reported.

          "Options" means rights, options or warrants to subscribe for, purchase
           -------
or otherwise acquire either Common Stock or Convertible Securities.

          "Other Securities" means any Capital Stock (other than Common Stock)
           ----------------
and any other securities of the Company or any other Person (corporate or
otherwise) which the Warrantholders at any time shall be entitled to receive, or
shall have received, upon the

                                      -14-
<PAGE>

exercise or partial exercise of the Warrants, in lieu of or in addition to
Common Stock, or which at any time shall be issuable or shall have been issued
in exchange for or in replacement of Common Stock or Other Securities pursuant
to Section 13 or otherwise.

          "Principal Office" has the meaning set forth in Section 3.
           ----------------

          "Purchasers" has the meaning set forth in the first paragraph of this
           ----------
Warrant Agreement.

          "Repurchase" means any transaction pursuant to which the Company or
           ----------
any of its Affiliates shall repurchase, redeem or otherwise acquire more than
25% of the Company's Common Stock.

          "Securities Purchase Agreement" has the meaning set forth in the
           -----------------------------
Recital.

          "Significant Corporate Event" means any Acquisition, Repurchase,
           ---------------------------
Change of Control, Liquidation or Public Offering.

          "Warrant Certificates" has the meaning set forth in Section 2.
           --------------------

          "Warrant Register" has the meaning set forth in Section 3.
           ----------------

          "Warrant Share" means as of the Issue Date one share of Common Stock
           -------------
per Warrant and thereafter the number of shares of Capital Stock and Other
Securities which may be issuable upon exercise of a Warrant as a result of any
adjustment pursuant to Section 13.

          "Warrantholder" means any registered holder of a Warrant as set forth
           -------------
in the Warrant Register.

          "Warrants" has the meaning set forth in the Recital.
           --------

     15.  Notices.  All notices and other written communications provided for
          -------
hereunder shall be given in writing and delivered in person or sent by overnight
delivery service (with charges prepaid) or by facsimile transmission, if the
original of such facsimile transmission is sent by overnight delivery service
(with charges prepaid) by the next succeeding Business Day and (i) if to any
Purchaser as set forth in Annex 1 to the Securities Purchase Agreement, its
nominee, addressed to such Purchaser at the address or fax number, or at such
other address or fax number as such Purchaser shall have specified to the
Company in writing, (ii) if to any other Warrantholder, addressed to such other
Warrantholder at such address or fax number as is specified for such
Warrantholder in the Warrant Register or the stock records of the Company, as
applicable and (iii) if to the Company, addressed to it as set forth in Annex 2
to the Securities Purchase Agreement or at such other address or fax number as
the Company shall specify to each Warrantholder in writing given in accordance
with this Section 15.  Notice given in accordance with this Section 15 shall be
effective upon the earlier of the date of delivery or the second Business Day at
the place of delivery after dispatch.

     16.  Supplements and Amendments. The Company and Purchasers may from time
          --------------------------
to time supplement or amend this Warrant Agreement without the approval of any
Warrantholder in order to cure any ambiguity or to correct or supplement any
provision contained herein which may be defective or inconsistent with any other
provision herein, or to

                                      -15-
<PAGE>

make any other provision in regard to matters or questions arising hereunder
which the Company and Purchasers may deem necessary or desirable and which shall
not have a material adverse effect on the interests of the Warrantholders. Any
amendment to Section 13 of this Warrant Agreement and any amendment or
supplement to this Warrant Agreement that has a material adverse effect on the
interests of the Warrantholders as such shall require the written consent of the
Majority Warrantholders. The consent of each Warrantholder shall be required for
any amendment to (i) this Warrant Agreement pursuant to which the Exercise Price
would be increased or the number of Warrant Shares issuable upon exercise of
Warrants would be decreased other than pursuant to adjustments provided in
Section 13 or (ii) the definition of Majority Warrantholders.

     17.  Successors. All the covenants and provisions of this Warrant Agreement
          ----------
by or for the benefit of the Company, the Purchasers or the Warrantholders shall
bind and inure to the benefit of their respective successors and assigns
hereunder; provided, except as provided in Section 13(viii), the obligations of
the Company hereunder may not be assigned without the prior written consent of
the Majority Warrantholders.

     18.  Benefits of This Warrant Agreement.  Nothing in this Warrant Agreement
          ----------------------------------
shall be construed to give to any Person other than the Company, the Purchasers
and the Warrantholders any legal or equitable right, remedy or claim under this
Warrant Agreement.

     19.  Availability of Information. The Company shall comply with the
          ---------------------------
reporting requirements of Sections 13 and 15(d) of the Exchange Act to the
extent it is required to do so under the Exchange Act. The Company shall also
cooperate with each Warrantholder in supplying such information as may be
necessary for such Warrantholder to complete and file any information reporting
forms currently or hereafter required by the SEC as a condition to the
availability of an exemption from the Securities Act for the sale of any
Warrants or Warrant Shares.

     20.  Taking of Record: Stock and Warrant Transfer Books. In the case of all
          --------------------------------------------------
dividends or other distributions by the Company to the holders of its Capital
Stock with respect to which any provision of Section 13 refers to the taking of
a record of such holders, the Company shall in each such case take such a record
as of the close of business on a Business Day.  The Company shall not at any
time, except upon complete dissolution, liquidation or winding up, close its
stock transfer books or Warrant transfer books so as to result in preventing or
delaying the exercise, conversion or transfer of any Warrants or Warrant Shares,
unless otherwise required by applicable law.

     21.  No Voting Rights. A Warrantholder, as such, shall not be entitled to
          ----------------
any voting or other rights as a member of the Company except as expressly
provided in this Warrant Agreement.

     22.  Counterparts; Effectiveness. This Warrant Agreement may be executed in
          ---------------------------
any number of counterparts and each of such counterparts shall for all purposes
be deemed to be an original, and all such counterparts shall together constitute
but one and the same instrument. this Warrant Agreement shall become effective
on the date on which each party hereto shall have received counterparts hereof
executed by each of the parties hereto. The execution and delivery hereof by the
Company is irrevocable.

                                      -16-
<PAGE>

     23.  Governing Law. THIS WARRANT AGREEMENT AND THE RIGHTS OF THE PARTIES
          -------------
SHALL BE GOVERNED BY, THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS (WITHOUT
GIVING EFFECT TO ANY LAWS OR RULES RELATING TO CONFLICTS OF LAWS THAT WOULD
CAUSE THE APPLICATION OF THE LAWS OF ANY JURISDICTION OTHER THAN THE
COMMONWEALTH OF MASSACHUSETTS).

                       [Signatures Follow on Next Page]

                                      -17-
<PAGE>

          IN WITNESS WHEREOF, each of the parties hereto has caused this Warrant
Agreement to be duly executed by its authorized officer, as of the day and year
first above written.

THE COMPANY:                  CLEAN HARBORS, INC.

                              By: /s/ Stephen H. Moynihan
                                  --------------------------------------
                                  Name: Stephen H. Moynihan
                                  Title: Senior Vice President















                      Signature Page to Warrant Agreement
<PAGE>

THE PURCHASERS:               JOHN HANCOCK LIFE INSURANCE
                                 COMPANY

                              By:  /s/  Steven S. Blewitt
                                   --------------------------
                                   Name:
                                   Title: MANAGING DIRECTOR


                              JOHN HANCOCK VARIABLE LIFE
                                INSURANCE COMPANY

                              By:  /s/  Steven S. Blewitt
                                   --------------------------
                                   Name:
                                   Title: AUTHORIZED SIGNATORY


                              SIGNATURE 4 LIMITED
                              By:  John Hancock Life Insurance Company,
                                   as Portfolio Advisor


                              By:  /s/  Steven S. Blewitt
                                   --------------------------
                                   Name:
                                   Title: MANAGING DIRECTOR


                              SIGNATURE 5 L.P.
                              By:  John Hancock Life Insurance Company,
                                   as Portfolio Advisor

                              By:  /s/  Steven S. Blewitt
                                   --------------------------
                                   Name:
                                   Title: MANAGING DIRECTOR


                      Signature Page to Warrant Agreement
<PAGE>

                              SPECIAL VALUE BOND FUND, LLC

                              By:  SVIM/MSM, LLC
                                   as Manager

                              By:  TENNENBAUM & CO., LLC
                                   as Managing Member of the Manager

                              By:  /s/  Michael E. Tennenbaum
                                   ------------------------------
                                   Name:   Michael E. Tennenbaum
                                   Title:  Member


                      Signature Page to Warrant Agreement
<PAGE>

                              ARROW INVESTMENT PARTNERS
                              By:  Grandview Capital Management, LLC,
                                   Investment Manager

                              By:  /s/  Robert E. Sydow
                                   -------------------------
                                   Name:   Robert E. Sydow
                                   Title:  President


                              BILL AND MELINDA GATES FOUNDATION
                              By:  Grandview Capital Management, LLC,
                                   Investment Manager

                              By:  /s/  Robert E. Sydow
                                   -------------------------
                                   Name:   Robert E. Sydow
                                   Title:  President


                      Signature Page to Warrant Agreement
<PAGE>

                                    WARRANT
                                    -------

THIS SECURITY WAS ORIGINALLY ISSUED IN A TRANSACTION EXEMPT FROM REGISTRATION
UNDER SECTION 5 OF THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED (THE
"ACT"), AND THIS SECURITY MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED IN
THE ABSENCE OF SUCH REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM.

THE TRANSFER OF THE SECURITY REPRESENTED BY THIS CERTIFICATE IS ALSO SUBJECT TO
THE CONDITIONS SPECIFIED IN (AND THE HOLDER HEREOF IS ENTITLED TO THE BENEFITS
OF) THAT CERTAIN WARRANT AGREEMENT DATED AS OF APRIL 30, 2001 (THE "WARRANT
                                                                    -------
AGREEMENT") AMONG THE ISSUER AND THE INSTITUTIONAL INVESTORS A PARTY THERETO
---------
(THE "PURCHASERS") AND THE BENEFITS OF THE REGISTRATION RIGHTS AGREEMENT DATED
      ----------
AS OF APRIL 30, 2001 (THE "REGISTRATION AGREEMENT") AMONG THE ISSUER AND THE
                           ----------------------
PURCHASERS AS EACH OF THE WARRANT AGREEMENT AND THE REGISTRATION AGREEMENT MAY
BE AMENDED, MODIFIED AND SUPPLEMENTED AND IN EFFECT FROM TIME TO TIME IN
ACCORDANCE WITH THE TERMS THEREOF.  A COPY OF EACH OF THE WARRANT AGREEMENT AND
THE REGISTRATION AGREEMENT WILL BE FURNISHED BY THE ISSUER UPON REQUEST.  THE
HOLDER OF THIS CERTIFICATE, BY ACCEPTANCE OF THIS CERTIFICATE, AGREES TO BE
BOUND BY THE PROVISIONS OF THE WARRANT AGREEMENT AND THE REGISTRATION AGREEMENT.

PPN: No.                                                      _________ Warrants
Certificate No. _____

                              CLEAN HARBORS, INC.

          This Warrant Certificate certifies that ____________, or its
registered assigns, is the registered holder ("Warrantholder") of _____________
warrants (the "Warrants"), with each Warrant initially entitling the
Warrantholder to purchase one share of the Common Stock (the "Common Stock") of
Clean Harbors, Inc., a Massachusetts corporation (the "Company") upon surrender
of this Warrant Certificate and payment of the Exercise Price at the Principal
Office of the Company, subject to the conditions set forth herein and in the
Warrant Agreement referred to on the reverse hereof.  Defined terms used in this
Warrant Certificate and not otherwise defined herein are used with the meanings
given in the Warrant Agreement.  The Exercise Price is $.01 per Warrant Share.
The number and type of Warrant Shares issuable upon exercise of this Warrant are
subject to adjustment upon the occurrence of certain events as set forth in the
Warrant Agreement.

          The Warrants represented by this Warrant Certificate may not be
exercised after 5:00 p.m., Boston, Massachusetts local time, on April 30, 2008
(or such later date as is specified in the Warrant Agreement) and, to the extent
not exercised on or before 5:00 p.m., Boston, Massachusetts local time on such
date, such Warrants shall become void.

          Reference is hereby made to the further provisions of this Warrant
Certificate set forth on the reverse hereof and such further provisions shall
for all purposes have the same effect as though fully set forth at this place.


<PAGE>

          THIS WARRANT AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH, AND THE RIGHTS OF THE PARTIES SHALL BE GOVERNED BY, THE LAWS OF
THE COMMONWEALTH OF MASSACHUSETTS (WITHOUT GIVING EFFECT TO ANY LAWS OR RULES
RELATING TO CONFLICTS OF LAWS THAT WOULD CAUSE THE APPLICATION OF THE LAWS OF
ANY JURISDICTION OTHER THAN THE COMMONWEALTH OF MASSACHUSETTS).

          IN WITNESS WHEREOF, Clean Harbors, Inc. has caused this Warrant
Certificate to be signed by its Chairman of the Board, President or Vice
President and by its Clerk or Assistant Clerk, thereunto duly authorized, and
has caused this Warrant Certificate to be duly executed, as of the day and year
first above written.

                              CLEAN HARBORS, INC.

                              By: ____________________________
                                     Name:
                                     Title:
[SEAL]

Attest:_____________________
       [Assistant] Clerk

DATED:______________________
<PAGE>

                         [Form of Warrant Certificate)

                                   [Reverse]

          The Warrants evidenced by this Warrant Certificate are part of a duly
authorized series of Warrants issued pursuant to a Warrant Agreement dated as of
April 30, 2001 (the "Warrant Agreement") by and among the Company and certain
institutional investors, which Warrant Agreement is hereby incorporated by
reference in and made a part of this Warrant Certificate and is hereby referred
to for a description of the rights, limitation of rights, obligations, duties
and immunities thereunder of the Company and the Warrantholder and other
registered holders of the Warrants.  A copy of the Warrant Agreement may be
obtained by the Warrantholder hereof upon written request to the Company.

          The Warrantholder may exercise Warrants represented by this Warrant
Certificate by surrendering this Warrant Certificate, with a completed Election
to Purchase in the form attached, together with payment of the Exercise Price at
the Principal Office of the Company.  In the event that upon any exercise of
Warrants evidenced hereby the number of Warrants exercised shall be less than
the total number of Warrants evidenced hereby, there shall be issued to the
Warrantholder hereof or its assignee a new Warrant Certificate evidencing the
Warrants not exercised or upon request of the Warrantholder, appropriate
notation on this Warrant Certificate shall be made and this Warrant Certificate
shall be returned to the Warrantholder.

          Payment of the Exercise Price may be made in cash or by certified bank
check to the order of the Company or by any combination thereof or as otherwise
provided in the Warrant Agreement.

          The Warrant Agreement provides that upon the occurrence of certain
events the Exercise Price set forth on the face hereof and the number and type
of Warrant Shares for which each Warrant is exercisable may, subject to certain
conditions, be adjusted. No fractions of a Warrant Share will be issued upon the
exercise of any Warrant, but the Company will pay the cash value thereof
determined as provided in the Warrant Agreement.

          This Warrant Certificate may be exchanged, in the manner and subject
to the limitations provided in the Warrant Agreement, without charge, for
another Warrant Certificate or Warrant Certificates of like tenor evidencing in
the aggregate a like number of Warrants.

          The Warrants represented by this Warrant Certificate may be
transferred subject to the limitations provided in and compliance with the
Warrant Agreement.

          The Company may deem and treat the Warrantholder as the absolute owner
of this Warrant Certificate (notwithstanding any notation of ownership or other
writing hereon made by anyone), for the purpose of any exercise hereof, of any
distribution to the Warrantholder, and for all other purposes, and the Company
shall not be affected by any notice to the contrary.  Except as specifically
provided in the Warrant Agreement, prior to exercise, the Warrants represented
by this Warrant Certificate do not entitle the Warrantholder to any rights as a
shareholder of the Company.
<PAGE>

                         FORM OF ELECTION TO PURCHASE
                         ----------------------------


                                                         Dated ___________, ____

          The undersigned hereby irrevocably elects to exercise _______ Warrants
to  purchase Common Stock represented by the within Warrant Certificate and
hereby makes payment of $.01 per Warrant Share, in payment of the Exercise Price
therefor as follows:

          $________ in cash or certified bank check

          $________ by cancellation of Warrants

          $________ by cancellation of principal outstanding under ____________
          [identify debt instrument]

          The Common Stock or other securities issuable upon exercise of such
Warrants shall be registered as follows:


                    INSTRUCTIONS FOR REGISTRATION OF SHARES
                    ------------ --- ------------ -- ------

Name_____________________________________________________________
    Note: If the name does not conform in all respects to the name of the
    Warrantholder as specified on the face of the enclosed Warrant Certificate,
    the Company may require evidence of compliance with the transfer provisions
    of the Warrant Agreement.


Address  __________________________________________________________

______________________________________
Social Security or other identifying
number of holder



                              Signature________________________________
                              Note: The signature must conform in all respects
                              to the name of the Warrantholder as specified on
                              the face of the enclosed Warrant Certificate.
<PAGE>

                                ASSIGNMENT FORM
                                ---------------

          FOR VALUE RECEIVED, ____________________ hereby sells, assigns and
transfers unto

Name_____________________________________________________________
          (please typewrite or print in block letters)

Address__________________________________________________________

__________________________________
Social Security or other
identifying number of assignee

its right to ___ Warrants to purchase Common Stock represented by the enclosed
Warrant Certificate and does hereby irrevocably constitute and appoint
__________________ its attorney, to transfer the same on the books of the
Company, with full power of substitution in the premises.

Date:_____________, _____


Signature________________________________
         Note: The signature must conform
         in all respects to the name of the
         holder as specified on the face
         of the enclosed Warrant Certificate.