Exhibit 2.2

                    FIRST AMENDMENT TO ACQUISITION AGREEMENT

     WHEREAS, Safety-Kleen Services, Inc. (the "Seller") and Clean Harbors, Inc.
(the "Purchaser"), are parties to an Acquisition Agreement dated as of February
22, 2002 (the "Acquisition Agreement");

     WHEREAS, the Seller and the Purchaser wish to amend certain provisions of
the Acquisition Agreement as set forth in this First Amendment to Acquisition
Agreement (this "Amendment");

     NOW, THEREFORE, the parties hereto agree as follows:

     1. Section 5.2 of the Acquisition Agreement is hereby amended by adding a
new Section 5.2 (k) which shall read as follows:

         (k) Purchaser's Deposit. Provided that this Agreement shall not by then
have been terminated in accordance with its terms by either the Seller or the
Purchaser for any reason, the Purchaser shall on May 30, 2002 make a deposit
(the "Purchaser's Deposit") in the form of a certified check payable to the
order of Lazard Freres & Co. LLC, as agent for the Seller, or other immediately
available funds, in the amount of Three Million Dollars ($3,000,000). The
Purchaser's Deposit shall be held in an interest-bearing escrow account and,
together with interest thereon, shall be applied at the Closing against the
Unadjusted Cash Purchase Price if the Closing shall take place in accordance
with this Agreement. If the Closing shall not take place for any reason other
than a termination by the Seller in accordance with Section 7.1(b), the
Purchaser's Deposit, together with interest earned thereon, shall be returned to
the Purchaser within two days following the earlier of either: (A) June 20, 2002
(or July 20, 2002 if such date has been extended in accordance with Section
7.1(g)) if by such date (or such extended date) the Bankruptcy Court shall not
have entered the Section 363/365 Order in favor of the Purchaser, (B) the date
on which this Agreement is terminated for any reason by either the Seller or the
Purchaser in accordance with this Agreement (other than a termination by the
Seller in accordance with Section 7.1(b)), or (C) October 15, 2002, provided
that the Purchaser is not then in material breach of this Agreement after the
Purchaser has received not less than 30 days prior written notice from the
Seller of such breach. If this Agreement shall be terminated by the Seller in
accordance with Section 7.1(b), the Purchaser's Deposit, together with interest
earned thereon, shall promptly be delivered to the Seller and, notwithstanding
any provision of Section 7.2 to the contrary, the receipt by the Seller of the
Purchaser's Deposit shall constitute the Seller's sole remedy for (and such
amount shall constitute liquidated damages in respect of) any breach by the
Purchaser of this Agreement (other than a breach by the Purchaser of its
obligations pursuant to Section 8.8 and the Confidentiality Agreement).

     2. Section 7.1(d) of the Acquisition Agreement is hereby amended to read as
follows:

                    (d) by the Purchaser (provided that the Purchaser is not
               then in material breach of any representation, warranty, covenant
               or other agreement contained herein) at or prior to the Due
               Diligence Expiration Date, if the Purchaser is not satisfied with
               its due diligence review of the Business because such due
               diligence



               review causes the Purchaser to determine in its reasonable
               judgment that either (i) the Seller is then in material breach of
               any representation, warranty, covenant or other agreement of the
               Seller contained in this Agreement, (ii) the Confidential
               Information Memorandum of the Business dated September 2001 which
               was delivered to the Purchaser contains either a material
               misrepresentation or omission with respect to the Business, or
               (iii) a Material Adverse Effect has occurred since the date of
               said Confidential Information Memorandum.

     3. Article XI of the Acquisition Agreement is hereby amended to change the
definition of "Due Diligence Expiration Date" to read as follows:

     "Due Diligence Expiration Date" means the date which is the later of (i)
April 30, 2002, or (ii) at the option of the Purchaser, five (5) days after the
Purchaser's receipt of the audited Balance Sheet as of August 31, 2001."

     4. Except as described in the preceding sections of this Amendment, the
Acquisition Agreement shall remain in full force and effect.

     IN WITNESS WHEREOF, the parties hereto have executed this Amendment under
seal as of March 8, 2002.



                                SAFETY-KLEEN SERVICES, INC.


                                By: /s/ Larry W. Singleton
                                    ----------------------------
                                    Name: Larry W. Singleton
                                    Title: Executive Vice President and
                                           Chief Financial Officer


                                CLEAN HARBORS, INC.


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



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