1
                                                                Exhibit 10(b)




                                AMENDMENT NO. 1
                          Dated as of October 16, 1995
                                       to
                           REVOLVING CREDIT AGREEMENT
                            Dated as of May 31, 1995


                 THIS AMENDMENT NO. 1 dated as of October 16, 1995 (this
"Amendment") is entered into by and among OHM Corporation ("OHM"), OHM
Remediation Services Corp. ("Remediation", and together with OHM, the
"Borrowers"), the financial institutions listed on the signature pages hereto
(collectively, the "Banks"), Citicorp USA, Inc., as administrative agent (in
such capacity, the "Administrative Agent") and Bank of America Illinois, as
issuing and paying agent and as co-agent (in such capacity, the "Issuing and
Paying Agent").


                             PRELIMINARY STATEMENT:
                             ---------------------

                 A.       The Borrowers, the Banks, the Administrative Agent
and the Issuing and Paying Agent have entered into that certain Revolving
Credit Agreement dated as of May 31, 1995 (the "Credit Agreement"; capitalized
terms used and not otherwise defined herein shall have the meanings ascribed to
them in the Credit Agreement as amended by this Amendment No. 1), pursuant to
which, among other things, the Banks have agreed to make certain loans, issue
certain letters of credit and make certain other financial accommodations to
the Borrowers upon the terms and conditions set forth therein.

                 B.  OHM proposes to issue up to $59,000,000 in principal
amount of its Senior Notes due 2000 pursuant to an Indenture to be entered into
among OHM, as issuer, WMX, as guarantor and a financial institution.

                 C.  Subject to the terms and conditions set forth below, the
Borrowers, the Banks, the Administrative Agent and the Issuing and Paying Agent
have, among other things, agreed to amend the Credit Agreement as hereinafter
set forth.

                 NOW, THEREFORE, in consideration of the premises set forth
herein, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:


                 SECTION 1.       AMENDMENT TO THE CREDIT AGREEMENT.  Subject
to the satisfaction of the conditions precedent set forth in SECTION 3 below,
the Credit Agreement shall be amended as follows:
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            1.01.  The definitions of "EBITDA", "EBITDA to Interest
Expense Ratio", "Funded Debt to EBITDA Ratio", "WMX Guaranty", "WMX
Intercreditor Agreement", and "WMX Reimbursement Agreement" are amended and
restated in their entirety as follows:

                     "'EBITDA' means, for any period, on a Consolidated basis
            for the Borrowers and their Subsidiaries, gross revenues MINUS
            direct subcontract costs MINUS costs of services MINUS selling,
            general and administration expenses PLUS depreciation expense and
            amortization expense for such period (in each case to the extent
            such items were included in selling, general and administration
            expenses and other costs of services), PLUS, in the case of any
            period which includes the fiscal quarter ending December 31, 1994,
            the amount of the Accounts Receivable Reserve PLUS, in the case of
            any period which includes the fiscal quarter ending June 30, 1995,
            expenses in the amount of $3,900,000 in the aggregate representing
            costs incurred (other than purchase accounting adjustments) made in
            connection with the Rust Transactions."

                     "'EBITDA TO INTEREST EXPENSE RATIO' means, as of the last
            day of any fiscal quarter, the ratio of (i) EBITDA for the
            preceding four fiscal quarter period ending as of such day to (ii)
            Interest Expense for such period MINUS income of the Borrowers from
            dividends and interest, whether accrued or received during such
            period."

                     "'FUNDED DEBT TO EBITDA RATIO' means, at any date, the
            ratio of (i) the aggregate amount of Funded Debt of the Borrowers
            and their Subsidiaries on a Consolidated basis as at such date
            MINUS the excess, if any, of (A) the amount of cash, cash
            equivalents and marketable securities held by the Borrowers and
            their Subsidiaries on such date OVER (B) $7,500,000, to (ii) EBITDA
            for the four fiscal quarter period ending as of the last day of the
            fiscal quarter with respect to which the Borrowers have most
            recently delivered quarterly financial statements pursuant to
            SECTION 5.03(B)."

                     "'WMX GUARANTY' means that certain Guaranty dated as of
            May 31, 1995, executed by WMX in favor of the Administrative Agent
            and the Issuing and Paying Agent and acknowledged by the Borrowers,
            and any subsequent guaranty of the Obligations executed by WMX in
            favor of the Administrative Agent and the Issuing and Paying Agent
            in the form (but not the amount) of the Guaranty dated May 31,
            1995."

                     "'WMX INTERCREDITOR AGREEMENT' means that certain
            Intercreditor Agreement dated as of May 31, 1995 among





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            WMX, the Administrative Agent and the Issuing and Paying Agent,
            acknowledged by the Borrowers, as the same may be amended,
            restated, supplemented or otherwise modified from time to time."

                "'WMX REIMBURSEMENT AGREEMENT' means the Reimbursement
            Agreement entered into between WMX and the Borrowers as of May 31,
            1995 providing for the reimbursement of WMX by the Borrowers upon
            payment being made by WMX under the WMX Guaranty dated as of that
            date, and any subsequent reimbursement agreement entered into
            between WMX and the Borrowers providing for the reimbursement of
            WMX by the Borrowers upon payment being made by WMX under any
            subsequent WMX Guaranty."

            1.02.  The following new definitions are added to SECTION 1.01
of the Credit Agreement, to be added in alphabetical order:

                "'SENIOR NOTE INDENTURE' means the Indenture to be entered
            into among OHM, as issuer, WMX, as guarantor, and a financial
            institution, as trustee, providing for the issuance of the Senior
            Notes."

                "'SENIOR NOTES' means the Senior Notes due 2000 in the
            original principal amount of $59,000,000 issued by OHM pursuant to
            the Senior Note Indenture."

                "'WMX SENIOR NOTE GUARANTY' means the guaranty by WMX of
            the Senior Notes, such guaranty included as part of the Senior Note
            Indenture."

                "'WMX SENIOR NOTE REIMBURSEMENT AGREEMENT' means the
            Reimbursement Agreement to be entered into between WMX and the
            Borrowers providing for the reimbursement of WMX by the Borrowers
            upon payment being made by WMX under the WMX Senior Note Guaranty."

            1.03.  SECTION 5.02(a) of the Credit Agreement is amended by
striking "and" at the end of clause (xiii), striking the period and
substituting ";and" at the end of clause (xiv), and adding the following new
clause (xv):

                "(xv) Liens securing obligations owed to WMX under the WMX 
            Senior Note Reimbursement Agreement,"

            1.04.  SECTION 5.02(h) of the Credit Agreement is amended by
amending and restating clause (iv) thereof as follows:

                "(iv)  the Borrowers may enter into and perform their 
            obligations under the WMX Reimbursement Agreement





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                 and the WMX Senior Note Reimbursement Agreement and any 
                 related security agreements; and"

                 1.05.  SECTION 5.02(i) of the Credit Agreement is amended by
amending and restating clause (vi) thereof as follows:

                        "(vi) Investments in (A) direct obligations and
                 repurchase agreements of the United States or any agency
                 or instrumentality thereof whose obligations constitute
                 full faith and credit obligations of the United States or
                 have a short-term rating of "A-1" or better by Standard
                 and Poor's or "P-1" or better by Moody's or a long-term
                 rating of "A-" or better by Standard & Poor's or "A3" or
                 better by Moody's, in each case having a maturity of six
                 months or less, (B) commercial paper, in an aggregate
                 amount not exceeding $10,000,000 per issuer, issued by
                 corporations organized in the United States and having
                 ratings equivalent to those described in CLAUSE (A) and a
                 maturity of six months or less, (C) certificates of
                 deposit or bankers acceptances in an aggregate amount not
                 exceeding $10,000,000 per issuer or accepting bank, issued
                 or created, as the case may be, by domestic or foreign
                 commercial banks with assets in excess of $10,000,000,000
                 and ratings equivalent to those described in CLAUSE (A),
                 and (D) Eurodollar time deposits in domestic or foreign
                 commercial banks with assets in excess of $10,000,000,000
                 in an aggregate amount not exceeding $10,000,000 per bank,
                 having a maturity of six months or less and ratings
                 equivalent to those described in CLAUSE (A);  (E)
                 municipal bonds, in an aggregate amount not exceeding
                 $10,000,000 per issuer, having a maturity of six months or
                 less and ratings equivalent to those in CLAUSE (A); and
                 (F) adjustable rate preferred stock or money market
                 preferred stock, in an aggregate amount not exceeding
                 $10,000,000 per issuer, having a maturity of six months or
                 less and ratings equivalent to those described in CLAUSE (A);"

                 1.06.  SECTION 5.02(j) of the Credit Agreement is amended by
striking "and" at the end of clause (ix), striking the period at the end of
clause (x) and substituting a semicolon therefor, and by adding the following:

                        "(xi) any Indebtedness owed to WMX under the WMX
                 Senior Note Reimbursement Agreement as a result of payments
                 made by WMX under the WMX Senior Note Guaranty or any
                 subrogation rights of WMX arising as a result of payments made
                 by WMX under the WMX Senior Note Guaranty; and





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                        (xii) Indebtedness represented by the Senior Notes."

                 1.07.  SECTION 5.02(m) of the Credit Agreement is amended by
inserting "$2,500,000" in the blank in the third line (referring to 25% of the
net cash proceeds received by OHM from the issuance of common stock on March
28, 1995), and "$33,318,500" in the blank in the sixth line (referring to 50%
of the increase in Net Worth arising from the Rust Transactions).

                 1.08     SECTION 5.02(m) of the Credit Agreement is further
amended by adding the following sentence at the end of such Section:

                          "The Borrowers and the Banks acknowledge that
                 $2,400,000 of the $3,000,000 of reductions to Net Worth
                 described in the foregoing clause (6) were made in the quarter
                 ending June 30, 1995."

                 1.09.  SECTION 5.02(o) of the Credit Agreement is amended and
  restated as follows:

                          "(o) MAXIMUM FUNDED DEBT TO EBITDA RATIO.  (1) During
                 any Facility B Level 1 or 2 Period, permit the Funded Debt to
                 EBITDA Ratio to exceed 4.50 to 1.0 as of the last day of any
                 fiscal quarter of the Borrowers, and (2) during any Facility B
                 Level 3, 4 or 5 Period, permit the Funded Debt to EBITDA Ratio
                 to exceed 4.50 to 1.0 at any time."

                 1.10.  SECTION 6.01(a) of the Credit Agreement is amended and
  restated as follows:

                        "(a) Either Borrower shall fail to pay (i)
                 any installment of principal of any Note when due; or (ii) any
                 reimbursement obligation with respect to a drawing under any
                 Letter of Credit when due; or (iii) any interest on any Note,
                 or any fees or other Obligations hereunder, in each case when
                 due or within one Business Day thereafter; or"

                 1.11.  SECTION 8.15(c) of the Credit Agreement is amended and
 restated as follows:

                          "(c)  Upon the written request of the Borrowers prior
                 to December 15, 1995, which request certifies the Borrower's
                 intent to have WMX execute and deliver the WMX Senior Note
                 Guaranty prior to December 15, 1995, and if the Senior Notes
                 are issued and the WMX Guaranty is executed and delivered
                 prior to December 15, 1995, the Administrative Agent and the
                 Issuing and Paying Agent shall release and terminate the WMX
                 Guaranty





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                 dated May 31, 1995 simultaneously with the execution and
                 delivery of the WMX Senior Note Guaranty."

                 SECTION 2.  FEES.  The Borrowers jointly and severally agree
to pay to the Issuing and Paying Agent, for the account of the Banks, the
following fees at the following times:

                          (a)  upon the execution and delivery of this
                 Amendment by each of the Banks, the Issuing and Paying Agent
                 and the Administrative Agent, an amendment fee (the "Amendment
                 Fee") for each Bank in an amount equal to 0.05% of such Bank's
                 Commitment; and

                          (b)  upon the release of the WMX Guaranty dated as of
                 May 31, 1995, the additional commitment fee (the "Additional
                 Commitment Fee") owed to each Bank upon the release of such
                 WMX Guaranty pursuant to the terms of the Commitment Fee
                 Letter.

                 SECTION 3.  CONDITIONS PRECEDENT.  With respect to the amended
and restated definitions of EBITDA, EBITDA TO INTEREST EXPENSE RATIO, WMX
GUARANTY, WMX INTERCREDITOR AGREEMENT and WMX REIMBURSEMENT AGREEMENT in
SECTIONS 1.01 hereof, and SECTIONS 1.05, 1.07, and 1.08 hereof, the amendments
to the Credit Agreement set forth in this Amendment shall become effective upon
the first Business Day upon which all of the following conditions shall be
satisfied:

                        (i) the Borrowers shall have paid the Amendment Fee;

                        (ii)  the representations and warranties contained in 
                 the Credit Agreement are true and correct as though made on 
                 such date;

                        (iii)  no Default or Event of Default has occurred and
                 is outstanding as of such date, unless the same shall be 
                 waived or cured hereby; and

                        (iv)  the Agent shall have received, on or before such
                 date, fifteen original counterparts of this Amendment, 
                 executed by each of the Borrowers, each of the Banks, the 
                 Issuing and Paying Agent and the Administrative Agent;

With respect to the remainder of the amendments to the Credit Agreement set
forth in SECTION 1 hereof, this Amendment shall become effective on the first
Business Day upon which, in addition to the foregoing conditions being
satisfied, all of the following conditions shall be satisfied:

                        (i)  the Borrowers shall have paid the Additional 
                 Commitment Fee;





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                (ii)  the Senior Note Indenture, in form and substance
         satisfactory to the Administrative Agent shall have been 
         executed and delivered by the parties thereto on or before 
         December 15, 1995;

                (iii)  the Senior Notes shall have been issued on or 
         before December 15, 1995 at an effective per annum interest 
         rate less than or equal to 7.50%;

         
               (iv)  the WMX Senior Note Guaranty shall have become 
         effective; and

                (v)  the WMX Intercreditor Agreement shall have been 
         amended, in a manner satisfactory to the Administrative Agent, 
         to take into account the issuance of the WMX Senior Note 
         Guaranty.

        SECTION 4.  REPRESENTATIONS AND WARRANTIES OF BORROWER;
REAFFIRMATION OF COVENANTS.  Each of the Borrowers hereby represents and
warrants that this Amendment has been duly authorized by all necessary
corporate action on the part of such Borrower and constitutes a legal, valid
and binding obligation of such Borrower, enforceable against it in accordance
with its terms.

         Each of the Borrowers hereby reaffirms all representations,
warranties and covenants made by it in the Credit Agreement, as amended hereby,
except to the extent any of such representations or warranties expressly speak
as of a prior date, and hereby agrees that, subject to the terms hereof, all
such representations, warranties and covenants shall be deemed to have been
re-made as of the effective date of this Amendment.

         SECTION 5.  EFFECT ON THE CREDIT AGREEMENT.

         5.1  Upon the effectiveness of this Amendment, each reference
in the Credit Agreement and in each of the other Transaction Documents to "this
Agreement," "hereunder," "hereof," "herein," or words of like import shall mean
and be a reference to the Credit Agreement as amended hereby, and each
reference to the Credit Agreement in any other document, instrument or
agreement executed and/or delivered in connection with the Credit Agreement
shall mean and be a reference to the Credit Agreement as amended hereby.

         5.2  Except as specifically set forth herein, the Credit
Agreement, each of the other Transaction Documents and all other documents,
amendments, instruments and agreements executed and/or delivered in connection
therewith shall remain in full force and effect and are hereby ratified and
confirmed.

         5.3  The execution, delivery and effectiveness of this
Amendment shall not operate as a waiver of any right, power or





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remedy of any of the Banks, the Issuing and Paying Agent or the Administrative
Agent under the Credit Agreement or any other document, instrument or agreement
executed in connection therewith, nor constitute a waiver of any provision
contained therein, except as specifically set forth herein.

                SECTION 6.  COST, EXPENSES, FEES.  Each of the Borrowers
hereby jointly and severally agrees to pay, on demand, all costs, fees and
expenses (including, without limitation, attorneys' fees, court costs, filing
charges and taxes) incurred by, or required to be paid by the Administrative
Agent in connection with the preparation, negotiation, execution, delivery and
administration of this Amendment and all other instruments, documents and
agreements executed and/or delivered pursuant to or in connection herewith.

                SECTION 7.  EXECUTION IN COUNTERPARTS.  This Amendment may be
executed by the parties hereto in separate counterparts, each of which when so
executed and delivered shall be deemed to be an original and all of which taken
together shall constitute but one and the same instrument.

                SECTION 8.  GOVERNING LAW.  THIS AMENDMENT SHALL BE GOVERNED
BY AND CONSTRUED IN ACCORDANCE WITH THE INTERNAL LAWS (AS OPPOSED TO THE
CONFLICT OF LAWS PROVISIONS) OF THE STATE OF NEW YORK.


                SECTION 9.  SECTION TITLES.  Section titles in this Amendment
are included herein for convenience of reference only and shall not affect in
any way the interpretation of any of the provisions hereof.

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

                                                   BORROWERS:

                                                   OHM CORPORATION


Attest:                                            By /s/ Pamela K.M. Beall
                                                     --------------------------
                                                     Title: Vice President,
                                                            Treasurer and
/s/ Randall M. Walters                                      Asst. Secretary
- ----------------------
Secretary

                                        OHM REMEDIATION SERVICES CORP.


                                                 By /s/ Pamela K.M. Beall       
                                                   ----------------------------
                                                    Title: Vice President,
                                                            Treasurer and
                                                            Asst. Secretary





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                       BANKS:

                           CITICORP USA, INC., Individually and
                                            as Administrative Agent


                                        By /s/ Carolyn R. Bodmer 
                                           ------------------------------------
                                        Title: Vice President


                           BANK OF AMERICA ILLINOIS,
                              Individually and as
                              Issuing and Paying Agent


                                        By /s/ Timothy J. Pepowski          
                                          -------------------------------------
                                           Title: Vice President


                           NBD BANK, N.A.

                                        By /s/ Daniel J. Pienta             
                                           ------------------------------------
                                           Title: Second Vice President


                           THE FIRST NATIONAL BANK OF BOSTON


                                        By /s/ Ann E. Howard                
                                           ------------------------------------
                                           Title: Managing Director


                           NATIONAL CITY BANK


                                        By /s/ Terri L. Cable               
                                           ------------------------------------
                                           Title: Vice President


                           COMERICA BANK


                                        By /s/ Dan M. Roman                 
                                           -------------------------------------
                                           Title: Vice President


                           BHF BANK


                                        By /s/ John Sykes                 
                                           -------------------------------------
                                           Title: AVP


                                        By /s/ David Fraenkel               
                                           -------------------------------------
                                           Title: VP

                           BANK ONE, LIMA, N.A.


                                        By /s/ Jeffrey L. Dodderer          
                                           -------------------------------------
                                           Title: Vice President




0067381.02  November 7, 1995

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