<PAGE>   1
                                                                   Exhibit 4(c)


                                SECOND AMENDMENT
                                       TO
                    REVOLVING CREDIT AND TERM LOAN AGREEMENT

         THIS SECOND AMENDMENT TO REVOLVING CREDIT AND TERM LOAN AGREEMENT (the
"Amendment"), dated as of April 7, 1998, is made and entered into by and among
MPW Industrial Services Group, Inc. ("MPW Group"), MPW Industrial Services, Inc.
("MPW, Inc."), MPW Industrial Services, Ltd. ("MPW, Ltd."), MPW Management
Services Corp. ("MPW Corp."), Weston Engineering, Inc. ("Weston"), Aquatech
Environmental, Inc. ("Aquatech), ESI International, Inc. ("ESII"), and ESI-North
Limited ("ESI", which, together the foregoing entities, shall be referred to
herein collectively as the "Borrowers" and individually as a "Borrower"), Bank
One, NA, a national banking association ("Bank One"), National City Bank
(successor by merger to National City Bank of Columbus), a national banking
association ("NCB"), and Bank One, NA, as Agent, acting in the manner and to the
extent described in the Agreement described herein.

                             BACKGROUND INFORMATION

         A. The Borrowers and the Banks entered into a certain Revolving Credit
and Term Loan Agreement dated as of December 10, 1997, as amended by a First
Amendment to Revolving Credit and Term Loan Agreement, dated as of February 11,
1998 (such agreement, as so amended, being referred to herein as the
"Agreement").

         B. The Banks and the Borrowers desire to amend certain provisions of
the Agreement and to make a new Subsidiary a party to the Agreement and other
applicable Facility Documents, upon the terms and conditions set forth herein.

                                   PROVISIONS

         NOW, THEREFORE, in consideration of the foregoing, the mutual covenants
and agreements hereunder, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the Borrowers, the
Banks and the Agent hereby agree as follows:

         SECTION 1. Capitalized Terms. Except as otherwise provided for herein,
the capitalized terms used herein shall have the same meanings as set forth in
the Agreement.

         SECTION 2. Amendment to Agreement.

                  (a) Section 7.6(a) of the Agreement is hereby amended in its
entirety to provide as follows:

                      (a) Consolidated Tangible Net Worth. Permit Consolidated 
          Tangible Net Worth to be less than (i) $26,500,000 prior to April 6,
          1998, (ii) $25,000,000 as and after April 7, 1998 through and
          including June 29, 1998, and (iii) $27,000,000 as and after June 30,
          1998, provided such amount shall increase





<PAGE>   2



         (but not decrease by any losses) quarterly on the last day of each
         Fiscal Quarter by 50% of Consolidated Net Income (determined at the end
         of each Fiscal Quarter for such Fiscal Quarter), commencing with the
         Fiscal Quarter ending September 30, 1998.

         SECTION 3. Adjustment in Applicable Margins. As of April 7, 1998, the
Applicable Margins with respect to the determination of the Interest Rates with
respect to the Loans shall be adjusted as follows:

                  (a) the Applicable Margin for Revolving Credit Loans bearing
interest based on the Base Rate shall be -50 basis points;

                  (b) the Applicable Margin for Revolving Credit Loans bearing
interest based on the Eurodollar Rate shall be +100 basis points;

                  (c) the Applicable Margin for Term Loans bearing interest
based on the Base Rate shall be -25 basis points; and

                  (d) the Applicable Margin for Term Loans bearing interest
based on the Eurodollar Rate shall be +125 basis points.

Such adjusted Applicable Margins shall remain in effect until otherwise changed
in accordance with the terms of the Agreement.

         SECTION 4. Truth of Representations and Warranties; No Defaults. The
Borrowers hereby represent and warrant that the following are true and correct
as of the date of this Amendment:

                  (a) The representations and warranties of the Borrowers
         contained in Article V of the Agreement are true and correct on and as
         of the date of this Amendment as if made on and as of such date unless
         stated to relate to a specific earlier date;

                  (b) No Default nor Event of Default has occurred; and

                  (c) All financial information heretofore provided to the Banks
         and the Agent is true, accurate and complete in all material respects.

         SECTION 5. Reaffirmation of Liability; Furnishing of Information. The
Borrowers hereby reaffirm their liability to the Banks and Agent under the
Agreement and all other Facility Documents. In addition, (i) the Borrowers agree
that the Banks and the Agent have performed all of their respective obligations
under the Facility Documents and that neither Bank nor the Agent is in default
under any obligation any of them has or ever did have to the Borrowers under the
Facility Documents or any other agreement; and (ii) the Banks and the Agent have
received all information and documentation required to be delivered to them by
the Borrowers pursuant to the Facility Documents.




                                       -2-

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         SECTION 6. Effectiveness of Amendment. All of the terms, covenants and
conditions of, and the obligations of the Borrowers under, the Agreement and the
Facility Documents shall remain in full force and effect as amended hereby.

         SECTION 7. Consent to Acquisition. The Banks hereby consent to the
purchase by the Borrowers of the assets of Vinewood Corporation and its
affiliates pursuant to, and in accordance with, the documentation and
information previously furnished to the Banks. Such consent shall include,
without limitation, the consent required of the Banks pursuant Section 2.11 of
the Agreement.

         SECTION 8. Conditions to Banks' Obligations. The obligations of the
Banks to enter into this Amendment and be bound by the terms hereof, including
without limitation the giving of the consent set forth in Section 7 hereof, are
subject to the satisfaction of the following conditions precedent:

                  (a) Additional Borrower. MPW Container Management Corp.,
an Ohio corporation, shall execute this Amendment to acknowledge and evidence
(i) its becoming a party to the Agreement as a "Borrower", and (ii) its
liability to the Banks under the Agreement and all other agreements and
instruments executed by the Borrower for the benefit of the Banks and/or the
Agent in connection with the Agreement, including the Facility Documents.

                  (b) Delivery of Documents. The Agent shall have received, for
the benefit of the Banks, the following, each in form and substance satisfactory
to the Agent and its counsel:

                      (i) Amended and Restated Promissory Notes. Amended
         and Restated Revolving Credit Promissory Notes in the form of Exhibit A
         attached hereto and incorporated herein by reference, duly executed and
         delivered by the Borrowers, including MPW Container Management Corp.;

                      (ii) Governing Documents of MPW Container Management
         Corp. True and complete certified copies of the articles (certificate)
         of incorporation (formation), code of regulations (by-laws), operating
         agreement or other governing documents of MPW Container Management
         Corp., and a copy of the resolutions (in form and substance
         satisfactory to the Agent) of the Board of Directors (or other
         governing Person) of MPW Container Management Corp. authorizing (i) the
         execution, delivery and performance of this Amendment, the Notes and
         the other Facility Documents, as applicable, (ii) the consummation of
         the transactions contemplated hereby and thereby, (iii) the borrowing
         and other financial transactions provided for in the Agreement, and
         (iv) the documents provided for in the Agreement, certified by the
         secretary or an assistant secretary (or other appropriate
         representative) of MPW Container Management Corp. Such certificate
         shall state that the resolutions set forth therein have not been
         amended, modified, revoked or rescinded as of the date hereof;




                                       -3-

<PAGE>   4



                           (iii) Good Standing Certificate. A copy of a
         certificate dated as of a recent date from the Secretary of State, or
         other appropriate authority of such jurisdiction, evidencing the good
         standing (or comparable status) of MPW Container Management Corp. in
         the jurisdiction of its incorporation (formation) and the State of
         Ohio;

                           (iv) Incumbency Certificate. A certificate of the
         secretary or an assistant secretary (or other appropriate
         representative) of MPW Container Management Corp. as to the incumbency
         and signature of the officer(s) or other representatives of MPW
         Container Management Corp. executing this Amendment, the Notes, the
         other Facility Documents and any certificate or other documents to be
         delivered pursuant hereto or thereto;

                           (v) Opinion Letter.  Opinion letter of the 
         Borrowers' legal counsel as to MPW Container Management Corp.; and

                           (vi) Other Requirements. Such other certificates,
         documents and other items as the Bank, in its reasonable discretion,
         deems necessary or desirable.

                  (c) Representations and Warranties. The representations and
warranties made by the Borrowers in this Amendment shall be true and correct in
all material respects as of the date of this Amendment.

         SECTION 9. Applicable Law. This Amendment shall be deemed to be a
contract made under the laws of the State of Ohio and for all purposes shall be
construed in accordance with the laws of such state.

         SECTION 10. Severability. Any provision of this Amendment which is
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective only to the extent of such prohibition or unenforceability,
without invalidating the remaining provisions hereof or affecting the validity
or enforceability of such provision in any other jurisdiction.

         SECTION 11. Counterparts. This Amendment may be executed in one or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

         SECTION 12. Headings. The headings of the sections of this Amendment
are for convenience only and shall not affect the construction of this
Amendment.

         SECTION 13. Expenses. The Borrowers agree to pay all out-of-pocket
expenses (including reasonable fees and expenses of counsel) of the Agent and
the Banks incurred in connection with this Amendment.




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         SECTION 14. Interpretation. This Amendment is to be deemed to have been
prepared jointly by the parties hereto, and any uncertainty or ambiguity
existing herein shall not be interpreted against any party but shall be
interpreted according to the rules for the interpretation of arm's length
agreements.

         SECTION 15. WAIVER OF JURY TRIAL. THE BANKS, THE AGENT AND THE
BORROWERS, AFTER CONSULTING OR HAVING HAD THE OPPORTUNITY TO CONSULT WITH
COUNSEL, KNOWINGLY, VOLUNTARILY AND INTENTIONALLY WAIVE ANY RIGHT ANY OF THEM
MAY HAVE TO A TRIAL BY JURY IN ANY LITIGATION BASED UPON OR ARISING OUT OF THE
AGREEMENT AS AMENDED BY THIS AMENDMENT, THE NOTES, THE OTHER FACILITY DOCUMENTS,
OR ANY RELATED INSTRUMENT OR AGREEMENT, OR ANY OF THE TRANSACTIONS CONTEMPLATED
THEREBY, OR ANY COURSE OF CONDUCT, DEALING, STATEMENTS (WHETHER ORAL OR
WRITTEN), OR ACTIONS OF ANY OF THEM. NEITHER THE BANKS, THE AGENT NOR THE
BORROWERS SHALL SEEK TO CONSOLIDATE, BY COUNTERCLAIM OR OTHERWISE, ANY ACTION IN
WHICH A JURY TRIAL HAS BEEN WAIVED WITH ANY OTHER ACTION IN WHICH A JURY TRIAL
CANNOT BE OR HAS NOT BEEN WAIVED. THESE PROVISIONS SHALL NOT BE DEEMED TO HAVE
BEEN MODIFIED IN ANY RESPECT OR RELINQUISHED BY THE BANKS, THE AGENT OR THE
BORROWERS EXCEPT BY A WRITTEN INSTRUMENT EXECUTED BY ALL OF THEM.

         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
executed by their duly authorized officers as of the date first written above.

BANKS:
Bank One, NA                           National City Bank (successor by merger
                                       to National City Bank of Columbus)

By:    /s/ Thomas E. Redmond           By:    /s/ Brian T. Strayton
   ------------------------------         ------------------------------------
Name:  Thomas E. Redmond               Name:  Brian T. Strayton
     ----------------------------           ----------------------------------

Title: Vice President                  Title: Vice President
      ---------------------------            ---------------------------------


AGENT:

Bank One, NA

By:    /s/ Thomas E. Redmond
   ------------------------------

Name:  Thomas E. Redmond
     ----------------------------

Title: Vice President
      ---------------------------




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BORROWERS:

MPW Industrial Services Group, Inc.             MPW Industrial Services, Inc.


By:    /s/ Daniel P. Buettin                    By:    /s/ Daniel P. Buettin
   ------------------------------                  ---------------------------

Name:  Daniel P. Buettin                        Name:  Daniel P. Buettin
     ----------------------------                    -------------------------

Title: VP & CFO                                 Title: VP & CFO
      ---------------------------                     ------------------------


MPW Industrial Services, Ltd.                   MPW Management Services Corp.

By:    /s/ Daniel P. Buettin                    By:    /s/ Daniel P. Buettin
   ------------------------------                  ---------------------------

Name:  Daniel P. Buettin                        Name:  Daniel P. Buettin
     ----------------------------                    -------------------------

Title: VP & CFO                                 Title: VP & CFO
      ---------------------------                     ------------------------


Weston Engineering, Inc.                        Aquatech Environmental, Inc.

By:    /s/ Daniel P. Buettin                    By:    /s/ Peter G. Schumacher
   ------------------------------                  ---------------------------

Name:  Daniel P. Buettin                        Name:  Peter G. Schumacher
     ----------------------------                    -------------------------

Title: VP & CFO                                 Title: VP
      ---------------------------                     ------------------------


ESI International, Inc.                         ESI-North Limited

By:    /s/ Daniel P. Buettin                    By:    /s/ Daniel P. Buettin
   ------------------------------                  ---------------------------

Name:  Daniel P. Buettin                        Name:  Daniel P. Buettin
     ----------------------------                    -------------------------

Title: President                                Title: VP & CFO
      ---------------------------                     ------------------------





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         MPW Container Management Corp., an Ohio corporation, enters into this
Amendment to acknowledge and evidence (i) its becoming a party to the Agreement
as a "Borrower", and (ii) its liability to the Banks under the Agreement and all
other agreements and instruments executed by the Borrower for the benefit of the
Banks and/or the Agent in connection with the Agreement, including the Facility
Documents.

                                               MPW Container Management Corp.

                                               By:    /s/ Daniel P. Buettin
                                                  ---------------------------

                                               Name:  Daniel P. Buettin
                                                    -------------------------

                                               Title: VP & CFO
                                                     ------------------------



                                       -7-

<PAGE>   8



                                    EXHIBIT A

            FORM OF AMENDED AND RESTATED REVOLVING CREDIT LOAN NOTES




<PAGE>   9



                 AMENDED AND RESTATED REVOLVING CREDIT LOAN NOTE


$10,500,000.00                 Columbus, Ohio                   April 7, 1998


         Promise to Pay. Not later than December 31, 2000, for value received,
the undersigned, MPW Industrial Services Group, Inc., MPW Industrial Services,
Inc., MPW Industrial Services, Ltd., MPW Management Services Corp., Weston
Engineering, Inc., Aquatech Environmental, Inc., ESI International, Inc.,
ESI-North Limited and MPW Container Management Corp. (collectively, the
"Borrowers"), jointly and severally, hereby promise to pay to the order of Bank
One, NA (the "Bank") or its assigns, as further provided herein, the principal
amount of Ten Million Five Hundred Thousand Dollars ($10,500,000) or, if such
principal is less, the aggregate unpaid principal amount of all Revolving Credit
Loans made by the Bank to the Borrowers pursuant to the Revolving Credit and
Term Loan Agreement referred to below, together with interest on the unpaid
principal balance from time to time outstanding hereunder until paid in full at
the rates of interest determined in accordance with such Revolving Credit and
Term Loan Agreement. Such interest shall be due and payable on the dates set
forth in such Revolving Credit and Term Loan Agreement. Both principal and
interest are payable in federal funds or other immediately available money of
the United States of America at the main office of the Agent (defined below)
located at 100 East Broad Street, Columbus, Ohio 43215, or such other address as
the Agent may hereafter designate by notice to the Borrowers.

         Loan Agreement. This Amended and Restated Revolving Credit Loan Note
amends and restates in its entirety the Revolving Credit Loan Note dated
December 10, 1997, in the original principal amount of $10,500,000, executed by
the Borrower and payable to the order of the Bank, and is one of the Revolving
Credit Loan Notes referred to in the Revolving Credit and Term Loan Agreement
among the Borrowers, the Bank, National City Bank (successor by merger to
National City Bank of Columbus) and Bank One, NA, as Agent (the "Agent"), dated
as of December 10, 1997, as the same may be amended, modified, supplemented,
restated or replaced from time to time (the "Agreement"), which Agreement, as so
amended, is incorporated by reference herein. This Amended and Restated
Revolving Credit Loan Note evidences the continuing indebtedness under the
Agreement and is not to be construed as a satisfaction or refinancing of such
indebtedness. All capitalized terms used herein shall have the same meanings as
are assigned to such terms in the Agreement. This Amended and Restated Revolving
Credit Loan Note is entitled to the benefits of and is subject to the terms,
conditions and provisions of the Agreement. The Agreement, among other things,
contains provisions for acceleration of the maturity hereof upon the happening
of certain stated events, and also for repayments and reborrowings on account of
the principal hereof prior to maturity upon the terms, conditions and provisions
specified therein.

         The Borrowers and each endorser and any other party liable on this
Amended and Restated Revolving Credit Loan Note severally waive demand,
presentment, notice of dishonor and protest, and consent to any extension or
postponement of time of its payment without limit as to the number or period, to
any substitution, exchange or release of all or part of any collateral securing
this Amended and Restated Revolving Credit Loan Note,





<PAGE>   10



to the addition of any party, and to the release or discharge of, or suspension
of any rights and remedies against, any person who may be liable for the payment
of this Amended and Restated Revolving Credit Loan Note.

         Setoff. Any and all moneys now or at any time hereafter owing to the
Borrowers from the holder hereof are hereby pledged for the security of this and
all other Debt from the Borrowers to the holder hereof, and may, upon the
occurrence and during the continuation of any Event of Default, be paid and
applied thereon whether such Debt be then due or is to become due, except for
(a) funds necessary to cover checks for the payment of taxes or employee
contributions in which the Borrowers have no beneficial interest issued to third
parties prior to the date any setoff is claimed by the Bank and (b) accounts
maintained, but not substantially overfunded, for the payment of taxes or
employee contributions in which the Borrowers have no beneficial interest.


BORROWERS:


MPW Industrial Services Group, Inc.             MPW Industrial Services, Inc.


By:                                             By:
   --------------------------------                ---------------------------
Name:                                           Name:
     ------------------------------                  -------------------------
Title:                                          Title:
      -----------------------------                   ------------------------


MPW Industrial Services, Ltd.                   MPW Management Services Corp.

By:                                             By:
   --------------------------------                ---------------------------
Name:                                           Name:
     ------------------------------                  -------------------------
Title:                                          Title:
      -----------------------------                   ------------------------


Weston Engineering, Inc.                        Aquatech Environmental, Inc.

By:                                             By:
   --------------------------------                ---------------------------
Name:                                           Name:
     ------------------------------                  -------------------------
Title:                                          Title:
      -----------------------------                   ------------------------


                                   Page 2 of 3

<PAGE>   11



ESI International, Inc.                         ESI-North Limited

By:                                             By:
   --------------------------------                ---------------------------
Name:                                           Name:
     ------------------------------                  -------------------------
Title:                                          Title:
      -----------------------------                   ------------------------


                                                MPW Container Management Corp.

                                                By:                           
                                                   ---------------------------
                                                Name:                         
                                                     -------------------------
                                                Title:                        
                                                      ------------------------
                                                                              




                                   Page 3 of 3

<PAGE>   12



                 AMENDED AND RESTATED REVOLVING CREDIT LOAN NOTE


$4,500,000.00                 Columbus, Ohio                    April 7, 1998


         Promise to Pay. Not later than December 31, 2000, for value received,
the undersigned, MPW Industrial Services Group, Inc., MPW Industrial Services,
Inc., MPW Industrial Services, Ltd., MPW Management Services Corp., Weston
Engineering, Inc., Aquatech Environmental, Inc., ESI International, Inc.,
ESI-North Limited and MPW Container Management Corp. (collectively, the
"Borrowers"), jointly and severally, hereby promise to pay to the order of
National City Bank (successor by merger to National City Bank of Columbus) (the
"Bank") or its assigns, as further provided herein, the principal amount of Four
Million Five Hundred Thousand Dollars ($4,500,000) or, if such principal is
less, the aggregate unpaid principal amount of all Revolving Credit Loans made
by the Bank to the Borrowers pursuant to the Revolving Credit and Term Loan
Agreement referred to below, together with interest on the unpaid principal
balance from time to time outstanding hereunder until paid in full at the rates
of interest determined in accordance with such Revolving Credit and Term Loan
Agreement. Such interest shall be due and payable on the dates set forth in such
Revolving Credit and Term Loan Agreement. Both principal and interest are
payable in federal funds or other immediately available money of the United
States of America at the main office of the Agent (defined below) located at 100
East Broad Street, Columbus, Ohio 43215, or such other address as the Agent may
hereafter designate by notice to the Borrowers.

         Loan Agreement. This Amended and Restated Revolving Credit Loan Note
amends and restates in its entirety the Revolving Credit Loan Note dated
December 10, 1997, in the original principal amount of $4,500,000, executed by
the Borrower and payable to the order of the Bank, and is one of the Revolving
Credit Loan Notes referred to in the Revolving Credit and Term Loan Agreement
among the Borrowers, the Bank, Bank One, NA and Bank One, NA, as Agent (the
"Agent"), dated as of December 10, 1997, as the same may be amended, modified,
supplemented, restated or replaced from time to time (the "Agreement"), which
Agreement, as so amended, is incorporated by reference herein. This Amended and
Restated Revolving Credit Loan Note evidences the continuing indebtedness under
the Agreement and is not to be construed as a satisfaction or refinancing of
such indebtedness. All capitalized terms used herein shall have the same
meanings as are assigned to such terms in the Agreement. This Amended and
Restated Revolving Credit Loan Note is entitled to the benefits of and is
subject to the terms, conditions and provisions of the Agreement. The Agreement,
among other things, contains provisions for acceleration of the maturity hereof
upon the happening of certain stated events, and also for repayments and
reborrowings on account of the principal hereof prior to maturity upon the
terms, conditions and provisions specified therein.

         The Borrowers and each endorser and any other party liable on this
Amended and Restated Revolving Credit Loan Note severally waive demand,
presentment, notice of dishonor and protest, and consent to any extension or
postponement of time of its payment without limit as to the number or period, to
any substitution, exchange or release of all or part of any collateral securing
this Amended and Restated Revolving Credit Loan Note,



<PAGE>   13



to the addition of any party, and to the release or discharge of, or suspension
of any rights and remedies against, any person who may be liable for the payment
of this Amended and Restated Revolving Credit Loan Note.

         Setoff. Any and all moneys now or at any time hereafter owing to the
Borrowers from the holder hereof are hereby pledged for the security of this and
all other Debt from the Borrowers to the holder hereof, and may, upon the
occurrence and during the continuation of any Event of Default, be paid and
applied thereon whether such Debt be then due or is to become due, except for
(a) funds necessary to cover checks for the payment of taxes or employee
contributions in which the Borrowers have no beneficial interest issued to third
parties prior to the date any setoff is claimed by the Bank and (b) accounts
maintained, but not substantially overfunded, for the payment of taxes or
employee contributions in which the Borrowers have no beneficial interest.

BORROWERS:

MPW Industrial Services Group, Inc.             MPW Industrial Services, Inc.


By:                                             By:
   --------------------------------                ---------------------------
Name:                                           Name:
     ------------------------------                  -------------------------
Title:                                          Title:
      -----------------------------                   ------------------------


MPW Industrial Services, Ltd.                   MPW Management Services Corp.

By:                                             By:
   --------------------------------                ---------------------------
Name:                                           Name:
     ------------------------------                  -------------------------
Title:                                          Title:
      -----------------------------                   ------------------------


Weston Engineering, Inc.                        Aquatech Environmental, Inc.

By:                                             By:
   --------------------------------                ---------------------------
Name:                                           Name:
     ------------------------------                  -------------------------
Title:                                          Title:
      -----------------------------                   ------------------------



                                   Page 2 of 3

<PAGE>   14


ESI International, Inc.                         ESI-North Limited

By:                                             By:
   --------------------------------                ---------------------------
Name:                                           Name:
     ------------------------------                  -------------------------
Title:                                          Title:
      -----------------------------                   ------------------------


                                                MPW Container Management Corp.

                                                By:                           
                                                   ---------------------------
                                                Name:                         
                                                     -------------------------
                                                Title:                        
                                                      ------------------------
                                                                              




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