INSITUFORM TECHNOLOGIES INC
SC 13D, 1995-06-01
WATER, SEWER, PIPELINE, COMM & POWER LINE CONSTRUCTION
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<PAGE>   1


                                 UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13D
                   Under the Securities Exchange Act of 1934
                              (Amendment No. __)*

                        -------------------------------

                          INSITUFORM MID-AMERICA, INC.
                                (Name of Issuer)

                      Class A Common Stock, $.01 par value
                         (Title of Class of Securities)

                                  45766H 10 1
                                 (CUSIP Number)

                        --------------------------------

                              Howard Kailes, Esq.
                          Krugman, Chapnick & Grimshaw
                            Park 80 West - Plaza Two
                         Saddle Brook, New Jersey 07663
      (Name, Address and Telephone Number of Person Authorized to Receive
                          Notices and Communications)

                        -------------------------------

                                  May 23, 1995
            (Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(b)(3) or (4), check the following box.
                                                                       -----
Check the following box if a fee is being paid with the statement.

       X
     -----

(A fee is not required only if the reporting person: (a) has a previous
statement on file reporting beneficial ownership of more than five percent of
the class of securities described in Item 1; and (2) has filed no amendment
subsequent thereto reporting beneficial ownership of five percent or less of
such class.) (See Rule 13d-7.)

Note:  Six copies of this statement, including all exhibits, should be filed
with the Commission.  See Rule 13d-1(a) for other parties to whom copies are to
be sent.

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities,
and for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.
<PAGE>   2
The information required on the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 ("Act") or otherwise subject to the liabilities of that section of
the Act but shall be subject to all other provisions of the Act (however, see
the Notes).
<PAGE>   3
CUSIP NO. 45766H 10 1

1    NAME OF REPORTING PERSON
     S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

     Insituform Technologies, Inc.

- --------------------------------------------------------------------------------
2    CHECK THE APPROPRIATE  BOX IF A MEMBER OF A GROUP*

     (a)
         -----
     (b)
         -----

- --------------------------------------------------------------------------------
3    SEC USE ONLY

- --------------------------------------------------------------------------------
4    SOURCE OF FUNDS*

     Not applicable

- --------------------------------------------------------------------------------
5    CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS
     2(d) or 2(e)

     -----

- --------------------------------------------------------------------------------
6    CITIZENSHIP OR PLACE OR ORGANIZATION

     Delaware

- --------------------------------------------------------------------------------
NUMBER OF SHARES BENEFICIALLY  OWNED BY EACH REPORTING PERSON WITH:

7    SOLE VOTING POWER

     -0-

- --------------------------------------------------------------------------------
8    SHARED VOTING POWER

     -0-

- --------------------------------------------------------------------------------
9    SOLE DISPOSITIVE POWER

     -0-

- --------------------------------------------------------------------------------
10   SHARED DISPOSITIVE POWER

     -0-

- --------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     -0-

- --------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES*

           (see footnote 1)
     -----

- --------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT  IN ROW (11)

     -0-

- --------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON*

     CO



 
<PAGE>   4

- ---------------
(1)    On May 23, 1995, Insituform Technologies, Inc. ("ITI"), ITI Acquisition
       Corp., a wholly-owned subsidiary of ITI ("ITI Sub"), and Insituform
       Mid-America, Inc. ("IMA") executed an Agreement and Plan of Merger dated
       such date which provides for the acquisition of IMA by ITI through the
       merger into IMA of ITI Sub, as a result of which all shares of the class
       A common stock, $.01 par value (the "IMA Class A Common Stock"), of IMA
       would be cancelled and represent the right to receive 1.15 shares of the
       class A common stock, $.01 par value, of ITI. On May 23, 1995, there were
       outstanding 8,282,676 shares of IMA Class A Common Stock, in addition to
       2,472,985 shares of the class B common stock, $.01 par value, of IMA (the
       holders of which have agreed to convert their shares into IMA Class A
       Common Stock on a share for share basis in connection with the Merger).

<PAGE>   5

CUSIP NO. 45766H 10 1

1    NAME OF REPORTING PERSON
     S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

     ITI Acquisition Corp.

- --------------------------------------------------------------------------------
2    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

     (a)
         -----
     (b)
         -----

- --------------------------------------------------------------------------------
3    SEC USE ONLY

- --------------------------------------------------------------------------------
4    SOURCE OF FUNDS*

     Not applicable

- --------------------------------------------------------------------------------
5    CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS
     2(d) or 2(e)

     -----

- --------------------------------------------------------------------------------
6    CITIZENSHIP OR PLACE OR ORGANIZATION

     Delaware

- --------------------------------------------------------------------------------
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:

7    SOLE VOTING POWER

     -0-

- --------------------------------------------------------------------------------
8    SHARED VOTING POWER

     -0-

- --------------------------------------------------------------------------------
9    SOLE DISPOSITIVE POWER

     -0-

- --------------------------------------------------------------------------------
10   SHARED DISPOSITIVE POWER

     -0-

- --------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     -0-

- --------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES*

           (see footnote 1)
     -----

- --------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

     -0-

- --------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON*

      CO

- --------------------------------------------------------------------------------




 
<PAGE>   6

- ---------------
(1)    On May 23, 1995, ITI, ITI Sub and IMA executed an Agreement and Plan
       of Merger dated such date which provides for the acquisition of IMA by
       ITI through the merger into IMA of ITI Sub.
<PAGE>   7
                             INTRODUCTORY STATEMENT
                             ----------------------

         On May 23, 1995, Insituform Technologies, Inc. ("ITI"), ITI
Acquisition Corp., a wholly-owned subsidiary of ITI ("ITI Sub"), and Insituform
Mid-America, Inc. ("IMA") executed an Agreement and Plan of Merger dated such
date (the "Merger Agreement") which provides for the acquisition of IMA by ITI
through the merger (the "Merger") into IMA of ITI Sub, as a result of which IMA
would become a wholly-owned subsidiary of ITI. Pursuant to Reg. Section
240.13d-4 under the Securities and Exchange Act of 1934, as amended (the
"Exchange Act"), the filing of this statement shall not be construed to mean
that ITI is the beneficial owner, for purposes of Sections 13(d) or 13(g) under
the Exchange Act, of any securities of IMA.

Item 1.  Security and Issuer.
         --------------------

         The securities to which this statement relates are shares of the class
A common stock, $.01 par value (the "IMA Class A Common Stock"), of Insituform
Mid-America, Inc., a Delaware corporation. The principal executive offices of
IMA are located at 17988 Edison Avenue, Chesterfield, Missouri 63005-3700.

Item 2.  Identity and Background.
         ------------------------

         This statement is filed by ITI and its wholly-owned subsidiary, ITI
Sub. ITI commercially exploits trenchless pipeline rehabilitation systems and
technologies through direct installation activities, manufacture of materials
and licensing to unaffiliated companies. ITI Sub was formed for purposes of
effectuating the Merger. The principal business and offices of each of ITI and
ITI Sub are located at 1770 Kirby Parkway-Suite 300, Memphis, Tennessee 38183.
The names, citizenship, business or residence address and principal occupation
of each executive officer and director of ITI and of ITI Sub is set forth in
Annex 1 attached hereto, which information is incorporated herein by reference.

         During the last five years neither ITI, ITI Sub, nor, to the best of
the knowledge of ITI and ITI Sub, any executive officer or director of ITI or
ITI Sub identified on Annex 1, has (a) been convicted in a criminal proceeding
(excluding traffic violations and similar misdemeanors) or (b) been a party to
a civil proceeding of a judicial or administrative body of competent
jurisdiction, and as a result of such proceeding was or is subject to a
judgment, decree or a final order enjoining future violations of, or
prohibiting or mandating activities subject to federal or state securities laws
or finding any violations with respect to such laws.



 
<PAGE>   8
Item 3.  Source of Funds.
         ----------------

         Not applicable.

Item 4.  Purpose of Transaction.
         -----------------------

         On May 23, 1995, ITI, ITI Sub and IMA executed the Merger Agreement,
which provides for the acquisition of IMA by ITI through the Merger. A copy of
the Merger Agreement and the press release announcing the execution of the
Merger Agreement are attached hereto, respectively, as Exhibits B and C.

         Pursuant to the Merger, at the Effective Time (as defined in the
Merger Agreement) holders of IMA Class A Common Stock will receive 1.15 shares
of the class A common stock, $.01 par value (the "ITI Common Stock"), of ITI
for each share of IMA Class A Common Stock held. Holders of class B common
stock, $.01 par value (the "IMA Class B Common Stock"), of IMA have agreed to
convert their shares into IMA Class A Common Stock on a share for share basis
in connection with the transaction).

         In addition, at the Effective Time all options to acquire IMA Class A
Common Stock which are outstanding at the Effective Time under IMA's Stock
Option Plan will be assumed by ITI upon the same terms and conditions as
contained under such plan, except that: (i) each such option will be
exercisable for that number of shares of ITI Common Stock (rounded to the
nearest whole share) into which the number of shares of IMA Class A Common
Stock subject to such option immediately prior to the Effective Time would be
convertible in the Merger if such shares were outstanding at the Effective
Time, and (ii) the option price per share of ITI Common Stock shall be an
amount obtained by dividing (x) the exercise price per share in effect on such
date times the number of shares of IMA Class A Common Stock previously covered
by such option, by (y) the number of shares of ITI Common Stock covered by the
option as so assumed.

         Consummation of the Merger and the transactions contemplated by the
Merger Agreement are subject to, among other things, approval by the
stockholders of both ITI and IMA, registration under the Securities Act of 1933
of the shares of ITI Common Stock to be issued in the Merger, receipt of a
legal opinion that the Merger will qualify as a tax-free reorganization,
confirmation that the Merger will qualify for pooling-of-interests accounting
treatment, expiration of the premerger notification period under the Hart-
Scott-Rodino Act, and other customary conditions.

         Pursuant to the Merger Agreement, IMA has agreed to deliver to ITI, at
or prior to closing thereunder, the resignation of each director and officer of
IMA and each subsidiary requested by ITI. As a result of the consummation of
the Merger, Jerome Kalishman, Robert Affholder and Alvin J. Siteman, all of
whom are currently directors of IMA, would join the ten current directors on
ITI's board. In addition, Mr. Kalishman, Chairman of the Board of IMA,
<PAGE>   9
would become Vice Chairman of the Board of ITI and would also be retained by
ITI as a consultant, and Mr. Affholder, President of IMA, would enter into an
employment agreement with ITI under which he would initially become chief
operating officer of ITI's North American contracting operations.

         In addition, pursuant to the Merger Agreement IMA has agreed that
following receipt of approval of the proposed transactions by ITI's and IMA's
stockholders, IMA will effect restructurings of IMA's subsidiaries and
transfers of the assets and liabilities of IMA and its subsidiaries that are
requested by ITI; provided that, if so requested by IMA in connection with any
particular transaction, ITI will agree, on a basis reasonably satisfactory to
IMA, to indemnify IMA and its subsidiaries against any out-of-pocket costs and
tax liabilities, arising out of such transaction if the transactions
contemplated by the Merger Agreement are not consummated.

         The arrangements between ITI and IMA continue the previously announced
moratorium on further assertion of any rights in dispute as a result of IMA's
acquisition of the pipeline rehabilitation business of Enviroq Corporation in
April 1995 without consent of ITI, except for certain procedural steps to
preserve the respective rights of the parties.  A copy of the arrangements (the
"Litigation Agreement") between ITI and IMA supplementing their outstanding
cooperation agreement and the Merger Agreement is attached hereto as Exhibit D.

         ITI presently plans to consummate the Merger after the occurrence of
all conditions precedent and, pursuant to the Merger, to assume control of IMA.
Subsequent to the consummation of the Merger, the IMA Class A Common Stock will
cease to be publicly traded and will become eligible for termination of
registration under the Exchange Act.

         Reference is hereby made to the full text of the Merger Agreement, the
related press release and the Litigation Agreement filed as, respectively,
Exhibit B, Exhibit C and Exhibit D hereto for further information with respect
to the terms of the transactions contemplated thereby.  Such text is hereby
incorporated by reference in this statement and qualifies all matters set forth
herein.

         Except as stated in response to this Item 4, neither ITI nor ITI Sub
have any plans or proposals which relate to or would result in any other action
specified in clauses (a) through (j) of Item 4 of Schedule 13D.

Item 5.  Interest in Securities of the Issuer.
         -------------------------------------

         As of June 1, 1995, excluding the effect of the Merger Agreement,
neither ITI nor ITI Sub beneficially owned, for purposes of Rule 13d-3 under
the Exchange Act, any shares of IMA Class A Common Stock and, during the sixty
days prior to the date of the
<PAGE>   10
Merger Agreement, neither ITI nor ITI Sub effected any transactions in the IMA
Class A Common Stock. As disclosed by such persons to ITI and ITI Sub, as of
June 1, 1995, except as set forth on Annex 1, none of the executive officers or
directors of either ITI or ITI Sub beneficially owned any shares of IMA Class A
Common Stock nor, during the sixty days prior to the date of the Merger
Agreement, did any such executive officer or director effect any transactions
in the IMA Class A Common Stock.

Item 6.  Contracts, Arrangements, Undertakings or Relationships
         with Respect to Securities of the Issuer.
         ------------------------------------------------------

         As more fully described under Item 4 herein, on May 23, 1995 ITI and
ITI Sub entered into the Merger Agreement with IMA.  Among other provisions,
the Merger Agreement states that, until the consummation of the Merger: (a)
except as otherwise permitted, no change shall be made or proposed in the
certificate of incorporation or by-laws, or any other organic instrument, of
IMA or of any subsidiary of IMA; (b) neither IMA nor any subsidiary shall (i)
issue, grant, sell or encumber any shares of its capital stock, (ii) issue,
grant, sell or encumber any security, option, warrant, put, call, subscription
or other right of any kind, fixed or contingent, that directly or indirectly
calls for the acquisition, issuance, sale, pledge or other disposition of any
shares of capital stock or other equity interests of IMA or any subsidiary,
except as contemplated by the Merger Agreement (without limitation, including
the grant of additional options covering up to 120,000 shares of IMA Class A
Common Stock), (iii) enter into any agreement, commitment or understanding
calling for any transaction referred to in clauses (i) or (ii) preceding, or
(iv) make any other changes in its equity capital structure except as
contemplated by the Merger Agreement; and (c) neither IMA nor any subsidiary
shall split, combine or reclassify any shares of its capital stock, (except for
any payment of regular semi-annual cash dividends) declare, set aside or pay
any dividend or other distribution (whether in cash, stock, securities,
indebtedness, rights or property or any combination thereof) in respect of any
shares of its capital stock or other equity interests, or redeem or otherwise
acquire any shares of its capital stock or other equity interests.

         In connection with the Merger Agreement, ITI and IMA have entered into
agreements, each dated May 23, 1995 (the "Conversion Letter Agreements"), with
the holders of all of the outstanding shares of IMA Class B Common Stock.
Pursuant to the Conversion Letter Agreements, such persons have agreed to
convert, immediately prior to the consummation of the transactions contemplated
by the Merger Agreement, each outstanding share of IMA Class B Common Stock
beneficially owned by them, respectively, into one share of IMA Class A Common
Stock in accordance with the terms of the IMA Class B Common Stock.  Copies of
the Conversion Letter Agreements are attached hereto as Exhibit E.
<PAGE>   11
         In connection with the Merger Agreement, ITI and IMA obtained
additional agreements, each dated May 23, 1995 (the "Pooling Letter
Agreements"), from (i) Interstate Properties and its partners, Steven Roth,
Russell B. Wight, Jr. and David Mandelbaum, and from Douglas K. Chick, Brian
Chandler, Ringwood Limited, Barford Limited and Parkwood Limited, constituting
the largest stockholders of ITI; (ii) each other director and executive officer
of ITI; (ii) Jerome and Nancy Kalishman, individually and as trustees and/or
tenants by the entirety, Xanadu Investments, L.P. and Robert W. Affholder,
constituting the largest stockholders of IMA; and (iv) each other director and
executive officer of IMA.  Pursuant to the Pooling Letter Agreements, and
subject to specified exceptions, such persons have agreed, among other things,
not to transfer or dispose of any shares of ITI Common Stock, IMA Class A
Common Stock of IMA Class B Common Stock owned by them, respectively,until the
earlier of:  (x) the termination of the Merger Agreement or (y) the date of the
first publication of the operating results of ITI covering at least a 30-day
period after the Merger has been consummated.  Copies of the Pooling Letter
Agreements are attached hereto as Exhibit F.

         In connection with execution of Pooling Letter Agreements by
Interstate Properties and its partners, ITI and IMA confirmed that such
agreements would not remain in effect if the Merger did not occur on or prior
to January 31, 1996, and ITI committed that, at the request of Interstate
Properties, it will use its best efforts to publish at the earliest practicable
date following the Effective Time the operating results of ITI covering the
first full calendar month after the Merger is consummated, consistent with the
release by ITI of year-end results. Copies of such arrangements are attached
hereto as Exhibit G.

         Except as stated in response to this Item 6, neither ITI nor ITI Sub,
nor, to the best of the knowledge of ITI and ITI Sub, any of the executive
officers or directors listed in Annex 1, is a party to any contract,
arrangement, understanding or relationship (legal or otherwise) with any person
with respect to any securities of IMA, including, but not limited to, the
transfer or voting of any such securities, finder's fees, joint ventures, loan
or option arrangements, puts or calls, guaranties of profits, divisions of
profit or loss, or the giving or withholding of proxies.

Item 7.  Material to be Filed as Exhibits.
         ---------------------------------

         Exhibit A   -    Agreement pursuant to Rule 13d-1(f)(1)(iii).

         Exhibit B   -    Agreement and Plan of Merger dated as of May 23, 1995
                          among Insituform Technologies, Inc., ITI Acquisition 
                          Corp. and Insituform Mid-America, Inc.

         Exhibit C   -    Joint Press Release dated May 24, 1995 of Insituform 
                          Technologies, Inc., and Insituform Mid-America, Inc.
                          
<PAGE>   12
         Exhibit D   -    Litigation Agreement dated as of May 23, 1995 between
                          Insituform Technologies, Inc. and Insituform Mid-
                          America, Inc.

         Exhibit E   -    Conversion Letters, each dated May 23, 1995, relating
                          to the conversion of shares of IMA Class B Common
                          Stock entered into by Insituform Technologies, Inc.
                          and Insituform Mid-America, Inc. and each of the
                          following:  Robert W. Affholder, Thomas Kalishman,
                          Susan Kalishman, John Kalishman, James Kalishman and
                          Xanadu Investments, L.P.

         Exhibit F   -    Letter Agreements, each dated May 23, 1995, relating
                          to the non-disposition of capital stock of Insituform
                          Technologies, Inc. and Insituform Mid-America, Inc.
                          entered into by Insituform Technologies, Inc., and
                          Insituform Mid-America, Inc. and each of the
                          following:  Paul A. Biddelman, Brian Chandler,
                          Douglas K.  Chick, William Gorham, Anthony W. Hooper,
                          James D. Krugman, David Mandelbaum, William A Martin,
                          R. William Pittman, Jean-Paul Richard, Steven Roth,
                          Silas Spengler, Raymond P. Toth, Sheldon Weinig,
                          Russell B. Wight, Jr., Interstate Properties,
                          Parkwood Limited, Ringwood Limited, Barford Limited,
                          Robert W. Affholder, Jerome Kalishman, Jerome
                          Kalishman and Nancy Kalishman, as tenants by the
                          entirety, Jerome Kalishman as trustee of each of the
                          Family Fund and Irrevocable Grandchildren's Trust,
                          Nancy Kalishman, Robert M.  Leopold, Lee M. Liberman,
                          Joseph F. Olson, Alvin J. Siteman, James L. Tadtman
                          and Xanadu Investments, L.P.

         Exhibit G   -    Letters, each dated May 23, 1995, executed to
                          Interstate Properties by Insituform Technologies,
                          Inc. and Insituform Mid-America, Inc.
<PAGE>   13
                                   SIGNATURE
                                   ---------
        

         After reasonable inquiry and to the best of our knowledge and belief,
we certify that the information set forth in this statement is true, complete
and correct.

Dated: June 1, 1995                     INSITUFORM TECHNOLOGIES, INC.



                                        By s/William A. Martin
                                          --------------------------------------
                                           William A. Martin
                                           Senior Vice President


Dated: June 1, 1995                     ITI ACQUISITION CORP.



                                        By s/William A. Martin
                                          --------------------------------------
                                           William A. Martin
                                           Vice President



 
<PAGE>   14
                                                                         Annex 1


<TABLE>
<CAPTION>
                                                                                                           IMA Class A
                                                                                    Principal Occupation,  Common Stock
Name and Business or                                       Position                     Employee and       Beneficially
 Residence Address                    Citizenship          with ITI                 Address of Employer       Owned    
- ---------------------                 -----------          --------                 ---------------------  ------------
<S>                                   <C>                  <C>                      <C>                    <C>
James D. Krugman                      United States        Chairman of              Partner                     --
Krugman, Chapnick &                                         the Board               Krugman, Chapnick &
 Grimshaw                                                                            Grimshaw
Park 80 West -                                                                      Park 80 West -
 Plaza Two                                                                           Plaza Two
Saddle Brook, New                                                                   Saddle Brook, New
 Jersey 07663                                                                        Jersey 07663

Jean-Paul Richard                     United States        Director,                President and               --
Insituform Technologies,                                    President and            Chief Executive
 Inc.                                                       Chief Execu-             Officer
1770 Kirby Parkway                                          tive Officer            Insituform Technologies,
Suite 300                                                                            Inc.
Memphis, Tennessee                                                                  1770 Kirby Parkway
 38138                                                                              Suite 300
                                                                                    Memphis, Tennessee 38138

William A. Martin                     United States        Senior Vice              Senior Vice President       --
Insituform Technologies,                                    President,               President, Chief
 Inc.                                                       Chief                    Financial Officer
1770 Kirby Parkway                                          Financial               Insituform Technologies,
Suite 300                                                   Officer                  Inc.
Memphis, Tennessee                                                                  1770 Kirby Parkway
 38138                                                                              Suite 300
                                                                                    Memphis, Tennessee 38138

R. William Pittman                    United States        Senior Vice              Senior Vice President-      --
Insituform Technologies,                                    President-               Operations
 Inc.                                                       Operations              Insituform Technologies,
1770 Kirby Parkway                                                                   Inc.
Suite 300                                                                           1770 Kirby Parkway
Memphis, Tennessee                                                                  Suite 300
 38138                                                                              Memphis, Tennessee 38138

Anthony W. Hooper                     United States        Senior Vice              Senior Vice President-      --
Insituform Technologies,                                    President-               Marketing
 Inc.                                                       Marketing               Insituform Technologies,
1770 Kirby Parkway                                                                   Inc.
Suite 300                                                                           1770 Kirby Parkway
Memphis, Tennessee                                                                  Suite 300
 38138                                                                              Memphis, Tennessee 38138

Raymond P. Toth                       United States        Vice President-          Vice President-             --
Insituform Technologies,                                    Human                    Human Resources
 Inc.                                                       Resources               Insituform Technologies,
1770 Kirby Parkway                                                                   Inc.
Suite 300                                                                           1770 Kirby Parkway
Memphis, Tennessee                                                                  Suite 300
 38138                                                                              Memphis, Tennessee 38138

Paul Biddelman                        United States        Director                 Treasurer                   --
Hanseatic Corporation                                                               Hanseatic Corporation
450 Park Avenue                                                                     450 Park Avenue
Suite 2302                                                                          Suite 2302
New York, New York 10022                                                            New York, New York 10022
</TABLE>



 
<PAGE>   15
<TABLE>
<S>                                   <C>                  <C>                      <C>                    <C>
Brian Chandler                        United Kingdom        Director                Private investor            --
8933 St. Gallen 60
Steiermark, Austria

Douglas K. Chick                      United Kingdom        Director                Private investor            --
Bays Hill Cottage
Barnet Lane
Elstree, Hertfordshire
United Kingdom

William Gorham                        United States         Director                President                   9,000*
The Urban Institute                                                                 The Urban Institute
2100 M. Street, N.W.                                                                2100 M Street, N.W.
Washington, D.C. 20037                                                              Washington, D.C. 20037

Steven Roth                           United States         Director                General Partner             --
Interstate Properties                                                               Interstate Properties
Park 80 West - Plaza Two                                                            Park 80 West - Plaza Two
Saddle Brook, New Jersey                                                            Saddle Brook, New Jersey
New Jersey 07663                                                                     07663

Silas Spengler                        United States         Director                Principal                   --
Sullivan Associates                                                                 Sullivan Associates
230 Park Avenue                                                                     230 Park Avenue
Room 863                                                                            Room 863
New York, New York                                                                  New York, New York 10169
 10169

Sheldon Weinig                        United States         Director                Consultant                  --
Sony Engineering and                                                                Sony Engineering and
 Manufacturing of America                                                           Manufacturing of America
Materials Research Corp.                                                            Materials Research Corp.
560 Route 303                                                                       560 Route 303
Orangeburg, New York 10962                                                          Orangeburg, New York 10962

Russell B. Wight, Jr.                 United States         Director                General Partner             --
Interstate Properties                                                               Interstate Properties
Park 80 West - Plaza Two                                                            Park 80 West - Plaza Two
Saddle Brook, New Jersey                                                            Saddle Brook, New Jersey
 07663                                                                               07663
</TABLE>

- -------------------------------
*    Represents 4,000 shares held jointly with Gail Gorham, Mr. Gorham's
     wife, and 5,000 shares held by an employee benefit plan on behalf
     of Mr. Gorham.



     Messrs. Krugman, Richard and Martin are the sole directors of ITI Sub;
and Messrs. Richard and Martin are, respectively, the President, and the Vice
President and Secretary, of ITI Sub.
<PAGE>   16
                               INDEX TO EXHIBITS

Exhibit A   -    Agreement pursuant to Rule
                 13d-1(f)(1)(iii)

Exhibit B   -    Agreement and Plan of Merger dated as of May 23, 1995 among
                 Insituform Technologies, Inc., ITI Acquisition Corp.  and
                 Insituform Mid-America, Inc.

Exhibit C   -    Joint Press Release dated May 24, 1995 of Insituform
                 Technologies, Inc. and Insituform Mid-America, Inc.

Exhibit D   -    Litigation Agreement dated as of May 23, 1995 between
                 Insituform Technologies, Inc. and Insituform Mid-America, Inc.

Exhibit E   -    Conversion Letters, each dated May 23, 1995, relating to the
                 conversion of shares of IMA Class B Common Stock entered into
                 by Insituform Technologies, Inc. and Insituform Mid-America,
                 Inc. and each of the following: Robert W. Affholder, Thomas
                 Kalishman, Susan Kalishman, John Kalishman, James Kalishman
                 and Xanadu Investments, L.P.

Exhibit F   -    Letter Agreements, each dated May 23, 1995, relating to the
                 non-disposition of capital stock of Insituform Technologies,
                 Inc. and Insituform Mid-America, Inc. entered into by
                 Insituform Technologies, Inc., and Insituform Mid-America,
                 Inc. and each of the following:  Paul A. Biddelman, Brian
                 Chandler, Douglas K. Chick, William Gorham, Anthony W. Hooper,
                 James D. Krugman, David Mandelbaum, William A Martin, R.
                 William Pittman, Jean-Paul Richard, Steven Roth, Silas
                 Spengler, Raymond P. Toth, Sheldon Weinig, Russell B. Wight,
                 Jr., Interstate Properties, Parkwood Limited, Ringwood
                 Limited, Barford Limited, Robert W. Affholder, Jerome
                 Kalishman, Jerome Kalishman and Nancy Kalishman, as tenants by
                 the entirety, Jerome Kalishman as trustee of each of the
                 Family Fund and Irrevocable Grandchildren's Trust, Nancy
                 Kalishman, Robert M. Leopold, Lee M. Liberman, Joseph F.
                 Olson, Alvin J. Siteman, James L. Tadtman and Xanadu
                 Investments, L.P.



 
<PAGE>   17
Exhibit G   -    Letters, each dated May 23, 1995, executed to Interstate
                 Properties by Insituform Technologies, Inc. and Insituform
                 Mid-America, Inc.

<PAGE>   1
                                                                       EXHIBIT A

        Pursuant to Rule 13d-1(f)(1)(iii) promulgated by the Securities and
Exchange Commission, the undersigned agree that the statement to which this
Exhibit is attached is filed on their behalf and in the capacities as set out
hereinbelow.


Dated: June 1, 1995                     INSITUFORM TECHNOLOGIES, INC.



                                        By s/William A. Martin
                                          --------------------------------------
                                          William A. Martin
                                          Senior Vice President


Dated: June 1, 1995                     ITI ACQUISITION CORP.



                                        By s/William A. Martin
                                          --------------------------------------
                                          William A. Martin
                                          Vice President

<PAGE>   1
                                                                      EXHIBIT B
- --------------------------------------------------------------------------------


 
        ---------------------------------------------------------------
 
                          AGREEMENT AND PLAN OF MERGER
 
                            DATED AS OF MAY 23, 1995

                                     AMONG
 
                         INSITUFORM TECHNOLOGIES, INC.,

                             ITI ACQUISITION CORP.

                                      AND

                          INSITUFORM MID-AMERICA, INC.
        ---------------------------------------------------------------


 
- --------------------------------------------------------------------------------
<PAGE>   2
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                                       PAGE
                                                                                       ----
<S>            <C>                                                                     <C>
ARTICLE I      THE MERGER............................................................    1
     1.1       The Merger............................................................    1
     1.2       Effect of Merger......................................................    2
     1.3       Certificate of Incorporation and By-Laws..............................    2
     1.4       Effective Time of Merger..............................................    2
     1.5       IMA Directors and Officers............................................    2
     1.6       Taking of Necessary Action; Further Action............................    2
ARTICLE II     CONVERSION OF SHARES..................................................    3
     2.1       Acquisition Sub Common Stock..........................................    3
     2.2       IMA Common Stock......................................................    3
     2.3       Options to Purchase Shares of IMA Common Stock........................    3
     2.4       ITI Common Stock......................................................    4
ARTICLE III    DISSENTING SHARES; EXCHANGE OF CERTIFICATES...........................    4
     3.1       Dissenting Shares.....................................................    4
     3.2       Exchange of Shares....................................................    4
     3.3       Dividends and Other Distributions.....................................    5
     3.4       IMA Stock Transfer Ledger.............................................    6
     3.5       Termination of Exchange Agency........................................    6
ARTICLE IV     CLOSING...............................................................    6
     4.1       Time and Place of Closing.............................................    6
     4.2       Certificate of Merger.................................................    6
ARTICLE V      REPRESENTATIONS AND WARRANTIES OF IMA.................................    7
     5.1       Incorporation.........................................................    7
     5.2       Authorization.........................................................    7
     5.3       Conflicts.............................................................    7
     5.4       Capitalization........................................................    8
     5.5       Subsidiaries..........................................................    8
     5.6       Securities Filings....................................................    9
     5.7       Financial Statements..................................................    9
     5.8       Absence of Undisclosed Liabilities....................................   10
     5.9       Absence of Certain Changes............................................   11
     5.10      Pooling...............................................................   12
     5.11      Taxes.................................................................   12
     5.12      Title.................................................................   12
     5.13      Real Estate and Leases................................................   12
     5.14      Contractual and Other Obligations.....................................   13
     5.15      Compensation..........................................................   14
     5.16      Employee Benefit Plans................................................   14
     5.17      Labor Relations.......................................................   16
     5.18      Interests of Insiders.................................................   16
     5.19      Insurance.............................................................   16
     5.20      Intellectual Property.................................................   16
     5.21      Disputes and Litigation...............................................   17
     5.22      Licenses; Franchises; Rights..........................................   17
     5.23      Brokers and Finders...................................................   18
ARTICLE VI     REPRESENTATIONS AND WARRANTIES
               OF ITI AND ACQUISITION SUB............................................   18
     6.1       Incorporation.........................................................   18
     6.2       Authorization.........................................................   18
</TABLE>
 
                                        i

 
<PAGE>   3
 
<TABLE>
<CAPTION>
                                                                                       PAGE
                                                                                       ----
<S>            <C>                                                                     <C>
     6.3       Conflicts.............................................................   19
     6.4       Capitalization........................................................   19
     6.5       Securities Filings....................................................   19
     6.6       Financial Statements..................................................   20
     6.7       Absence of Undisclosed Liabilities....................................   20
     6.8       Absence of Certain Changes............................................   20
     6.9       Pooling...............................................................   20
     6.10      Interests of Insiders.................................................   21
     6.11      Disputes and Litigation...............................................   21
     6.12      Brokers or Finders....................................................   21
ARTICLE VII    CERTAIN COVENANTS.....................................................   21
     7.1       IMA Stockholders' Meeting.............................................   21
     7.2       ITI Stockholders' Meeting.............................................   21
     7.3       ITI Board of Directors................................................   22
     7.4       ITI Officers..........................................................   22
     7.5       Registration Statement; Proxy Statement...............................   22
     7.6       HSR Act; Other Governmental and Judicial Filings......................   23
     7.7       Conduct of Business of IMA............................................   23
     7.8       IMA Capitalization....................................................   25
     7.9       Interim Financial Statements; Audited Enviroq Statements..............   26
     7.10      Conduct of Business of ITI; ITI Capitalization........................   26
     7.11      Due Diligence; SEC Filings............................................   27
     7.12      Notification of Certain Matters.......................................   28
     7.13      Accounting and Tax Treatment..........................................   28
     7.14      Forbearance...........................................................   28
     7.15      Restructuring Transactions............................................   29
     7.16      Indemnification.......................................................   29
     7.17      Registration Rights...................................................   29
     7.18      Additional Agreements.................................................   30
ARTICLE VIII   PUBLICITY.............................................................   30
     8.1       Publicity.............................................................   30
ARTICLE IX     CONDITIONS TO OBLIGATIONS OF EACH PARTY...............................   31
     9.1       Hart-Scott-Rodino Antitrust Improvements Act..........................   31
     9.2       Merger Approval.......................................................   31
     9.3       Amendments to ITI's Certificate of Incorporation......................   31
     9.4       Amendments to ITI's By-Laws...........................................   31
     9.5       Effectiveness of Registration Statement...............................   31
     9.6       Pooling-of-Interests..................................................   31
     9.7       Conversion of IMA Class B Common Stock................................   31
     9.8       No Prohibition on Consummation........................................   31
     9.9       Tax Opinion...........................................................   32
     9.10      ITI Board; Officers...................................................   32
ARTICLE X      CONDITIONS TO OBLIGATIONS OF IMA......................................   32
   10.1        Opinion of Counsel for ITI and Acquisition Sub........................   32
   10.2        Representations; Warranties; Covenants................................   32
   10.3        Certified Resolutions.................................................   32
   10.4        Kalishman and Affholder Agreements....................................   32
   10.5        Fairness Opinion......................................................   33
   10.6        Letter of ITI's Accountants...........................................   33
   10.7        Director Indemnification Agreements...................................   33
</TABLE>
 
                                       ii

 
<PAGE>   4
 
<TABLE>
<CAPTION>
                                                                                       PAGE
                                                                                       ----
<S>            <C>                                                                     <C>
   10.8        Litigation............................................................   33
   10.9        Other Certificates....................................................   33
ARTICLE XI     CONDITIONS TO OBLIGATIONS OF ITI AND ACQUISITION SUB..................   33
   11.1        Opinion of Counsel for IMA............................................   33
   11.2        Representations; Warranties; Covenants................................   33
   11.3        Certified Resolutions; Capitalization.................................   34
   11.4        Affiliate Undertakings................................................   34
   11.5        Kalishman and Affholder Agreements....................................   34
   11.6        Dissenters' Rights....................................................   34
   11.7        Third Party Consents..................................................   34
   11.8        Resignations..........................................................   35
   11.9        Fairness Opinion......................................................   35
   11.10       Letter of Accountants for IMA and Enviroq.............................   35
   11.11       A-Y-K-E Equipment.....................................................   35
   11.12       Litigation............................................................   35
   11.13       Other Certificates....................................................   35
ARTICLE XII    TERMINATION...........................................................   35
   12.1        Termination...........................................................   35
   12.2        Effect of Termination.................................................   36
ARTICLE XIII   MISCELLANEOUS.........................................................   36
   13.1        Notices...............................................................   36
   13.2        Survival of Representations...........................................   37
   13.3        Cooperation Agreement.................................................   37
   13.4        Entire Agreement......................................................   37
   13.5        Modification..........................................................   37
   13.6        Further Action........................................................   37
   13.7        Expenses..............................................................   38
   13.8        Governing Law.........................................................   38
   13.9        Captions..............................................................   38
   13.10       Accounting Terms......................................................   38
   13.11       Specific Performance..................................................   38
   13.12       Assignment............................................................   38
   13.13       No Third Party Beneficiary............................................   38
   13.14       Partial Invalidity....................................................   38
   13.15       Counterparts..........................................................   38
Schedule 5.3   --  IMA Third Party Consents
Schedule 5.5   --  Subsidiaries
Schedule 5.8   --  Certain IMA Liabilities
Schedule 5.9   --  Certain IMA Changes since December 31, 1994
Schedule 5.11  --  Tax Deficiencies
Schedule 5.12  --  Exceptions to Title
Schedule 5.13  --  Real Estate
Schedule 5.14  --  Certain Contracts and Agreements
Schedule 5.15  --  Key Employees
Schedule 5.16  --  Employee Benefit Plans
Schedule 5.18  --  IMA Related Party Transactions
Schedule 5.19  --  Insurance and Bonding Arrangements
Schedule 5.20  --  Intellectual Property
Schedule 5.21  --  IMA Litigation
Schedule 5.22  --  State Contractor Permits
</TABLE>
 
                                       iii

 
<PAGE>   5
 
<TABLE>
<S>            <C>
Schedule 6.3   --  ITI Third Party Consents
Schedule 6.4   --  ITI Stock Commitments
Schedule 6.7   --  Certain ITI Liabilities
Schedule 6.8   --  Certain ITI Changes since December 31, 1994
Schedule 6.10  --  ITI Related Party Transactions
Schedule 6.11  --  ITI Litigation
Schedule 7.7   --  Conduct of IMA Business
Schedule 7.8   --  IMA Dividends
Schedule 7.10  --  Conduct of ITI Business
Exhibit A      --  Agreement of Merger
Exhibit B      --  Pooling Letter
Exhibit C-1    --  KPMG Peat Marwick Comfort Letter
Exhibit C-2    --  Deloitte & Touche Comfort Letter
Exhibit D      --  BDO Seidman Comfort Letter
Exhibit E      --  Amendments to ITI Certificate of Incorporation
Exhibit F      --  Amendments to ITI By-Laws
Exhibit G      --  Conversion Letter
Exhibit H      --  Opinion of Messrs. Krugman, Chapnick & Grimshaw
Exhibit I      --  Opinion of Messrs. Thompson & Mitchell
Exhibit J      --  Rule 145 Letter
Exhibit K      --  Affholder Agreement
Exhibit L      --  Kalishman Agreements
</TABLE>
 
                                       iv

 
<PAGE>   6
 
                             INDEX OF DEFINED TERMS
 
<TABLE>
<S>                                                                       <C>
Acquisition Sub.........................................................  Recitals
Acquisition Sub Common Stock............................................  Recitals
Affiliate Agreement.....................................................  Section 11.4
Agreement...............................................................  Recitals
Benefit Plans...........................................................  Section 5.16
business day............................................................  Section 4.1
Certificate of Merger...................................................  Section 1.4
Class I Directors.......................................................  Section 7.3
Class II Directors......................................................  Section 7.3
Class III Directors.....................................................  Section 7.3
Closing.................................................................  Section 4.1
Closing Date............................................................  Section 4.1
Code....................................................................  Section 2.3
Confidentiality Agreement...............................................  Section 7.11(c)
Constituent Corporations................................................  Recitals
Cooperation Agreement...................................................  Section 13.3
Defined Benefit Plans...................................................  Section 5.15
Demand Registration.....................................................  Section 7.17(b)
Dissenting Shares.......................................................  Section 3.1(a)
Effective Time..........................................................  Section 1.4
ERISA...................................................................  Section 5.15
Environmental Laws......................................................  Section 5.22(c)
Enviroq.................................................................  Section 5.6
Enviroq Audited Financial Statements....................................  Section 5.7(b)
Enviroq Form 10-K.......................................................  Section 5.6
Enviroq Form 10-Q.......................................................  Section 5.6
Enviroq Interim Financial Statements....................................  Section 5.7(d)
Enviroq Pro Forma Financial Statements..................................  Section 5.7(e)
Enviroq Proxy Statement.................................................  Section 5.6
Exchange Act............................................................  Section 5.3
Exchange Agent..........................................................  Section 3.2(a)
GCL.....................................................................  Section 1.1
Group...................................................................  Section 7.3
HSR Act.................................................................  Section 5.3
IGL Group...............................................................  Section 7.3
IMA.....................................................................  Recitals
IMA Agreements..........................................................  Section 5.14(a)
IMA Audited Financial Statements........................................  Section 5.7(a)
IMA Financial Statements................................................  Section 5.7(c)
IMA Group...............................................................  Section 7.3
IMA Interim Financial Statements........................................  Section 5.7(c)
IMA's business or condition.............................................  Section 5.4
IMA Preferred Stock.....................................................  Recitals
IMA Convertible Preferred Stock.........................................  Recitals
IMA Class A Convertible Preferred Stock.................................  Recitals
IMA Class A Common Stock................................................  Recitals
IMA Class B Common Stock................................................  Recitals
IMA Common Stock........................................................  Recitals
</TABLE>
 
                                        v

 
<PAGE>   7

 
<TABLE>
<S>                                                                       <C>
IMA Form 10-K...........................................................  Section 5.6
IMA Form 10-Q...........................................................  Section 5.6
IMA Option Plan.........................................................  Section 2.3(a)
IMA Options.............................................................  Section 2.3(a)
IMA SEC Documents.......................................................  Section 5.6
INA Group...............................................................  Section 7.3
Incidental Registration.................................................  Section 7.17(b)(ii)
Insider.................................................................  Section 5.14(a)
Insituform Process......................................................  Section 5.19
Intellectual Property...................................................  Section 5.20
ITI.....................................................................  Recitals
ITI Audited Financial Statements........................................  Section 6.6(a)
ITI Interim Financial Statements........................................  Section 6.6(b)
ITI Form 10-K...........................................................  Section 6.5
ITI Form 10-Q...........................................................  Section 6.5
ITI Common Stock........................................................  Section 2.2(a)
ITI Preferred Stock.....................................................  Section 6.4
ITI SEC Documents.......................................................  Section 6.5
Joint Proxy Statement...................................................  Section 7.5(b)
Lien....................................................................  Section 5.9
Material Adverse Effect.................................................  Section 5.1(b)
Merger..................................................................  Recitals
Multiemployer Plans.....................................................  Section 5.16
NuPipe Process..........................................................  Section 5.20
PBGC....................................................................  Section 5.16
Plan of Merger..........................................................  Section 4.1
Prior Registration Rights Agreement.....................................  Section 7.17(b)
Registrable Securities..................................................  Section 7.17(b)(i)
Registration Rights Agreement...........................................  Section 7.17(a)
Registration Statement..................................................  Section 7.5(a)
Removal Pleadings.......................................................  Section 13.3
Stockholder.............................................................  Section 7.17(a)
Subsidiary..............................................................  Section 5.1(b)
Subsidiary..............................................................  Section 5.5
SEC.....................................................................  Section 2.3(c)
Securities Act..........................................................  Section 3.2(c)
Surviving Corporation...................................................  Section 1.1
Term....................................................................  Section 7.3
</TABLE>
 
                                       vi

 
<PAGE>   8
 
                          AGREEMENT AND PLAN OF MERGER
 
     AGREEMENT AND PLAN OF MERGER dated as of this 23rd day of May, 1995
(hereinafter referred to as this "Agreement"), by and among INSITUFORM
TECHNOLOGIES, INC., a corporation organized and existing under the laws of the
State of Delaware (hereinafter referred to as "ITI"), ITI ACQUISITION CORP., a
corporation organized and existing under the laws of the State of Delaware and a
wholly-owned subsidiary of ITI (hereinafter referred to as "Acquisition Sub"),
and INSITUFORM MID-AMERICA, INC., a corporation organized and existing under the
laws of the State of Delaware (hereinafter referred to as "IMA"; and, together
with Acquisition Sub, as the "Constituent Corporations").
 
                                  WITNESSETH:
 
     WHEREAS, IMA, together with its Subsidiaries (as hereinafter defined), is
primarily engaged in the application of trenchless and other technologies to the
rehabilitation, construction and improvement of pipeline systems, and is a
licensee of the Insituform(R) Process (as more particularly hereinafter
described, the "Insituform Process") and the NuPipe(R) Process (as more
particularly hereinafter described, the "NuPipe Process"), in those states and
other territories covered by license agreements extended by, respectively,
Insituform North America Corp. and NuPipe, Inc., both wholly-owned subsidiaries
of ITI; and
 
     WHEREAS, IMA, pursuant to its certificate of incorporation (filed in the
office of the Secretary of State of the State of Delaware on December 22, 1983,
as subsequently amended on, respectively, January 6 and February 8, 1984,
November 6, 1985 and December 10, 1986), has an authorized capital stock
consisting of: 500,000 shares of preferred stock, $.01 par value (hereinafter
referred to as the "IMA Preferred Stock"), none of which are presently issued
and outstanding; 10,000 shares of convertible preferred stock, $100 par value
(hereinafter referred to as the "IMA Convertible Preferred Stock"), none of
which are presently issued and outstanding; 500 shares of class A convertible
preferred stock, $1,000 par value (hereinafter referred to as the "IMA Class A
Convertible Preferred Stock"), none of which are presently issued and
outstanding; 13,000,000 shares of class A common stock, $.01 par value
(hereinafter referred to as the "IMA Class A Common Stock"), of which 8,282,676
shares are presently issued and outstanding, and 6,000,000 shares of class B
common stock, $.01 par value (hereinafter referred to as the "IMA Class B Common
Stock", and together with the IMA Class A Common Stock, the "IMA Common Stock"),
of which 2,472,985 shares are presently issued and outstanding; and
 
     WHEREAS, Acquisition Sub has been duly organized as a corporation under the
laws of the State of Delaware, and, pursuant to its certificate of incorporation
(filed in the office of the Secretary of State of the State of Delaware on March
16, 1995), has an authorized capital stock consisting of 10,000 shares of common
stock, $.01 par value (hereinafter referred to as the "Acquisition Sub Common
Stock"), of which 1,000 shares are issued and outstanding and held by ITI; and
 
     WHEREAS, the respective Boards of Directors of the Constituent
Corporations, and of ITI, deem it advisable and in the best interests of such
corporations and their stockholders, respectively, that Acquisition Sub be
merged into and with IMA (hereinafter referred to as the "Merger"), in
accordance with the terms and conditions hereinafter set forth, so that IMA
shall become a subsidiary of ITI;
 
     NOW, THEREFORE, in consideration of the mutual covenants and agreements
hereinafter set forth, the parties hereby agree as follows:
 
                                   ARTICLE I
 
                                   THE MERGER
 
     1.1  The Merger.
 
     At the Effective Time (as hereinafter defined), in accordance with this
Agreement and the Delaware General Corporation Law (hereinafter referred to as
the "GCL"), Acquisition Sub shall be merged into and with IMA, the separate
corporate existence of Acquisition Sub shall cease and IMA shall continue as the

 
<PAGE>   9
 
surviving corporation, governed by the laws of the State of Delaware, under the
corporate name it possesses immediately prior to the Effective Time. IMA, from
and after the Effective Time, is hereinafter sometimes referred to as the
"Surviving Corporation".
 
     1.2  Effect of Merger.
 
        (a) At the Effective Time, the Surviving Corporation shall possess all
the rights, privileges, immunities and franchises, as well as of a public as of
a private nature, of the Constituent Corporations. All of the rights,
privileges, immunities and franchises, and all property, real and personal, and
all debts due on whatever account to each of the Constituent Corporations, shall
be taken and deemed to be transferred to and vested in the Surviving Corporation
without further act or deed; and all of the property, rights, privileges,
immunities, powers, franchises and all and every other interest of each of the
Constituent Corporations thereafter shall be vested as effectively and fully in
the Surviving Corporation as they were in each of the Constituent Corporations.
 
        (b) The Surviving Corporation shall be responsible and liable for all of
the liabilities, obligations and penalties of each of the Constituent
Corporations; provided, however, that the liabilities, obligations and penalties
of the Constituent Corporations shall not be affected by the Merger, and that
the rights of the creditors of the Constituent Corporations, or any liens upon
the property of the Constituent Corporations shall not be impaired by the
Merger, and any claim existing or action or proceeding, civil or criminal,
pending by or against the Constituent Corporations may be prosecuted to judgment
as if the Merger had not taken place, or the Surviving Corporation may be
proceeded against or substituted in the place of the Constituent Corporations.
 
     1.3  Certificate of Incorporation and By-Laws.
 
     The certificate of incorporation and by-laws of IMA, as in effect
immediately prior to the Effective Time, shall be the certificate of
incorporation and by-laws of the Surviving Corporation and thereafter shall
continue to be its certificate of incorporation and by-laws until changed as
provided therein and under the laws of the State of Delaware. The first annual
meeting of the stockholders of the Surviving Corporation held after the
Effective Time shall be the next annual meeting of stockholders provided for in
the by-laws of IMA.
 
     1.4  Effective Time of Merger.
 
     The Merger shall become effective at the time of filing of a certificate of
merger with respect to the Merger (hereinafter referred to as the "Certificate
of Merger") in the office of the Secretary of State of the State of Delaware, as
required by the GCL. Such time is herein referred to as the "Effective Time".
 
     1.5  IMA Directors and Officers.
 
     At the Effective Time and until their successors have been duly elected and
have qualified, the Board of Directors of the Surviving Corporation shall
consist of three members, and the members of the Board of Directors of
Acquisition Sub shall become the directors of the Surviving Corporation; and at
the Effective Time and until their successors have been duly elected and have
qualified, the officers of Acquisition Sub shall become the officers of the
Surviving Corporation.
 
     1.6  Taking of Necessary Action; Further Action.
 
     IMA, ITI and Acquisition Sub, respectively, shall take all such lawful
action as may be necessary or appropriate in order to effectuate the
transactions contemplated by this Agreement. In case at any time after the
Effective Time, any further action is necessary or desirable to carry out the
purposes of this Agreement and to vest the Surviving Corporation with full title
to all assets, rights, privileges, powers, immunities, purposes and franchises
of either of the Constituent Corporations, the officers and directors of such
corporation shall take all such lawful and necessary action.
 
                                        2

 
<PAGE>   10
 
                                   ARTICLE II
 
                              CONVERSION OF SHARES
 
     The manner and basis of converting in the Merger the outstanding shares of
IMA Common Stock and Acquisition Sub Common Stock into shares of the capital
stock of the Surviving Corporation are as follows:
 
     2.1  Acquisition Sub Common Stock.
 
     Each share of the 1,000 shares of Acquisition Sub Common Stock issued and
outstanding immediately prior to the Effective Time shall, by virtue of the
Merger and without any action by the holder thereof, be deemed cancelled and
converted into and shall represent the right to receive one share of the class A
common stock, $.01 par value, of the Surviving Corporation.
 
     2.2  IMA Common Stock.
 
        (a) Each share of IMA Class A Common Stock issued and outstanding
immediately prior to the Effective Time (including, without limitation, all
shares of IMA Class A Common Stock issued upon conversion of the IMA Class B
Common Stock as hereinafter provided, but other than Dissenting Shares [as
defined and to the extent provided in Section 3.1 hereof], if any), shall, by
virtue of the Merger and without any action by the holder thereof, be deemed
cancelled and converted into and shall represent the right to receive 1.15
shares of the class A common stock, $.01 par value (hereinafter referred to as
the "ITI Common Stock"), of ITI.
 
        (b) Solely to avoid the expense and inconvenience to ITI and Acquisition
Sub, and not as separately bargained for consideration, no fractional shares of
ITI Common Stock shall be issued in the Merger and no dividend, stock split or
interest shall relate to any such fractional shares, and such fractional shares
shall not entitle the owner thereof to any rights of a security holder. In lieu
of issuing certificates for fractional shares of ITI Common Stock, the Exchange
Agent (as hereinafter defined) shall, on behalf of all holders of such
fractional shares, on or before the tenth day following the Effective Time,
aggregate all such fractional shares and sell the resulting shares of ITI Common
Stock for the accounts of holders of such respective fractional shares, and such
holders shall thereafter be entitled to receive on a pro rata basis the net
proceeds of the sale thereof, without interest thereon, upon the surrender of
all of such holder's certificates for exchange pursuant to Section 3.2 hereof.
 
     2.3  Options to Purchase Shares of IMA Common Stock.
 
        (a) All options (hereinafter referred to as the "IMA Options") to
acquire IMA Class A Common Stock outstanding, whether or not exercisable at the
Effective Time, under the Insituform Mid-America, Inc. Stock Option Plan
(hereinafter referred to as the "IMA Option Plan"), shall remain outstanding
following the Effective Time. At the Effective Time, the IMA Options shall, by
virtue of the Merger and without any further action on the part of IMA or the
holder thereof, be assumed by ITI in such manner that ITI: (i) is a corporation
"assuming a stock option in a transaction to which Section 424(a) applies"
within the meaning of Section 424 of the United States Internal Revenue Code of
1986, as amended (hereinafter referred to as the "Code"); or (ii) to the extent
that Section 424 of the Code does not apply to any such IMA Options, would be
such a corporation were Section 424 of the Code applicable to such IMA Options.
From and after the Effective Time, all references to IMA in the IMA Stock Option
Plan and the applicable stock option agreements issued thereunder shall be
deemed to refer to ITI, except that each reference to the name of such plan
therein (or any predecessor thereof) shall be deemed a reference to the
"Insituform Mid-America, Inc. Stock Option Plan", and provided that each
reference to the "Stock Option Committee" or "Committee" therein shall be deemed
a reference to ITI's Compensation Committee. Each IMA Option assumed by ITI
shall be exercisable upon the same terms and conditions as under the IMA Stock
Option Plan and the applicable option agreement issued thereunder, except that:
 
               (A) each such IMA Option shall be exercisable for that whole
     number of shares of ITI Common Stock (rounded to the nearest whole share)
     into which the number of shares of IMA Class A Common Stock subject to such
     IMA Option immediately prior to the Effective Time would be convertible
     under Section 2.2 hereof if such shares were outstanding at the Effective
     Time; and
 
                                        3

 
<PAGE>   11
 
               (B) the option price per share of ITI Class A Common Stock shall
     be an amount equal to the quotient obtained by dividing (x) the product
     obtained by multiplying the exercise price per share of IMA Class A Common
     Stock subject to such IMA Option in effect immediately prior to the
     Effective Time by the number of shares of IMA Class A Common Stock subject
     to such option immediately prior to the Effective Time, by (y) the number
     of shares of ITI Common Stock covered by the option as so assumed (the
     option price as so determined being rounded upward to the nearest full
     cent).
 
No payment or adjustment shall be made for fractional shares which otherwise
would be issuable upon exercise of any IMA Option assumed as aforesaid.
 
        (b) The assumption of IMA Options pursuant hereto shall not confer on
any holder thereof any additional benefits which such holder did not have
immediately prior to the Effective Time, result in any acceleration of any
vesting or exercise schedule for any IMA Option, or release any holder of any
IMA Option of any obligations or restrictions applicable to his option or the
shares obtainable upon exercise of such option. At the Effective Time, the IMA
Option Plan shall, by virtue of the Merger and without any further action on the
part of IMA, be deemed terminated, except for the rights of the holders of
outstanding IMA Options subject to the terms and provisions hereinbefore set
forth, and no further options shall be granted thereunder.
 
        (c) As soon as practicable following the Effective Time, ITI shall
prepare and file with the Securities and Exchange Commission (hereinafter
referred to as the "SEC"), a registration statement on Form S-8 under the
Securities Act of 1933, as amended (hereinafter referred to as the "Securities
Act"), with respect to the shares of ITI Common Stock deliverable by ITI upon
exercise of the IMA Options, as so assumed.
 
     2.4  ITI Common Stock.
 
     The Merger shall effect no change in any shares of ITI Common Stock issued
by ITI prior to the Effective Time.
 
                                  ARTICLE III
 
                               DISSENTING SHARES;
                            EXCHANGE OF CERTIFICATES
 
     3.1  Dissenting Shares.
 
     Notwithstanding anything in this Agreement to the contrary, shares of IMA
Common Stock which are issued and outstanding immediately prior to the Effective
Time and which are held by stockholders who have not voted such shares in favor
of the Merger and, if entitled to elect to demand the appraisal of such shares
pursuant to Section 262 of the GCL, shall have delivered a written demand for
payment of the fair value of such shares within the time and in the manner
provided in said Section 262 (herein referred to as "Dissenting Shares") shall
not be converted into or be exchangeable for the right to receive the
consideration provided in Article II of this Agreement,unless and until such
holder shall have failed to perfect or shall have effectively withdrawn or lost
his right to appraisal and payment under the GCL. If any such holder shall have
so failed to perfect or shall have effectively withdrawn or lost such right,
such holder's shares of IMA Common Stock shall thereupon be deemed to have been
converted into and to have become exchangeable for, at the Effective Time, the
right to receive the consideration therefor specified under Article II hereof,
without any interest thereon.
 
     3.2  Exchange of Shares.
 
        (a) Prior to the Effective Time, Acquisition Sub shall designate
American Stock Transfer & Trust Company, or, at its election, a bank or trust
company or similar entity, reasonably satisfactory to IMA, which is authorized
to exercise corporate trust or stock powers, to act as the exchange agent
(hereinafter referred to as the "Exchange Agent") in the Merger. Promptly after
the Effective Time, ITI shall cause the delivery to the Exchange Agent of
certificates evidencing the shares of ITI Common Stock contemplated to be issued
by Section 2.2 hereof.
 
                                        4

 
<PAGE>   12
 
        (b) As soon as practicable after the Effective Time, but in no event
later than 15 business days after the Effective Time, the Exchange Agent shall
send a notice and transmittal form to each holder of a certificate theretofore
evidencing shares of IMA Common Stock, advising such holders of the terms of the
exchange effected by the Merger and the procedure for surrendering to the
Exchange Agent (who may appoint forwarding agents with the approval of ITI) such
record holder's certificate(s) evidencing IMA Common Stock for exchange for
certificates evidencing shares of ITI Common Stock. Each holder of a certificate
theretofore evidencing shares of IMA Common Stock, upon surrender of the same to
the Exchange Agent in accordance with such transmittal form, shall be entitled
to receive, in exchange for such certificate, a certificate evidencing the
number of full shares of ITI Common Stock for which the shares of IMA Common
Stock theretofore represented by the certificate so surrendered shall have been
exchanged pursuant to Section 2.2 hereof and the cash in lieu of fractional
shares hereinabove contemplated, and the certificate so surrendered shall
forthwith be cancelled.
 
        (c) If any certificate evidencing shares of ITI Common Stock is to be
issued in a name other than that in which the certificate surrendered in
exchange therefor is registered, or if any payment of cash is to be made to a
person other than the person in whose name such certificate is registered, it
shall be a condition of the issuance thereof or such payment, as the case may
be, that the certificate so surrendered shall be properly endorsed and otherwise
in proper form for transfer and that the person requesting such exchange (i) pay
to the Exchange Agent any transfer or other taxes required by reason of the
issuance of a certificate for shares of ITI Common Stock in any name other than
that of, and payment of cash to a person other than, the registered holder of
the certificate surrendered or (ii) establish to the satisfaction of the
Exchange Agent that such transfer or other taxes have been paid or are not
applicable. Certificates representing shares of ITI Common Stock issued to IMA
"affiliates", within the meaning of Rule 145 under the Securities Act, shall
bear the legend referred to in Paragraph (a)(ii) of Section 11.4 hereof.
 
        (d) In the event any certificate representing any shares of IMA Common
Stock shall have been lost, stolen or destroyed, upon the making of an affidavit
of that fact by the person claiming such certificate to be lost, stolen or
destroyed, the Exchange Agent shall issue in exchange for such lost, stolen or
destroyed certificate the consideration payable in exchange therefor pursuant to
Article II. The Exchange Agent or the Surviving Corporation may, in its
discretion and as a condition precedent to the issuance thereof, require the
owner of such lost, stolen or destroyed certificate to give the Exchange Agent a
bond in such reasonable sum as it may direct as indemnity against any claim that
may be made against the Surviving Corporation with respect to the certificate
alleged to have been lost, stolen or destroyed.
 
     3.3  Dividends and Other Distributions.
 
     No dividends or other distributions to holders of ITI Common Stock as of
any date subsequent to the Effective Time shall be paid to the holders of
outstanding certificates formerly representing shares of IMA Common Stock until
such certificates are so surrendered. Subject to the effect, if any, of
applicable law upon surrender of certificates evidencing shares of IMA Common
Stock, there shall be paid to the record holders of ITI Common Stock issued in
exchange therefor (i) the amount of dividends or other distributions with a
record date for payment after the Effective Time that have theretofore been paid
with respect to full shares of ITI Common Stock as of any date subsequent to the
Effective Time which have not yet been paid to a public official pursuant to
abandoned property laws and (ii) at the appropriate payment date, the amount of
dividends or other distributions with a record date after the Effective Time but
prior to surrender and a payment date subsequent to surrender. No interest shall
be payable with respect to the payment of such dividends or other distributions
on surrender of outstanding certificates. Notwithstanding the foregoing, neither
ITI, Acquisition Sub, the Exchange Agent nor any other party hereto shall be
responsible or liable to any holder of shares of IMA Common Stock for any ITI
Common Stock, or dividends or distributions thereon or cash, including cash in
lieu of fractional share interests, delivered to any public official pursuant to
applicable escheat laws.
 
     3.4  IMA Stock Transfer Ledger.
 
     At the Effective Time, it shall be deemed that the stock transfer books of
IMA are closed, and no transfer of IMA Common Stock on the books of IMA shall
thereafter be made or consummated. Until surrendered
 
                                        5

 
<PAGE>   13
 
and exchanged in accordance with the provisions of Section 3.2 hereof, the
outstanding certificates evidencing shares of IMA Common Stock immediately prior
to the Effective Time shall, from and after the Effective Time, be deemed for
all corporate purposes to evidence the right to receive the number of shares of
ITI Common Stock, together with cash in lieu of fractional shares, into which
the shares of IMA Common Stock theretofore evidenced by such certificate or
certificates shall have been so converted, together with any dividends or other
distributions thereon pursuant to Section 3.3 hereof, as though such surrender
and exchange had taken place.
 
     3.5  Termination of Exchange Agency.
 
     Any portion of the shares of ITI Common Stock or cash in lieu of fractional
shares, which remains undistributed to the holders of IMA Common Stock for one
year after the Effective Time shall be delivered to ITI, upon demand, and any
holders of IMA Common Stock who have not theretofore complied with this Article
III shall thereafter look only to ITI for the shares of ITI Common Stock, any
cash in lieu of fractional shares of ITI Common Stock to which they are entitled
pursuant to Paragraph (b) of Section 2.2 hereof and any dividends or other
distributions with respect to ITI Common Stock to which they are entitled
pursuant to Section 3.3. Any portion of such remaining shares or cash unclaimed
by holders of IMA Common Stock as of a date which is immediately prior to such
time as such shares or amounts would otherwise escheat to or become property of
any governmental entity shall, to the extent permitted by applicable law, become
the property of ITI free and clear of any claims or interest of any person
previously entitled thereto.
 
                                   ARTICLE IV
 
                                    CLOSING
 
     4.1  Time and Place of Closing.
 
     IMA, ITI and Acquisition Sub shall regularly communicate and consult with
each other with respect to the fulfillment of the various conditions to the
obligations under this Agreement of the parties hereto. The exchange of
certificates, opinions and other documents contemplated by this Agreement
(hereinafter referred to as the "Closing") shall be held at the offices of
Messrs. Krugman, Chapnick & Grimshaw, Park 80 West-Plaza Two, Saddle Brook, New
Jersey 07663, at 10:00 A.M., local time, at such time and date (hereinafter
referred to as the "Closing Date") as the parties may determine, such date to
fall within ten business days after the satisfaction or waiver of the last of
the conditions set forth in Articles IX, X and XI hereof to be satisfied or
waived (other than conditions with respect to actions the parties shall take at
the Closing), and provided that ITI may delay the Closing for up to 15 business
days after the date on which the Closing would otherwise occur as aforesaid in
order to effectuate the restructurings contemplated by Section 7.15 hereof, or
such other time and date as may be agreed upon by the parties hereto. For
purposes of this Agreement, "business day" shall mean any day on which the
principal offices of the SEC in Washington, D.C. are open to accept filings, or,
in the case of determining a date when any payment is due, any day on which
banks are not required or authorized to close in the City of New York.
 
     4.2  Certificate of Merger.
 
     In the event that, at or prior to the Closing, none of the parties has
exercised any right it may have to terminate this Agreement, and no condition to
the obligations of the parties exists that is not waived, the parties shall, on
the Closing Date, execute the agreement of merger, in the form attached hereto
as Exhibit A (hereinafter referred to as the "Plan of Merger"), appropriately
completed, and, as soon thereafter as is practicable cause an appropriate
Certificate of Merger to be executed by the Constituent Corporations and filed
with the Secretary of State of the State of Delaware in accordance with the GCL.
 
                                        6

 
<PAGE>   14
 
                                   ARTICLE V
 
                     REPRESENTATIONS AND WARRANTIES OF IMA
 
     IMA represents, warrants and covenants that:
 
     5.1  Incorporation.
 
        (a) IMA is duly organized, validly existing and in good standing under
the laws of the State of Delaware and has full corporate power and authority to
own or hold under lease the assets and properties which it owns or holds under
lease, to conduct its business as currently conducted, to perform all its
obligations under the agreements to which it is a party, including, without
limitation, this Agreement, and to consummate the Merger. IMA is in good
standing in each other jurisdiction wherein the failure so to qualify,
individually or in the aggregate, would have a Material Adverse Effect (as
hereinafter defined). The copies of IMA's certificate of incorporation and
by-laws, each as currently in effect, which have been delivered to ITI and
Acquisition Sub by IMA are complete and correct.
 
        (b) For purposes of this Agreement:
 
               (i) "Material Adverse Effect" with respect to a party shall mean
     any change in, or effect on such party or any subsidiary thereof (as
     hereinafter defined) which is, or with reasonable probability might be,
     materially adverse to the business, properties, operations, income, assets,
     prospects or condition, financial or otherwise of such party and its
     subsidiaries, taken as a whole; and the term "Material Adverse Effect" used
     without a specific reference to a party shall mean a Material Adverse
     Effect with respect to IMA and its Subsidiaries, taken as a whole; and
 
               (ii) each reference to a "subsidiary" or "subsidiaries" of any
     person means any corporation, partnership, joint venture or other legal
     entity of which such person (either alone or through or together with any
     other subsidiary), owns, directly or indirectly, more than 50% of the stock
     or other equity interests the holder of which are generally entitled to
     vote for the election of the board of directors or other governing body of
     such corporation or other legal entity.
 
     5.2  Authorization.
 
     The execution and delivery of this Agreement, the performance by IMA of its
covenants and agreements hereunder and the consummation by IMA of the
transactions contemplated hereby have been duly authorized by all necessary
corporate action of IMA, other than the approval of the holders of IMA Common
Stock contemplated under Section 7.1 hereof. When executed and delivered by IMA,
this Agreement shall constitute the valid and legally binding obligation of IMA,
enforceable against IMA in accordance with its terms, except as may be limited
by bankruptcy, insolvency or other laws affecting generally the enforceability
of creditors' rights and by limitations on the availability of equitable
remedies.
 
     5.3  Conflicts.
 
     Neither the execution and delivery of this Agreement, nor the consummation
of the transactions contemplated herein, will violate any provision of IMA's
certificate of incorporation or by-laws, as currently in effect, or, subject to
approval of this Agreement by the holders of IMA Common Stock as contemplated
under Section 7.1 hereof and compliance with the regulatory requirements
hereinafter specified in this Section 5.3, any law, rule, regulation, writ,
judgment, injunction, decree, determination, award or other order of any court,
government or governmental agency or instrumentality, domestic or foreign,
binding upon IMA or any of its Subsidiaries or, except as set forth on Schedule
5.3(A) attached hereto and other than any such conflicts, breaches, creation,
imposition or termination which would not have a Material Adverse Effect,
conflict with or result in any breach of any of the terms of or the creation or
imposition of any mortgage, deed of trust, pledge, lien, security interest or
other charge or encumbrance of any nature pursuant to, or create any cause for
termination under, the terms of any contract or agreement to which IMA or any
Subsidiary is a party or by which IMA or any Subsidiary or any of their
respective properties or assets is bound. Other than the approval of this
Agreement by the holders of IMA Common Stock contemplated under Section 7.1
hereof and except for compliance with the requirements of the federal
Hart-Scott-Rodino Antitrust Improvements Act of 1976,
 
                                        7

 
<PAGE>   15

 
as amended (hereinafter referred to as the "HSR Act"), the Securities Act, with
respect to the Registration Statement (as hereinafter defined), the securities
or blue sky laws of the various states, the federal Securities Exchange Act of
1934, as amended (hereinafter referred to as the "Exchange Act"), with respect
to the Joint Proxy Statement (as hereinafter defined), and except as set forth
on Schedule 5.3(A) and (C) and any such consents, approvals, authorizations,
filings or registrations with or notices to any such person or entity other than
any governmental agency or instrumentality the failure to effectuate which would
not have a Material Adverse Effect, no consents, approvals or authorizations, or
registrations with any governmental agency or authority or any other person or
entity and, except as set forth on Schedule 5.3(B), filings with or notices to
any such person or entity, are required in connection with the execution and
delivery of this Agreement by IMA or the consummation by IMA of the transactions
contemplated hereby.
 
     5.4  Capitalization.
 
     The authorized capital stock of IMA consists of 500,000 shares of IMA
Preferred Stock, none of which are issued and outstanding, 10,000 shares of IMA
Convertible Preferred Stock, none of which are issued and outstanding, 500
shares of IMA Class A Convertible Preferred Stock, none of which are issued and
outstanding on the date hereof, 13,000,000 shares of IMA Class A Common Stock,
of which 8,282,676 shares are issued and outstanding, and 6,000,000 shares of
IMA Class B Common Stock, of which 2,472,985 shares are issued and outstanding
on the date hereof. No shares of any class or series of the capital stock of IMA
are held as treasury stock. All of the outstanding shares of IMA Common Stock
are, and all outstanding shares of IMA Class A Common Stock issuable upon
exercise of IMA Options will be, duly authorized, validly issued and fully paid
and non-assessable, issued without violation of the preemptive rights of any
person. There are no subscriptions, warrants, options, calls, commitments by or
agreements to which IMA is bound relating to the issuance, conversion, or
purchase of any shares of IMA Common Stock, or any other capital stock of IMA,
except for the IMA Options granted by IMA pursuant to the IMA Option Plan,
covering an aggregate of 365,040 shares of IMA Class A Common Stock on the date
hereof, and except for this Agreement. IMA has delivered to ITI and Acquisition
Sub true and complete copies of each form of certificate or agreement evidencing
options granted and outstanding under the IMA Option Plan. IMA is not a party to
any agreement or arrangement relating to the voting or control of any of its
capital stock, or obligating IMA, directly or indirectly, to sell any assets in
a transaction which is not in the ordinary course or which is otherwise material
to the businesses, financial condition, results of operations or prospects of
IMA and its Subsidiaries, taken as a whole (hereinafter referred to as "IMA's
business or condition"), except for this Agreement. IMA has no currently
outstanding obligations to register any securities under the Securities Act,
under any arrangements that would require any such registration as a result of
this agreement or the transactions contemplated hereby or under any arrangements
that would permit any party to such arrangements other than IMA to require IMA
to file a registration statement under the Securities Act.
 
     5.5  Subsidiaries.
 
     Schedule 5.5(1), (2) and (3) annexed hereto sets forth the name of each
corporation, partnership, joint venture, business trust or other legal entity in
which IMA, directly or indirectly, beneficially or legally owns or holds any
capital stock or other proprietary interest (herein referred to, individually,
as a "Subsidiary" and, collectively, as the "Subsidiaries"), the jurisdiction of
its incorporation or formation, and IMA's direct or indirect ownership thereof.
Neither IMA nor any Subsidiary, directly or indirectly, beneficially or legally
owns or holds any capital stock of ITI. Each corporate Subsidiary is a
corporation duly organized and in good standing under the laws of the
jurisdiction of its incorporation, and has full corporate power and authority to
own or hold under lease the assets and properties which it owns or holds under
lease and to perform all its obligations under the agreements to which it is a
party and to conduct such Subsidiary's business. Each Subsidiary consisting of a
joint venture, partnership, or limited liability partnership is duly organized,
validly existing and, in the case of any limited liability partnership, in good
standing as such entity under the laws of the jurisdiction of its formation, and
has full partnership authority to own or hold under lease the assets or
properties which it owns or holds under lease and to perform all of its
obligations under the agreements to which it is a party and to conduct such
Subsidiary's business. Each Subsidiary is in good standing in each other
jurisdiction wherein the failure so to qualify would, individually or in the
aggregate, have a Material Adverse Effect. All of the outstanding shares of the
capital stock of each Subsidiary are so owned and are duly
 
                                        8

 
<PAGE>   16
 
authorized and validly issued, fully paid and non-assessable, issued without
violation of the preemptive rights of any person, and, except as identified on
Schedule 5.5(4), are owned free and clear of any mortgages, deeds of trust,
pledges, liens, security interests or any charges or encumbrances of any nature.
Except as set forth in Schedule 5.5(5), no shares of capital stock or other
proprietary interest of any Subsidiary is subject to any option, call,
commitment or other agreement of any nature, and there are no subscriptions,
warrants, options, calls, commitments by or agreements to which IMA or any
Subsidiary is bound relating to the issuance or purchase of any shares of
capital stock of any Subsidiary. Except for partnership and joint venture
arrangements as set forth on Schedule 5.5(2) and (3), neither IMA nor any
Subsidiary is party to any agreement or arrangement relating to the voting or
control of any capital stock of any Subsidiary, or obligating IMA or any
Subsidiary to sell any assets of any Subsidiary in a transaction which is not in
the ordinary course or which is otherwise material to IMA's business or
condition. The copies of the certificates of incorporation and by-laws, or other
instruments of formation, as currently in effect, of each such Subsidiary, which
have been delivered or made available to ITI by IMA are complete and correct.
 
     5.6  Securities Filings.
 
     IMA and each Subsidiary have made all filings with the SEC that it has been
required to make under the Securities Act, and the rules and regulations
promulgated thereunder, and the Exchange Act, and the rules and regulations
promulgated thereunder. IMA has provided to ITI and Acquisition Sub complete and
correct copies of all reports, registration statements, final prospectuses,
definitive proxy statements and other filings made by IMA or any Subsidiary with
the SEC, including all exhibits to such filings, since October 1, 1989 (all such
documents that have been filed with the SEC, as amended, hereinafter referred to
as the "IMA SEC Documents"), including, without limitation, IMA's Annual Report
on Form 10-K for the fiscal year ended September 30, 1994, as filed with the SEC
on January 3, 1995 (together with all documents incorporated therein by
reference, hereinafter referred to as the "IMA Form 10-K"), and its Quarterly
Report on Form 10-Q for the quarter ended March 31, 1995, as filed with the SEC
on May 15, 1995 (hereinafter referred to as the "IMA Form 10-Q"), the Annual
Report on Form 10-K for the fiscal year ended March 26, 1994 of IMA Merger Sub,
Inc. (formerly, Enviroq Corporation; hereinafter referred to as "Enviroq"), as
filed with the SEC on June 24, 1994 (together with all documents incorporated
therein by reference, hereinafter referred to as the "Enviroq Form 10-K"),
Enviroq's Quarterly Report on Form 10-Q for the quarter ended December 24, 1994,
as filed with the SEC on February 7, 1995 (hereinafter referred to as the
"Enviroq Form 10-Q"), and Enviroq's Proxy Statement dated March 14, 1995
(hereinafter referred to as the "Enviroq Proxy Statement"). The IMA SEC
Documents comply in all material respects with the requirements of the
Securities Act or the Exchange Act, as the case may be, and neither any of the
IMA SEC Documents (as of the date of their respective filing with the SEC), or
any information relating to IMA or any of its Subsidiaries contained in this
Agreement or any schedule hereto, contains any untrue statement of a material
fact or omits to state a material fact required to be stated therein or
necessary to make the statements therein, in light of the circumstances under
which they were made, not misleading.
 
     5.7  Financial Statements.
 
        (a) The consolidated financial statements (hereinafter referred to,
collectively, as the "IMA Audited Financial Statements") of IMA and its
consolidated subsidiaries contained or incorporated by reference in the IMA Form
10-K in response to "Item 8. Consolidated Financial Statements and Supplementary
Data", are true and correct and have been prepared in conformity with generally
accepted accounting principles consistently applied throughout the periods to
which such financial statements relate. The IMA Audited Financial Statements
fully and fairly present, in conformity with such principles as so utilized, the
consolidated financial position and results of operations and cash flows of IMA
and its consolidated subsidiaries, at the dates shown and for the periods
therein specified, except as described therein.
 
        (b) The consolidated financial statements (hereinafter referred to,
collectively, as the "Enviroq Audited Financial Statements") of Enviroq and its
consolidated subsidiaries contained or incorporated by reference in the Enviroq
Form 10-K in response to "Item 8. Consolidated Financial Statements and
Supplementary Data", are true and correct and have been prepared in conformity
with generally accepted accounting principles consistently applied throughout
the periods to which such financial statements relate.
 
                                        9

 
<PAGE>   17
 
        The Enviroq Audited Financial Statements fully and fairly present, in
conformity with such principles as so utilized, the consolidated financial
position and results of operations and cash flows of Enviroq and its
consolidated subsidiaries, at the dates shown and for the periods therein
specified, except as described therein.
 
        (c) The consolidated financial statements (hereinafter referred to as
the "IMA Interim Financial Statements", and, together with the IMA Audited
Financial Statements, herein referred to as the "IMA Financial Statements") of
IMA and its consolidated subsidiaries contained in the IMA Form 10-Q in response
to "Item 1. Financial Statements" are true and correct and have been prepared in
conformity with generally accepted accounting principles consistently applied
throughout the periods to which such financial statements relate, except as
permitted by Form 10-Q. The IMA Interim Financial Statements fully and fairly
present the consolidated financial position and results of operations and cash
flows of IMA and its consolidated subsidiaries, at the dates shown and for the
periods therein specified, subject to normal year-end adjustments in accordance
with generally accepted accounting principles and except as described therein.
 
        (d) The consolidated financial statements (hereinafter referred to as
the "Enviroq Interim Financial Statements") of Enviroq and its consolidated
subsidiaries contained in the Enviroq Form 10-Q in response to "Item 1.
Financial Statements" are true and correct and have been prepared in conformity
with generally accepted accounting principles consistently applied throughout
the periods to which such financial statements relate, except as permitted by
Form 10-Q. The Enviroq Interim Financial Statements fully and fairly present the
consolidated financial position and results of operations and cash flows of
Enviroq and its consolidated subsidiaries, at the dates shown and for the
periods therein specified, subject to normal year-end adjustments in accordance
with generally accepted accounting principles and except as described therein.
 
        (e) The consolidated pro forma financial statements (hereinafter
referred to as the "Enviroq Pro Forma Financial Statements") of Enviroq and its
consolidated subsidiaries contained in the Enviroq Proxy Statement are true and
correct and have been prepared in all material respects in conformity with
Article 11 of Regulation S-X promulgated by the SEC. The Enviroq Pro Forma
Financial Statements fully and fairly present the consolidated financial
position and results of operations of Enviroq and its consolidated subsidiaries,
at the dates shown and for the periods therein specified, after giving pro forma
effect to the transactions described therein.
 
        (f) Each of IMA and each Subsidiary: (i) make and keep books, records,
and accounts, which, in reasonable detail, accurately and fairly reflect the
transactions and dispositions of their respective assets; and (ii) maintain a
system of internal accounting controls sufficient to provide reasonable
assurances that (A) transactions are executed in accordance with management's
general or specific authorization; (B) transactions are recorded as necessary
(I) to permit preparation of financial statements in conformity with generally
accepted accounting principles or any other criteria applicable to such
statements, and (II) to maintain accountability for assets; (C) access to assets
is permitted only in accordance with management's general or specific
authorization; and (D) the recorded accountability for assets is compared with
the existing assets at reasonable intervals and appropriate action is taken with
respect to any differences.
 
     5.8  Absence of Undisclosed Liabilities.
 
     Except to the extent disclosed in the IMA Form 10-K or the IMA Form 10-Q
(in each case without reference to the exhibits thereto), or the Enviroq Pro
Forma Financial Statements (after giving effect to the transactions described
therein), or incurred after December 31, 1994 (or, in the case of Enviroq or its
subsidiaries, December 24, 1994) in the ordinary course of business and
consistent with past practice, neither IMA, nor any of the Subsidiaries has any
liabilities, whether accrued, absolute, contingent, or otherwise, whether due or
to become due and whether the amount thereof is readily ascertainable or not,
other than liabilities which, individually or in the aggregate, would not have a
Material Adverse Effect, or any unrealized or anticipated losses from any
unfavorable commitments or sales of products, other than those which,
individually or in the aggregate, would not have a Material Adverse Effect, in
each case under this Section 5.8 except as set forth in Schedule 5.8.
 
                                       10

 
<PAGE>   18
 
     5.9  Absence of Certain Changes.
 
     Subsequent to December 31, 1994 (or, in the case of Enviroq or its
subsidiaries, December 24, 1994), neither IMA nor any Subsidiary has:
 
        (a) except as disclosed in Schedule 5.9 attached hereto, declared, set
aside or made any payment or distribution upon any capital stock or, directly or
indirectly, purchased, redeemed or otherwise acquired or disposed of any shares
of capital stock;
 
        (b) except as disclosed in Schedule 5.9 attached hereto, incurred any
liability or obligation under agreements or otherwise, except current
liabilities entered into or incurred in the ordinary course of business
consistent with past practice; issued any notes or other corporate debt
securities or paid or discharged any outstanding indebtedness, except in the
ordinary course of business consistent with past practice; or, in a manner that
would, individually or in the aggregate, have a Material Adverse Effect, waived
any of its respective rights;
 
        (c) mortgaged, pledged or subjected to any Lien (as hereinafter defined)
any of its assets or properties; entered into any lease of real property or
buildings; or, except in the ordinary course of business consistent with past
practice, entered into any lease of machinery or equipment, or sold or
transferred any tangible or intangible asset or property;
 
        (d) effected any increase in salary, wages or other compensation of any
kind, whether current or deferred, to any employee or agent, other than routine
increases in the ordinary course of business consistent with past practice or as
was required from time to time by governmental legislation affecting wages
(provided, however, that in no event was any such increase in compensation made
with respect to any employee or agent earning in excess of $50,000 per annum,
except as identified in Schedule 5.9); except as set forth in Schedule 5.9, made
any bonus, pension, option, deferred compensation, or retirement payment,
severance, profit sharing, or like payment to any employee or agent, except as
required by the terms of plans or arrangements existing prior to such date
(provided, however, that in no event was any such payment made with respect to
any employee or agent earning in excess of $50,000 per annum, except as
identified in Schedule 5.9); or entered into any salary, wage, severance, or
other compensation agreement with a term of one year or longer with any employee
or agent or made any contribution to any trust or plan for the benefit of any
employee or agent, except as required by the terms of plans or arrangements
existing prior to such date;
 
        (e) except as set forth in Schedule 5.9, entered into any transaction
other than in the ordinary course of business consistent with past practice,
except in connection with the execution and performance of this Agreement and
the transactions contemplated hereby;
 
        (f) suffered any damage, destruction, or loss to any of its assets or
properties (whether or not covered by insurance) except for damage, destruction
or loss occurring in the ordinary course of business which, individually or in
the aggregate, would not have a Material Adverse Effect; or
 
        (g) suffered any Material Adverse Effect;
 
and, since December 31, 1994 (or, in the case of Enviroq and its subsidiaries,
December 24, 1994), there has been no condition, development or contingency
which, so far as reasonably may be foreseen, may, individually or in the
aggregate, have a Material Adverse Effect. For purposes of this Agreement, the
term "Lien" shall be defined to mean any mortgage, deed of trust, security
interest, pledge, lien, or other charge or encumbrance of any nature whatsoever
except: (a) liens disclosed in the IMA Financial Statements; (b) liens for
taxes, assessments, or governmental charges or levies not yet due and
delinquent; and (c) liens consisting of zoning or planning restrictions,
easements, permits, any other restrictions or limitations on the use of real
property or irregularities in title thereto which do not materially detract from
the value of, or impair the use of, such property by IMA or any of its
Subsidiaries.
 
     5.10  Pooling.
 
     As of the date hereof, there has not been any action taken by IMA or any
Subsidiary or affiliate under Rule 1-02 of Regulation S-X of the SEC that would
prevent the Merger from being accounted for as a
 
                                       11

 
<PAGE>   19
 
pooling-of-interests. Contemporaneously with the execution and delivery of this
Agreement, IMA has delivered to ITI an executed letter agreement, substantially
in the form of Exhibit B attached hereto (together with such changes therein as
may reasonably have been requested by ITI or IMA, such reasonableness to be
determined in good faith by BDO Seidman), from each such affiliate.
 
     5.11  Taxes.
 
     IMA and each Subsidiary have filed or caused to be filed all foreign,
federal, state, provincial, municipal and other tax returns, reports and
declarations required to be filed by it so as to prevent any Lien of any nature
on the assets or properties of IMA or any of the Subsidiaries, and have paid or
shall pay all taxes which have been or shall become due with respect to the
periods covered by said returns or pursuant to any assessment received by it in
connection therewith. Except as set forth in Schedule 5.11, the Internal Revenue
Service has not examined the federal tax returns of IMA or any of the
Subsidiaries for any period subsequent to September 30, 1993; and only periods
subsequent to September 30, 1993 remain open for examination and assessment of
additional federal income taxes. All assessments and charges (including
penalties and interest, if any) related to periods ended on or before September
30, 1994 have been paid by IMA and each Subsidiary, including any necessary
adjustments with state and local tax authorities, and, except as set forth in
Schedule 5.11, no deficiency in payment of any taxes for any period has been
asserted by any taxing authority which remains unsettled at the date hereof.
Adequate provision has been made in the IMA Financial Statements for the payment
of all then accrued and unpaid federal and other taxes of IMA and its
Subsidiaries, whether or not yet due and payable and whether or not disputed by
IMA. Neither IMA nor any Subsidiary has agreed to the extension of the statute
of limitations with respect to any tax return for any open year.
 
     5.12  Title.
 
     IMA and its Subsidiaries have good and marketable title to all of their
respective assets and properties, in each case, except as set forth on Schedule
5.12(1), (2), (3), (4) and (5), free and clear of all Liens. IMA and the
Subsidiaries lease or own all properties and assets necessary for the operation
of their respective businesses as presently conducted, and the assets and
properties of IMA and its Subsidiaries include all of the assets, of every kind
and nature, whether tangible or intangible, and wherever located, which are
utilized by IMA or its Subsidiaries in the conduct of their respective
businesses. Neither IMA nor its Subsidiaries have received notice of any
violation of, or default under, any law, ordinance, order, regulation, or
governmental or contractual requirement relating to the assets and properties of
IMA or its Subsidiaries which remains uncured or has not been dismissed, other
than with respect to any violation which, individually or in the aggregate,
would not have a Material Adverse Effect and other than as identified on
Schedule 5.12(7). All leases and licenses pursuant to which IMA or the
Subsidiaries lease or license personal and intangible property from others, are
in good standing, valid and effective in accordance with their respective terms,
and there is not, under any of such leases or licenses, any existing default, or
event of default (or event which with notice or lapse of time, or both, would
constitute a default, or would constitute a basis for a claim of force majeure
or other claim of excusable delay or non-performance) caused, by IMA or any
Subsidiary or, to the best of IMA's knowledge, any other party. All the tangible
personal property owned or leased by IMA or its Subsidiaries is in good
operating condition and repair, subject only to ordinary wear and tear, and
conforms in all respects to all applicable laws, ordinances, orders, regulations
or governmental or contractual requirements relating to their operation, except
for any such non-conformity which, individually or in the aggregate, would not
have a Material Adverse Effect.
 
     5.13  Real Estate and Leases.
 
        (a) Set forth in Schedule 5.13 attached hereto is a brief description of
every parcel of real estate owned by IMA or any Subsidiary (including, in each
case, a description of the improvements and uses, the annual taxes payable and
depreciation reserve of any improvements), and lease agreements (including, in
each case, the annual rental payable and the expiration date, the cost and
depreciation reserve of any leasehold improvements and a brief description of
the property covered) under which IMA or any of its Subsidiaries is lessee of,
or holds or operates, any real estate owned by any third party. Each of such
leases and agreements is in full force and effect and constitutes a legal, valid
and binding obligation of the respective parties thereto.
 
                                       12

 
<PAGE>   20
 
        Neither IMA nor any Subsidiary is in default under any such lease or
agreement, nor, to the best of the knowledge of IMA, is any other party to any
such lease or agreement in default thereunder, and no event has occurred, or is
alleged to have occurred, which constitutes, or with lapse of time or giving of
notice or both would constitute, a default by IMA or any Subsidiary or, to the
best of the knowledge of IMA, any other party to any such lease or agreement, or
a basis for a claim of force majeure or other claim of excusable delay or
non-performance thereunder by IMA or any Subsidiary or, to the best of the
knowledge of IMA, any other party, other than with respect to any default, event
or claim which, individually or in the aggregate, would not have any Material
Adverse Effect.
 
        (b) IMA or a Subsidiary has good, clear and marketable title to the
properties set forth on Schedule 5.13 and all fixtures thereon in fee simple
absolute, subject to no Liens (other than covenants, easements and restrictions
of record which do not, individually or in the aggregate, materially impair the
value or the present use of such properties and other than as set forth in
Schedule 5.13). There is no option or right held by any third party to purchase
any such properties or any part thereof, or any of the fixtures and equipment
thereon. All buildings, driveways and other improvements on such properties,
respectively, are within its boundary lines, and no improvements on adjoining
properties extend across the boundary lines onto such properties.
 
        (c) The foundation, floor and roof of the buildings and all other
structural and mechanical components of the properties owned or leased by IMA or
its Subsidiaries are sound and free of any structural, mechanical or other
defect, and all heating, ventilating, air conditioning, electrical, plumbing and
other mechanical systems and equipment thereon are in good working order, in
each case except for construction-in-progress and except insofar as would not,
individually or in the aggregate, have a Material Adverse Effect. There are no
condemnation or eminent domain proceedings pending or threatened with respect to
the properties owned or leased by IMA or any Subsidiary, all required
certificates of occupancy and other government permits necessary to utilize such
properties as they are presently utilized have been obtained, and such
properties, and the operation thereof, conform to all existing building, zoning,
and other laws and ordinances relating to their use or occupancy, in each case
except insofar as would not, individually or in the aggregate, have a Material
Adverse Effect.
 
     5.14  Contractual and Other Obligations.
 
        (a) As used in this Agreement, the term the "IMA Agreements" shall mean
all mortgages, indentures, notes, agreements, contracts, leases, licenses,
franchises, obligations, instruments or other commitments, arrangements or
understandings of any kind, whether written or oral, binding or non-binding, to
which IMA or any of the Subsidiaries is a party or by which IMA or any of the
Subsidiaries or any of their respective properties may be bound or affected,
other than those which by their terms have expired prior to the date hereof.
There is no IMA Agreement which is material to IMA's business or condition and
which is not otherwise listed in the IMA Form 10-K or otherwise identified
pursuant to the immediately succeeding sentence. Set forth or provided for on
Schedule 5.14 attached hereto is a list, without regard to materiality, of each
of the following IMA Agreements which is not otherwise listed in the IMA Form
10-K: (i) any mortgage, indenture, note, or other instrument, agreement or
arrangement for or relating to any borrowing of money by IMA or any Subsidiary,
or any other installment obligation in excess, individually, of $100,000 per
year; (ii) any guaranty, direct or indirect, by IMA or any Subsidiary of any
obligation for borrowings or otherwise, excluding endorsements made for
collection in the ordinary course of business and guaranties of construction
performance bonds in the ordinary course of business disclosed on Schedule 5.19;
(iii) any IMA Agreement made other than in the ordinary course of its business
or providing for the grant of any preferential rights to purchase or lease any
assets of IMA or any Subsidiary, except for such agreements which, individually
and in the aggregate, are not material to IMA's business or condition; (iv) any
obligation to make payments, contingent or otherwise, arising out of the prior
acquisition of the business, assets or stock of other companies; (v) any
collective bargaining agreement with any trade or labor union; (vi) any IMA
Agreement to which any officer or director of IMA or any stockholder (herein
referred to collectively, as the "Insiders") of IMA beneficially owning (within
the meaning of Section 13(d) of the Exchange Act) more than 5% of the
outstanding shares of IMA Class A Common Stock, or any shares of IMA Class B
Common Stock, is a party; (vii) any IMA Agreement containing noncompetition or
other limitations restricting the conduct of the
 
                                       13

 
<PAGE>   21
 
        business of IMA or any Subsidiary; (viii) any license agreements to
which IMA or any Subsidiary is a party relating to any Intellectual Property (as
hereinafter defined), other than the Insituform Process or the NuPipe Process;
and (ix) any partnership, shareholder agreement, joint venture or similar
agreement.
 
        (b) No event has occurred, or, is alleged to have occurred, which
constitutes or with lapse of time or giving of notice or both, would constitute
a default or a basis for a claim of force majeure or other claim of excusable
delay or non-performance by IMA or any Subsidiary under any IMA Agreements,
except for any such default or claim which, individually or in the aggregate,
would not have a Material Adverse Effect. To the best of the knowledge of IMA,
no party with whom IMA or any Subsidiary has any IMA Agreement is in default in
the performance of any covenant or condition thereunder or has failed in
performance thereunder by reason of a claim of force majeure or other claim of
excusable delay or non-performance thereunder, except for any such default or
claim which, individually or in the aggregate, would not have a Material Adverse
Effect.
 
     5.15  Compensation.
 
     Except as disclosed in the IMA Form 10-K (including, without limitation,
the proxy statement incorporated therein) or in Schedule 5.14 or Schedule
5.15(2) attached hereto, neither IMA nor any Subsidiary has any agreement with
any employee with regard to compensation, whether individually or collectively,
except agreements terminable by IMA or any Subsidiary at will without penalty,
or oral agreements terminable by IMA or a Subsidiary on not more than 30 days'
notice without penalty, and set forth in Schedule 5.15 is a list of all
employees of IMA and each Subsidiary other than hourly employees subject to
collective bargaining agreements, entitled to receive annual compensation in
excess of $50,000 and their respective positions and salaries. Except for those
unions identified on Schedule 5.14 as parties to IMA Agreements, no union or
other collective bargaining unit has been certified or recognized by IMA or any
Subsidiary as representing any of their respective employees. Without reference
to any plans or proposals of ITI (other than the execution, delivery and
performance of this Agreement), neither IMA nor ITI will incur any liability
with respect to any payment due or damage suffered by any employee of IMA or any
Subsidiary, including, but not limited to, any claims for severance, termination
benefits or similar claims, by virtue of the operation of the Merger and the
transactions contemplated hereby.
 
     5.16  Employee Benefit Plans.
 
     Except as listed and accurately described in Schedule 5.16, IMA and the
Subsidiaries do not maintain or sponsor and are not required to make
contributions to any pension, profit-sharing, bonus, incentive, welfare, or
other employee benefit plan. All pension, profit-sharing, bonus, incentive,
welfare, or other employee benefit plans within the meaning of Section 3(3) of
the Employee Retirement Income Security Act of 1974, as amended (hereinafter
referred to as "ERISA"), in which the employees of IMA or its Subsidiaries
participate, or with respect to which IMA or the Subsidiaries have any liability
or obligation (such plans and related trusts, insurance, and annuity contracts,
funding media, and related agreements and arrangements, other than any
"multiemployer plan" (within the meaning of section 3(37) or ERISA) being
hereinafter referred to as the "Benefit Plans", and such multiemployer plans
being hereinafter referred to as the "Multiemployer Plans") comply in form and
as administered in all material respects with all requirements of the U.S.
Department of Labor, the Internal Revenue Service and the Pension Benefit
Guaranty Corp. (hereinafter referred to as "PBGC") promulgated under ERISA and
with all other applicable law (including, without limitation, the health care
continuation coverage requirements of Section 4980B of the Code). Neither IMA
nor any of its Subsidiaries has taken or failed to take any action with respect
to either the Benefit Plans or the Multiemployer Plans which might create any
material liability on the part of IMA, any Subsidiary or ITI. Each "fiduciary"
(within the meaning of section 3(21)(a) of ERISA) as to each Benefit Plan and,
to the best of the knowledge of IMA, as to each Multiemployer Plan has complied
in all material respects with the requirements of ERISA and all other applicable
law in respect of each such Plan. All required employer and employee
contribution and premiums under the Benefit Plans and the Multiemployer Plans to
the date hereof have been paid, the respective fund or funds established under
the Benefit Plans and the Multiemployer Plans are funded in accordance with all
applicable laws and such plans, and no material past service funding liabilities
exist thereunder. IMA has furnished to ITI and Acquisition Sub copies of all
 
                                       14

 
<PAGE>   22
 
Benefit Plans, and of all documents relating thereto required by ITI, including,
without limitation, annual reports and financial statements with respect to such
Benefit Plans for all periods ended on a date subsequent to September 30, 1991
during which IMA or any Subsidiary was a sponsor or participating employer in or
was required to make contributions to such Benefit Plans. Such financial
statements are true and correct in all material respects, and none of the
actuarial assumptions underlying such statements have changed since the
respective dates thereof. In addition, as of the date hereof:
 
        (i) No Benefit Plan which is a "defined benefit plan" (within the
meaning of Section 3(35) of ERISA) (hereinafter referred to as the "Defined
Benefit Plans") or, to the best of the knowledge of IMA, Multiemployer Plan has
incurred an "accumulated funding deficiency" (within the meaning of section
412(a) of the Code), whether or not waived, and there are no excise taxes due or
hereafter to become due, based upon current facts and circumstances, under
section 4971 of the Code with respect to the funding of any Benefit Plan;
 
        (ii) No "reportable event" (within the meaning of section 4043 of ERISA)
has occurred with respect to any Defined Benefit Plan or, to the best of the
knowledge of IMA, any Multiemployer Plan; there have been no terminations of any
Defined Benefit Plan or, to the best of the knowledge of IMA, any Multiemployer
Plan or any related trust; no such termination of any of the foregoing
reasonably can be expected to occur, whether as a consequence of the execution
and delivery of this Agreement, the consummation of the transactions
contemplated herein, or otherwise;
 
        (iii) Neither IMA nor any Subsidiary has withdrawn (partially or totally
within the meaning of ERISA) from any Benefit Plan or any Multiemployer Plan;
and neither the execution and delivery of this Agreement nor the consummation of
the transactions contemplated herein will result in the withdrawal (partial or
total within the meaning of ERISA) from any Benefit Plan or Multiemployer Plan,
or in any withdrawal or other liability of any nature to IMA, any Subsidiary, or
ITI under any Benefit Plan or any Multiemployer Plan;
 
        (iv) No "prohibited transaction" (within the meaning of section 406 of
ERISA or section 4975(c) of the Code) has occurred with respect to any Benefit
Plan or, to the best of the knowledge of IMA, any Multiemployer Plan;
 
        (v) There is no excess of the aggregate present value of accrued
benefits on a termination basis over the aggregate value of the assets of the
Defined Benefit Plans, and no withdrawal liability of IMA and the Subsidiaries
with respect to the Multiemployer Plans;
 
        (vi) There are no contributions which are, or hereafter will be,
required to have been made to trusts in connection with "defined contribution
plans" (within the meaning of section 3(34) of ERISA) with respect to services
rendered by employees of IMA or the Subsidiaries prior to the date hereof, and
all PBGC premiums due on or before the date of this Agreement by IMA or any
Subsidiary have been paid in full, including any late fees, interest and
penalties;
 
        (vii) Other than claims in the ordinary course for benefits with respect
to the Benefit Plans or the Multiemployer Plans, there are no actions, suits, or
claims pending with respect to any Benefit Plan or any Multiemployer Plan or any
circumstances known to IMA which might give rise to any such action, suit or
claims; and there are presently no outstanding judgments, decrees or orders of
any court or any government or administrative agency against or affecting any
Benefit Plan, the assets of any Benefit Plan or any Benefit Plan fiduciary; and
 
        (viii)  Other than the pension benefits payable under the Benefit Plans
and except as set forth on Schedule 5.16, neither IMA nor any Subsidiary is
under any obligation to provide benefits or coverage under a Benefit Plan to
retirees of IMA or any Subsidiary or other former employees of IMA or any
Subsidiary (or the beneficiaries of such retirees or former employees),
including but not limited to retiree health care coverage (except as may be
mandated by the Consolidated Omnibus Budget Reconciliation Act of 1985).
 
                                       15

 
<PAGE>   23
 
     5.17  Labor Relations.
 
     There are no controversies pending or threatened between IMA and any
Subsidiary and any of their respective employees which, individually or in the
aggregate, are reasonably likely to result in a Material Adverse Effect, and,
there are no organizational efforts currently being made or threatened involving
any of such employees. IMA has complied with all laws relating to the employment
of labor, including without limitation, any provisions thereof relating to
wages, hours, collective bargaining and the payment of social security and
similar taxes, and is not liable for any arrearage of wages or any taxes or
penalties for failure to comply with any of the foregoing, except for any such
non-compliance or such amounts which, individually or in the aggregate, would
not have a Material Adverse Effect.
 
     5.18  Interests of Insiders.
 
     Except pursuant to an IMA Agreement identified on Schedule 5.14(vi) or
Schedule 5.18, no Insider has, nor does any officer or director of any of the
Subsidiaries have, any interest in any property, real or personal, tangible or
intangible, used in or pertaining to the businesses engaged in by IMA or any
Subsidiary, except for the legal rights of stockholders and except for rights
under existing employee benefit plans described in Section 5.16 hereof. Except
as set forth on Schedule 5.14(vi) or Schedule 5.18, no Insider owns, nor do any
officers of directors of any Subsidiary own, directly or indirectly, any
interest in, or is a director, officer or employee of, any business which is a
competitor or significant supplier of IMA or any Subsidiary.
 
     5.19  Insurance.
 
     As of the date of this Agreement, IMA and its Subsidiaries maintain
insurance policies, and bonding arrangements, covering all of their respective
assets and properties, and in each case the various occurrences which may arise
in connection with the operation of their respective businesses, except those
occurrences which, individually or in the aggregate, would not have a Material
Adverse Effect. Schedule 5.19 attached hereto accurately summarizes the
principal terms of all such policies and bonding arrangements. Such policies and
bonding arrangements are in full force and effect, all premiums and other
amounts due thereon have been paid, and IMA and the Subsidiaries have complied
with the provisions of such policies and bonding arrangements. Such insurance
and such bonding arrangements are of comparable amounts and coverage as that
which companies engaged in similar businesses would maintain in accordance with
good business practice. There are no notices of any pending or threatened
terminations or premium increases with respect to any such policies or bonding
arrangements, and such policies and bonding arrangements will not be modified as
a result of or terminate or lapse by reason of, the transactions contemplated by
this Agreement.
 
     5.20  Intellectual Property.
 
     Other than the rights of IMA and its Subsidiaries, each as licensee, to the
subject matter (herein referred to as the "Insituform Process") under their
respective license agreements with Insituform North America Corp., and the
rights, of IMA and its Subsidiaries, as licensee, to the subject matter (herein
referred to as the "NuPipe Process") under agreements with NuPipe, Inc., set
forth in Schedule 5.20 attached hereto is a list and brief description of all of
IMA's and each Subsidiary's patents, invention disclosures, registered and
common law trademarks, service marks, tradenames, copyrights, licenses and other
similar rights and applications for each of the foregoing (together with those
rights under license relative to the Insituform Process and the NuPipe Process,
hereinafter referred to as the "Intellectual Property"). IMA and its
Subsidiaries, respectively, own all right, and title and interest in and to all
such Intellectual Property, except as set forth in Schedule 5.20(1)(a) free and
clear of all Liens. Neither IMA nor any of its Subsidiaries has, except as set
forth in Schedule 5.20, granted any outstanding licenses or other rights, and
has no obligations to grant licenses or other rights, under any such
Intellectual Property. The Intellectual Property listed in Schedule 5.20,
together with those rights under license relative to the Insituform Process and
the NuPipe Process, respectively, are all such rights necessary to the operation
and the conduct of the business of IMA and its Subsidiaries as currently
conducted; no adverse claims have been made, and no dispute has arisen, with
respect to any of the said Intellectual Property (including without limitation
those under license relative to the Insituform Process and the NuPipe Process,
respectively); and the operations of IMA and each Subsidiary and the use by each
of the Intellectual Property identified on Schedule 5.20 would not involve
infringement or
 
                                       16

 
<PAGE>   24
 
claimed infringement of any patent, trademark, servicemark, tradename,
copyright, license or similar right, except for any such infringement which,
individually or in the aggregate, would not have a Material Adverse Effect.
Without limiting the generality of the foregoing or any other provision
contained in this Agreement: the license identified under Schedule 5.20(3)(b) is
in full force and effect; no event has occurred, or is alleged to have occurred,
which constitutes or with lapse of time or giving of notice or both, would
constitute a material default or a basis for a claim of force majeure or other
material claim of excusable delay or non-performance by IMA under such license;
to the best of the knowledge of IMA, no party to such license other than IMA is
in default in any material respect in the performance of any covenant or
condition thereunder or has failed in performance thereunder in any material
respect by reason of a claim of force majeure or other claim of excusable delay
or non-performance thereunder; and the execution and delivery of this Agreement
and the consummation of the Merger will not adversely affect or otherwise impair
the ability of the Surviving Corporation fully to enjoy the benefits of such
license. Except as set forth on Schedule 5.20(3)(a), no license or other right
has in any manner been granted by IMA or any of its Subsidiaries which
constrains IMA or any Subsidiary from utilizing or commercializing any patent,
registered or common law trademark, service name, tradename, copyright, license
or other similar right. To the best of the knowledge of IMA, and except as would
not have a Material Adverse Effect, neither IMA nor any Subsidiary has suffered
any of its trade secrets, know-how or other confidential intellectual or
intangible property rights utilized in connection with the Business to enter
into the public domain.
 
     5.21  Disputes and Litigation.
 
     Except as described in the IMA Form 10-K or as set forth on Schedule 5.21,
there is no action, suit, proceeding, or claim, pending or threatened, and no
investigation by any court or government or governmental agency or
instrumentality, domestic or foreign, pending or threatened, against IMA or any
of its Subsidiaries, before any court, government or governmental agency or
instrumentality, domestic or foreign, nor is there any outstanding order, writ,
judgment, stipulation, injunction, decree, determination, award, or other order
of any court or government or governmental agency or instrumentality, domestic
or foreign, against IMA or any of its Subsidiaries, except for any such matter
which, individually or in the aggregate, would not have a Material Adverse
Effect.
 
     5.22  Licenses; Franchises; Rights.
 
        (a) Each of IMA and its Subsidiaries has (or has made timely application
for) all franchises, licenses, permits and other governmental and
non-governmental approvals necessary to enable it to carry on its business as
currently conducted, and the employees and agents of IMA and its Subsidiaries
also have all such franchises, licenses, permits, governmental and other
approvals required of them in carrying out their duties on behalf of IMA and the
Subsidiaries, except for such franchises, licenses, permits and other approvals
the failure to hold which, individually or in the aggregate, would not have a
Material Adverse Effect. All such franchises, licenses, permits, and
governmental and other approvals are in full force and effect, there has been no
default or breach thereunder, and there is no pending or threatened proceeding
under which any may be revoked, terminated or suspended, except insofar as would
not, individually or in the aggregate, have a Material Adverse Effect. The
execution and delivery of this Agreement, and the consummation of the Merger,
will not adversely affect or otherwise impair the ability of the Surviving
Corporation fully to enjoy the benefits of any such franchises, licenses,
permits or governmental and other approvals. Schedule 5.22 attached hereto
identifies each permit, license and other approval required by any national,
state, commonwealth, or territorial government (but not by any county,
municipality or local authority) to be maintained by IMA or any Subsidiary in
order to conduct its current construction operations. Neither IMA nor any
Subsidiary has violated, or is alleged to have violated, any law, rule,
regulation, judgment, stipulation, injunction, decree, determination, award or
other order of any government, or governmental agency or instrumentality,
domestic or foreign, binding upon IMA or any Subsidiary which violation,
individually or in aggregate, would have a Material Adverse Effect.
 
        (b) Without limiting the generality of the foregoing, neither IMA nor
any Subsidiary: (i) has filed any notice under any Environmental Law (as
hereinafter defined) indicating past or present treatment, storage, or disposal
of a hazardous waste or reporting a spill or release of a hazardous or toxic
waste, substance
 
                                       17

 
<PAGE>   25
 
        or constituent, or other substance into the environment, or (ii) has any
liability, contingent or otherwise, under any Environmental Law in connection
with any release of any hazardous or toxic waste, substance or constituent, or
other substance on property, now or formerly owned or leased by IMA or any of
its Subsidiaries, which, individually or in the aggregate, would have a Material
Adverse Effect. No hazardous materials and no hazardous substances have been
generated, treated, stored or disposed of or placed in violation of any
Environmental Law on any property owned or leased by IMA or any Subsidiary or on
or into any waste disposal site owned or operated by a third party except for
violations which, individually or in the aggregate, would not have a Material
Adverse Effect.
 
        (c) For purposes hereof, "Environmental Laws" shall mean any and all
federal, state or local laws, statutes, ordinances, rules, regulations, orders,
or determinations of any federal, state or local governmental authority
pertaining to health or the environment, including with limitations, the federal
Clean Air Act, as amended, Comprehensive Environmental Response, Compensation
and Liability Act of 1980, as amended, Water Pollution Control Act, as amended,
Occupational Safety and Health Act of 1970, as amended, Resource Conservation
and Recovery Act of 1976, as amended, Safe Drinking Water Act, as amended, Toxic
Substances Control Act, as amended, Superfund Amendments and Reauthorization Act
of 1986, as amended, Hazardous Materials Transportation Act, as amended, and all
other environmental, conservation or protection laws.
 
     5.23  Brokers and Finders.
 
     Neither IMA, nor any Subsidiary, nor any director, officer, agent or
employee thereof has employed any broker or finder or has incurred or will incur
any broker's, finder's or similar fees, commissions or expenses, in each case in
connection with the transactions contemplated by this Agreement, except for a
fee payable to Wertheim Schroder & Co. pursuant to a financial advisory
agreement with IMA, a copy of which agreement and all amendments thereto has
been furnished to ITI and Acquisition Sub prior to the date of this Agreement.
 
                                   ARTICLE VI
 
                         REPRESENTATIONS AND WARRANTIES
                           OF ITI AND ACQUISITION SUB
 
     ITI and Acquisition Sub hereby, jointly and severally, represent, warrant,
and covenant as follows:
 
     6.1  Incorporation.
 
     Each of ITI and Acquisition Sub is a corporation duly organized, validly
existing, and in good standing under the laws of the State of Delaware and has
full corporate power and authority to own or hold under lease the assets and
properties which it owns or holds under lease, to conduct its businesses as
currently conducted, to perform all its obligations under the agreements to
which it is a party, including, without limitation, this Agreement and to
consummate the Merger. Each is in good standing in each other jurisdiction
wherein the failure so to qualify, individually or in the aggregate, would have
a Material Adverse Effect with respect to ITI.
 
     6.2  Authorization.
 
     The execution and delivery of this Agreement by each, the performance by
each of its covenants and agreements hereunder and the consummation by each of
the transactions contemplated hereby have been duly authorized by all necessary
corporate action of each, other than the approval of the holders of ITI Common
Stock contemplated under Section 7.2 hereof. When executed and delivered by
each, this Agreement, shall constitute their valid and legally binding
obligations, respectively, enforceable against them in accordance with its
terms, except as may be limited by bankruptcy, insolvency, or other laws
affecting generally the enforceability of creditors' rights and by limitations
on the availability of equitable remedies.
 
                                       18

 
<PAGE>   26
 
     6.3  Conflicts.
 
     Neither the execution and delivery of this Agreement, nor the consummation
of the transactions contemplated herein, will violate any provision of its
certificate of incorporation or of its by-laws, as currently in effect (but
subject to the adoption of the amendments thereto contemplated by this
Agreement), or, subject to approval of this Agreement by the holders of ITI
Common Stock contemplated under Section 7.2 hereof and compliance with the
regulatory requirements hereinafter specified in this Section 6.3, any law,
rule, regulation, writ, judgment, injunction, decree, determination, award, or
other order of any court, government or governmental agency or instrumentality,
domestic or foreign, binding upon ITI or Acquisition Sub, or, except as set
forth on Schedule 6.3 attached hereto and other than any such conflicts,
breaches, creation, imposition or termination which would not have a Material
Adverse Effect with respect to ITI, conflict with or result in any breach of any
of the terms of or constitute a default under or result in the termination of or
the creation or imposition of any mortgage, deed of trust, pledge, lien,
security interest or other charge or encumbrance of any nature pursuant to the
terms of any contract or agreement to which it is a party to or by which it or
any of its assets and properties are bound. Other than the approval of this
Agreement by the holders of ITI Common Stock as contemplated under Section 7.2
hereof and except for compliance with the requirements of the HSR Act, the
Securities Act, with respect to the Registration Statement, the securities and
blue sky laws of the various states, the Exchange Act, with respect to the Proxy
Statement, and except as set forth on Schedule 6.3 and any such consents,
approvals, authorizations, filings or registrations with or notices to any such
person or entity other than any governmental agency or instrumentality the
failure to effectuate which would not have a Material Adverse Effect with
respect to ITI, no consents, approvals or authorizations, or filings or
registrations with, or notices to, any governmental agency or authority or any
other person or entity are required in connection with the execution and
delivery of this Agreement by ITI or Acquisition Sub or the consummation by ITI
or Acquisition Sub of the transactions contemplated hereby.
 
     6.4  Capitalization.
 
     The authorized capital stock of ITI consists of 2,000,000 shares of
preferred stock, $.01 par value (hereinafter referred to as "ITI Preferred
Stock"), none of which are issued and outstanding, and 25,000,000 shares of ITI
Common Stock, of which 14,402,085 shares are issued and outstanding on the date
hereof. The shares of ITI Common Stock to be issued to holders of IMA Common
Stock in the Merger will, at the Effective Time, and the shares of ITI Common
Stock to be issued upon exercise of IMA Options assumed by ITI in accordance
with this Agreement will, upon exercise thereof in accordance with the terms
thereof, be duly authorized, validly issued and fully paid and non-assessable,
issued without violation of the preemptive rights of any person. There are no
subscriptions, warrants, options, calls, commitments by or agreements to which
ITI is bound on the date hereof relating to the issuance, conversion or purchase
of any shares of ITI Common Stock, or any other capital stock of ITI, except as
set forth on Schedule 6.4 attached hereto and except for: (x) options granted by
ITI pursuant to option plans in effect on the date hereof and options granted to
ITI's President, covering an aggregate of 1,167,600 shares of ITI Common Stock
on the date hereof, and (y) warrants to purchase an aggregate of 350,877 shares
of ITI Common Stock issued contemporaneously with ITI's 8.5% Senior Subordinated
Note due July 26, 2002.
 
     6.5  Securities Filings.
 
     ITI and each Subsidiary has made all filings with the SEC that it has been
required to make under the Securities Act and the rules and regulations
promulgated thereunder and the Exchange Act and the rules and regulations
promulgated thereunder. ITI has provided to IMA a complete and correct copy of
all reports, registration statements, final prospectuses, definitive proxy
statements and other filings made by ITI or any Subsidiary with the SEC,
including all exhibits to such filings, since January 1, 1990 (all such
documents that have been filed with the SEC, as amended, hereinafter referred to
as the "ITI SEC Documents"), including, without limitation, ITI's Annual Report
on Form 10-K for the fiscal year ended December 31, 1994, as filed with the SEC
on March 31, 1995 (together with all documents incorporated therein by
reference, hereinafter referred to as the "ITI Form 10-K") and its Quarterly
Report on Form 10-Q for the quarter ended March 31, 1995, as filed with the SEC
on May 15, 1995 (hereinafter referred to as the "ITI Form 10-Q"). The ITI SEC
Documents comply in all material respects with the requirements of the
Securities Act or the Exchange Act,
 
                                       19

 
<PAGE>   27
 
as the case may be, and neither the ITI SEC Documents (as of the date of filing
with the SEC), nor any information relating to ITI or any of its subsidiaries
contained in this Agreement or any schedule hereto, contains any untrue
statement of a material fact or omits to state a material fact required to be
stated therein or necessary to make the statements therein, in light of the
circumstances under which they were made, not misleading.
 
     6.6  Financial Statements.
 
        (a) The consolidated financial statements (hereinafter referred to,
collectively, as the "ITI Audited Financial Statements") of ITI and its
consolidated subsidiaries contained in the ITI Form 10-K in response to "Item 8.
Consolidated Financial Statements and Supplementary Data" are true and correct
and have been prepared in conformity with generally accepted accounting
principles consistently applied throughout the periods to which such financial
statements relate. The ITI Audited Financial Statements fully and fairly
present, in conformity with such principles as so utilized, the consolidated
financial position and results of operations and cash flows of ITI and its
consolidated subsidiaries, at the dates shown and for the periods therein
specified, except as described therein.
 
        (b) The consolidated financial statements (hereinafter referred to,
collectively, as the "ITI Interim Financial Statements") of ITI and its
consolidated subsidiaries contained in the ITI Form 10-Q in response to "Item 1.
Financial Statements" are true and correct and have been prepared in conformity
with generally accepted accounting principles consistently applied throughout
the periods to which such financial statements relate, except as permitted by
Form 10-Q. The ITI Interim Financial Statements fully and fairly present the
consolidated financial position and results of operations and cash flows of ITI
and its consolidated subsidiaries, at the dates shown and for the periods
therein specified, subject to normal year-end adjustments in accordance with
generally accepted accounting principles and except as described therein.
 
     6.7  Absence of Undisclosed Liabilities.
 
     Except to the extent disclosed in the ITI Form 10-K or the ITI Form 10-Q
(in each case without reference to the exhibits thereto) or incurred after
December 31, 1994 in the ordinary course of business and consistent with past
practice, neither ITI, nor any of its subsidiaries has any liabilities, whether
accrued, absolute, contingent, or otherwise, whether due or to become due and
whether the amount thereof is readily ascertainable or not, other than
liabilities which, individually or in the aggregate, would not have a Material
Adverse Effect, or any unrealized or anticipated losses from any unfavorable
commitments or sales of products, other than those which, individually or in the
aggregate, would not have a Material Adverse Effect with respect to ITI, in each
case under this Section 6.7 except as set forth in Schedule 6.7.
 
     6.8  Absence of Certain Changes.
 
     Except as set forth in Schedule 6.8:(i) subsequent to December 31, 1994 and
except as disclosed in the ITI Form 10-K or the ITI Form 10-Q, neither ITI nor
any subsidiary has suffered any Material Adverse Effect with respect to ITI; and
(ii) since December 31, 1994 and except as disclosed in the ITI Form 10-K or the
ITI Form 10-Q, there has been no condition, development or contingency which, so
far as reasonably may be foreseen, may, individually or in the aggregate, have a
Material Adverse Effect with respect to ITI.
 
     6.9  Pooling.
 
     As of the date hereof, there has not been any action taken by ITI or any
subsidiaries or affiliates under Rule 1-02 of Regulation S-X of the SEC that
would prevent the Merger from being accounted for as a pooling-of-interests.
Contemporaneously with the execution and delivery of this Agreement, ITI has
delivered to IMA an executed letter agreement, substantially in the form of
Exhibit B attached hereto (together with such changes therein as may reasonably
have been requested by IMA or ITI, such reasonableness to be determined in good
faith by BDO Seidman), from each such affiliate.
 
     6.10  Interests of Insiders.
 
     Except as disclosed in the ITI Form 10-K (including the amendments thereto
and Schedule 6.10 attached hereto), as of the date hereof no officer or director
of ITI, nor any stockholder beneficially owning
 
                                       20

 
<PAGE>   28
 
(within the meaning of Section 13(d) of the Exchange Act) more than 5% of the
outstanding shares of ITI Common Stock, has, nor does any officer or director of
any of ITI's subsidiaries have, any interest in any property, real or personal,
tangible or intangible, used in or pertaining to the businesses engaged in by
ITI or any subsidiary of ITI, except for the legal rights of stockholders and
except for rights under existing employee benefit plans. As of the date hereof,
no such party owns, directly or indirectly, any interest in, or is a director,
officer or employee of, any business which is a competitor or significant
supplier of ITI or any of its subsidiaries.
 
     6.11  Disputes and Litigation.
 
     Except as described in the ITI Form 10-K or the ITI Form 10-Q or as set
forth in Schedule 6.11, there is no action, suit, proceeding, or claim, pending
or threatened, and no investigation by any court or government or governmental
agency or instrumentality, domestic or foreign, pending or threatened, against
ITI or any of its subsidiaries, before any court, government or governmental
agency or instrumentality, domestic or foreign, nor is there any outstanding
order, writ, judgment, stipulation, injunction, decree, determination, award, or
other order of any court or government or governmental agency or
instrumentality, domestic or foreign, against ITI, except for any such matter
which, individually or in the aggregate, would not have a Material Adverse
Effect with respect to ITI.
 
     6.12  Brokers or Finders.
 
     Neither ITI nor Acquisition Sub, nor any director, officer, agent or
employee thereof, has employed any broker or finder or has incurred or will
incur any broker's, finder's or similar fees, commissions or expenses, in each
case in connection with the transactions contemplated by this Agreement, except
for a fee payable to Merrill Lynch & Co. pursuant to a financial advisory
agreement with ITI, a copy of which agreement and all amendments thereto have
been furnished to IMA prior to the date of this Agreement.
 
                                  ARTICLE VII
 
                               CERTAIN COVENANTS
 
     7.1  IMA Stockholders' Meeting.
 
     IMA, acting through its Board of Directors, shall take all action necessary
in accordance with applicable law and its certificate of incorporation and
by-laws, to convene as promptly as practicable a special meeting of the holders
of shares of IMA Common Stock, to vote upon this Agreement, the Merger and the
transactions contemplated hereby, and shall include in the Joint Proxy Statement
the recommendation (subject to the fiduciary duty of the Board of Directors
under applicable law) of its Board of Directors that the holders of the shares
of IMA Common Stock vote in favor of the adoption and approval of this
Agreement, the Merger and the transactions contemplated hereby. IMA shall use
its best efforts to solicit from such stockholders proxies in favor of such
adoption and approval and shall take all other action necessary or, in the
reasonable opinion of ITI, helpful to secure a favorable vote for the purpose of
voting on and approving this Agreement, the Merger and the transactions
contemplated hereby. IMA shall adjourn such stockholders' meeting to a later
date, at the reasonable request of ITI, if (i) the requisite vote of holders of
the shares of IMA Common Stock has not been obtained; or (ii) ITI shall
otherwise request an adjournment in order to attempt to increase the percentage
of the vote in favor of the foregoing.
 
     7.2  ITI Stockholders' Meeting.
 
     ITI, acting through its Board of Directors, shall take all action
necessary, in accordance with applicable law and its certificate of
incorporation and by-laws, to convene as promptly as practicable an annual or
special meeting of the holders of shares of ITI Common Stock, to vote upon this
Agreement, the issuance of ITI Common Stock in the Merger and the transactions
contemplated hereby, including, without limitation, an amendment to its
certificate of incorporation so as to increase the authorized number of shares
of ITI Class A Common Stock, and to modify provisions relating to its board of
directors, as set forth under Section 9.3 hereof, and shall include in the Joint
Proxy Statement the recommendation (subject to the fiduciary duty of the Board
of Directors under applicable law) of its Board of Directors that the holders of
ITI Common Stock
 
                                       21

 
<PAGE>   29
 
vote in favor of such Agreement, issuance and transactions. ITI shall use its
best efforts to solicit from such stockholders proxies in favor of such matters
and shall take all other action necessary to secure a favorable vote.
 
     7.3  ITI Board of Directors.
 
     ITI shall take such action as may be necessary so that the ITI Board of
Directors will be expanded as of the Effective Time and pursuant to ITI's
certificate of incorporation, amended as contemplated under Section 9.3 hereof,
and ITI's by-laws, amended as contemplated by Section 9.4 hereof, to include the
following persons: William Gorham, Alvin J. Siteman, Silas Spengler and Sheldon
Weinig, for a one-year term expiring in 1996 (hereinafter referred to as "Class
I Directors"); Robert W. Affholder, Paul A. Biddelman, Douglas K. Chick and
Steven Roth, for a two-year term expiring in 1997 (hereinafter referred to as
"Class II Directors"); and Brian Chandler, Jerome Kalishman, James D. Krugman,
Jean-Paul Richard and Russell B. Wight, Jr., for a three-year term expiring in
1998 (hereinafter referred to as "Class III Directors"). Other than Mr. Richard,
the directors shall be grouped as follows: (i) Messrs. Biddelman, Chandler,
Chick, Krugman and Spengler shall be referred to as the "INA Group"; (ii)
Messrs. Gorham, Roth, Weinig and Wight shall be referred to as the "IGL Group";
and Messrs. Affholder, Kalishman and Siteman shall be referred to as the "IMA
Group" (each of the INA Group, the IGL Group and the IMA Group, hereinafter
referred to as a "Group"). During the period from the Effective Time until
December 9, 1998 (hereinafter referred to as the "Term"), ITI shall nominate and
recommend for re-election to the ITI Board of Directors, upon expiration of
their terms, the Class I Directors, the Class II Directors and the Class III
Directors. If during the Term any director resigns or is unable to serve for any
reason, such vacancy shall be filled with a designee chosen by the remaining
members of that director's Group and thereafter ITI shall nominate and recommend
such designee for election to the ITI Board of Directors as provided in the
previous sentence. The provisions of this paragraph (a) shall be deemed to
restate and amend, and supersede, the provisions of Section 7.3 of the Agreement
dated as of July 3, 1992 among ITI, INA Acquisition Corp. and Insituform Group
Limited.
 
     7.4  ITI Officers.
 
     ITI shall take such action as may be necessary so that Jerome Kalishman
shall be appointed to the office of Vice Chairman of the Board of ITI at the
Effective Time in accordance with and subject to the provisions of the by-laws
of ITI, amended as contemplated under Section 9.4 hereof.
 
     7.5  Registration Statement; Proxy Statement.
 
        (a)  ITI shall (i) prepare and file with the SEC as soon as reasonably
practicable a Registration Statement on Form S-4 (or another appropriate form)
under the Securities Act (herein referred to as the "Registration Statement"),
and preliminary joint proxy materials which comply as to form with the
requirements of the Exchange Act, with respect to the transactions contemplated
by this Agreement, (ii) use its best efforts to have the Registration Statement
declared effective by the SEC under the Securities Act and the preliminary joint
proxy materials cleared by the SEC under the Exchange Act as promptly as
practicable, and (iii) take all such action as may be required under state blue
sky or securities laws in connection with the transactions contemplated by this
Agreement. IMA will promptly furnish ITI with all information (and shall update
such information) concerning IMA and its Subsidiaries, and their respective
businesses and affairs and IMA's designees to the ITI Board of Directors,
including, without limitation, financial statements, financial statement
schedules, and pro forma financial statements and information, which, in the
reasonable judgment of ITI or its counsel, may be required or appropriate for
inclusion in the Registration Statement, and shall cooperate with and assist ITI
in the preparation of all such materials.
 
        (b)  Promptly after the Registration Statement (including the definitive
joint proxy material contained therein (herein referred to as the "Joint Proxy
Statement")) becomes effective, IMA and ITI shall cause the Joint Proxy
Statement to be mailed to their respective stockholders and, if necessary, after
the Joint Proxy Statement shall have been so mailed, promptly circulate amended,
supplemental or supplemented proxy material and, if required in connection
therewith, resolicit proxies. Neither IMA nor ITI shall use any proxy material
in connection with the meetings of their respective stockholders hereinabove
referred without the prior approval of the other parties hereto, which approval
shall not be unreasonably withheld.
 
                                       22

 
<PAGE>   30
 
        (c)  IMA and ITI each represents and warrants to the other that at the
time the Registration Statement and any post-effective amendment thereto becomes
effective, and the Joint Proxy Statement and any other related proxy soliciting
material filed with the SEC is cleared, and at all times subsequent thereto up
to and including the Effective Time, none of the information set forth therein
with respect to (in the case of IMA), IMA, its directors, officers, stockholders
or any Subsidiary or (in the case of ITI) ITI, its directors, officers,
stockholders or any of its subsidiaries will contain any untrue statement of a
material fact or omit to state any material fact required to be stated therein
or necessary in order to make the statements therein, in light of the
circumstances under which they are made, not misleading.
 
        (d)  IMA shall cause to be delivered to ITI (i) a letter of KPMG Peat
Marwick LLP, IMA's independent auditors, and (ii) a letter of Deloitte & Touche,
Enviroq's independent auditors, each dated within two business days before the
date as of which the Registration Statement becomes effective and addressed to
ITI, in form and substance reasonably satisfactory to ITI, to the effect set
forth on, respectively, Exhibit C-1 and Exhibit C-2 hereto.
 
        (e)  ITI shall cause to be delivered to IMA a letter of BDO Seidman,
ITI's independent auditors, dated within two business days before the date as of
which the Registration Statement becomes effective and addressed to IMA, in form
and substance reasonably satisfactory to IMA, to the effect set forth on Exhibit
D hereto.
 
     7.6  HSR Act; Other Governmental and Judicial Filings.
 
     As soon as practicable after the date hereof, IMA, ITI and Acquisition Sub
will cooperate in the preparation and filing of all materials necessary or
desirable to obtain the approval of the transactions contemplated hereby or the
disclaimer of jurisdiction with respect thereto by any regulatory body or other
governmental or judicial authority that has jurisdiction over the transactions
contemplated hereby, including, without limitation, all filings, with the
Federal Trade Commission and the U.S. Department of Justice required under the
HSR Act.
 
     7.7  Conduct of Business of IMA.
 
     IMA covenants and agrees that, except as consented to in writing by ITI,
from and after the date of this Agreement and until the Effective Time, IMA and
each Subsidiary shall:
 
        (a)  Make no purchase, sale, or lease in respect of, nor introduce any
method of management or operation in respect of, its business or its assets and
properties, except in a manner consistent with prior practice and as set forth
in IMA's capital expenditure budget previously provided to ITI and except as set
forth in Schedule 7.7(1).
 
        (b)  Maintain, preserve, and in no way further encumber its assets and
properties other than in the ordinary course of business consistent with past
practice after the date hereof, and not enter into any agreement to effectuate
the foregoing after the Effective Time.
 
        (c)  Use its best efforts: (i) to preserve its present business
organization intact, (ii) to keep available the services of the present
employees assigned to it, and (iii) to preserve its present relationships with
entities or persons having business dealings with IMA or any of the
Subsidiaries, in each case except insofar as would not have a Material Adverse
Effect.
 
        (d)  Maintain its books and records in accordance with good business
practices, on a basis consistent with prior practice.
 
        (e)  Comply in all material respects with all laws, rules, regulations,
writs, statutes, ordinance, judgments, injunctions, decrees, determinations,
awards, and other orders of every court, government and governmental agency and
instrumentality, domestic or foreign, applicable to it and to the conduct of its
business and perform in all material respects all its obligations without
default.
 
        (f)  Not incur, or agree to incur, any indebtedness for money borrowed,
except in the ordinary course of business under its line of credit dated
February 14, 1995 among IMA, The Boatmen's National Bank of St. Louis and Mark
Twain Bank, subtracting therefrom the amount of $8.6 million set forth on the
 
                                       23

 
<PAGE>   31
 
        foregoing budget and intended for use in the development referenced in
Paragraph (q) of this Section 7.7, but adding thereto amounts utilized for such
development to the extent permitted by said Paragraph (q); or issue any bond,
debenture, note, or similar obligation, or any guarantee any obligation of any
person or entity, except for guarantees of construction performance bonds in the
ordinary course of business.
 
        (g)  Not mortgage, pledge, or subject to Lien any of its assets and
properties, other than encumbrances in existence on the date hereof.
 
        (h)  Not make any loans, advances or contributions to, or investments
in, or guarantees of, any other person (other than a wholly-owned subsidiary and
other than short-term investments in the ordinary course of business in
obligations of the United States of America for which the full faith and credit
of the United States of America is pledged to provide for the payment of
principal and interest, or certificates of deposit issued by a commercial bank
or banks having at least $100,000,000 in individual capital and surplus, and
other than foreign currency hedging transactions in the ordinary course of
business consistent with past practice); and without limiting the generality of
the foregoing, not acquire any shares of ITI Common Stock.
 
        (i)  Maintain and pay all premiums with respect to all policies of
insurance relating to its business, and its assets and properties, as are
presently held in its name and timely renew all such policies or substitute
substantially similar coverage therefor.
 
        (j)  Not make any change adverse to it in any material respect in the
terms of any IMA Agreement (nor, without the prior review thereof and consent
thereto of ITI, which consent shall not unreasonably be withheld, enter into
definitive arrangements implementing the matters described under Item (5) of
Schedule 5.5), nor approve, amend or modify any IMA Agreement to which an
Insider is a party.
 
        (k)  Not make any capital expenditure (including, without limitation
expenditures for property, plant and equipment) or appropriations or commitments
with respect thereto, except (subject to the provisions of Paragraph (q) of this
Section 7.7) to the extent of the total dollar amount and, to the extent
indicated therein, at the times set forth in IMA's capital expenditure budget
which has been previously furnished to ITI.
 
        (l)  Not acquire or agree to acquire by merging or consolidating with,
or by purchasing a substantial equity interest in or substantial portion of the
assets of, or by any other manner, any business or any corporation, partnership,
joint venture, association or other business organization or division thereof or
otherwise acquire or agree to acquire any assets outside the ordinary course of
business consistent with past practice; or consummate or implement the
transactions contemplated by Items (2)(b) and (c) of Schedule 5.5, or by Items
(ix)(3) and (4) of Schedule 5.14, in each case without prior review and approval
of the terms thereof by ITI, which approval shall not unreasonably be withheld.
 
        (m)  Not take any action described in Section 5.9(d) hereof except as
set forth in Schedule 7.7(2), nor amend, modify, supplement, or in any way
change in any material respect any plan or arrangement established for the
benefit of its employees.
 
        (n)  Not enter into any license or sublicense agreement or other
arrangement conferring any rights to utilize any Intellectual Property the
rights to which are held by IMA or any Subsidiary.
 
        (o)  Not settle or compromise any litigation involving the payment of,
or an agreement to pay over time an amount in cash, notes, or other property,
except that IMA may in good faith obtain the release of any and all claims and
potential claims described under Item (3) of Schedule 5.21 in exchange for a
settlement not in excess of $400,000 without the consent of ITI, and, if in
excess of such amount, with the consent of ITI, which consent shall not
unreasonably be withheld; and except that IMA may in good faith obtain the
release of any and all claims and potential claims described under Item (5) of
Schedule 5.21 in exchange for a settlement not in excess of $750,000 without the
consent of ITI, and, if in excess of such amount with the consent of ITI, which
consent shall not unreasonably be withheld.
 
        (p)  Not pay, discharge or satisfy claims, liabilities or obligations
(absolute, accrued, contingent or otherwise and whether due or to become due)
which involve payments or commitments to make payments exceeding $100,000 in the
aggregate, other than (A) liabilities or obligations incurred in the ordinary
course of
 
                                       24

 
<PAGE>   32
 
        business and consistent with past practice, and (B) scheduled repayments
of current portions of and interest on long term indebtedness or repayments
under existing revolving credit agreements.
 
        (q)  Notwithstanding any other provision contained in this Agreement, or
the schedules hereto, to the contrary, not take any action in furtherance of the
utilization for commercial purposes of the development contemplated by Item (1)
of Schedule 5.8 (and Items (e)(2) of Schedule 5.9 and (i)(10) of Schedule 5.14),
nor acquire nor install any equipment or machinery on any such property, nor
take any action in furtherance of any loan arrangements contemplated by said
schedules, without the prior consent of ITI in each case; it being understood
and agreed that, without the consent of ITI: (i) IMA shall be permitted to
complete construction of such facility in accordance with the plans contemplated
by the capital expenditure budget referenced in Section 7.7(f) without the
contemplated tower and manufacturing equipment (and subject to the provisions
regarding financing hereinabove set forth); and (ii) IMA shall be permitted to
acquire (but not install) manufacturing equipment which it has ordered prior to
the date hereof.
 
        (r)  Take any action or fail to take any action which would result in
any breach of any of its representations, warranties or covenants contained
herein.
 
     7.8  IMA Capitalization.
 
     Except as consented to in writing by ITI, from and after the date of this
Agreement and until the Effective Time:
 
        (a)  No change shall be made or proposed in the certificate of
incorporation or by-laws, or (subject to Section 7.7(l)) partnership or joint
venture agreement, or any other organic instrument of IMA or of any Subsidiary.
 
        (b)  Neither IMA nor any Subsidiary shall: (i) issue, grant, sell or
encumber any shares of its capital stock, (ii) issue, grant, sell or encumber
any security, option, warrant, put, call, subscription or other right of any
kind, fixed or contingent, that directly or indirectly calls for the
acquisition, issuance, sale, pledge or other disposition of any shares of
capital stock or other equity interests of IMA or any Subsidiary (other than
pursuant to the arrangements described under Item (5) of Schedule 5.5 or under
item (1) of Schedule 7.8), (iii) enter into any agreement, commitment or
understanding calling for any transaction referred to in clause (i) or (ii) of
this Paragraph (b), or (iv) make any other changes in its equity capital
structure except, in all such cases under this Paragraph (b), for the issuance
of shares of IMA Common Stock upon exercise of the IMA Options, and conversion
of shares of IMA Class B Common Stock, which are outstanding prior to the
execution and delivery of this Agreement and pursuant to the present terms
thereof and except for the issuance by a Subsidiary of shares to IMA or to a
wholly-owned Subsidiary.
 
        (c)  Neither IMA nor any Subsidiary shall split, combine or reclassify
any shares of its capital stock, or (other than as set forth under item (2) of
Schedule 7.8) declare, set aside or pay any dividend or other distribution
(whether in cash, stock, securities, indebtedness, rights or property or any
combination thereof) in respect of any shares of its capital stock or other
equity interests, or redeem or otherwise acquire any shares of the capital stock
or other equity interests.
 
     7.9  Interim Financial Statements; Audited Enviroq Statements.
 
        (a)  IMA shall deliver to ITI all regularly prepared audited and
unaudited consolidated and consolidating financial statements of IMA and its
Subsidiaries, respectively, prepared after the date of this Agreement, in the
format historically published or utilized internally, as the case may be, and
any financial statements prepared for filing with the SEC, as soon as each is
available. Without limiting the provisions of Section 7.7(l), the financial
statements delivered by IMA to ITI shall include pro forma financial statements
or information prepared to illustrate any merger or acquisition occurring
subsequent to the most recent financial statement delivered before the Effective
Time.
 
        (b)  To the extent not furnished pursuant to Paragraph (a) immediately
preceding, within 30 days after the end of each calendar month after the date of
this Agreement, IMA will deliver to ITI unaudited consolidated statements of
income for such calendar month and the corresponding calendar month of the
preceding fiscal year. All such financial statements shall be true and correct
and prepared in accordance with
 
                                       25

 
<PAGE>   33
 
        generally accepted accounting principles consistently applied and shall
fully and fairly present, in conformity with such principles as so utilized, the
consolidated financial position, results of operations and cash flows of IMA and
its consolidated subsidiaries as at the date or for the periods indicated (and
shall be accompanied by a certificate of the chief financial or accounting
officer of IMA to such effect), except as otherwise indicated in such statements
and subject to normal and recurring year-end audit adjustments which would not,
individually or in the aggregate, have a Material Adverse Effect. All unaudited
financial statements delivered pursuant to this Paragraph (b) shall be prepared
on a basis consistent with the IMA Interim Financial Statements.
 
        (c)  IMA shall prepare or cause the preparation of the consolidated
financial statements and financial statement schedules of Enviroq and its
subsidiaries as of March 25, 1995 and March 26, 1994 and for the years ended,
respectively, March 25, 1995, March 26, 1994 and March 27, 1993, as required to
be filed by IMA pursuant to Form 8-K promulgated by the SEC in connection with
the consummation of the transactions under the agreement dated November 2, 1994
entered into by IMA and Enviroq among other parties. Such financial statements
and schedules shall be true and correct and prepared in accordance with
generally accepted accounting principles consistently applied and shall fully
and fairly present, in conformity with such principles as so utilized, the
consolidated financial position, results of operations and cash flows of Enviroq
and its consolidated subsidiaries as of the dates and for the periods indicated.
As promptly as practicable after the date hereof, IMA shall deliver to ITI such
financial statements and related financial statement schedules, together with
the audit reports of Deloitte & Touche with respect thereto. IMA shall furnish
ITI with access to all computations, calculations and determinations made in
preparing such financial statements and schedules and shall consult with ITI and
its auditors in the completion of such financial statements and schedules.
 
     7.10  Conduct of Business of ITI; ITI Capitalization.
 
        (a)  ITI covenants and agrees that, except as set forth on Schedule 7.10
attached hereto or consented to in writing by IMA, from and after the date of
this Agreement and until the Effective Time, ITI and each subsidiary shall:
 
               (i)  Make no purchase, sale, or lease in respect of, nor
     introduce any method of management or operation in respect of, its business
     or its assets and properties, except in a manner in all material respects
     consistent with prior practice.
 
               (ii)  Use its best efforts: (x) to preserve its present business
     organization intact, and (y) to preserve its present relationships with
     entities or persons having business dealings with ITI or any of its
     subsidiaries, in each case except insofar as would not have a Material
     Adverse Effect with respect to ITI.
 
               (iii)  Maintain its books and records in accordance with good
     business practices, on a basis consistent with prior practice.
 
               (iv)  Maintain in all material respects the current character of
     the business of ITI and its subsidiaries, taken as a whole, other than as
     contemplated under this Agreement and not enter into any agreement to
     effectuate the foregoing after the Effective Time.
 
        (b)  ITI shall not other than as set forth on Schedule 7.10, (i) issue,
grant, sell or encumber any shares of its capital stock, (ii) issue, grant, sell
or encumber any security, option, warrant, put, call, subscription or other
right of any kind, fixed or contingent, that directly or indirectly calls for
the acquisition, issuance, sale, pledge or other disposition of any shares of
capital stock of ITI, (iii) enter into any agreement, commitment or
understanding calling for any transaction referred to in clause (i) or (ii) of
this Paragraph (b) or (iv) make any other changes in its equity capital
structure, except, in all such cases under this Paragraph (b), for (1) issuances
or grants of options to purchase shares of ITI Common Stock pursuant to any
option plan of ITI in effect on the date of this Agreement or pursuant to any
options or warrants outstanding on the date of this Agreement or set forth on
Schedule 7.10, and (2) any transaction or transactions relating directly or
indirectly (through issuance, grant or sale of rights, warrants, options or
otherwise) to the issuance of up to an aggregate number of shares of ITI Common
Stock which would not, without reference to any transaction or transactions, or
issuance, prior to the date of this Agreement, or any transaction or
transactions described
 
                                       26

 
<PAGE>   34
 
        under clause (1) immediately preceding, require the filing of a Report
on Form 10-C under the rules of the SEC.
 
        (c)  Except as consented to in writing by IMA or as set forth on
Schedule 7.10, ITI shall not split, combine or reclassify any shares of its
capital stock, declare, set aside or pay any dividend or other distribution
(whether in case, stock, securities, indebtedness, rights or property or any
combination thereof) in respect of any shares of its capital stock or other
equity interests, or redeem or otherwise acquire any shares of its capital stock
or other equity interests.
 
        (d)  ITI shall deliver prior communication to IMA of any agreement
proposed to be entered into after the date hereof with any beneficial owner (as
defined pursuant to Section 13(d) of the Exchange Act) of more than 5% of the
outstanding shares of ITI Common Stock, in each case other than the matters set
forth on Schedule 7.10.
 
     7.11  Due Diligence; SEC Filings.
 
        (a)  IMA shall afford ITI and its officers, employees, accountants,
counsel and other authorized representatives reasonable access, during ordinary
business hours, to its plants, properties, books and records, and those of its
Subsidiaries, and shall use its best efforts to cause its representatives to,
furnish to ITI such additional financial and operating data and other
information as to its and its Subsidiaries' respective businesses and properties
as ITI may from time to time reasonably request. IMA shall furnish ITI with
copies of all filings with the SEC by it or any Subsidiary subsequent to the
date hereof, which shall be prepared in all material respects in accordance with
the rules and regulations promulgated by the SEC if any such filings are made
prior to the Effective Time.
 
        (b)  ITI shall provide IMA and its officers, employees, accountants,
counsel and other authorized representatives such information concerning ITI and
its subsidiaries as may be reasonably necessary for IMA to ascertain the
accuracy and completeness of the information furnished by ITI for inclusion in
the Registration Statement and to verify the warranties and covenants of ITI
herein contained. ITI shall furnish IMA with copies of all filings with the SEC
subsequent to the date hereof, which shall be prepared in all material respects
in accordance with the rules and regulations promulgated by the SEC if any such
filings are made prior to the Effective Time.
 
        (c)  All information provided to ITI or its representatives by or on
behalf of IMA or any Subsidiary, or to IMA or its representatives by or on
behalf of ITI or any subsidiary of ITI, before or after the date of this
Agreement in connection with the transactions contemplated by this Agreement
shall, notwithstanding the absence of any other specific reference thereto, be
governed by the Confidentiality Agreement dated June 30, 1994, as amended
(hereinafter referred to as the "Confidentiality Agreement") executed by ITI and
IMA.
 
     7.12  Notification of Certain Matters.
 
        (a)  Between the date hereof and the Effective Time, each party will
give prompt notice in writing to the other parties, of: (i) the occurrence, or
failure to occur, of any event, which occurrence or failure would be likely to
cause any of its representations or warranties contained in this Agreement to be
untrue or inaccurate in any material respect from the date hereof to the
Effective Time, (ii) any notice or other communication from any person alleging
that the consent of such person is or may be required in connection with the
transactions contemplated by this Agreement, (iii) any notice or other
communication from any governmental or regulatory agency or authority in
connection with the transactions contemplated by this Agreement, (iv) any
actions, suits, claims, investigations or proceedings commenced or, to the best
of its knowledge, threatened against the notifying party or any subsidiary or
relating to or involving or otherwise affecting the notifying party or which
relate to the consummation of the transactions contemplated by this Agreement,
and (v) any material failure of the notifying party or any officer, director,
employee or agent thereof to comply with or satisfy any covenant, condition or
agreement to be complied with or satisfied by it hereunder.
 
                                       27

 
<PAGE>   35
 
        (b)  IMA will (i) confer on a regular and frequent basis with one or
more designated representatives of ITI to report operational matters and to
report the general status of ongoing operations, and (ii) notify ITI of any
emergency or other change in the normal course of business or in the operation
of the properties of IMA or any Subsidiary and of any governmental complaints,
investigations or hearings (or communications indicating that the same may be
contemplated) or adjudicatory proceedings involving any property of IMA or any
Subsidiary, and will keep ITI fully informed of such events and permit ITI's
representatives access to all materials prepared in connection therewith. ITI
will notify IMA of any emergency or other change in the normal course of
business, or in the operation of the properties of ITI or any subsidiary, and of
any governmental complaints, investigations or hearings (or communications
indicating that the same may be contemplated) or adjudicatory proceedings
involving any property of ITI or any subsidiary, in each case if such event
would, individually or in the aggregate, have a Material Adverse Effect with
respect to ITI, and will keep IMA fully informed of such events.
 
        (c)  The giving of any such notice under this Section 7.12 shall in no
way change or modify the representations and warranties or the conditions to any
party's obligations contained herein or otherwise affect the remedies available
to any party hereunder.
 
     7.13  Accounting and Tax Treatment.
 
     Each of the parties undertakes and agrees to use its best efforts to cause
the transactions contemplated by this Agreement and the Merger to qualify for
pooling-of-interests accounting treatment under generally accepted accounting
principles. None of the parties will take a position on their respective tax
returns or elsewhere, nor take any action or fail to take any action, that is or
would be inconsistent with the treatment of the transactions contemplated by
this Agreement and the Merger as a reorganization within the meaning of Sections
368(a)(1)(A) and 368(a)(2)(E) of the Code unless counsel to the party taking the
inconsistent position shall have advised such party that there is no basis for
the party to do otherwise.
 
     7.14  Forbearance.
 
     IMA agrees that, from and after the date hereof and until the Effective
Time, it shall not, and shall not permit any Subsidiary, or any officers,
directors, employees, agents or representatives of IMA or of any Subsidiary to,
directly or indirectly, initiate, solicit or encourage discussions, inquiries or
proposals, or participate in any negotiation or discussion for the purpose or
with the intention of leading to any proposal, concerning any merger,
consolidation or other business combination involving IMA or any Subsidiary or
any acquisition of any equity interest in IMA or any Subsidiary, or a material
portion of the assets of, IMA and its Subsidiaries, taken as a whole, or any
similar transaction, or effectuate any such transaction, in each case, except
for the Merger. Notwithstanding the foregoing, IMA may furnish information
concerning its business, properties or assets, and may engage in negotiations
and discussions in connection with such a transaction, if the Board of Directors
of IMA, based on the written opinion of counsel reasonably satisfactory to IMA,
determines that the exercise of its fiduciary responsibilities requires that
such information be furnished or such negotiations be commenced. IMA shall
notify ITI immediately of any such inquiry (including the terms thereof and the
person making such inquiry) which it may receive in respect of any possible such
transaction.
 
     7.15  Restructuring Transactions.
 
     Following the receipt of the approvals by IMA and ITI stockholders
contemplated by Sections 7.1 and 7.2, respectively, IMA shall effect
restructurings of IMA's Subsidiaries and transfers of the assets and liabilities
of IMA and its Subsidiaries that are requested by ITI; provided that, if so
requested by IMA in connection with any particular transaction, ITI shall agree,
on a basis reasonably satisfactory to IMA, to indemnify IMA and its Subsidiaries
against any out-of-pocket costs and tax liabilities, arising out of such
transaction if the transactions contemplated by this Agreement are not
consummated. No such restructuring or other transfer of assets or liabilities
shall be undertaken if such restructuring or transfer would, in the reasonable
judgment of Messrs. Thompson & Mitchell (as reasonably concurred with by Messrs.
Krugman, Chapnick & Grimshaw), impede in any material respect Messrs. Thompson &
Mitchell's ability to render the tax opinion described in Section 9.9.
 
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<PAGE>   36
 
     7.16  Indemnification.
 
     From and after the Effective Time, ITI and the Surviving Corporation shall,
to the extent permitted by the GCL and other law, honor all obligations of IMA
pursuant to Section 8(b) of IMA's certificate of incorporation, Article IX of
its by-laws, and those indemnification agreements with directors set forth on
Schedule 5.14, in each case in effect on the date hereof, which provide for
indemnification of officers and directors of IMA with respect to events
occurring prior to the Effective Time; it being acknowledged and agreed that no
such provisions shall obligate ITI to procure or maintain any insurance
coverage.
 
     7.17  Registration Rights.
 
        (a)  Prior to the mailing of the Joint Proxy Statement, ITI will use its
best efforts to enter into a registration rights agreement (hereinafter referred
to as the "Registration Rights Agreement") with each person who signs an
Affiliate Agreement (as hereinafter defined), other than those who, immediately
following the consummation of the Merger, would own less than 1% of the
outstanding shares of ITI Common Stock (hereinafter referred to, individually,
as a "Stockholder" and, collectively, as the "Stockholders").
 
        (b)  The Registration Rights Agreement will provide for the following
registration rights and other provisions substantially similar to those
provisions contained in the Registration Rights Agreement dated October 19, 1992
(hereinafter referred to as the "Prior Registration Rights Agreement") among
ITI, Interstate Properties and the Ringwood Group named therein, and will become
effective on the date of the first publication of the operating results of ITI
covering at least a 30-day period after the Merger has been consummated:
 
               (i)  Demand Registration.  A Stockholder may make a written
     request for registration under the Securities Act (hereinafter referred to
     as a "Demand Registration") of all or part of the shares of ITI Common
     Stock that it or its Affiliates beneficially own (hereinafter referred to
     as the "Registrable Securities"); provided, that ITI shall not be obligated
     (i) to effect more than one Demand Registration for each Stockholder and
     its Affiliates unless ITI qualifies and is entitled to use a Registration
     Statement on Form S-3 (in which case such Stockholder shall be entitled to
     a total of three Demand Registrations), (ii) to effect a Demand
     Registration for less than 500,000 shares of ITI Common Stock, (iii) to
     effect a Demand Registration if such written request is given after the
     sixth anniversary of the consummation of the Merger, (iv) to effect a
     Demand Registration for any Registrable Securities if, in the written
     opinion of counsel to ITI, such Registrable Securities could, within three
     months of the date of a Stockholder's request but based on the facts and
     circumstances known at the date of such request, be publicly offered and
     sold without registration under the Securities Act (and such Stockholder
     shall provide such information as counsel to ITI shall reasonably request
     in connection with such opinion) or (v) to effect a Demand Registration in
     any other circumstances exempted from such requirement pursuant to the
     Prior Registration Rights Agreement. Such request will specify the number
     of shares of Registrable Securities proposed to be sold and will also
     specify the intended method of disposition thereof. A registration will not
     count as a Demand Registration until it has become effective.
 
               (ii)  Incidental Registration.  If ITI proposes to file a
     registration statement under the Securities Act (other than a Registration
     Statement on Form S-4 of Form S-8) relating to an underwritten public
     offering of shares of ITI Common Stock to be offered for its own account or
     the account of others at any time prior to the sixth anniversary of the
     consummation of the Merger, and if the managing underwriter for such
     proposed offering advises ITI that the inclusion of some or all of the
     Registrable Securities in such registration statement would not interfere
     with the successful marketing of ITI Common Stock, ITI shall (i) provide
     written notice of the proposed offering to the Stockholders, setting forth
     a description of the intended method of distribution, and (ii) use its best
     efforts to register pursuant to such registration statement (hereinafter
     referred to as an "Incidental Registration") such number of Registrable
     Securities as shall be specified in a written request by each Stockholder
     made within 20 days after such written notice from ITI, subject to such
     limits as may have been set by ITI's Board of Directors or the managing
     underwriter on the number of Registrable Securities which may be included
     in the proposed offering; provided, however, that, for purposes of this
     sentence, the use by ITI of its "best efforts" shall not require any
     reduction in the amount or sale price of the securities it proposes to
 
                                       29

 
<PAGE>   37
 
     distribute for its own account. ITI shall not be obligated to effect an
     Incidental Registration for any Registrable Securities (x) if in the
     written opinion of counsel to ITI, such Registrable Securities could,
     within three months of the date of a Stockholder's request but based on the
     facts and circumstances known at the date of such request, be publicly
     offered and sold without registration under the Securities Act (and the
     Stockholder shall provide such information as counsel to ITI shall
     reasonably request in connection with such opinion) or (y) in any other
     circumstances exempted from such requirement pursuant to the Prior
     Registration Rights Agreement.
 
     7.18  Additional Agreements.
 
     Subject to the terms and conditions of this Agreement, each of the parties
hereto shall cooperate with one another and use its best efforts to complete in
a timely manner the transactions contemplated by this Agreement, including (i)
using its best efforts to comply with any and all applicable rules and
regulations, and to send all notices to, make all declarations, filings and
registrations with, and obtain all consents, authorizations, approvals and
waivers from third parties and governmental and regulatory bodies required to
consummate the transactions contemplated hereby or comply with any and all
applicable rules and regulations governing such transactions, and (ii)
furnishing the other parties with all information necessary or advisable for the
matters referred to in Sections 7.5 and 7.6 hereof and any other statements or
applications made by or on behalf of any party to any governmental or regulatory
body in connection with the transactions contemplated by this Agreement.
 
                                  ARTICLE VIII
 
                                   PUBLICITY
 
     8.1  Publicity.
 
     None of the parties hereto shall, nor shall any such party cause or allow
any affiliate, directly or indirectly, to issue any press release or otherwise
make any public announcement or statement with respect to the matters
contemplated hereby without the prior approval of all parties (which consent
shall not be unreasonably withheld); provided that nothing herein shall prohibit
any party hereto or any of their affiliates from making any announcement or
disclosure required to be made by it or them under applicable law if it or its
affiliates determines in good faith that it is appropriate to do so and, if
practicable, gives prior notice to the other parties hereto of such
determination.
 
                                   ARTICLE IX
 
                           CONDITIONS TO OBLIGATIONS
                                 OF EACH PARTY
 
     The obligations of each of ITI, Acquisition Sub and IMA to consummate the
Merger and the Closing are subject to the following conditions precedent, any or
all of which may be waived by such party at its sole discretion:
 
     9.1  Hart-Scott-Rodino Antitrust Improvements Act.
 
     The waiting period (and any extensions thereof) applicable to the
consummation of the transactions contemplated hereby required under the HSR Act
shall have expired or been terminated.
 
     9.2  Merger Approval.
 
     This Agreement, the Merger and the transactions contemplated hereby shall
have been duly approved and adopted by the requisite vote of the respective
stockholders of ITI and IMA in accordance with applicable law and the rules
promulgated by the National Association of Securities Dealers, Inc.
 
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<PAGE>   38

 
     9.3  Amendments to ITI's Certificate of Incorporation.
 
     The amendments to ITI's certificate of incorporation which are contemplated
by Section 7.2, in the respective forms thereof attached hereto as Exhibit E-1
and Exhibit E-2 shall have been approved by the requisite vote of ITI
stockholders entitled to vote thereon and duly filed in accordance with the
requirements of the GCL.
 
     9.4  Amendments to ITI's By-Laws.
 
     The amendments to ITI's by-laws in the form thereof attached hereto as
Exhibit F shall have been adopted by the Board of Directors of ITI.
 
     9.5  Effectiveness of Registration Statement.
 
     Prior to the first date on which the Joint Proxy Statement is mailed to
stockholders, the SEC shall have declared the Registration Statement effective
and, at or prior to the time required, any required approvals of state
securities administrators shall have been obtained. At the Closing and the
Effective Time, the Registration Statement shall be effective and no stop order
suspending the effectiveness of the Registration Statement or similar
restraining order shall have been threatened or initiated by the SEC or any
state or foreign securities administrator.
 
     9.6  Pooling-of-Interests.
 
     ITI shall have received an opinion from BDO Seidman, dated the Closing
Date, in form and substance reasonably satisfactory to ITI and to IMA, to the
effect that the transactions contemplated by this Agreement and the Merger will
qualify for pooling-of-interests accounting treatment under generally accepted
accounting principles.
 
     9.7  Conversion of IMA Class B Common Stock.
 
     At or prior to the Effective Time, all of the shares of IMA Class B Common
Stock issued and outstanding immediately prior to the Effective Time shall have
been converted into shares of IMA Class A Common Stock on a share for share
basis in accordance with IMA's certificate of incorporation, as currently in
effect; and, in furtherance thereof, each holder of shares of IMA Class B Common
Stock shall have executed and delivered to ITI and IMA a letter in the form of
Exhibit G attached hereto (together with such changes therein as may reasonably
be requested by ITI).
 
     9.8  No Prohibition on Consummation.
 
     No order, stay, judgment, injunction or decree shall have been issued and
be in effect by any court restraining or prohibiting the consummation of the
transactions contemplated hereby. No statute, rule or regulation shall have been
promulgated or enacted by any foreign or United States federal or state
government, governmental authority or governmental agency, which would prevent
or make illegal the consummation of the transactions contemplated hereby,
including the Merger.
 
     9.9  Tax Opinion.
 
     IMA shall have received from Messrs. Thompson & Mitchell, an opinion, dated
the Closing Date, in form and substance reasonably satisfactory to IMA and to
ITI and its counsel, to the effect that the Merger will be treated for federal
income tax purposes as a reorganization within the meaning of Sections
368(a)(1)(A) and 368(a)(2)(E) of the Code, and that ITI, Acquisition Sub and IMA
will each be a party to that reorganization within the meaning of Section 368(b)
of the Code.
 
     9.10  ITI Board; Officers.
 
     ITI's Board of Directors and its offices shall have been expanded and
filled, respectively, as set forth under Sections 7.3 and 7.4 hereof.
 
                                       31

 
<PAGE>   39
 
                                   ARTICLE X
 
                        CONDITIONS TO OBLIGATIONS OF IMA
 
     The obligation of IMA to consummate the Merger and the Closing is subject
to the following additional conditions precedent, any or all of which may be
waived by IMA at its sole discretion:
 
     10.1  Opinion of Counsel for ITI and Acquisition Sub.
 
     IMA shall have received an opinion of Messrs. Krugman, Chapnick & Grimshaw,
counsel for ITI and Acquisition Sub, dated the Closing Date, in form and
substance reasonably satisfactory to IMA and its counsel, to the effect set
forth in Exhibit H.
 
     10.2  Representations; Warranties; Covenants.
 
     The representations and warranties of ITI and Acquisition Sub contained in
this Agreement shall be true and correct in all material respects at and as of
the Closing Date with the same effect as though all such representations and
warranties were made at and as of the Closing Date (except for representations
and warranties which are as of a specific date or which relate to a specific
period other than or not including the Closing Date, as the case may be, and
except for changes therein contemplated or permitted by this Agreement and
provided, however, that if any such representation or warranty is already
qualified by materiality, for purposes of determining whether this condition has
been satisfied, such representation or warranty must be true and correct in all
respects); and ITI and Acquisition Sub shall have complied with their respective
covenants contained under this Agreement in all material respects; and ITI and
Acquisition Sub shall have delivered to IMA a certificate to that effect, dated
the Closing Date, signed by its Chairman of the Board, its President and Chief
Executive Officer or one of its Vice Presidents.
 
     10.3  Certified Resolutions.
 
     IMA shall have received a certificate of the Secretary or an Assistant
Secretary of each of ITI and Acquisition Sub, in form and substance satisfactory
to IMA, with respect to the authorization by their respective boards of
directors and stockholders of the execution and delivery of this Agreement and
the consummation of the transactions contemplated herein, the number of
authorized shares of the capital stock of ITI as of the Closing Date and the
number of issued and outstanding shares of the capital stock of ITI, and the
number of shares subject to outstanding options and warrants, convertible
securities or similar obligations to issue capital stock, as of such date.
 
     10.4  Kalishman and Affholder Agreements.
 
     ITI shall have executed and delivered to Robert W. Affholder the agreement
in the form attached hereto as Exhibit K, and shall have executed and delivered
to Jerome Kalishman the agreements in the respective forms attached hereto in
Exhibit L, in each case dated the Closing Date.
 
     10.5  Fairness Opinion.
 
     IMA shall have received from Wertheim Schroder & Co. Incorporated on or
prior to the date of mailing of the Joint Proxy Statement its opinion that the
terms of the Merger are fair to the holders of IMA Common Stock from a financial
point of view, and such opinion shall not have been withdrawn between the date
of its delivery and the Effective Time.
 
     10.6  Letter of ITI's Accountants.
 
     IMA shall have received a letter of BDO Seidman, ITI's independent
auditors, dated the Closing Date, addressed to IMA, in form and substance
reasonably satisfactory to IMA and counsel for IMA, making the statements
required by Paragraph (e) of Section 7.5 on the basis of procedures set forth
therein carried out by them not more than three business days prior to the
Closing Date.
 
     10.7  Director Indemnification Agreements.
 
     ITI shall have executed to Jerome Kalishman, Robert W. Affholder and Alvin
J. Siteman its customary form of director indemnification agreement, in each
case dated the Closing Date.
 
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<PAGE>   40
 
     10.8  Litigation.
 
     No action, suit or proceeding against any current director of IMA relating
to the consummation of any of the transactions contemplated in this Agreement,
and seeking material damages in connection therewith, shall be pending or
threatened which IMA, in good faith and with the advice of Messrs. Thompson &
Mitchell, reasonably believes makes it undesirable to proceed with the
consummation of the transactions contemplated hereby.
 
     10.9  Other Certificates.
 
     IMA shall have received such additional certificates, instruments and other
documents, in form and substance satisfactory to IMA and counsel for IMA, as IMA
shall have reasonably requested in connection with compliance with the
conditions set forth in this Article X.
 
                                   ARTICLE XI
 
              CONDITIONS TO OBLIGATIONS OF ITI AND ACQUISITION SUB
 
     The obligations of each of ITI and Acquisition Sub to consummate the Merger
and the Closing are subject to the following conditions precedent, any or all of
which may be waived by such party at its sole discretion:
 
     11.1  Opinion of Counsel for IMA.
 
     ITI shall have received an opinion of Messrs. Thompson & Mitchell, counsel
for IMA, dated the Closing Date, in form and substance reasonably satisfactory
to ITI and its counsel to the effect set forth in Exhibit I.
 
     11.2  Representations; Warranties; Covenants.
 
     The representations and warranties of IMA contained in this Agreement shall
be true and correct in all material respects at and as of the Closing Date with
the same effect as through all such representations and warranties were made at
and as of the Closing Date (except for representations and warranties which are
as of a specific date or which relate to a specific period other than or not
including the Closing Date, as the case may be, and except for changes therein
contemplated or permitted by this Agreement, and provided, however, that if any
such representation or warranty is already qualified by materiality, for
purposes of determining whether this condition has been satisfied, such
representation or warranty must be true and correct in all respects); and IMA
shall have complied with all of its covenants contained in this Agreement in all
material respects; and IMA shall have delivered to ITI a certificate to that
effect, dated the Closing Date, signed by its Chairman of the Board, its
President or one of its Vice Presidents.
 
     11.3  Certified Resolutions; Capitalization.
 
        (a)  ITI shall have received a certificate of the Secretary or an
Assistant Secretary of IMA in form and substance satisfactory to ITI, with
respect to the authorization by the board of directors and the stockholders of
IMA of the execution and delivery of this Agreement and the consummation of the
transactions contemplated herein, the number of authorized shares of the capital
stock of IMA as of the Closing Date and the number of issued and outstanding,
fully paid and non-assessable shares of the capital stock of IMA as of such date
(which shall not include any shares other than the shares of IMA Class A Common
Stock outstanding on the date hereof, the shares of IMA Class A Common Stock
issued upon conversion of shares of IMA Class B Common Stock outstanding on the
date hereof, and any shares of IMA Class A Common Stock issued upon exercise of
IMA Options outstanding on the date hereof and exercisable prior to the
Effective Time).
 
        (b)  ITI shall have received assurances, reasonably satisfactory to it,
that at and after the Effective Time, there shall not exist any security,
option, warrant, right, put, call, subscription, agreement, commitment,
understanding or claim of any kind, fixed or contingent (including the IMA
Options), that directly or indirectly calls for IMA or (except as identified
under Item (5) of Schedule 5.5) any of its Subsidiaries to acquire, issue,
deliver or sell, or to cause to be acquired, issued, delivered or sold, any
shares of the capital
 
                                       33

 
<PAGE>   41
 
        stock of or equity interest in IMA or any Subsidiary or obligating IMA
or any Subsidiary to grant, extend or enter into any of the foregoing.
 
     11.4  Affiliate Undertakings.
 
        (a)  ITI shall have received an agreement, in form and substance
reasonably satisfactory to it (herein referred to as an "Affiliate Agreement"),
executed and delivered by each officer and director of IMA and each other holder
of securities of IMA who, in the opinion of counsel for ITI, after review of
opinions of counsel for IMA, is or may be an "affiliate" of IMA within the
meaning of Rule 145 under the Securities Act, to the effect set forth in Exhibit
J, stating that:
 
               (i)  no disposition shall be made by such "affiliate" of shares
     of ITI Common Stock, except in accordance with the applicable provisions of
     the Securities Act and the rules and regulations thereunder; and
 
               (ii) the certificates evidencing such shares received pursuant to
     the Merger shall bear a legend setting forth such restrictions in a form
     satisfactory to ITI.
 
        (b)  ITI shall also have received from IMA or from the stockholders of
IMA, as the case may be, representations with respect to such other matters as
ITI reasonably may require in order to be assured that the Merger will
constitute a tax-free reorganization under Section 368 of the Code.
 
     11.5  Kalishman and Affholder Agreements.
 
     Robert W. Affholder shall have executed and delivered to ITI an agreement
in the form thereof contained in Exhibit K attached hereto, dated the Closing
Date, and Jerome Kalishman shall have executed and delivered to ITI the
agreements in the respective forms thereof attached hereto as Exhibit L attached
hereto, in each case dated the Closing Date.
 
     11.6  Dissenters' Rights.
 
     The holders of not more than 5% of the outstanding shares of IMA Common
Stock shall, at the Closing Date, be entitled to demand payment of the fair
value of their shares as dissenting shareholders.
 
     11.7  Third Party Consents.
 
     All notices to, and declarations, filings and registrations with, and
consents, authorizations, approvals and waivers from, governmental and
regulatory bodies required to consummate the transactions contemplated hereby
shall have been made or obtained, and all other notices, consents or waivers
with respect to the transactions contemplated by this Agreement shall have been
made or obtained.
 
     11.8  Resignations.
 
     ITI shall have received the resignations of all such officers and directors
of IMA and each Subsidiary requested by it.
 
     11.9  Fairness Opinion.
 
     ITI shall have received from Merrill Lynch & Co. on or prior to the date of
mailing of the Joint Proxy Statement its opinion that the terms of the Merger
are fair to the holders of ITI Common Stock from a financial point of view, and
such opinion shall not have been withdrawn between the date of its delivery and
the Effective Time.
 
     11.10  Letter of Accountants for IMA and Enviroq.
 
     ITI shall have received a letter of KPMG Peat Marwick LLP, IMA's
independent auditors, and Deloitte & Touche, L.L.P., Enviroq's independent
auditors, each dated the Closing Date, addressed to ITI, in form and substance
reasonably satisfactory to ITI and counsel for ITI, making the statements
required by Paragraph (d) of Section 7.5, on the basis of procedures set forth
therein carried out by them, respectively, not more than three business days
prior to the Closing Date.
 
                                       34

 
<PAGE>   42
 
     11.11  A-Y-K-E Equipment.
 
     IMA or Affholder, Inc. shall have entered into arrangements, reasonably
satisfactory to ITI, with respect to: (x) the purchase, at fair market value
determined by an independent appraiser qualified in such matters and reasonably
satisfactory to ITI, or (y) the long-term lease, at fair market rental rates
determined by an appraiser as aforesaid, which at the option of ITI may be on a
non-exclusive basis and from time to time, and terminable by IMA on the same or
substantially similar basis as is contained in the arrangements currently in
effect, or (z) the modification of the arrangements currently in effect pursuant
to terms reasonably satisfactory to ITI, in each case under clauses (x), (y) and
(z) immediately preceding with respect to such equipment covered by the
Equipment Lease dated October 10, 1989, as from time to time supplemented,
between Affholder, Inc. and A-Y-K-E Partnership and such other equipment, tools,
machinery, supplies and other properties owned or controlled by said partnership
and used, useable or useful in the business of IMA or any Subsidiary thereof, as
shall in each case be identified by ITI.
 
     11.12  Litigation.
 
     No action, suit or proceeding against any party hereto relating to the
consummation of any of the transactions contemplated in this Agreement or any
governmental action seeking to delay or enjoin any such transactions shall be
pending or threatened and no investigation by any governmental or regulatory
body shall have been commenced (and be pending), seeking to restrain or prohibit
(or questioning the validity or legality of) the consummation of the
transactions contemplated by this Agreement, including the Merger, or seeking
material damages in connection therewith which ITI, in good faith and with the
advice of Messrs. Krugman, Chapnick & Grimshaw, reasonably believes makes it
undesirable to proceed with the consummation of the transactions contemplated
hereby.
 
     11.13  Other Certificates.
 
     ITI shall have received such additional certificates, instruments and other
documents, in form and substance satisfactory to ITI and counsel for ITI, as it
shall have reasonably requested in connection with the transactions contemplated
hereunder.
 
                                  ARTICLE XII
 
                                  TERMINATION
 
     12.1  Termination.
 
     This Agreement may be terminated and the Merger abandoned at any time prior
to the Effective Time, whether prior to or after approval by the stockholders of
either IMA or ITI, by the consent of all parties hereto, or by either IMA or ITI
if: (i) the other party shall have breached in any material respect any of its
representations or warranties contained in this Agreement; (ii) any such
representation or warranty shall not be correct or accurate in all material
respects at and as of the Closing Date with the same effect as if made at such
time (with such exceptions as are permitted by Sections 10.2 and 11.2,
respectively); (iii) the other party shall have failed to comply in all material
respects with any of its covenants or agreements contained in this Agreement to
be complied with or performed by it at or prior to the Closing; (iv) at the
stockholders meeting (including any adjournment or postponement thereof) of the
other party called pursuant to Section 7.1 or 7.2, as the case may be, or any
successor meeting called for the same purpose, the requisite affirmative
approval of the stockholders of the other party shall not have been obtained;
(v) if a permanent injunction is entered, enforced or deemed applicable to this
Agreement, or the Plan of Merger, which prohibits the consummation of the
transactions contemplated hereby and thereby and all appeals of such injunction
shall have been taken and shall have been unsuccessful; (vi) if any governmental
entity, the consent of which is a condition to the obligation of such party to
consummate the transactions contemplated hereby, shall have determined not to
grant its consent and all appeal of such determination shall have been taken and
shall have been unsuccessful; or (vii) the Closing shall not have occurred on or
prior to January 31, 1996.
 
                                       35

 
<PAGE>   43
 
     12.2  Effect of Termination.
 
     In the event of termination of this Agreement pursuant to Section 12.1
hereof, all rights of all parties hereto shall cease and terminate, except for
such rights as any party may otherwise have for breach of contract (other than
breaches which are not willful), including, without limitation, rights for any
such breaches of any representations, warranties or covenants contained herein,
and, provided that the provisions of this Section 12.2 and Sections 7.11(c),
13.3, 13.7 and 13.8 shall survive any such termination.
 
                                  ARTICLE XIII
 
                                 MISCELLANEOUS
 
     13.1  Notices.
 
     All notices, requests or instruction hereunder shall be in writing and
delivered personally or sent by registered or certified mail, postage prepaid or
by telecopy (or like transmission), as follows:
 
                            (1) if to IMA:
 
                               17988 Edison Avenue
                               Chesterfield, Missouri 63005-3700
 
                               Attention: Chairman
 
                               Fax: (314) 537-1214
 
                               with a copy to:
 
                               Thomas A. Litz, Esq.
                               Thompson & Mitchell
                               One Mercantile Center
                               St. Louis, Missouri 63101
 
                               Fax: (314) 342-1717
 
                            (2) if to ITI or Acquisition Sub:
 
                               1770 Kirby Parkway
                               Suite 300
                               Memphis, Tennessee 38138
 
                               Attention: President and Chief Executive
                                         Officer
 
                               Fax: (901) 759-7513
 
                               with a copy to:
 
                               Howard Kailes, Esq.
                               Krugman, Chapnick & Grimshaw
                               Park 80 West -- Plaza Two
                               Saddle Brook, New Jersey 07663
 
                               Fax: (201) 845-9627
 
Any of the above addresses may be changed at any time by notice given as
provided above; provided, however, that any such notice of change of address
shall be effective only upon receipt. All notices and other communications given
to any party hereto in accordance with the provisions hereof shall be deemed to
have been given on the date of receipt, provided that any notice or other
communication that is received other than during regular business hours of the
recipient shall be deemed to have been given at the opening of business on the
next business day of the recipient.
 
                                       36

 
<PAGE>   44
 
     13.2  Survival of Representations.
 
     The respective representations and warranties of the parties contained in
this Agreement shall not be deemed waived or otherwise affected by any
investigation of any party. The representations, warranties, covenants and
agreements of the parties hereto herein contained in Articles I, II and III and
Sections 7.3, 7.16 and 7.17 of this Agreement shall survive the Effective Time.
All other representations, warranties, covenants and agreements in and pursuant
to this Agreement shall not survive the Effective Time.
 
     13.3  Cooperation Agreement.
 
     The parties acknowledge and agree, on behalf of themselves and their
subsidiaries, respectively, that: (x) ITI, IMA and Enviroq have entered into an
Amended and Restated Cooperation Agreement dated April 28, 1995 (hereinafter
referred to as the "Cooperation Agreement"); (y) the Cooperation Agreement shall
extend in full force and effect through the Effective Time or such earlier date
as shall occur upon the termination of this Agreement; and (z) without limiting
any provision contained in the Cooperation Agreement, neither the execution and
delivery of this Agreement, nor the performance hereof, shall operate as a
waiver of any right, power or privilege subject to the Cooperation Agreement,
and none of such execution, performance nor delivery shall prejudice the rights
of any party hereto with respect to the subject matter of the Cooperation
Agreement.
 
     13.4  Entire Agreement.
 
     This Agreement and the documents referred to herein (including, without
limitation, the Confidentiality Agreement and the Cooperation Agreement),
together with the letter dated this date with respect to the Cooperation
Agreement, contain the entire agreement between the parties hereto with respect
to the transactions contemplated hereby, and supersede all prior understandings,
arrangements and agreements with respect to the subject matter hereof. No
modification hereof shall be effective unless in writing and signed by the party
against which it is sought to be enforced.
 
     13.5  Modification.
 
     At any time prior to the Effective Time, the parties hereto may, by written
agreement, make any modification or amendment of this Agreement approved by
their respective Boards of Directors; provided however, that the per share
number of shares of ITI Common Stock to be received by holders of the IMA Common
Stock in the Merger, as set forth in Article II hereof, shall not be amended or
modified without the approval of such holders at any time after such holders
have approved this Agreement, and any and all such modifications and amendments
shall conform to the requirements of the GCL.
 
     13.6  Further Action.
 
     Each of the parties hereto shall use such party's reasonable best efforts
to take such actions as may be necessary or reasonably requested by the other
parties hereto to carry out and consummate the transactions contemplated by this
Agreement.
 
     13.7  Expenses.
 
     Each of the parties hereto shall bear such party's own expenses in
connection with this Agreement and the transactions contemplated hereby.
 
     13.8  Governing Law.
 
     This Agreement shall be governed by and construed in accordance with the
laws of the State of Delaware applicable in the case of agreements made and to
be performed entirely within such State.
 
     13.9  Captions.
 
     The captions appearing herein are for the convenience of the parties only
and shall not be construed to affect the meaning of the provisions of this
Agreement.
 
                                       37

 
<PAGE>   45
 
     13.10  Accounting Terms.
 
     All accounting terms used herein which are not expressly defined in this
Agreement shall have the respective meanings given to them in accordance with
generally accepted accounting principles on the date hereof.
 
     13.11  Specific Performance.
 
     ITI, Acquisition Sub and IMA recognize that any breach of the terms of this
Agreement may give rise to irreparable harm for which money damages would not be
an adequate remedy, and accordingly agree that, in addition to other remedies,
any nonbreaching party shall be entitled to an injunction or injunctions to
prevent breaches of the provisions of this Agreement and to enforce the terms
and provisions of this Agreement and the Plan of Merger by a decree of specific
performance in any action instituted in any court of the United States or any
state hereof having jurisdiction without the necessity of proving the inadequacy
as a remedy of money damages.
 
     13.12  Assignment.
 
     This Agreement and all of the provisions hereof shall be binding upon and
inure to the benefit of the parties hereto and their respective successors and
permitted assigns, but neither this Agreement nor any of the rights, interests,
or obligations hereunder may be assigned by any of the parties hereto without
the prior written consent of the other parties and any such attempted assignment
without consent shall be void.
 
     13.13  No Third Party Beneficiary.
 
     This Agreement is not intended, and shall not be construed, to confer any
rights or remedies hereunder upon any party other than the parties hereto and
those parties designated as directors pursuant to Section 7.3 and those parties
entitled to indemnification under Section 7.16, which parties shall be entitled
to enforce their rights under such provisions to which they are entitled to
benefits.
 
     13.14  Partial Invalidity.
 
     Any term or provision of this Agreement that is invalid or unenforceable in
any jurisdiction shall, as to such jurisdiction, be ineffective to the extent of
such invalidity or unenforceability without rendering invalid or unenforceable
the remaining terms and provisions of this Agreement, or any such terms in any
other jurisdiction. If any provision of this Agreement is so broad as to be
unenforceable, such provision shall be interpreted to be only so broad as is
enforceable.
 
     13.15  Counterparts.
 
     This Agreement may be executed in counterparts, each of which shall be
deemed an original, but all of which taken together shall constitute one and the
same instrument.
 
                                       38

 
<PAGE>   46
 
     IN WITNESS WHEREOF, this Agreement has duly executed by the parties hereto
as of the date first above written.
 
<TABLE>
<S>                                               <C>
ATTEST:                                           INSITUFORM MID-AMERICA, INC.
 
/s/  JOSEPH A. OLSON                              By /s/  JEROME KALISHMAN
- ---------------------------------------------        ------------------------------------------
Vice President-Finance and Administration            Chairman
 
ATTEST:                                           INSITUFORM TECHNOLOGIES,INC.
 
/s/  HOWARD KAILES                                By /s/  JEAN-PAUL RICHARD
- ---------------------------------------------        ------------------------------------------
Secretary                                            President
 
ATTEST:                                           ITI ACQUISITION CORP.
 
/s/  HOWARD KAILES                                By /s/  JEAN-PAUL RICHARD
- ---------------------------------------------        ------------------------------------------
Assistant Secretary                                  President
</TABLE>
 
                                       39

 
<PAGE>   47

 
                                                                       EXHIBIT A
 
                              AGREEMENT OF MERGER
 
     This Agreement of Merger dated as of           , 1995 (hereinafter referred
to as the "Plan of Merger"), pursuant to Section 251 of the Delaware General
Corporation Law, as amended (hereinafter referred to as the "GCL"), is entered
into by and among INSITUFORM MID-AMERICA, INC., a corporation organized and
existing under the laws of the State of Delaware (hereinafter referred to as
"IMA"); ITI Acquisition Corp., a corporation organized and existing under the
laws of the State of Delaware (hereinafter referred to as "Acquisition Sub"; IMA
and Acquisition Sub being hereinafter sometimes collectively referred to as the
"Constituent Corporations"); and INSITUFORM TECHNOLOGIES, INC., a corporation
organized and existing under the laws of the State of Delaware, as a third party
hereto (hereinafter referred to as "ITI").
 
                                  WITNESSETH:
 
     WHEREAS, Acquisition Sub is a corporation duly organized and existing under
the laws of the State of Delaware, having been incorporated on March 16, 1995,
and having an authorized capital stock of 10,000 shares of common stock, $.01
par value (the "Acquisition Sub Common Stock"), of which 1,000 shares are issued
and outstanding and held by ITI; and
 
     WHEREAS, IMA is a corporation duly organized and existing under the laws of
the State of Delaware, having been incorporated on December 22, 1983, and having
an authorized capital stock consisting of 500,000 shares of preferred stock,
$.01 par value, none of which are presently issued and outstanding; 10,000
shares of convertible preferred stock, $100 per value, none of which are
presently issued and outstanding; 500 shares of class A convertible preferred
stock, $1,000 per value, none of which are presently issued and outstanding;
10,000,000 shares of class A common stock, $.01 par value (hereinafter referred
to as the "IMA Class A Common Stock"), of which           shares are presently
issued and outstanding; and 6,000,000 shares of class B common stock, $.01 par
value, none of which are presently issued and outstanding; and
 
     WHEREAS, the respective Boards of Directors of the parties deem it
advisable and in the best interests of said corporations that Acquisition Sub be
merged (hereinafter referred to as the "Merger") with and into IMA as authorized
by the State of Delaware, under and pursuant to the terms and conditions
hereinafter set forth, as a result of which IMA will become a wholly-owned
subsidiary of ITI; and
 
     WHEREAS, the respective Boards of Directors of Acquisition Sub and IMA
have, by resolutions duly adopted, approved and adopted this Plan of Merger; and
 
     WHEREAS, the respective Boards of Directors of Acquisition Sub and IMA have
directed that this Plan of Merger be submitted to a vote of their respective
stockholders, and the respective stockholders of Acquisition Sub and IMA have,
by resolutions duly adopted, approved and adopted this Plan of Merger;
 
     NOW, THEREFORE, in consideration of the premises and the mutual covenants
and agreements herein contained, and for the purpose of setting forth the terms
and conditions of said merger, the mode of carrying the same into effect, the
manner and basis of converting the shares of Acquisition Sub into shares of the
Surviving Corporation (as hereinafter defined), and the shares of IMA into
shares of the class A common stock, $.01 par value (hereinafter referred to as
the "ITI Common Stock"), of ITI, and such other details and provisions as are
deemed necessary or advisable, the parties hereto have agreed and do hereby
agree, subject to the conditions hereinafter set forth, as follows:
 
                                   ARTICLE I
 
                    MERGER AND NAME OF SURVIVING CORPORATION
 
     At the Effective Time (as defined in Article VII hereof), in accordance
with the terms and provisions of this Agreement and in accordance with the GCL,
Acquisition Sub shall be merged into and with IMA. As a result of the Merger,
the separate corporate existence of Acquisition Sub shall cease and IMA shall
continue
 
                                        1

 
<PAGE>   48
 
as the surviving corporation, governed by the laws of the State of Delaware,
under the corporate name it possesses immediately prior to the Effective Time.
IMA, from and after the Effective Time, is hereinafter sometimes referred to as
the "Surviving Corporation".
 
                                   ARTICLE II
 
                         TERMS AND CONDITIONS OF MERGER
 
     The terms and conditions of the Merger are (in addition to those set forth
elsewhere in this Plan of Merger) as follows:
 
        (a)  At the Effective Time, the Surviving Corporation shall possess all
the rights, privileges, powers and franchises, as well as of a public or of a
private nature, of the Constituent Corporations. All of the rights, privileges,
powers and franchises, and all property, real and personal, and all debts due on
whatever account to each of the Constituent Corporations, shall be taken and
deemed to be transferred to and vested in the Surviving Corporation without
further act or deed; and all of the property, rights, privileges, powers,
franchises and all and every other interest of each of the Constituent
Corporations thereafter shall be vested as effectively and fully in the
Surviving Corporation as they were in each of the Constituent Corporations.
 
        (b)  The Surviving Corporation shall be responsible and liable for all
of the liabilities, obligations and penalties of each of the Constituent
Corporations; provided, however, that the liabilities, obligations and penalties
of the Constituent Corporations shall not be affected by the Merger, and that
the rights of the creditors of the Constituent Corporations, or any liens upon
the property of the Constituent Corporations shall not be impaired by the
Merger, and any claim existing or action or proceeding, civil or criminal,
pending by or against the Constituent Corporations may be prosecuted to judgment
as if the Merger had not taken place, or the Surviving Corporation may be
proceeded against or substituted in the place of the Constituent Corporations.
 
        (c)  At the Effective Time and until their successors have been duly
elected and have qualified, the Board of Directors of the Surviving Corporation
shall consist of James D. Krugman, Jean-Paul Richard and William A. Martin; and,
at the Effective Time and until their successors have been duly elected and have
qualified, the officers of the Surviving Corporation shall be as follows:
 
<TABLE>
<CAPTION>
                                    NAME                                OFFICE
            ----------------------------------------------------   -----------------
            <S>                                                    <C>
            Jean-Paul Richard...................................   President
            William A. Martin...................................   Vice President
            William A. Martin...................................   Secretary
</TABLE>
 
                                  ARTICLE III
 
                              CONVERSION OF SHARES
 
     The manner and basis of converting in the Merger the outstanding shares of
IMA Class A Common Stock and Acquisition Sub Common Stock into shares of the
capital stock of the Surviving Corporation are as follows:
 
        (a)  Each share of the Acquisition Sub Common Stock issued and
outstanding immediately prior to the Effective Time shall, by virtue of the
Merger and without any action by the holder thereof, be deemed cancelled and
converted into and shall represent and be exchanged for the right to receive one
validly issued, fully-paid and non-assessable share of the class A common stock,
$.01 par value (hereinafter referred to as the "Surviving Common Stock"), of the
Surviving Corporation.
 
        (b)  Each share of the IMA Class A Common Stock issued and outstanding
immediately prior to the Effective Time (other than Dissenting Shares [as
defined and to the extent provided in Paragraph (a) of Article IV hereof], if
any) shall, by virtue of the Merger and without any action by the holder
thereof, be
 
                                        2

 
<PAGE>   49
 
        deemed cancelled and converted into and shall represent the right to
receive 1.15 shares of ITI Common Stock.
 
        (c)  Solely to avoid the expense and inconvenience to ITI and
Acquisition Sub, and not as separately bargained for consideration, no
fractional shares of ITI Common Stock shall be issued in the Merger and no
dividend, stock split or interest shall relate to any such fractional shares,
and such fractional shares shall not entitle the owner thereof to any rights of
a security holder. In lieu of issuing certificates for fractional shares of ITI
Common Stock, the Exchange Agent (as hereinafter defined) shall, on behalf of
all holders of such fractional shares, on or before the tenth day following the
Effective Time, aggregate all such fractional shares and sell the resulting
shares of ITI Common Stock for the accounts of holders of such respective
fractional shares, and such holders shall thereafter be entitled to receive on a
pro rata basis the net proceeds of the sale thereof, without interest thereon,
upon the surrender of all of such holder's certificates for exchange pursuant to
the provisions hereinafter set forth.
 
        (d)  All options (hereinafter referred to as the "IMA Options") to
acquire IMA Class A Common Stock outstanding, whether or not exercisable at the
Effective Time, under the Insituform Mid-America, Inc. Stock Option Plan
(hereinafter referred to as the "IMA Option Plan"), shall remain outstanding
following the Effective Time. At the Effective Time, the IMA Options shall, by
virtue of the Merger and without any further action on the part of IMA or the
holder thereof, be assumed by ITI in such manner that ITI: (i) is a corporation
"assuming a stock option in a transaction to which Section 424(a) applies"
within the meaning of Section 424 of the United States Internal Revenue Code of
1986, as amended; or (ii) to the extent that Section 424 of the Code does not
apply to any such IMA Options, would be such a corporation were Section 424 of
the Code applicable to such IMA Options. From and after the Effective Time, all
references to IMA in the IMA Stock Option Plan and the applicable stock option
agreements issued thereunder shall be deemed to refer to ITI, except that each
reference to the name of such plan therein shall be deemed a reference to the
"Insituform Mid-America, Inc. Stock Option Plan", and provided that each
reference to the "Stock Option Committee" or "Committee" therein shall be deemed
a reference to ITI's Compensation Committee. Each IMA Option assumed by ITI
shall be exercisable upon the same terms and conditions as under the IMA Stock
Option Plan and the applicable option agreement issued thereunder, except that:
 
             (A)  each such IMA Option shall be exercisable for that whole
        number of shares of ITI Common Stock (rounded to the nearest whole
        share) into which the number of shares of IMA Class A Common Stock
        subject to such IMA Option immediately prior to the Effective Time would
        be convertible under this Article III if such shares were outstanding at
        the Effective Time; and
 
             (B)  the option price per share of ITI Common Stock shall be an
        amount equal to the quotient obtained by dividing (x) the product
        obtained by multiplying the exercise price per share of IMA Class A
        Common Stock subject to such IMA Option in effect immediately prior to
        the Effective Time by the number of shares of IMA Class A Common Stock
        subject to such option immediately prior to the Effective Time, by (y)
        the number of shares of ITI Common Stock covered by the option as so
        assumed (the option price as so determined being rounded upward to the
        nearest full cent).
 
No payment or adjustment shall be made for fractional shares which otherwise
would be issuable upon exercise of any IMA Option assumed as aforesaid.
 
        (e)  The Merger shall effect no change in any shares of ITI Common Stock
issued by ITI prior to the Effective Time.
 
                                   ARTICLE IV
 
                               DISSENTING SHARES;
                            EXCHANGE OF CERTIFICATES
 
        (a)  Notwithstanding anything in this Plan of Merger to the contrary,
shares of IMA Common Stock which are issued and outstanding immediately prior to
the Effective Time and which are held by
 
                                        3

 

<PAGE>   50
 
stockholders who have not voted such shares in favor of the Merger and, if
entitled to elect to demand the appraisal of such shares pursuant to Section 262
of the GCL, shall have delivered a written demand for payment of the fair value
of such shares within the time and in the manner provided in Section 262 of the
GCL (herein referred to as "Dissenting Shares") shall not be converted into or
be exchangeable for the right to receive the consideration provided in Article
III of this Plan of Merger, unless and until such holder shall have failed to
perfect or shall have effectively withdrawn or lost his right to appraisal and
payment under the GCL. If any such holder shall have so failed to perfect or
shall have effectively withdrawn or lost such right, such holder's shares of IMA
Common Stock shall thereupon be deemed to have been converted into and to have
become exchangeable for, at the Effective Time, the right to receive the
consideration therefor specified under Article III hereof, without any interest
thereon.
 
        (b)  Prior to the Effective Time, Acquisition Sub shall designate
American Stock Transfer & Trust Company, or, at its election, a bank or trust
company or similar entity, reasonably satisfactory to IMA, which is authorized
to exercise corporate trust or stock powers, to act as the exchange agent
(hereinafter referred to as the "Exchange Agent") in the Merger. Promptly after
the Effective Time, ITI shall cause the delivery to the Exchange Agent of
certificates evidencing the shares of ITI Common Stock contemplated to be issued
by Article III hereof.
 
        (c)  As soon as practicable after the Effective Time, but in no event
later than 15 business days after the Effective Time, the Exchange Agent shall
send a notice and transmittal form to each holder of a certificate theretofore
evidencing shares of IMA Class A Common Stock, advising such holders of the
terms of the exchange effected by the Merger and the procedure for surrendering
to the Exchange Agent (who may appoint forwarding agents with the approval of
ITI) such record holder's certificate(s) evidencing IMA Class A Common Stock for
exchange for certificates evidencing shares of ITI Common Stock. Each holder of
a certificate theretofore evidencing shares of IMA Class A Common Stock, upon
surrender of the same to the Exchange Agent in accordance with such transmittal
form, shall be entitled to receive, in exchange for such certificate, a
certificate evidencing the number of full shares of ITI Common Stock for which
the shares of IMA Class A Common Stock theretofore represented by the
certificate so surrendered shall have been exchanged pursuant to Article III
hereof and the cash in lieu of fractional shares hereinabove contemplated, and
the certificate so surrendered shall forthwith be cancelled.
 
        (d)  If any certificate evidencing shares of ITI Common Stock is to be
issued in a name other than that in which the certificate surrendered in
exchange therefor is registered, or if any payment of cash is to be made to a
person other than the person in whose name such certificate is registered, it
shall be a condition of the issuance thereof or such payment, as the case may
be, that the certificate so surrendered shall be properly endorsed and otherwise
in proper form for transfer and that the person requesting such exchange (i) pay
to the Exchange Agent any transfer or other taxes required by reason of the
issuance of a certificate for shares of ITI Common Stock in any name other than
that of, and payment of cash to a person other than, the registered holder of
the certificate surrendered or (ii) establish to the satisfaction of the
Exchange Agent that such transfer or other taxes have been paid or are not
applicable. Certificates representing shares of ITI Common Stock issued to IMA
"affiliates", within the meaning of Rule 145 under the Securities Act of 1933,
as amended, shall bear a legend to the effect that no disposition shall be made
by such "affiliate" of shares of ITI Common Stock, except in accordance with the
applicable provisions of said Act and the rules and regulations thereunder.
 
        (e)  In the event any certificate representing any shares of IMA Class A
Common Stock shall have been lost, stolen or destroyed, upon the making of an
affidavit of that fact by the person claiming such certificate to be lost,
stolen or destroyed, the Exchange Agent shall issue in exchange for such lost,
stolen or destroyed certificate the consideration payable in exchange therefor
pursuant to Article III. The Exchange Agent or the Surviving Corporation may, in
its discretion and as a condition precedent to the issuance thereof, require the
owner of such lost, stolen or destroyed certificate to give the Exchange Agent a
bond in such reasonable sum as it may direct as indemnity against any claim that
may be made against the Surviving Corporation with respect to the certificate
alleged to have been lost, stolen or destroyed.
 
                                        4

 
<PAGE>   51
 
        (f)  No dividends or other distributions to holders of ITI Common Stock
as of any date subsequent to the Effective Time shall be paid to the holders of
outstanding certificates formerly representing shares of IMA Class A Common
Stock until such certificates are so surrendered. Subject to the effect, if any,
of applicable law upon surrender of certificates evidencing shares of IMA Class
A Common Stock, there shall be paid to the record holders of ITI Common Stock
issued in exchange therefor (i) the amount of dividends or other distributions
with a record date for payment after the Effective Time that have theretofore
been paid with respect to full shares of ITI Common Stock as of any date
subsequent to the Effective Time which have not yet been paid to a public
official pursuant to abandoned property laws and (ii) at the appropriate payment
date, the amount of dividends or other distributions with a record date after
the Effective Time but prior to surrender and a payment date subsequent to
surrender. No interest shall be payable with respect to the payment of such
dividends or other distributions on surrender of outstanding certificates.
Notwithstanding the foregoing, neither ITI, Acquisition Sub, the Exchange Agent
nor any other party hereto shall be responsible or liable to any holder of
shares of IMA Class A Common Stock for any ITI Common Stock, or dividends or
distributions thereon or cash, including cash in lieu of fractional share
interests, delivered to any public official pursuant to applicable escheat laws.
 
        (g)  At the Effective Time, it shall be deemed that the stock transfer
books of IMA are closed, and no transfer of IMA Class A Common Stock on the
books of IMA shall thereafter be made or consummated. Until surrendered and
exchanged in accordance with the provisions hereinabove set forth, the
outstanding certificates evidencing shares of IMA Class A Common Stock
immediately prior to the Effective Time shall, from and after the Effective
Time, be deemed for all corporate purposes to evidence the right to receive the
number of shares of ITI Common Stock, together with cash in lieu of fractional
shares, into which the shares of IMA Class A Common Stock theretofore evidenced
by such certificate or certificates shall have been so converted, together with
any dividends or other distributions thereon pursuant to paragraph (f)
immediately preceding, as though such surrender and exchange had taken place.
 
        (h)  Any portion of the shares of ITI Common Stock or cash in lieu of
fractional shares, which remains undistributed to the holders of IMA Class A
Common Stock for one year after the Effective Time shall be delivered to ITI,
upon demand, and any holders of IMA Class A Common Stock who have not
theretofore complied with the provisions herein set forth shall thereafter look
only to ITI for the shares of ITI Common Stock, any cash in lieu of fractional
shares of ITI Common Stock to which they are entitled pursuant to Article III
hereof and any dividends or other distributions with respect to ITI Common Stock
to which they are entitled pursuant to paragraph (f) immediately preceding. Any
portion of such remaining shares or cash unclaimed by holders of IMA Class A
Common Stock as of a date which is immediately prior to such time as such shares
or amounts would otherwise escheat to or become property of any governmental
entity shall, to the extent permitted by applicable law, become the property of
ITI free and clear of any claims or interest of any person previously entitled
thereto.
 
                                   ARTICLE V
 
                    CERTIFICATE OF INCORPORATION AND BYLAWS
 
        (a)  The certificate of incorporation of IMA as in effect immediately
prior to the Effective Time shall, at the Effective Time, be and constitute the
certificate of incorporation of the Surviving Corporation until thereafter
amended in accordance with the provisions thereof and applicable law.
 
        (b)  The By-laws of IMA as in effect immediately prior to the Effective
Time shall, at the Effective Time, be and constitute the By-laws of the
Surviving Corporation until thereafter amended in accordance with the provisions
thereof or applicable law.
 
                                        5

 
<PAGE>   52
 
                                   ARTICLE VI
 
                    OTHER PROVISIONS WITH RESPECT TO MERGER
 
        (a)  For the convenience of the parties and to facilitate the filing and
recording of the Merger Agreement, any number of counterparts hereof may be
executed, and each such counterpart shall be deemed to be an original
instrument, but all such counterparts together shall constitute but one
agreement.
 
        (b)  The Merger Agreement and the legal relations between the parties
hereto shall be governed by and construed in accordance with the laws of the
State of Delaware.
 
        (c)  From time to time, as and when required by the Surviving
Corporation or by its successors or assigns, there shall be executed and
delivered on behalf of Acquisition Sub such deeds and other instruments, and
there shall be taken or caused to be taken by it all such further and other
action, as shall be appropriate, advisable or necessary in order to vest,
perfect or confirm, of record or otherwise, in the Surviving Corporation the
title to and possession of all property, interests, assets, rights, privileges,
immunities, powers, franchises and authority of Acquisition Sub and otherwise to
carry out the purposes of this Merger Agreement, and the officers and directors
of the Surviving Corporation are fully authorized in the name and on behalf of
Acquisition Sub or otherwise, to take any and all such action and to execute and
deliver any and all such deeds and other instruments.
 
                                  ARTICLE VII
 
                                 EFFECTIVE TIME
 
     The Merger shall become effective at the time of filing of a Certificate of
Merger with respect to the Merger, setting forth the information required, in
the office of the Secretary of State of the State of Delaware, as required by
the GCL. Such time is herein referred to as the "Effective Time."
 
     IN WITNESS WHEREOF, Acquisition Sub and IMA, ITI (as a third party), have
caused this Merger Agreement to be executed and delivered as of the date first
above written.
 
                                          INSITUFORM MID-AMERICA, INC.,
                                          a Delaware corporation
 
                                          By
                                          --------------------------------------
                                             Chairman
 
                                          --------------------------------------
                                             Secretary
 
                                          ITI ACQUISITION CORP.,
                                          a Delaware corporation
 
                                          By
                                          --------------------------------------
                                             President
 
                                          --------------------------------------
                                             Secretary
 
                                        6


 
<PAGE>   53
 
                                          INSITUFORM TECHNOLOGIES, INC.,
                                          a Delaware corporation
 
                                          By
                                          --------------------------------------
                                             President
 
                                          --------------------------------------
                                             Secretary
 
                                        7

 
<PAGE>   54
 
                                                                       EXHIBIT B
 
                                                                          , 1995
 
Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee 38138
 
Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005
 
Gentlemen:
 
     In furtherance of the Agreement and Plan of Merger dated May 23, 1995 (the
"Agreement") among Insituform Technologies, Inc., a Delaware corporation (the
"Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for the
sale, transfer, pledge, hypothecation, conveyance or other disposition of any
shares of Class A Common Stock, $.01 par value ("IMA Class A Common Stock"), of
IMA, any shares of Class B Common Stock $.01 par value ("IMA Class B Common
Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value (the "ITI
Common Stock"), of the Company, owned by the undersigned from the date hereof
until the earlier of (i) the termination of the Agreement or (ii) the date of
the first publication of the operating results of the Company covering at least
a 30-day period after the merger of IMA and ITI Sub has been consummated,
without the prior written consent of the Company, except that the undersigned
may convert any shares of IMA Class B Common Stock into shares of IMA Class A
Common Stock prior to the consummation of the transactions contemplated by the
Agreement.
 
     In order to enable you to enforce the aforesaid covenant, the undersigned
hereby consents to placing stop-transfer orders with the transfer agents,
respectively, of the IMA Class A Common Stock, with respect to any of the IMA
Class A Common Stock registered in the name of the undersigned or beneficially
owned by the undersigned, and with the transfer agent of the IMA Class B Common
Stock, with respect to any of the IMA Class B Common Stock registered in the
name of the undersigned or beneficially owned by the undersigned, and with the
transfer agent of the ITI Common Stock, with respect to any of the ITI Common
Stock registered in the name of the undersigned or beneficially owned by the
undersigned.
 
                                          --------------------------------------
 
                                       1

 
<PAGE>   55
 
                                                                     EXHIBIT C-1
 
     The letter to be delivered to ITI from IMA's independent auditors referred
to in Section 7.5(d) of the Agreement shall be in form and substance reasonably
satisfactory to ITI and contain statements by such auditors to the effect that:
 
     (1)  They are independent certified public accountants with respect to IMA
within the meaning of the Securities Act and the applicable published rules and
regulations thereunder.
 
     (2)  In their opinion, the consolidated financial statements and financial
statement schedules audited by them and included or incorporated by reference in
the Registration Statement comply as to form in all material respects with the
applicable accounting requirements of the Securities Act and the Exchange Act
and the related published rules and regulations.
 
     (3)  They have read the minutes of meetings of the stockholders and the
boards of directors of IMA and its subsidiaries for the period from the date of
the most recent financial statements of IMA included or incorporated by
reference in the Registration Statement to such date not more than five business
days prior to the date when the Registration Statement becomes effective; they
have carried out other procedures to a specified date not more than five
business days prior to the date as of when the Registration Statement becomes
effective, which do not constitute an audit in accordance with generally
accepted accounting principles, as follows:
 
          (a)  With respect to the periods covered by the unaudited financial
     statements of IMA and its consolidated subsidiaries included or
     incorporated by reference in the Registration Statement, they have (i)
     performed the procedures specified by the American Institute of Certified
     Public Accountants for a review of interim financial information as
     described in SAS No. 71, "Interim Financial Information," on the most
     recent unaudited condensed consolidated balance sheet, the unaudited
     condensed consolidated statements of income and cash flows, and the most
     recent unaudited condensed consolidated statement of stockholders' equity
     included or incorporated by reference in the Registration Statement; and
     (ii) inquired of certain officials of IMA who have responsibility for
     financial and accounting matters whether the unaudited condensed
     consolidated financial statements referred to in 3(a)(i) comply as to form
     in all material respects with the applicable accounting requirements of the
     Securities Act and the Exchange Act and the related published rules and
     regulations.
 
          (b)  With respect to the period from the date of the most recent
     financial statements of IMA and its consolidated subsidiaries included or
     incorporated by reference in the Registration Statement to the end of the
     next to last month prior to the calendar month in which the Registration
     Statement becomes effective, they have (i) read the unaudited consolidated
     financial statements of IMA and subsidiaries for each month of both (x) the
     current year for which available and (y) the corresponding month of the
     prior year, furnished to us by IMA, officials of IMA having advised them
     that no such financial statements as of any date or for any subsequent
     period were available; and (ii) inquired of certain officials of IMA who
     have responsibility for financial and accounting matters whether the
     unaudited consolidated financial statements referred to in 3(b)(i) are
     stated on a basis substantially consistent with that of the audited
     consolidated financial statements included or incorporated by reference in
     the Registration Statement.
 
     (4)  Nothing came to their attention as a result of the foregoing
procedures that caused them to believe that:
 
          (a)  (i) any material modifications should be made to the unaudited
     condensed consolidated financial statements described in 3(a)(i), included
     or incorporated by reference in the Registration Statement, for them to be
     in conformity with generally accepted accounting principles; or (ii) the
     unaudited condensed consolidated financial statements described in 3(a)(i)
     do not comply as to form in all material respects with the applicable
     accounting requirements of the Securities Act and the Exchange Act and the
     related published rules and regulations.
 
          (b)  (i) as of the end of the next to last month prior to the calendar
     month in which the Registration Statement becomes effective, there was,
     except as set forth in such letter, any change in the
 
                                      1

 
<PAGE>   56
 
     capital stock, increase in long-term debt, or decrease in consolidated net
     current assets or stockholders' equity of the consolidated companies as
     compared with amounts shown in the most recent unaudited condensed
     consolidated balance sheet of IMA included or incorporated by reference in
     the Registration Statement, or (ii) for the period from the date of the
     most recent balance sheet of IMA included or incorporated by reference in
     the Registration Statement to the end of the month immediately preceding
     the date when the Registration Statement becomes effective, unless the
     Registration Statement becomes effective within the first 15 calendar days
     of a month, in which case the end of the next to last month prior to the
     calendar month in which the Registration Statement becomes effective, there
     were, except as set forth in such letter, any decreases, as compared to the
     corresponding period in the preceding year, in consolidated net contract
     revenues or in the total or per-share amounts of income before
     extraordinary items or of net income, except in all instances for changes,
     increases, or decreases that the Registration Statement discloses have
     occurred or may occur.
 
     (5)  They have inquired of certain officials of IMA who have responsibility
for financial and accounting matters whether (a) at a date not more than five
business days prior to the date as of when the Registration Statement becomes
effective, there was any change in the capital stock, increase in long-term debt
or any decreases in consolidated net current assets or stockholders' equity of
the consolidated companies as compared with amounts shown on most recent balance
sheet of IMA included or incorporated by reference in the Registration
Statement, or (b) for the period from the date of the most recent consolidated
balance sheet of IMA included or incorporated by reference in the Registration
Statement to a date not more than five business days prior to the date as of
when the Registration Statement becomes effective, there was any decrease, as
compared with the corresponding period in the preceding year, in consolidated
net contract revenues or in the total or per-share amounts of income before
extraordinary items or of net income; and, on the basis of these inquiries and
their reading of the minutes as described in (3), nothing came to their
attention that caused them to believe that there was, except as set forth in
such letter, any such change, increase, or decrease except in all instances for
changes, increased, or decreases that the Registration Statement discloses have
occurred or may occur.
 
     (6)  They have: (a) read the unaudited pro forma condensed consolidated
balance sheet, and the unaudited pro forma condensed consolidated statements of
income included in the Registration Statement, and (b) inquired of certain
officials of IMA and of ITI who have responsibility for financial and accounting
matters about (i) the basis for their determination of the pro forma
adjustments, and (ii) whether the unaudited pro forma condensed consolidated
financial statements comply as to form in all material respects with the
applicable accounting requirements of Rule 11-02 of Regulation S-X; and (c)
proved the arithmetic accuracy of the application of the pro forma adjustments
to the historical amounts in the unaudited pro forma condensed consolidated
financial statements; and nothing, except as set forth in such letter, came to
their attention as a result of the procedures specified in this paragraph (6)
that caused them to believe that the unaudited pro forma condensed consolidated
financial statements included in the Registration Statement do not comply as to
form in all material respects with the applicable accounting requirements of
Rule 11-02 of Regulation S-X and that the pro forma adjustments have not been
properly applied to the historical amounts in the compilation of those
statements.
 
                                      2

 
<PAGE>   57
 
                                                                     EXHIBIT C-2
 
     The letter to be delivered to ITI from Enviroq's independent auditors
referred to in Section 7.5(d) of the Agreement shall be in form and substance
reasonably satisfactory to ITI and contain statements by such auditors to the
effect that:
 
     (1)  They are independent certified public accountants with respect to
Enviroq within the meaning of the Securities Act and the published rules and
regulations thereunder.
 
     (2)  In their opinion, the consolidated financial statements and financial
statement schedules audited by them and included or incorporated by reference in
the Registration Statement comply as to form in all material respects with the
applicable accounting requirements of the Securities Act and the Exchange Act
and the related published rules and regulations.
 
     (3)  They have read the minutes of meetings of the stockholders and the
boards of directors of Enviroq and its subsidiaries for the period from the date
of the most recent financial statements of Enviroq included or incorporated by
reference in the Registration Statement to such date not more than five business
days prior to the date when the Registration Statement becomes effective; they
have carried out other procedures to a specified date not more than five
business days prior to the date as of when the Registration Statement becomes
effective, which do not constitute an audit in accordance with generally
accepted accounting principles, as follows:
 
          (a)  With respect to the periods covered by the unaudited financial
     statements of Enviroq and its consolidated subsidiaries included or
     incorporated by reference in the Registration Statement, they have (i)
     performed the procedures specified by the American Institute of Certified
     Public Accountants for a review of interim financial information as
     described in SAS No. 71, "Interim Financial Information," on the most
     recent unaudited condensed consolidated balance sheet, the unaudited
     condensed consolidated statements of income and cash flows, and the most
     recent unaudited condensed consolidated statement of stockholders' equity
     included or incorporated by reference in the Registration Statement; and
     (ii) inquired of certain officials of Enviroq who have responsibility for
     financial and accounting matters whether the unaudited condensed
     consolidated financial statements referred to in 3(a)(i) comply as to form
     in all material respects with the applicable accounting requirements of the
     Securities Act and the Exchange Act and the related published rules and
     regulations.
 
          (b)  With respect to the period from the date of the most recent
     financial statements of Enviroq and its consolidated subsidiaries included
     or incorporated by reference in the Registration Statement to the end of
     the period immediately preceding the date of the acquisition of Enviroq by
     IMA, they have (i) read the unaudited consolidated financial statements of
     Enviroq and subsidiaries for each month of both (x) the current year for
     which available and (y) the corresponding month of the prior year,
     furnished to us by Enviroq, officials of Enviroq having advised them that
     no such financial statements as of any date or for any subsequent period
     were available; and (ii) inquired of certain officials of Enviroq who have
     responsibility for financial and accounting matters whether the unaudited
     consolidated financial statements referred to in 3(b)(i) are stated on a
     basis substantially consistent with that of the audited consolidated
     financial statements included or incorporated by reference in the
     Registration Statement.
 
     (4)  Nothing came to their attention as a result of the foregoing
procedures that caused them to believe that:
 
          (a)  (i) any material modifications should be made to the unaudited
     condensed consolidated financial statements described in 3(a)(i), included
     or incorporated by reference in the Registration Statement, for them to be
     in conformity with generally accepted accounting principles; or (ii) the
     unaudited condensed consolidated financial statements described in 3(a)(i)
     do not comply as to form in all material respects with the applicable
     accounting requirements of the Securities Act and the Exchange Act and the
     related published rules and regulations.
 
          (b)  (i) as of the end of the period immediately preceding the
     acquisition of Enviroq by IMA, there was, except as set forth in such
     letter, any change in the capital stock, increase in long-term debt, or
 
                                      1
        
 
<PAGE>   58
 
     decrease in consolidated net current assets or stockholders' equity of the
     consolidated companies as compared with amounts shown in the most recent
     unaudited condensed consolidated balance sheet of Enviroq included or
     incorporated by reference in the Registration Statement, or (ii) for the
     period from the date of the most recent balance sheet of Enviroq included
     or incorporated by reference in the Registration Statement to the end of
     the month immediately preceding the acquisition of Enviroq by IMA, there
     were, except as set forth in such letter, any decreases, as compared to the
     corresponding period in the preceding year, in consolidated net contract
     revenues or in the total or per-share amounts of income before
     extraordinary items or of net income, except in all instances for changes,
     increases, or decreases that the Registration Statement discloses have
     occurred.
 
     (5)  They have: (a) read the unaudited pro forma condensed consolidated
balance sheet, and the unaudited pro forma condensed consolidated statements of
income included in the Registration Statement, and (b) inquired of certain
officials of Enviroq, IMA and of ITI who have responsibility for financial and
accounting matters about (i) the basis for their determination of the pro forma
adjustments, and (ii) whether the unaudited pro forma condensed consolidated
financial statements comply as to form in all material respects with the
applicable accounting requirements of Rule 11-02 of Regulation S-X; and (c)
proved the arithmetic accuracy of the application of the pro forma adjustments
to the historical amounts in the unaudited pro forma condensed consolidated
financial statements; and nothing, except as set forth in such letter, came to
their attention as a result of the procedures specified in this paragraph (5)
that caused them to believe that the unaudited pro forma condensed consolidated
financial statements included in the Registration Statement do not comply as to
form in all material respects with the applicable accounting requirements of
Rule 11-02 of Regulation S-X and that the pro forma adjustments have not been
properly applied to the historical amounts in the compilation of those
statements.
 
                                      2

 

<PAGE>   59
 
                                                                       EXHIBIT D
 
     The letter to be delivered to IMA from ITI's independent auditors referred
to in Section 7.5(e) of the Agreement shall be in form and substance reasonably
satisfactory to IMA and contain statements by such auditors to the effect that:
 
     (1)  They are independent certified public accountants with respect to ITI
within the meaning of the Securities Act and the applicable published rules and
regulations thereunder.
 
     (2)  In their opinion, the consolidated financial statements audited by
them and included or incorporated by reference in the Registration Statement
comply as to form in all material respects with the applicable accounting
requirements of the Securities Act and the Exchange Act and the related
published rules and regulations.
 
     (3)  They have read the minutes of meetings of the stockholders and the
boards of directors of ITI and its subsidiaries for the period from the date of
the most recent financial statements of ITI included or incorporated by
reference in the Registration Statement to such date not more than five business
days prior to the date when the Registration Statement becomes effective; they
have carried out other procedures to a specified date not more than five
business days prior to the date as of when the Registration Statement becomes
effective, which do not constitute an audit in accordance with generally
accepted accounting principles, as follows:
 
          (a)  With respect to the periods covered by the unaudited financial
     statements of ITI and its consolidated subsidiaries included or
     incorporated by reference in the Registration Statement, they have (i)
     performed the procedures specified by the American Institute of Certified
     Public Accountants for a review of interim financial information as
     described in SAS No. 71, "Interim Financial Information," on the most
     recent unaudited condensed consolidated balance sheet, the unaudited
     condensed consolidated statements of income and cash flows, and the most
     recent unaudited condensed consolidated statement of stockholders' equity
     included or incorporated by reference in the Registration Statement; and
     (ii) inquired of certain officials of ITI who have responsibility for
     financial and accounting matters whether the unaudited condensed
     consolidated financial statements referred to in 3(a)(i) comply as to form
     in all material respects with the applicable accounting requirements of the
     Securities Act and the Exchange Act and the related published rules and
     regulations.
 
          (b)  With respect to the period from the date of the most recent
     financial statements of ITI and its consolidated subsidiaries included or
     incorporated by reference in the Registration Statement to the end of the
     next to last month prior to the calendar month in which the Registration
     Statement becomes effective, they have (i) read the unaudited consolidated
     financial statements of ITI and subsidiaries for each month of both (x) the
     current year for which available and (y) the corresponding month of the
     prior year, furnished to them by ITI, officials of ITI having advised them
     that no such financial statements as of any date or for any subsequent
     period were available; and (ii) inquired of certain officials of ITI who
     have responsibility for financial and accounting matters whether the
     unaudited consolidated financial statements referred to in 3(b)(i) are
     stated on a basis substantially consistent with that of the audited
     consolidated financial statements included or incorporated by reference in
     the Registration Statement.
 
     (4)  Nothing came to their attention as a result of the foregoing
procedures that caused them to believe that:
 
          (a)  (i) any material modifications should be made to the unaudited
     condensed consolidated financial statements described in 3(a)(i), included
     or incorporated by reference in the Registration Statement, for them to be
     in conformity with generally accepted accounting principles; or (ii) the
     unaudited condensed consolidated financial statements described in 3(a)(i)
     do not comply as to form in all material respects with the applicable
     accounting requirements of the Securities Act and the Exchange Act and the
     related published rules and regulations.
 
          (b)  (i) as of the end of the next to last month prior to the calendar
     month in which the Registration Statement becomes effective, there was,
     except as set forth in such letter, any change in the
 
                                       1

 

<PAGE>   60
 
     capital stock, increase in long-term debt, or decrease in consolidated net
     current assets or stockholders' equity of the consolidated companies as
     compared with amounts shown in the most recent unaudited condensed
     consolidated balance sheet of ITI included or incorporated by reference in
     the Registration Statement, or (ii) for the period from the date of the
     most recent balance sheet of ITI included or incorporated by reference in
     the Registration Statement to the end of the next to last month prior to
     the calendar month in which the Registration Statement becomes effective,
     there were, except as set forth in such letter, any decreases, as compared
     to the corresponding period in the preceding year, in consolidated net
     sales or in the total or per-share amounts of income before extraordinary
     items or of net income, except in all instances for changes, increases, or
     decreases that the Registration Statement discloses have occurred or may
     occur.
 
     (5)  They have inquired of certain officials of ITI who have responsibility
for financial and accounting matters whether (a) at a date not more than five
business days prior to the date as of when the Registration Statement becomes
effective, there was any change in the capital stock, increase in long-term debt
or any decreases in consolidated net current assets or stockholders' equity of
the consolidated companies as compared with amounts shown on most recent balance
sheet of ITI included or incorporated by reference in the Registration
Statement, or (b) for the period from the date of the most recent balance sheet
of ITI included or incorporated by reference in the Registration Statement to a
date not more than five business days prior to the date as of when the
Registration Statement becomes effective, there was any decrease, as compared
with the corresponding period in the preceding year, in consolidated net sales
or in the total or per-share amounts of income before extraordinary items or of
net income; and, on the basis of these inquiries and their reading of the
minutes as described in (3), nothing came to their attention that caused them to
believe that there was, except as set forth in such letter, any such change,
increase, or decrease except in all instances for changes, increased, or
decreases that the Registration Statement discloses have occurred or may occur.
 
     (6)  They have: (a) read the unaudited pro forma condensed consolidated
balance sheet, and the unaudited pro forma condensed consolidated statements of
income included in the Registration Statement, and (b) inquired of certain
officials of ITI and of IMA who have responsibility for financial and accounting
matters about (i) the basis for their determination of the pro forma
adjustments, and (ii) whether the unaudited pro forma condensed consolidated
financial statements comply as to form in all material respects with the
applicable accounting requirements of Rule 11-02 of Regulation S-X; and (c)
proved the arithmetic accuracy of the application of the pro forma adjustments
to the historical amounts in the unaudited pro forma condensed consolidated
financial statements; and nothing, except as set forth in such letter, came to
their attention as a result of the procedures specified in this paragraph (6)
that caused them to believe that the unaudited pro forma condensed consolidated
financial statements included in the Registration Statement do not comply as to
form in all material respects with the applicable accounting requirements of
Rule 11-02 of Regulation S-X and that the pro forma adjustments have not been
properly applied to the historical amounts in the compilation of those
statements.
 
                                      2

 

<PAGE>   61
 
                                                                     EXHIBIT E-1
 
                          AMENDMENT TO ARTICLE FOURTH
                                    OF ITI'S
                          CERTIFICATE OF INCORPORATION
 
     The first paragraph of Article FOURTH of ITI's certificate of incorporation
shall be amended as follows:
 
          FOURTH: The corporation shall be authorized to issue forty-two million
     (42,000,000) shares consisting of forty million (40,000,000) Class A common
     shares, par value one cent ($.01) per share; and two million (2,000,000)
     Preferred shares, par value ten cents ($.10) per share ("Preferred Stock").
 
                                      1

 

<PAGE>   62
 
                                                                     EXHIBIT E-2
 
                         AMENDMENT TO ARTICLE SIXTH OF
                       ITI'S CERTIFICATE OF INCORPORATION
 
     The sixth sentence of paragraph (2) of Article SIXTH of ITI's certificate
of incorporation shall be amended as follows:
 
        "Vacancies, created from an increase in the size of the Board of
        Directors, shall be filled by the affirmative vote of a majority
        of the Board of Directors then in office, or such greater
        affirmative vote of directors as may be specified from time to
        time in the By-laws of the corporation, provided that a quorum
        is present, and any other vacancy occurring in the Board of
        Directors may be filled by a majority of the directors then in
        office, which appointments shall be made in accordance with
        Section 7.3 of the Agreement and Plan of Merger dated as of May
        23, 1995 among the corporation, ITI Acquisition Corp. and
        Insituform Mid-America, Inc."
 
                                      2

 

<PAGE>   63
 
                                                                       EXHIBIT F
 
                           AMENDMENTS TO ITI BY-LAWS
 
     (i)  The first sentence of Section 2 of Article III shall be amended to
read as follows:
 
     "The board of directors shall consist of thirteen directors."
 
     (ii)  The first sentence of Section 1 of Article IV shall be deleted and
the following inserted in lieu thereof:
 
             "The officers of the corporation shall be a chairman of the
        board, a vice chairman of the board, a president, one or more
        senior vice presidents, one or more vice presidents, a secretary
        and a treasurer, each of whom shall be elected by the
        directors."
 
     (iii)  Sections 4A and 5 of Article IV shall be deleted and the following
inserted in lieu thereof:
 
     4A.  CHAIRMAN OF THE BOARD.
 
             The Chairman of the Board shall preside, when present, at
        all meetings of the Board of Directors and at all meetings of
        the stockholders and will perform such other duties as may be
        prescribed from time to time by the Board or these By-laws.
 
     4B.  VICE CHAIRMAN OF THE BOARD.
 
             In the absence of the Chairman of the Board or in the event
        of his death, inability or refusal to act, the Vice Chairman of
        the Board shall perform the duties of the Chairman of the Board
        and, when so acting, shall have all the powers of and be subject
        to all the restrictions on the Chairman of the Board. The Vice
        Chairman of the Board shall perform such other duties as may be
        prescribed from time to time by the Board or these by-laws.
 
     5.  PRESIDENT.
 
             The President shall be the chief executive officer of the
        corporation and, subject to the control of the Board of
        Directors, shall have general and active management of the
        business of the corporation, and shall see that all orders and
        resolutions of the Board and stockholders are carried into
        effect. He shall have the general authority to execute bonds,
        deeds and contracts, in the name of the corporation and affix
        the corporate seal thereto; to sign stock certificates; to cause
        the employment or appointment of such employees and agents of
        the corporation as the proper conduct of operations may require,
        and to fix their compensation, subject to the provisions of
        these By-laws; to remove or suspend any employee or agent who
        shall have been employed or appointed under his authority or
        under authority of an officer subordinate to him; and, in
        general, to exercise all the powers and authority usually
        appertaining to the chief executive officer of a corporation.
 
     (iv)  Each reference to "chief executive officer" contained in Section 2 of
Article 1, Section 4 of Article 1, and Section 1 of Article VI shall be deleted.
 
     (v)  The proviso contained in Article XI shall be amended to read as
follows:
 
        "provided, further, however, that the size of the Board of
        Directors, as set forth in Section 2 of Article III, may only be
        amended by a vote of at least 80% of the members of the Board of
        Directors or by a vote of the stockholders, representing a
        majority of the shares issued and outstanding, at any annual
        stockholders' meeting or at any special stockholders' meeting."
 
                                      1

 

<PAGE>   64

 
                                                                       EXHIBIT G
 
                                                                          , 1995
 
Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee 38138
 
Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005
 
Gentlemen:
 
     In connection with the transactions contemplated by the Agreement and Plan
of Merger dated May 23, 1995 (the "Agreement") among Insituform Technologies,
Inc., a Delaware corporation (the "Company"), ITI Acquisition Corp., a Delaware
corporation ("ITI Sub"), and Insituform Mid-America, Inc., a Delaware
corporation ("IMA"), the undersigned hereby agrees to convert or to cause the
conversion of, immediately prior to the consummation of the transactions
contemplated by the Agreement, each outstanding share of Class B Common Stock,
$.01 par value ("Class B Common Stock"), of IMA, that may be beneficially owned
by the undersigned into one share of Class A Common Stock, $.01 par value, of
IMA in accordance with the terms of IMA's certificate of incorporation, as
currently in effect.
 
     The undersigned represents and warrants to the Company that the undersigned
is the record and beneficial owner of        shares of Class B Common Stock. The
undersigned is not the record or beneficial owner of any other shares of Class B
Common Stock.
 
     In the event that the merger of IMA and ITI Sub contemplated by the
Agreement is terminated this Agreement shall be null and void.
 
                                          --------------------------------------
 
                                      1

 

<PAGE>   65
 
                                                                       EXHIBIT H
 
     The opinion to be delivered to IMA from counsel to ITI and Acquisition Sub
referred to in Section 10.1 of the Agreement shall be in form and substance
reasonably satisfactory to IMA and its counsel to the effect that:
 
     (i)  Each of ITI and Acquisition Sub is a corporation duly organized,
validly existing and in good standing under the laws of the State of Delaware,
and has full corporate power and authority to perform all its obligations under
the Agreement and, in the case of Acquisition Sub, to consummate the Merger.
 
     (ii)  The Agreement has been duly authorized, executed and delivered by ITI
and Acquisition Sub, and the consummation of the Merger has been duly approved
by Acquisition Sub, and the Agreement constitutes the valid and legally binding
obligation of ITI and Acquisition Sub enforceable against each in accordance
with its terms, except as enforceability may be limited by bankruptcy,
insolvency, or other laws affecting generally the enforceability of creditors'
rights and by limitations on the availability of equitable remedies.
 
     (iii)  The authorized capital stock of ITI consists of 2,000,000 shares of
ITI Preferred Stock and 40,000,000 shares of ITI Common Stock. When (a) the
applicable provisions of the Securities Act and such "blue sky laws" or other
state or foreign jurisdiction securities laws as may be applicable shall have
been complied with, (b) the ITI Common Stock shall have been issued and
delivered in accordance with the Agreement, and (c) the provisions of the GCL
requiring the filing of the Certificate of Merger shall have been complied with,
the shares of ITI Common Stock to be issued to holders of IMA Common Stock in
the Merger will, at the Effective Time, be duly authorized, validly issued and
fully-paid and non-assessable, issued without violation of the preemptive rights
of any person.
 
     (iv)  Upon the filing of the Certificate of Merger in the offices of the
Secretary of State of the State of Delaware, all filings required to made by ITI
or Acquisition Sub with, and all consents required to be obtained by ITI or
Acquisition Sub from, any governmental and regulatory authorities in order for
the Merger to become effective in accordance with this Agreement and the GCL
will have been made or obtained.
 
     (v)  Except for the matters set forth in such opinion and in the documents
theretofore delivered to IMA by ITI identified in such opinion, such counsel
knows of no action, suit or proceeding which, individually or in the aggregate,
materially would impair the ability of ITI or Acquisition Sub to fulfill its
obligations under the Agreement.
 
     The opinion referred to in Section 10.1 may, if in the opinion of counsel
for ITI and Acquisition Sub it is reasonable to rely thereon, be given in
reliance upon opinions of counsel of jurisdictions other than the States of New
Jersey and New York and the District of Columbia.
 
                                      1

 
<PAGE>   66
 
                                                                       EXHIBIT I
 
     The opinion to be delivered to ITI from counsel to IMA referred to in
Section 11.1 of the Agreement shall be in form and substance reasonably
satisfactory to ITI and its counsel to the effect that:
 
     (i)  IMA is a corporation duly organized, validly existing and in good
standing under the laws of the State of Delaware, and has full corporate power
and authority to perform all its obligations under this Agreement and to
consummate the Merger.
 
     (ii)  The Agreement has been duly authorized, executed and delivered, and
the consummation of the Merger has been duly approved, by IMA, and the Agreement
constitutes the valid and legally binding obligation of IMA enforceable against
IMA in accordance with its terms, except as enforceability may be limited by
bankruptcy, insolvency, or other laws affecting generally the enforceability of
creditors' rights and by limitations on the availability of equitable remedies.
 
     (iii)  The authorized capital stock of IMA consists of 500,000 shares of
IMA Preferred Stock, 10,000 shares of IMA Convertible Preferred Stock, 500
shares of IMA Class A Convertible Preferred Stock, 13,000,000 shares of IMA
Class A Common Stock and 6,000,000 shares of IMA Class B Common Stock. All of
the outstanding shares of IMA Class A Common Stock outstanding immediately prior
to the Merger are duly authorized, validly issued and fully-paid and
non-assessable, and were issued without violation of the preemptive rights of
any person
 
     (iv)  Upon the filing of the Certificate of Merger in the offices of the
Secretary of State of the State of Delaware, all filings required to made by IMA
with, and all consents required to be obtained by IMA from, any governmental and
regulatory authorities in order for the Merger to become effective in accordance
with the Agreement and the GCL will have been made or obtained.
 
     (v)  Except for the matters set forth in such opinion and in the documents
theretofore delivered to ITI by IMA identified in such opinion, such counsel
knows of no action, suit or proceeding which, individually or in the aggregate,
materially would impair the ability of IMA to fulfill its obligations under the
Agreement.
 
     The opinion referred to in Section 11.1 may, if in the opinion of counsel
for IMA it is reasonable to rely thereon, be given in reliance upon opinions of
counsel of jurisdictions other than the States of Illinois and Missouri and the
District of Columbia.
 
                                      1

 
<PAGE>   67
 
                                                                       EXHIBIT J
 
                                                                           ,1995
 
Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee 38138
 
Gentlemen:
 
     In connection with the transactions contemplated by the Agreement and Plan
of Merger dated as of May 23, 1995 (the "Agreement") among Insituform
Technologies, Inc., a Delaware corporation (the "Company"), ITI Acquisition
Corp., a Delaware corporation, and Insituform Mid-America, Inc., a Delaware
corporation, the undersigned agrees that (i) the undersigned shall make no
disposition of any shares of Class A Common Stock, $.01 par value ("Company
Common Stock"), of the Company, that it receives pursuant to the Merger (as
defined in the Agreement), except in accordance with the applicable provisions
of the Securities Act of 1933, as amended, and the rules and regulations
thereunder; and (ii) the certificates evidencing such shares received pursuant
to the Merger shall bear a customary legend setting forth such restrictions.
 
     The undersigned represents that it has no present plan, intention, or
arrangement to sell, transfer or otherwise dispose of any shares of Company
Common Stock received pursuant to the Merger, and shall not change such
intention or enter into any such arrangement, prior to the Effective Time (as
defined in the Agreement).
 
                                          --------------------------------------
 
                                      1

 
<PAGE>   68

 
                                                                       EXHIBIT K
 
                              EMPLOYMENT AGREEMENT
 
     AGREEMENT made this      day of           , 1995 between Robert W.
Affholder, residing at                         (hereinafter referred to as the
"Employee"), and Insituform Technologies, Inc., a corporation organized and
existing under the laws of the State of Delaware (hereinafter referred to as the
"Corporation").
 
                              W I T N E S S E T H:
 
     WHEREAS, the Corporation has entered into an Agreement and Plan of Merger
dated as of May 23, 1995 (hereinafter referred to as the "Merger Agreement")
with Insituform Mid-America, Inc., a Delaware corporation (hereinafter referred
to as "IMA"), and ITI Acquisition Corp., a Delaware corporation and wholly-owned
subsidiary of the Corporation (hereinafter referred to as "Acquisition Sub"),
pursuant to the terms and subject to the conditions of which the Corporation has
agreed to the merger of Acquisition Sub into IMA, as a result of which IMA will
become a wholly-owned subsidiary of the Corporation; and
 
     WHEREAS, it is a condition to the closing under the Merger Agreement that
the parties hereto execute and deliver this Agreement;
 
     NOW, THEREFORE, in consideration of the mutual covenants and agreements
herein set forth, the Employee hereby agrees with the Corporation as follows:
 
                                   SECTION I
 
     A.  The Corporation hereby agrees to employ the Employee, and the Employee
hereby agrees to be employed by the Corporation, for the Employment Term (as
hereinafter defined) and upon the other terms and conditions set forth herein.
 
     B.  The Employee hereby agrees to serve the Corporation faithfully,
diligently and to the best of his ability, under the direction of the board of
directors and of the President of the Corporation, initially as principal
operating officer for North American contracting operations of the Corporation,
and thereafter in such other executive staff position as shall be designated by
the President of the Corporation. The Employee shall render such services as the
Corporation may from time to time require of him, and shall devote all of his
business time to the performance thereof; provided that, it shall not be a
violation of this Paragraph B for the Employee to (i) serve on corporate, civic,
political or charitable boards or committees, or (ii) manage personal
investments, so long as such activities do not significantly interfere with the
performance of the Employee's responsibilities as an employee of the Corporation
in accordance with this Agreement or violate the Corporation's conflict of
interest policy as in effect from time to time. The precise services and duties
which the Employee is obligated to perform hereunder may from time to time be
changed, amended, extended or curtailed by the President of the Corporation.
 
     C.  The Employee shall render his services and perform his duties hereunder
at the principal offices of the Corporation or any Affiliate (as hereinafter
defined), as determined by the Corporation, in the metropolitan St. Louis area;
provided, however, that the Corporation may require the Employee to travel in
the regular business of the Corporation and its Affiliates for such purposes and
periods as may be reasonable considering the duties and responsibilities of the
Employee.
 
                                   SECTION II
 
     A.  Subject to the provisions of this Agreement hereinafter contained, for
purposes of this Agreement the period (herein referred to as the "Employment
Term") of the Employee's obligations under Section I hereof shall commence on
the date hereof and shall continue for a period of three years thereafter.
 
                                      1

 
<PAGE>   69
 
     B.  If the Employee shall, during the Employment Term fail to perform his
duties under this Agreement owing to illness or other incapacity which shall
continue for a period of more than six months, the Corporation shall have the
right to terminate the Employment Term as of a date to be specified in a notice
to that effect, whereupon the Employee shall continue to receive his salary at
the rate provided in Section III up to the last day of the Corporation's regular
payroll accounting period in which such termination shall take effect.
 
     C.  The Employment Term may further be terminated, at the option of the
Corporation, upon ten days prior written notice, for "cause" (as hereinafter
defined).
 
     D.  In the event of the Employee's death during the Employment Term, the
Employment Term shall terminate immediately and the Employee's legal
representatives shall be entitled to receive his salary at the rate provided in
Section III up to the last day of the Corporation's regular payroll accounting
period in which his death shall occur.
 
                                  SECTION III
 
     A.  The Corporation hereby agrees to pay, and the Employee hereby agrees to
accept, as full compensation for the services to be rendered by him under
Section I hereunder, an annual salary of $250,000, payable in equal installments
at the end of such regular payroll accounting periods as are established by the
Corporation, or in such other installments upon which the parties hereto shall
mutually agree.
 
     B.  The Corporation shall reimburse the Employee for reasonable and
necessary expenses incurred by him on behalf of the Corporation in the
performance of his duties hereunder during the Employment Term, provided that
such expenses are adequately documented in accordance with the Corporation's
then customary policies.
 
     C.  During the Employment Term, the Employee shall be entitled to
participate in all medical and other employee benefit plans, including vacation,
sick leave, and other fringe benefits, offered or provided by the Corporation to
employees similarly situated. Such benefits shall include, but not be limited
to, the use of the automobile heretofore provided to him by IMA, for his
activities hereunder (and with a reasonably similar replacement vehicle at the
expiration of the lease therefor). During the Employment Term, the Corporation
shall furnish to the Employee office facilities appropriate to his performance
hereunder and secretarial assistance in connection therewith.
 
                                   SECTION IV
 
     A.  The Employee shall hold in absolute secrecy and treat confidentially
all Confidential Material (as hereinafter defined), and not disclose, reproduce,
publish, distribute or by any other means disseminate, in whole or in part, any
Confidential Material, except as shall be authorized by the Disclosing Party (as
hereinafter defined). The Employee shall not in any manner use for his benefit
or for the benefit of others any Confidential Material, except as shall be
authorized by the Disclosing Party.
 
     B.  Subsequent to the date hereof and for a period (hereinafter referred to
as the "Covenant Term") expiring at the later of (x) two years after the
termination or expiration of all service rendered by the Employee to the
Corporation or any of its Affiliates, whether as employee, consultant, director
or otherwise, unless any such termination shall be effectuated by the
Corporation or any Affiliate without "cause", or (y) five years after the date
of this Agreement, the Employee shall not engage, directly or indirectly,
whether as principal, agent, distributor, representative, stockholder or
otherwise, in any activities which are in any way competitive with the business
conducted by the Corporation or any Affiliate thereof, within any territory in
which the Corporation or any Affiliate, directly or indirectly, conducts such
business.
 
     C.  The Employee hereby assigns to the Corporation the entire right, title
and interest in and to any and all inventions, trade secrets, improvements,
plans and specifications: (i) which he alone, or in conjunction with others, may
make, conceive or develop; and (ii) which relate to or derive from any subject
matter or problem with respect to which the Employee shall have become informed
by reason of his relations with the
 
                                      2
 
<PAGE>   70
 
Corporation or any Affiliate, or to any product or process involved in the
business of the Corporation or any Affiliate.
 
     D.  The Employee further agrees that he will promptly disclose fully to the
Corporation the aforesaid inventions, trade secrets, improvements, plans and
specifications and will at any time render to the Corporation such reasonable
cooperation and assistance (excluding financial assistance) as the Corporation
may deem to be advisable in order to obtain copyrights or patents, as the case
may be, on or otherwise perfect or defend the Corporation's rights in each such
invention, trade secret, improvement, plan or specification, including, but not
limited to, the execution of any and all applications for copyrights or patents,
assignments of copyrights or patents and other instruments in writing which the
Corporation, its officers or attorneys may reasonably deem necessary or
desirable, and the aforesaid obligation shall be binding on the assigns,
executors, administrators and other legal representatives of the Receiving
Party.
 
     E.  For purposes of this Agreement: (i) "Confidential Material" shall mean
any and all information furnished to the Employee, whether before or after the
date hereof, by the Corporation, any Affiliate, or any of their respective
licensees, or any of their respective employees, directors, agents or
representatives (each herein referred to as a "Disclosing Party"), or acquired,
received, developed or learned by the Employee in the course of his relations
with any Disclosing Party or relating to the business and affairs of the
Corporation or any Affiliate, or any licensee thereof, or to any product or
process involved in the business of the Corporation or any Affiliate, or the
proprietary plans, policies, business or affairs of any Disclosing Party;
provided, however, that the term "Confidential Material" shall not include
information which:
 
          (x)  becomes or has become generally available to the public other
     than as a result of a disclosure by the Employee;
 
          (y)  was available to the Employee on a non-confidential basis prior
     to its disclosure to the Employee by the Disclosing Party; or
 
          (z)  becomes available to the Employee on a non-confidential basis
     from a source other than the Disclosing Party, provided that such source is
     not bound by a confidentiality agreement with the Disclosing Party;
 
     (ii) "Affiliate" shall mean any person or entity directly or indirectly
controlled by the Corporation; and (iii) "cause" shall mean the Employee's
neglect of duties, breach of his employment or other relationship with the
Corporation , conflict of interest, or refusal to follow directives of the
Corporation , in each case (if such matter is susceptible of correction) if not
corrected within ten days after written notice thereof by the Corporation , to
the Employee (or if such correction may not reasonably be completed within such
period, if diligent efforts to effectuate such correction shall not have been
initiated within such period and continued through and completed within 30 days
of such notice); or conviction of a crime.
 
     F.  In view of the irreparable harm and damage which would be incurred by
the Corporation or any Affiliate, or any other Disclosing Party, in the event of
any violation by the Employee of any of the provisions hereof, the Employee
hereby consents and agrees that, if he violates any such provisions, the
Corporation or any Affiliate, or (with respect to such secrecy or non-use
obligations) such other Disclosing Party, shall be entitled to an injunction or
similar equitable relief to be issued by any court of competent jurisdiction
restraining the undersigned from committing or continuing any such violation.
 
                                   SECTION V
 
     The Employee hereby represents, warrants and covenants that:
 
     A.  He is duly authorized to execute and deliver this Agreement and to
perform his covenants and agreements hereunder. When executed and delivered by
him, this Agreement shall constitute his valid and legally binding agreement
enforceable against him in accordance with the terms hereof, except as may be
limited by bankruptcy, insolvency or other laws affecting generally the
enforceability of creditors' rights and by limitations on the availability of
equitable remedies.
 
                                      3

 
<PAGE>   71
 
     B.  Neither the execution and delivery of this Agreement, nor the
consummation of the transactions contemplated herein, will violate any law,
rule, regulation, writ, judgment, injunction, decree, determination, award, or
order of any court or governmental agency or instrumentality, domestic or
foreign, or conflict with or result in any breach of any of the terms of or
constitute a default under or result in the termination or for the creation of
any mortgage, deed of trust, pledge, lien security interest or other charge or
encumbrance of any nature pursuant to the terms of any contract or agreement to
which he is a party or by which he or any of his assets or properties is bound.
 
                                   SECTION VI
 
     A.  All notices, requests, instructions or documents hereunder shall be in
writing and delivered personally or sent by registered or express mail, postage
prepaid, as follows:
 
                             (i)  if to the Employee:
 
                                ------------------------------------------------
 
                                ------------------------------------------------
 
                                ------------------------------------------------
 
                                with a copy to:
 
                                Thomas Litz, Esq.
                                Thompson & Mitchell
                                One Mercantile Center
                                St. Louis, Missouri 63101
 
                            (ii)  to the Corporation:
 
                                1770 Kirby Parkway
                                Suite 300
                                Memphis, Tennessee 38138
 
                                with a copy to:
 
                                Howard Kailes, Esq.
                                Krugman, Chapman & Grimshaw
                                Park 80 West -- Plaza Two
                                Saddle Brook, New Jersey 07663
 
or to such other address as either party may designate by written notice to the
other party. If delivered personally, the date on which such notice, request,
instruction or document is delivered shall be the date on which such delivery is
made, and if delivered by mail, the date on which deposited in the mail. Each
notice, request, instruction or document shall bear the date on which it is
delivered.
 
     B.  This Agreement is personal as to the Employee and shall not be
assignable by the Employee. Subject to the foregoing, all of the terms and
provisions of this Agreement shall be binding upon and shall inure to the
benefit of and be enforceable by the parties hereto and their respective
successors and assigns and legal representatives and (with respect to any
secrecy or non-use obligations) any other Disclosing Party.
 
     C.  This Agreement constitutes the complete understanding between the
parties hereto with respect to the transactions contemplated herein, no
statement, representation, warranty or covenant has been made by either party
hereto except as expressly set forth herein and therein, and no modification
hereof shall be effective unless in writing and signed by a party against which
it is sought to be enforced.
 
                                      4

 
<PAGE>   72
 
     D.  This Agreement shall be governed by and construed in accordance with
the laws of the State of Tennessee applicable in the case of agreements made and
to be performed entirely within such State.
 
     E.  It is the intention of the Employee and the Corporation that the
provisions of this Agreement shall be enforced to the fullest extent permissible
under the laws and public policies of each jurisdiction in which enforcement is
sought, but that the unenforceability of any provisions of this Agreement shall
not render unenforceable, or impair, the remainder of this Agreement.
Accordingly, if any provision hereof is determined to be invalid or
unenforceable, either in whole or in part, this Agreement shall be deemed
amended to delete or modify, as necessary, the offending provision and to alter
the remainder of this Agreement in order to render it valid and enforceable.
 
     F.  This Agreement may be executed in counterparts, each of which shall be
deemed an original, but all of which, taken together, shall constitute one and
the same instrument.
 
     IN WITNESS WHEREOF, this Agreement has been duly executed by the parties
hereto as of the date first above written.
 
                                          INSITUFORM TECHNOLOGIES, INC.
 
                                          By
 
                                          --------------------------------------
                                          EMPLOYEE:
 
                                          --------------------------------------
                                          Robert W. Affholder
 

                                      5


 
<PAGE>   73
 
                                                                     EXHIBIT L-1
 
                                   AGREEMENT
 
     AGREEMENT made this        day of             , 1995 between Jerome
Kalishman residing at                (hereinafter referred to as the "Vice
Chairman"), and Insituform Technologies, Inc., a corporation organized and
existing under the laws of the State of Delaware (hereinafter referred to as the
"Corporation").
 
                                  WITNESSETH:
 
     WHEREAS, the Corporation has entered into an Agreement and Plan of Merger
dated as of May 23, 1995 (hereinafter referred to as the "Merger Agreement")
with Insituform Mid-America, Inc., a Delaware corporation (hereinafter referred
to as "IMA"), and ITI Acquisition Corp., a Delaware corporation and wholly-owned
subsidiary of the Corporation (hereinafter referred to as "Acquisition Sub"),
pursuant to the terms and subject to the conditions of which the Corporation has
agreed to the merger of Acquisition Sub into IMA, as a result of which IMA will
become a wholly-owned subsidiary of the Corporation; and
 
     WHEREAS, it is a condition to the closing under the Merger Agreement that
the parties hereto execute and deliver this Agreement;
 
     NOW, THEREFORE, in consideration of the mutual covenants and agreements
herein set forth, the Vice Chairman hereby agrees with the Corporation as
follows:
 
                                   SECTION I
 
     During the Term (as hereinafter defined), ITI shall engage and the Vice
Chairman shall serve as Vice Chairman of the Board of Directors of the
Corporation. The Corporation acknowledges that the duties to be performed by the
Vice Chairman under this Agreement do not require him to serve on a full-time
basis and that the Vice Chairman will not be available to serve on a full-time
basis.
 
                                   SECTION II
 
     A.  Subject to the provisions of this Agreement hereinafter contained, for
purposes of this Agreement the period (herein referred to as the "Term") of the
Vice Chairman's obligations under Section I hereof shall commence on the date
hereof and shall continue for a period expiring on December 9, 1998, or until
such other date prior thereto on which the Vice Chairman's engagement terminates
pursuant hereto.
 
     B.  If the Vice Chairman shall, during the Term fail to perform his duties
under this Agreement owing to illness or other incapacity which shall continue
for a period of more than six months, the Corporation shall have the right to
terminate the Term as of a date to be specified in a notice to that effect,
whereupon the Vice Chairman shall continue to receive his retainer at the rate
provided in Section III up to the last day of the Corporation's regular payroll
accounting period in which such termination shall take effect.
 
     C.  The Term may further be terminated, at the option of the Corporation,
upon ten days' prior written notice, for "cause" (as hereinafter defined).
 
     D.  In the event of the Vice Chairman's death during the Term, the Term
shall terminate immediately and the Vice Chairman's legal representatives shall
be entitled to receive his retainer at the rate provided in Section III up to
the last day of the Corporation's regular payroll accounting period in which his
death shall occur.
 
     E.  The Vice Chairman shall have the right, upon at least 60 days' written
notice delivered to the Corporation, to terminate the Term.
 
                                      1

 
<PAGE>   74
 
                                  SECTION III
 
     A.  The Corporation hereby agrees to pay, and the Vice Chairman hereby
agrees to accept, as full compensation for the services to be rendered by him
under Section I hereunder, an annual fee of $100,000, payable in equal
installments at the end of such regular payroll accounting periods as are
established by the Corporation, or in such other installments upon which the
parties hereto shall mutually agree.
 
     B.  The Corporation shall reimburse the Vice Chairman for reasonable and
necessary expenses incurred by him on behalf of the Corporation in the
performance of his duties hereunder during the Term, provided that such expenses
are adequately documented in accordance with the Corporation's then customary
policies. During the Term, the Vice Chairman shall, to the extent such plans
permit coverage of the Vice Chairman thereunder in accordance with the terms
thereof generally applicable, be entitled to participate at the Corporation's
expense in the Corporation's group medical, life and accident insurance plans
or, if not so eligible, the Vice Chairman shall receive from the Corporation, at
its expense, coverage substantially similar thereto. The Vice Chairman shall
receive the use of the automobile heretofore provided to him by IMA, for his
activities hereunder (and with a reasonably similar replacement vehicle at the
expiration of the lease therefor). During the Term, the Corporation shall
furnish to the Vice Chairman office facilities appropriate to his performance
hereunder and secretarial assistance in connection therewith.
 
                                   SECTION IV
 
     A.  The Vice Chairman shall hold in absolute secrecy and treat
confidentially all Confidential Material (as hereinafter defined), and not
disclose, reproduce, publish, distribute or by any other means disseminate, in
whole or in part, any Confidential Material, except as shall be authorized by
the Disclosing Party (as hereinafter defined). The Vice Chairman shall not in
any manner use for his benefit or for the benefit of others any Confidential
Material, except as shall be authorized by the Disclosing Party.
 
     B.  Subsequent to the date hereof and for a period (hereinafter referred to
as the "Covenant Term") expiring at the later of (x) two years after the
termination or expiration of all service rendered by the Vice Chairman to the
Corporation or any of its Affiliates (as hereinafter defined), whether as
employee, consultant, director or otherwise, unless any such termination shall
be effectuated by the Corporation or any Affiliate without "cause" (as
hereinafter defined), or (y) five years after the date of this Agreement, the
Vice Chairman shall not engage, directly or indirectly, whether as principal,
agent, distributor, representative, stockholder or otherwise, in any activities
which are in any way competitive with the business conducted by the Corporation
or any Affiliate thereof, within any territory in which the Corporation or any
Affiliate, directly or indirectly, conducts such business.
 
     C.  The Vice Chairman hereby assigns to the Corporation the entire right,
title and interest in and to any and all inventions, trade secrets,
improvements, plans and specifications: (i) which he alone, or in conjunction
with others, may make, conceive or develop; and (ii) which relate to or derive
from any subject matter or problem with respect to which the Vice Chairman shall
have become informed by reason of his relations with the Corporation or any
Affiliate, or to any product or process involved in the business of the
Corporation or any Affiliate.
 
     D.  The Vice Chairman further agrees that he will promptly disclose fully
to the Corporation the aforesaid inventions, trade secrets, improvements, plans
and specifications and will at any time render to the Corporation such
reasonable cooperation and assistance (excluding financial assistance) as the
Corporation may deem to be advisable in order to obtain copyrights or patents,
as the case may be, on or otherwise perfect or defend the Corporation's rights
in each such invention, trade secret, improvement, plan or specification,
including, but not limited to, the execution of any and all applications for
copyrights or patents, assignments of copyrights or patents and other
instruments in writing which the Corporation, its officers or attorneys may
reasonably deem necessary or desirable, and the aforesaid obligation shall be
binding on the assigns, executors, administrators and other legal
representatives of the Receiving Party.
 
     E.  For purposes of this Agreement: (i) "Confidential Material" shall mean
any and all information furnished to the Vice Chairman, whether before or after
the date hereof, by the Corporation, any Affiliate, or
 
                                      2

 
<PAGE>   75
 
any of their respective licensees, or any of their respective employees,
directors, agents or representatives (each herein referred to as a "Disclosing
Party"), or acquired, received, developed or learned by the Vice Chairman in the
course of his relations with any Disclosing Party or relating to the business
and affairs of the Corporation or any Affiliate, or any licensee thereof, or to
any product or process involved in the business of the Corporation or any
Affiliate, or the proprietary plans, policies, business or affairs of any
Disclosing Party; provided, however, that the term "Confidential Material" shall
not include information which:
 
          (x)  becomes or has become generally available to the public other
     than as a result of a disclosure by the Vice Chairman;
 
          (y)  was available to the Vice Chairman on a non-confidential basis
     prior to its disclosure to the Vice Chairman by the Disclosing Party; or
 
          (z)  becomes available to the Vice Chairman on a non-confidential
     basis from a source other than the Disclosing Party, provided that such
     source is not bound by a confidentiality agreement with the Disclosing
     Party;
 
     (ii)  "Affiliate" shall mean any person or entity directly or indirectly
controlled by the Corporation; and (iii) "cause" shall mean the Vice Chairman's
neglect of duties, breach of his engagement with the Corporation , conflict of
interest, or refusal to follow directives of the Board of Directors of the
Corporation, in each case (if such matter is susceptible of correction) if not
corrected within ten days after written notice thereof by the Corporation to the
Vice Chairman (or if such correction may not reasonably be completed within such
period, if diligent efforts to effectuate such correction shall not have been
initiated within such period and continued through and completed within 30 days
of such notice); or conviction of a crime.
 
     F.  In view of the irreparable harm and damage which would be incurred by
the Corporation or any Affiliate, or any other Disclosing Party, in the event of
any violation by the Vice Chairman of any of the provisions hereof, the Vice
Chairman hereby consents and agrees that, if he violates any such provisions,
the Corporation or any Affiliate, or (with respect to such secrecy or non-use
obligations) such other Disclosing Party, shall be entitled to an injunction or
similar equitable relief to be issued by any court of competent jurisdiction
restraining the undersigned from committing or continuing any such violation.
 
                                   SECTION V
 
     The Vice Chairman hereby represents, warrants and covenants that:
 
     A.  He is duly authorized to execute and deliver this Agreement and to
perform his covenants and agreements hereunder. When executed and delivered by
him, this Agreement shall constitute his valid and legally binding agreement
enforceable against him in accordance with the terms hereof, except as may be
limited by bankruptcy, insolvency or other laws affecting generally the
enforceability of creditors' rights and by limitations on the availability of
equitable remedies.
 
     B.  Neither the execution and delivery of this Agreement, nor the
consummation of the transactions contemplated herein, will violate any law,
rule, regulation, writ, judgment, injunction, decree, determination, award, or
order of any court or governmental agency or instrumentality, domestic or
foreign, or conflict with or result in any breach of any of the terms of or
constitute a default under or result in the termination or for the creation of
any mortgage, deed of trust, pledge, lien security interest or other charge or
encumbrance of any nature pursuant to the terms of any contract or agreement to
which he is a party or by which he or any of his assets or properties is bound.
 
                                      3

 
<PAGE>   76
 
                                   SECTION VI
 
     A.  All notices, requests, instructions or documents hereunder shall be in
writing and delivered personally or sent by registered or express mail, postage
prepaid, as follows:
 
                            (i)  if to the Vice Chairman:
 
                               -------------------------------------------------
 
                               -------------------------------------------------
 
                               -------------------------------------------------
 
                               with a copy to:
 
                               Thomas Litz, Esq.
                               Thompson & Mitchell
                               One Mercantile Center
                               St. Louis, Missouri 63101
 
                            (ii)  to the Corporation:
 
                                1770 Kirby Parkway
                                Suite 300
                                Memphis, Tennessee 38138
 
                                with a copy to:
 
                                Howard Kailes, Esq.
                                Krugman, Chapman & Grimshaw
                                Park 80 West -- Plaza Two
                                Saddle Brook, New Jersey 07663
 
or to such other address as either party may designate by written notice to the
other party. If delivered personally, the date on which such notice, request,
instruction or document is delivered shall be the date on which such delivery is
made, and if delivered by mail, the date on which deposited in the mail. Each
notice, request, instruction or document shall bear the date on which it is
delivered.
 
     B.  This Agreement is personal as to the Vice Chairman and shall not be
assignable by the Vice Chairman. Subject to the foregoing, all of the terms and
provisions of this Agreement shall be binding upon and shall inure to the
benefit of and be enforceable by the parties hereto and their respective
successors and assigns and legal representatives and (with respect to any
secrecy or non-use obligations) any other Disclosing Party.
 
     C.  This Agreement constitutes the complete understanding between the
parties hereto with respect to the transactions contemplated herein, no
statement, representation, warranty or covenant has been made by either party
hereto except as expressly set forth herein and therein, and no modification
hereof shall be effective unless in writing and signed by a party against which
it is sought to be enforced.
 
     D.  This Agreement shall be governed by and construed in accordance with
the laws of the State of Tennessee applicable in the case of agreements made and
to be performed entirely within such State.
 
     E.  It is the intention of the Vice Chairman and the Corporation that the
provisions of this Agreement shall be enforced to the fullest extent permissible
under the laws and public policies of each jurisdiction in which enforcement is
sought, but that the unenforceability of any provisions of this Agreement shall
not render unenforceable, or impair, the remainder of this Agreement.
Accordingly, if any provision hereof is determined to be invalid or
unenforceable, either in whole or in part, this Agreement shall be deemed
 
                                      4

 
<PAGE>   77
 
amended to delete or modify, as necessary, the offending provision and to alter
the remainder of this Agreement in order to render it valid and enforceable.
 
     F.  This Agreement may be executed in counterparts, each of which shall be
deemed an original, but all of which, taken together, shall constitute one and
the same instrument.
 
     IN WITNESS WHEREOF, this Agreement has been duly executed by the parties
hereto as of the date first above written.
 
                                          INSITUFORM TECHNOLOGIES, INC.


                                          By
                                            ------------------------------------
                                             VICE CHAIRMAN:
 
                                            ------------------------------------
                                             Jerome Kalishman
 
                                      5


 
<PAGE>   78
 
                                                                     EXHIBIT L-2
 
                              CONSULTING AGREEMENT
 
     AGREEMENT made this      day of           , 1995 between Jerome Kalishman
residing at             (hereinafter referred to as the "Consultant"), and
Insituform Technologies, Inc., a corporation organized and existing under the
laws of the State of Delaware (hereinafter referred to as the "Corporation").
 
                              W I T N E S S E T H:
 
     WHEREAS, the Corporation has entered into an Agreement and Plan of Merger
dated as of May 23, 1995 (hereinafter referred to as the "Merger Agreement")
with Insituform Mid-America, Inc., a Delaware corporation (hereinafter referred
to as "IMA"), and ITI Acquisition Corp., a Delaware corporation and wholly-owned
subsidiary of the Corporation (hereinafter referred to as "Acquisition Sub"),
pursuant to the terms and subject to the conditions of which the Corporation has
agreed to the merger of Acquisition Sub into IMA, as a result of which IMA will
become a wholly-owned subsidiary of the Corporation; and
 
     WHEREAS, it is a condition to the closing under the Merger Agreement that
the parties hereto execute and deliver this Agreement;
 
     NOW, THEREFORE, in consideration of the mutual covenants and agreements
herein set forth, the Consultant hereby agrees with the Corporation as follows:
 
                                   SECTION I
 
     A.  The Corporation hereby retains the Consultant to act as a consultant
and advisor to the Corporation in connection with its business, and the
Consultant hereby agrees to act in such capacity, for the Consulting Term (as
hereinafter defined) and upon the other terms and conditions set forth herein.
 
     B.  The Consultant hereby agrees to serve the Corporation faithfully,
diligently and to the best of his ability under the direction of the board of
directors and of the President of the Corporation. In connection with his duties
hereunder, the Consultant shall hold himself available, upon reasonable prior
notice from the Corporation, to provide the Corporation with such services as
the Corporation may from time to time reasonably require of him.
 
                                   SECTION II
 
     A.  Subject to the provisions of this Agreement hereinafter contained, for
purposes of this Agreement the period (herein referred to as the "Consulting
Term") of the Consultant's obligations under Section I hereof shall commence on
the date hereof and shall continue for a period of two years thereafter.
 
     B.  If the Consultant shall, during the Consulting Term fail to perform his
duties under this Agreement owing to illness or other incapacity which shall
continue for a period of more than six months, the Corporation shall have the
right to terminate the Consulting Term as of a date to be specified in a notice
to that effect, whereupon the Consultant shall continue to receive his retainer
at the rate provided in Section III up to the last day of the month in which
such termination shall take effect.
 
     C.  The Consulting Term may further be terminated, at the option of the
Corporation, upon ten days' prior written notice, for "cause" (as hereinafter
defined).
 
     D.  In the event of the Consultant's death during the Consulting Term, the
Consulting Term shall terminate immediately and the Consultant's legal
representatives shall be entitled to receive his retainer at the rate provided
in Section III up to the last day of the month in which his death shall occur.
 
     E.  The Consultant shall have the right, upon at least 60 days' written
notice delivered to the Corporation, to terminate the Consulting Term.
 
                                       1

 
<PAGE>   79

 
                                  SECTION III
 
     A.  The Corporation hereby agrees to pay, and the Consultant hereby agrees
to accept, as full compensation for the services to be rendered by him under
Section I hereunder, an annual fee of $150,000, payable in substantially equal
monthly installments in arrears, or in such other installments upon which the
parties hereto shall mutually agree.
 
     B.  The Corporation shall reimburse the Consultant for reasonable and
necessary expenses incurred by him on behalf of the Corporation in the
performance of his duties hereunder during the Consulting Term, provided that
such expenses are adequately documented in accordance with the Corporation's
then customary policies. The Consultant shall receive the use of the automobile
heretofore provided to him by IMA, for his activities hereunder (and with a
reasonably similar replacement vehicle at the expiration of the lease therefor).
During the Consulting Term, the Corporation shall furnish to the Consultant
office facilities appropriate to his performance hereunder and secretarial
assistance in connection therewith.
 
                                   SECTION IV
 
     A.  The Consultant shall hold in absolute secrecy and treat confidentially
all Confidential Material (as hereinafter defined), and not disclose, reproduce,
publish, distribute or by any other means disseminate, in whole or in part, any
Confidential Material, except as shall be authorized by the Disclosing Party (as
hereinafter defined). The Consultant shall not in any manner use for his benefit
or for the benefit of others any Confidential Material, except as shall be
authorized by the Disclosing Party.
 
     B.  Subsequent to the date hereof and for a period (hereinafter referred to
as the "Covenant Term") expiring at the later of (x) two years after the
termination or expiration of all service rendered by the Consultant to the
Corporation or any of its Affiliates (as hereinafter defined), whether as
employee, consultant, director or otherwise, unless any such termination shall
be effectuated by the Corporation or any Affiliate without "cause" (as
hereinafter defined), or (y) five years after the date of this Agreement, the
Consultant shall not engage, directly or indirectly, whether as principal,
agent, distributor, representative, stockholder or otherwise, in any activities
which are in any way competitive with the business conducted by the Corporation
or any Affiliate thereof, within any territory in which the Corporation or any
Affiliate, directly or indirectly, conducts such business.
 
     C.  The Consultant hereby assigns to the Corporation the entire right,
title and interest in and to any and all inventions, trade secrets,
improvements, plans and specifications: (i) which he alone, or in conjunction
with others, may make, conceive or develop; and (ii) which relate to or derive
from any subject matter or problem with respect to which the Consultant shall
have become informed by reason of his relations with the Corporation or any
Affiliate, or to any product or process involved in the business of the
Corporation or any Affiliate.
 
     D.  The Consultant further agrees that he will promptly disclose fully to
the Corporation the aforesaid inventions, trade secrets, improvements, plans and
specifications and will at any time render to the Corporation such reasonable
cooperation and assistance (excluding financial assistance) as the Corporation
may deem to be advisable in order to obtain copyrights or patents, as the case
may be, on or otherwise perfect or defend the Corporation's rights in each such
invention, trade secret, improvement, plan or specification, including, but not
limited to, the execution of any and all applications for copyrights or patents,
assignments of copyrights or patents and other instruments in writing which the
Corporation, its officers or attorneys may reasonably deem necessary or
desirable, and the aforesaid obligation shall be binding on the assigns,
executors, administrators and other legal representatives of the Receiving
Party.
 
     E.  For purposes of this Agreement: (i) "Confidential Material" shall mean
any and all information furnished to the Consultant, whether before or after the
date hereof, by the Corporation, any Affiliate, or any of their respective
licensees, or any of their respective employees, directors, agents or
representatives (each herein referred to as a "Disclosing Party"), or acquired,
received, developed or learned by the Consultant in the course of his relations
with any Disclosing Party or relating to the business and affairs of the
Corporation or any Affiliate, or any licensee thereof, or to any product or
process involved in the business of the
 
                                      2

 
<PAGE>   80
 
Corporation or any Affiliate, or the proprietary plans, policies, business or
affairs of any Disclosing Party; provided, however, that the term "Confidential
Material" shall not include information which:
 
          (x)  becomes or has become generally available to the public other
     than as a result of a disclosure by the Consultant;
 
          (y)  was available to the Consultant on a non-confidential basis prior
     to its disclosure to the Consultant by the Disclosing Party; or
 
          (z)  becomes available to the Consultant on a non-confidential basis
     from a source other than the Disclosing Party, provided that such source is
     not bound by a confidentiality agreement with the Disclosing Party;
 
(ii)  "Affiliate" shall mean any person or entity directly or indirectly
controlled by the Corporation; and (iii) "cause" shall mean the Consultant's
neglect of duties, breach of his consulting or other relationship with the
Corporation , conflict of interest, or refusal to follow directives of the
Corporation, in each case (if such matter is susceptible of correction) if not
corrected within ten days after written notice thereof by the Corporation to the
Consultant (or if such correction may not reasonably be completed within such
period, if diligent efforts to effectuate such correction shall not have been
initiated within such period and continued through and completed within 30 days
of such notice); or conviction of a crime.
 
     F.  In view of the irreparable harm and damage which would be incurred by
the Corporation or any Affiliate, or any other Disclosing Party, in the event of
any violation by the Consultant of any of the provisions hereof, the Consultant
hereby consents and agrees that, if he violates any such provisions, the
Corporation or any Affiliate, or (with respect to such secrecy or non-use
obligations) such other Disclosing Party, shall be entitled to an injunction or
similar equitable relief to be issued by any court of competent jurisdiction
restraining the undersigned from committing or continuing any such violation.
 
                                   SECTION V
 
     The Consultant hereby represents, warrants and covenants that:
 
     A.  He is duly authorized to execute and deliver this Agreement and to
perform his covenants and agreements hereunder. When executed and delivered by
him, this Agreement shall constitute his valid and legally binding agreement
enforceable against him in accordance with the terms hereof, except as may be
limited by bankruptcy, insolvency or other laws affecting generally the
enforceability of creditors' rights and by limitations on the availability of
equitable remedies.
 
     B.  Neither the execution and delivery of this Agreement, nor the
consummation of the transactions contemplated herein, will violate any law,
rule, regulation, writ, judgment, injunction, decree, determination, award, or
order of any court or governmental agency or instrumentality, domestic or
foreign, or conflict with or result in any breach of any of the terms of or
constitute a default under or result in the termination or for the creation of
any mortgage, deed of trust, pledge, lien security interest or other charge or
encumbrance of any nature pursuant to the terms of any contract or agreement to
which he is a party or by which he or any of his assets or properties is bound.
 
                                       3

 
<PAGE>   81
 
                                   SECTION VI
 
     A. All notices, requests, instructions or documents hereunder shall be in
writing and delivered personally or sent by registered or express mail, postage
prepaid, as follows:
 
                            (i)  if to the Consultant:
 
                               -------------------------------------------------
 
                               -------------------------------------------------
 
                               -------------------------------------------------
 
                               with a copy to:
 
                               Thomas Litz, Esq.
                               Thompson & Mitchell
                               One Mercantile Center
                               St. Louis, Missouri 63101
 
                            (ii) to the Corporation:
 
                               1770 Kirby Parkway
                               Suite 300
                               Memphis, Tennessee 38138
 
                               with a copy to:
 
                               Howard Kailes, Esq.
                               Krugman, Chapman & Grimshaw
                               Park 80 West -- Plaza Two
                               Saddle Brook, New Jersey 07663
 
or to such other address as either party may designate by written notice to the
other party. If delivered personally, the date on which such notice, request,
instruction or document is delivered shall be the date on which such delivery is
made, and if delivered by mail, the date on which deposited in the mail. Each
notice, request, instruction or document shall bear the date on which it is
delivered.
 
     B.  This Agreement is personal as to the Consultant and shall not be
assignable by the Consultant. Subject to the foregoing, all of the terms and
provisions of this Agreement shall be binding upon and shall inure to the
benefit of and be enforceable by the parties hereto and their respective
successors and assigns and legal representatives and (with respect to any
secrecy or non-use obligations) any other Disclosing Party.
 
     C.  This Agreement constitutes the complete understanding between the
parties hereto with respect to the transactions contemplated herein, no
statement, representation, warranty or covenant has been made by either party
hereto except as expressly set forth herein and therein, and no modification
hereof shall be effective unless in writing and signed by a party against which
it is sought to be enforced.
 
     D.  This Agreement shall be governed by and construed in accordance with
the laws of the State of Tennessee applicable in the case of agreements made and
to be performed entirely within such State.
 
     E.  It is the intention of the Consultant and the Corporation that the
provisions of this Agreement shall be enforced to the fullest extent permissible
under the laws and public policies of each jurisdiction in which enforcement is
sought, but that the unenforceability of any provisions of this Agreement shall
not render unenforceable, or impair, the remainder of this Agreement.
Accordingly, if any provision hereof is determined to be invalid or
unenforceable, either in whole or in part, this Agreement shall be deemed
amended to delete or modify, as necessary, the offending provision and to alter
the remainder of this Agreement in order to render it valid and enforceable.
 
                                       4

 
<PAGE>   82
 
     F.  This Agreement may be executed in counterparts, each of which shall be
deemed an original, but all of which, taken together, shall constitute one and
the same instrument.
 
     IN WITNESS WHEREOF, this Agreement has been duly executed by the parties
hereto as of the date first above written.
 
                            INSITUFORM TECHNOLOGIES, INC.
 

                            By
                               ---------------------------------------------
                               CONSULTANT:

                               ---------------------------------------------
                               Jerome Kalishman
 
                                       5

 

<PAGE>   1
                                                                      EXHIBIT C




                  INSITUFORM TECHNOLOGIES, INC. AND INSITUFORM
                          MID-AMERICA, INC. TO COMBINE

                 Memphis, TN and St. Louis, MO -- May 24, 1995 -- Insituform
Technologies, Inc. ("ITI") (Nasdaq National Stock Market:INSUA) and Insituform
Mid-America, Inc. ("IMA") (Nasdaq National Stock Market:INSMA) jointly announced
that they have entered into a definitive agreement which provides for the
combination of ITI and IMA in a transaction in which holders of IMA's Class A
Common Stock will receive 1.15 shares of ITI's Class A Common Stock for each
share of IMA Class A Common Stock held. Holders of IMA's Class B Common Stock
have agreed to convert their shares into IMA Class A Common Stock on a share for
share basis in connection with the transaction. The combination will be effected
through the merger into IMA of a subsidiary of ITI formed for that purpose, as a
result of which IMA would become a wholly-owned subsidiary of ITI.

                 The transaction is conditioned, upon, among other things,
approval by the stockholders of both ITI and IMA, registration under the
Securities Act of 1933 of the ITI shares to be issued in the transaction,
receipt of a legal opinion that the transaction will qualify as a tax-free
reorganization, confirmation that the transaction will qualify for
pooling-of-interests accounting treatment, expiration of the premerger
notification period under the Hart-Scott-Rodino Act, and other customary
conditions. ITI and IMA expect the transaction to be consummated toward the end
of the third quarter of 1995.

                 As a result of the consummation of the transaction, three
directors designated by IMA would join the ten current directors on ITI's
board. James D. Krugman would continue as Chairman of the Board and Jean-Paul
Richard as President and Chief Executive Officer of ITI. Jerome Kalishman,
Chairman of the Board of IMA, would become Vice Chairman of the Board of ITI,
and Robert W. Affholder, President of IMA, would become Chief Operating Officer
of ITI's North American contracting operations, which would be headquartered in
Chesterfield, MO.

                 The arrangements between the parties continue the previously
announced moratorium on further assertion of any rights in dispute as a result
of IMA's acquisition of the pipeline rehabilitation business of Enviroq
Corporation in April 1995 without consent of ITI, except for certain procedural
steps to preserve the respective rights of the parties.

                 Mr. Richard said that, "I am obviously delighted that an
agreement could be reached between ITI and IMA to combine the two companies. The
strategic logic for such a merger is, in ITI's opinion, extremely strong. The
most obvious reason for the merger

<PAGE>   2

is achieving greater "critical mass".  This means having better economies of
scale, greater operations flexibility and the enhanced ability to fund key
strategic initiatives such as technology development, industrial marketing and
overseas territorial expansion.  We believe another major reason for the
transaction is the high degree to which the two companies complement one
another. ITI has strong technology development and manufacturing skills as well
as a wide international presence. IMA has a broad contracting capability and a
strong contracting culture, and is also well positioned to take advantage of the
large and growing U.S. gas rehabilitation market with its PALTEM(R) hoselining
technology. This merger constitutes a major step in our efforts to build the
leading worldwide trenchless rehabilitation business."

         Mr. Kalishman added, "Those who follow the Insituform industry should
fully understand the strategic advantages of this combination. Among other
objectives, we look forward to the expansion of opportunities for employees of
both companies, and to a successful conclusion of the merger and the
development of the leading world-wide trenchless rehabilitation business."

                 Insituform Technologies, Inc. provides state-of-the-art
techniques for the reconstruction of deteriorated pipelines utilizing
trenchless processes, and owns the worldwide rights to the INSITUFORM(R)
process. By eliminating the need for disruptive excavation, ITI believes the
INSITUFORM(R) process provides a cost-effective solution to the problem of
deteriorated pipe systems.  Insituform Technologies, Inc. also offers the
NUPIPE(R) Process in the United States and overseas and is engaged in the
rehabilitation of pipeline for the mining and oil and gas industry under the
ULTRAPIPE(R) name.

         Insituform Mid-America, Inc. is a leader in the utilization of
trenchless technologies for rehabilitation, new construction and improvement of
sewer, pipe and conduit systems.

                                 #### #### ####


CONTACT:                                       ITI'S INVESTOR RELATIONS COUNSEL:
Insituform Technologies, Inc.                  The Equity Group Inc.
Jean-Paul Richard, Pres. & CEO                 Linda Latman
(901) 759-7473                                 (212) 836-9609

Insituform Mid-America, Inc.
Jerome Kalishman, Chairman
(314) 532-6173


<PAGE>   1
                                                                      EXHIBIT D


                                  May 23, 1995



Insituform Mid-America, Inc.
P.O. Box 1026
17988 Edison Avenue
Chesterfield, Missouri  63005

Dear Sirs:

         This letter shall memorialize the agreement between Insituform
Technologies, Inc., for itself and on behalf of Insituform Acquisition Corp.,
Insituform North America Corp., NuPipe, Inc. and Insituform California, Inc.
(collectively "ITI"), and Insituform Mid-America, Inc., for itself and on
behalf of IMA Merger Sub, Inc. (formerly, Enviroq Corporation), Insituform
Southeast, Inc., NuPipe Southeast, Inc. and E-Midsouth, Inc. (collectively
"IMA") with respect to the manner in which the parties will proceed with the
litigation currently pending in the United States District Court for the
Western District of Tennessee, Western Division, entitled Insituform North
America Corp., and NuPipe, Inc.,Plaintiffs vs. Insituform Southeast, Inc.,
NuPipe Southeast, Inc., Enviroq Corporation and Insituform Mid-America, Inc.,
Defendants, Docket No. 95-2329 (the "Litigation").

         IMA and ITI have concurrently herewith entered into an Agreement and
Plan of Merger dated this date (the "Merger Agreement"), Section 13.3 of which
provides that ITI and IMA will extend the Cooperation Agreement (the
"Cooperation Agreement") as defined in the Merger Agreement through the
Effective Time (as defined in the Merger Agreement) or such earlier date as
shall occur upon the termination of the Merger Agreement (which, under the
provisions of Section 12.1 of the Merger Agreement may be effectuated by a
party if closing has not occurred on or prior to January 31, 1996).

         To effectuate the purposes of the Cooperation Agreement in the context
of the Merger Agreement, we have agreed to the following:

         1.      The parties in the Litigation shall submit a joint motion to
the Court seeking to stay all proceedings in the Litigation until January 31,
1996 or the earlier termination of the Merger Agreement.

         2.      If the Court declines to grant the requested relief, the
following procedure shall be the exclusive procedure utilized with respect to
the subject matter of the Litigation or the Consent (as defined in the
Cooperation Agreement):

                 (a)      The parties in the Litigation shall sign a
Stipulation of Dismissal dismissing the Litigation without prejudice;
<PAGE>   2
                 (b)      In the event (i) the Effective Time does not occur on
or before January 31, 1996, or (ii) the Merger Agreement is terminated prior to
that time, plaintiffs may recommence the Litigation by filing a complaint
(substantially in the form heretofore filed by plaintiffs) in the United States
District Court for the Western District of Tennessee within thirty (30) days of
January 31, 1996 or such earlier date as the Merger Agreement is terminated;

                 (c)      In the event plaintiffs do not commence proceedings
contemplated by the preceding paragraph (b)  defendants in the Litigation may
demand that plaintiffs reinstitute litigation in the United States District
Court for the Western District of Tennessee by filing a complaint
(substantially in the form heretofore filed by plaintiffs) which complaint
shall be filed by plaintiffs in the United States District Court for the
Western District of Tennessee within thirty (30) days of receipt of such demand
(provided, however, that such demand by defendants shall not be deemed to be a
waiver of any defenses to jurisdiction or venue defendants otherwise could
assert in the Litigation);

                 (d)      If plaintiffs do not commence proceedings within the
time specified in the preceding paragraph (c), defendants may file a lawsuit 
in the United States District Court for the Western District of Tennessee or 
another state or federal court in Tennessee or any other state raising claims 
otherwise involved in the Litigation; and

                 (e)      In the event litigation is commenced or recommenced
in the United States District Court for the Western District of Tennessee or
another jurisdiction, no party shall assert any defense relating to any statute
of limitations, laches or any other passage of time as a result of the
dismissal of the Litigation and reinstitution of proceedings.

         Subject to the foregoing, the Cooperation Agreement shall extend in
full force and effect.

         Please confirm your consent to the foregoing by signing the copy of
this letter in the space provided.

                                        Very truly yours,

                                        INSITUFORM TECHNOLOGIES, INC.


                                        By: s/J.P. Richard
                                           -------------------------------------
                                             J.P. Richard, President
AGREED TO:
INSITUFORM MID-AMERICA, INC.

By: s/Jerome Kalishman      
   ---------------------------
   Jerome Kalishman,
   Chief Executive Officer and
   Chairman of the Board


<PAGE>   1
                                                                      EXHIBIT E





                                  May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In connection with the transactions contemplated by the Agreement and
Plan of Merger dated May 23, 1995 (the "Agreement") among Insituform
Technologies, Inc., a Delaware corporation (the "Company"), ITI Acquisition
Corp., a Delaware corporation ("ITI Sub"), and Insituform Mid-America, Inc., a
Delaware corporation ("IMA"), the undersigned hereby agrees to convert or to
cause the conversion of, immediately prior to the consummation of the
transactions contemplated by the Agreement, each outstanding share of Class B
Common Stock, $.01 par value ("Class B Common Stock"), of IMA, that may be
beneficially owned by the undersigned into one share of Class A Common Stock,
$.01 par value, of IMA in accordance with the terms of IMA's certificate of
incorporation, as currently in effect.

         The undersigned represents and warrants to the Company that the
undersigned is the record and beneficial owner of 471,300 shares of Class B
Common Stock. The undersigned is not the record or beneficial owner of any
other shares of Class B Common Stock.

         In the event that the merger of IMA and ITI Sub contemplated by the
Agreement is terminated  this Agreement shall be null and void.



                                                  s/Robert W. Affholder
                                                  ------------------------------
                                                  Robert W. Affholder

<PAGE>   2





                                  May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In connection with the transactions contemplated by the Agreement and
Plan of Merger dated May 23, 1995 (the "Agreement") among Insituform
Technologies, Inc., a Delaware corporation (the "Company"), ITI Acquisition
Corp., a Delaware corporation ("ITI Sub"), and Insituform Mid-America, Inc., a
Delaware corporation ("IMA"), the undersigned hereby agrees to convert or to
cause the conversion of, immediately prior to the consummation of the
transactions contemplated by the Agreement, each outstanding share of Class B
Common Stock, $.01 par value ("Class B Common Stock"), of IMA, that may be
beneficially owned by the undersigned into one share of Class A Common Stock,
$.01 par value, of IMA in accordance with the terms of IMA's certificate of
incorporation, as currently in effect.

         The undersigned represents and warrants to the Company that the
undersigned is the record and beneficial owner of 26,666 shares of Class B
Common Stock. The undersigned is not the record or beneficial owner of any
other shares of Class B Common Stock.

         In the event that the merger of IMA and ITI Sub contemplated by the
Agreement is terminated  this Agreement shall be null and void.



                                                  s/Thomas N. Kalishman
                                                  ------------------------------
                                                  Thomas N. Kalishman


 
<PAGE>   3





                                  May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In connection with the transactions contemplated by the Agreement and
Plan of Merger dated May 23, 1995 (the "Agreement") among Insituform
Technologies, Inc., a Delaware corporation (the "Company"), ITI Acquisition
Corp., a Delaware corporation ("ITI Sub"), and Insituform Mid-America, Inc., a
Delaware corporation ("IMA"), the undersigned hereby agrees to convert or to
cause the conversion of, immediately prior to the consummation of the
transactions contemplated by the Agreement, each outstanding share of Class B
Common Stock, $.01 par value ("Class B Common Stock"), of IMA, that may be
beneficially owned by the undersigned into one share of Class A Common Stock,
$.01 par value, of IMA in accordance with the terms of IMA's certificate of
incorporation, as currently in effect.

         The undersigned represents and warrants to the Company that the
undersigned is the record and beneficial owner of 26,666 shares of Class B
Common Stock. The undersigned is not the record or beneficial owner of any
other shares of Class B Common Stock.

         In the event that the merger of IMA and ITI Sub contemplated by the
Agreement is terminated  this Agreement shall be null and void.



                                                  s/John F. Kalishman
                                                  ------------------------------
                                                  John F. Kalishman


<PAGE>   4





                                  May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In connection with the transactions contemplated by the Agreement and
Plan of Merger dated May 23, 1995 (the "Agreement") among Insituform
Technologies, Inc., a Delaware corporation (the "Company"), ITI Acquisition
Corp., a Delaware corporation ("ITI Sub"), and Insituform Mid-America, Inc., a
Delaware corporation ("IMA"), the undersigned hereby agrees to convert or to
cause the conversion of, immediately prior to the consummation of the
transactions contemplated by the Agreement, each outstanding share of Class B
Common Stock, $.01 par value ("Class B Common Stock"), of IMA, that may be
beneficially owned by the undersigned into one share of Class A Common Stock,
$.01 par value, of IMA in accordance with the terms of IMA's certificate of
incorporation, as currently in effect.

         The undersigned represents and warrants to the Company that the
undersigned is the record and beneficial owner of 26,666 shares of Class B
Common Stock. The undersigned is not the record or beneficial owner of any
other shares of Class B Common Stock.

         In the event that the merger of IMA and ITI Sub contemplated by the
Agreement is terminated  this Agreement shall be null and void.



                                                  s/Susan Kalishman
                                                  ------------------------------
                                                  Susan Kalishman


<PAGE>   5





                                  May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In connection with the transactions contemplated by the Agreement and
Plan of Merger dated May 23, 1995 (the "Agreement") among Insituform
Technologies, Inc., a Delaware corporation (the "Company"), ITI Acquisition
Corp., a Delaware corporation ("ITI Sub"), and Insituform Mid-America, Inc., a
Delaware corporation ("IMA"), the undersigned hereby agrees to convert or to
cause the conversion of, immediately prior to the consummation of the
transactions contemplated by the Agreement, each outstanding share of Class B
Common Stock, $.01 par value ("Class B Common Stock"), of IMA, that may be
beneficially owned by the undersigned into one share of Class A Common Stock,
$.01 par value, of IMA in accordance with the terms of IMA's certificate of
incorporation, as currently in effect.

         The undersigned represents and warrants to the Company that the
undersigned is the record and beneficial owner of 26,666 shares of Class B
Common Stock. The undersigned is not the record or beneficial owner of any
other shares of Class B Common Stock.

         In the event that the merger of IMA and ITI Sub contemplated by the
Agreement is terminated  this Agreement shall be null and void.



                                                  s/James F. Kalishman
                                                  ------------------------------
                                                  James F. Kalishman


<PAGE>   6





                                  May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In connection with the transactions contemplated by the Agreement and
Plan of Merger dated May 23, 1995 (the "Agreement") among Insituform
Technologies, Inc., a Delaware corporation (the "Company"), ITI Acquisition
Corp., a Delaware corporation ("ITI Sub"), and Insituform Mid-America, Inc., a
Delaware corporation ("IMA"), the undersigned hereby agrees to convert or to
cause the conversion of, immediately prior to the consummation of the
transactions contemplated by the Agreement, each outstanding share of Class B
Common Stock, $.01 par value ("Class B Common Stock"), of IMA, that may be
beneficially owned by the undersigned into one share of Class A Common Stock,
$.01 par value, of IMA in accordance with the terms of IMA's certificate of
incorporation, as currently in effect.

         The undersigned represents and warrants to the Company that the
undersigned is the record and beneficial owner of 1,895,021 shares of Class B
Common Stock. The undersigned is not the record or beneficial owner of any
other shares of Class B Common Stock.

         In the event that the merger of IMA and ITI Sub contemplated by the
Agreement is terminated  this Agreement shall be null and void.

                                               XANADU INVESTMENTS, L.P.


                                               s/Jerome Kalishman
                                               ---------------------------------
                                               Jerome Kalishman, General Partner



<PAGE>   1
                                                                   EXHIBIT F




                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common

<PAGE>   2

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                  s/Paul A. Biddelman
                                                  ------------------------------


<PAGE>   3





                                  May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May  23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it has not or will not sell, transfer, pledge,
hypothecate or otherwise convey or dispose of or enter into any contract or
arrangement for the sale, transfer, pledge, hypothecation, conveyance or other
disposition of any shares of Class A Common Stock, $.01 par value ("IMA Class A
Common Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA
Class B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par
value (the "ITI Common Stock"), of the Company, owned by the undersigned from
the date hereof until the earlier of (i) the termination of the Agreement or
(ii) the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement, and except that the foregoing agreement shall
not extend to (a) the pledge by Ringwood Limited, individually or together with
Parkwood Limited, of 200,000 shares of ITI Common Stock pursuant to a Secured
Loan Agreement dated July 3, 1992, as hereinbefore and hereinafter from time to
time amended, among the undersigned, Douglas K. Chick, Ringwood Limited and
Sanmartin Company, and (b) the pledge by Ringwood Limited of 255,801 shares of
ITI Common Stock pursuant to a Stock Pledge Agreement dated July 3, 1992, as
hereinbefore and hereinafter from time to time amended, among the undersigned,
Ringwood Limited, Brian Chandler and the Company, and

 
<PAGE>   4

(c) open market brokerage transactions in the over-the-counter market
effectuated on or prior to August 1, 1995 by Parkwood Limited, Ringwood Limited
and/or Brian Chandler covering up to 30,000 shares of ITI Class A Common Stock
in the aggregate.


         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common Stock, with respect
to any of the ITI Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned.




                                                  s/Brian Chandler
                                                  ------------------------------
                                                  Brian Chandler





<PAGE>   5





                                  May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May  23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it has not or will not sell, transfer, pledge,
hypothecate or otherwise convey or dispose of or enter into any contract or
arrangement for the sale, transfer, pledge, hypothecation, conveyance or other
disposition of any shares of Class A Common Stock, $.01 par value ("IMA Class A
Common Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA
Class B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par
value (the "ITI Common Stock"), of the Company, owned by the undersigned from
the date hereof until the earlier of (i) the termination of the Agreement or
(ii) the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement, and except that the foregoing agreement shall
not extend to (a) the pledge by by Ringwood Limited, individually or together
with Parkwood Limited, of 200,000 shares of ITI Common Stock pursuant to a
Secured Loan Agreement dated July 3, 1992, as hereinbefore and hereinafter from
time to time amended, among the undersigned, Ringwood Limited, Brian Chandler
and Sanmartin Company, and (b) the pledge by Ringwood Limited of 255,801 shares
of ITI Common Stock pursuant to a Stock Pledge Agreement dated July 3, 1992, as
hereinbefore and hereinafter from time to time amended, among the undersigned,
Ringwood Limited, Brian Chandler and the Company and

 
<PAGE>   6

(c) open market brokerage transactions in the over-the-counter market
effectuated on or prior to August 1, 1995 by Ringwood Limited, Parkwood Limited
and/or Brian Chandler covering up to 30,000 shares of ITI Class A Common Stock
in the aggregate.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common Stock, with respect
to any of the ITI Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned.




                                                  s/Douglas K. Chick            
                                                  ------------------------------
                                                  Douglas K. Chick





<PAGE>   7





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement, and except that the foregoing agreement shall
not extend to open market brokerage transactions in the over-the-counter market
effectuated on or prior to August 1, 1995 covering up to 24,000 shares of ITI
Common Stock in the aggregate.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the

<PAGE>   8

undersigned, and with the transfer agent of the IMA Class B Common Stock, with
respect to any of the IMA Class B Common Stock registered in the name of the
undersigned or beneficially owned by the undersigned, and with the transfer
agent of the ITI Common Stock, with respect to any of the ITI Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned.




                                                  s/William Gorham
                                                  ------------------------------
                                                  William Gorham



<PAGE>   9





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common

<PAGE>   10

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                  s/Anthony W. Hooper
                                                  ------------------------------


 
<PAGE>   11





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common

<PAGE>   12

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                  s/James D. Krugman
                                                  ------------------------------





<PAGE>   13





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common

 
<PAGE>   14

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                   s/David Mandelbaum
                                                   -----------------------------
                                                   David Mandelbaum



<PAGE>   15





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common

 
<PAGE>   16

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                   s/William A. Martin
                                                   -----------------------------


<PAGE>   17





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common


 
<PAGE>   18

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                   s/Robert W. Pittman
                                                   -----------------------------



<PAGE>   19





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common

 
<PAGE>   20

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                  s/Jean-Paul Richard
                                                  ------------------------------



<PAGE>   21





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common

 
<PAGE>   22

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                  s/Steven Roth
                                                  ------------------------------





<PAGE>   23





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common

 
<PAGE>   24

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                  s/Silas Spengler
                                                  ------------------------------





<PAGE>   25





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common

 
<PAGE>   26

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                  s/Raymond P. Toth
                                                  ------------------------------





<PAGE>   27





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common

 
<PAGE>   28

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                  s/Sheldon Weinig
                                                  ------------------------------





<PAGE>   29





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common

 
<PAGE>   30

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                  s/Russell B. Wight, Jr.
                                                  ------------------------------





<PAGE>   31





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common

 
<PAGE>   32

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                                  s/Russell B. Wight, Jr.
                                                  ------------------------------
                                                  Interstate Properties





<PAGE>   33





                                  May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it has not or will not sell, transfer, pledge,
hypothecate or otherwise convey or dispose of or enter into any contract or
arrangement for the sale, transfer, pledge, hypothecation, conveyance or other
disposition of any shares of Class A Common Stock, $.01 par value ("IMA Class A
Common Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA
Class B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par
value (the "ITI Common Stock"), of the Company, owned by the undersigned from
the date hereof until the earlier of (i) the termination of the Agreement or
(ii) the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement, and except that the foregoing agreement shall
not extend to (a) the pledge  by Ringwood Limited, individually or together
with Parkwood Limited, of 200,000 shares of ITI Common Stock pursuant to a
Secured Loan Agreement dated July 3, 1992, as hereinbefore and hereinafter from
time to time amended, among Ringwood Limited, Douglas K. Chick, Brian Chandler
and Sanmartin Company, and (b) the pledge by Ringwood Limited of 255,801 shares
of ITI Common Stock pursuant to a Stock Pledge Agreement dated July 3, 1992, as
hereinbefore and hereinafter from time to time amended, among Ringwood Limited,
Brian Chandler, Douglas K. Chick and the Company

 
<PAGE>   34

and (c) open market brokerage transactions in the over-the-counter market
effectuated on or prior to August 1, 1995 by Ringwood Limited, Parkwood Limited
and/or Brian Chandler covering up to 30,000 shares of ITI Class A Common Stock
in the aggregate..

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common Stock, with respect
to any of the ITI Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned.

                                            BARFORD LIMITED, as Trustee
                                             of the Anthony Basmadjian
                                             Settlement



                                            By s/Howard Kailes
                                              ---------------------------------
                                               Howard Kailes
                                               Attorney-in-Fact





 
<PAGE>   35





                                  May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it has not or will not sell, transfer, pledge,
hypothecate or otherwise convey or dispose of or enter into any contract or
arrangement for the sale, transfer, pledge, hypothecation, conveyance or other
disposition of any shares of Class A Common Stock, $.01 par value ("IMA Class A
Common Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA
Class B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par
value (the "ITI Common Stock"), of the Company, owned by the undersigned from
the date hereof until the earlier of (i) the termination of the Agreement or
(ii) the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement, and except that the foregoing agreement shall
not extend to (a) the pledge by the undersigned, individually or together with
Ringwood Limited, of 200,000 shares of ITI Common Stock pursuant to a Secured
Loan Agreement dated July 3, 1992, as hereinbefore and hereinafter from time to
time amended, among Ringwood Limited, Douglas K. Chick, Brian Chandler and
Sanmartin Company, and (b) the pledge by Ringwood Limited of 255,801 shares of
ITI Common Stock pursuant to a Stock Pledge Agreement dated July 3, 1992, as
hereinbefore and hereinafter from time to time amended, among Ringwood Limited,
Brian Chandler, Douglas K. Chick and the Company




 
<PAGE>   36

and (c) open market brokerage transactions in the over-the-counter market
effectuated on or prior to August 1, 1995 by the undersigned, Ringwood Limited
and/or Brian Chandler covering up to 30,000 shares of ITI Class A Common Stock
in the aggregate.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common Stock, with respect
to any of the ITI Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned.

                                            PARKWOOD LIMITED, as Trustee
                                             of the Anthony Basmadjian "P"
                                             Settlement



                                            By s/Howard Kailes
                                              ---------------------------------
                                               Howard Kailes
                                               Attorney-in-Fact




 
<PAGE>   37
                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it has not or will not sell, transfer, pledge,
hypothecate or otherwise convey or dispose of or enter into any contract or
arrangement for the sale, transfer, pledge, hypothecation, conveyance or other
disposition of any shares of Class A Common Stock, $.01 par value ("IMA Class A
Common Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA
Class B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par
value (the "ITI Common Stock"), of the Company, owned by the undersigned from
the date hereof until the earlier of (i) the termination of the Agreement or
(ii) the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement, and except that the foregoing agreement shall
not extend to (a) the pledge of 200,000 shares of ITI Common Stock by the
undersigned individually, or together with Parkwood Limited, pursuant to a
Secured Loan Agreement dated July 3, 1992, as hereinbefore and hereinafter from
time to time amended, among the undersigned, Douglas K. Chick, Brian Chandler
and Sanmartin Company, and (b) the pledge of 255,801 shares of ITI Common Stock
pursuant to a Stock Pledge Agreement dated July 3, 1992, as hereinbefore and
hereinafter from time to time amended, among the undersigned, Brian Chandler,
Douglas K. Chick and the Company and (c) open market


 
<PAGE>   38
brokerage transactions in the over-the-counter market effectuated on or prior
to August 1, 1995 by the undersigned, Parkwood Limited and/or Brian Chandler
covering up to 30,000 shares of ITI Class A Common Stock in the aggregate.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common Stock, with respect
to any of the ITI Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned.

                                           RINGWOOD LIMITED


                                           By s/Howard Kailes
                                             -----------------------------------
                                              Howard Kailes
                                              Attorney-in-Fact



 
<PAGE>   39
                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common



 
<PAGE>   40
Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                        s/Robert W. Affholder
                                        ----------------------------------------
                                        Robert W. Affholder
<PAGE>   41





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common


 
<PAGE>   42
Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                        s/Jerome Kalishman
                                        ----------------------------------------
                                        Jerome Kalishman

<PAGE>   43




                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common


 
<PAGE>   44

Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.


                                        s/Jerome Kalishman
                                        ----------------------------------------


                                        s/Nancy Kalishman
                                        ----------------------------------------
                                        Jerome Kalishman and
                                         Nancy Kalishman, as tenants
                                         by the entirety



<PAGE>   45


                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common


 
<PAGE>   46
Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                        s/Jerome Kalishman
                                        ----------------------------------------
                                        Jerome Kalishman as Trustee for
                                         the Jerome Kalishman and Nancy
                                         Kalishman Family Fund
                                         by the entirety

<PAGE>   47





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common


 
<PAGE>   48
Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                        s/Jerome Kalishman
                                        ----------------------------------------
                                        Jerome Kalishman, as Trustee
                                        of the Jerome Kalishman and
                                        Nancy Kalishman Irrevocable
                                        Grandchildren's Trust


<PAGE>   49



                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common



 
<PAGE>   50
Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                        s/Nancy F. Kalishman
                                        ----------------------------------------
                                        Nancy F. Kalishman


<PAGE>   51



                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common



 
<PAGE>   52
Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                        s/Robert M. Leopold
                                        ----------------------------------------
                                        Robert M. Leopold
<PAGE>   53





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common



 
<PAGE>   54
Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                        s/Lee M. Liberman
                                        ----------------------------------------
                                        Lee M. Liberman
<PAGE>   55





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common



 
<PAGE>   56
Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                        s/Joseph F. Olson
                                        ----------------------------------------
                                        Joseph F. Olson
<PAGE>   57





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common



 
<PAGE>   58
Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                        s/Alvin J. Siteman
                                        ----------------------------------------
                                        Alvin J. Siteman
<PAGE>   59





                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common



 
<PAGE>   60
Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.




                                        s/James L. Tadtman
                                        ----------------------------------------
                                        James L. Tadtman



<PAGE>   61


                                                                    May 23, 1995

Insituform Technologies, Inc.
1770 Kirby Parkway
Suite 300
Memphis, Tennessee  38138

Insituform Mid-America, Inc.
17988 Edison Avenue
Chesterfield, Missouri 63005


Gentlemen:

         In furtherance of the Agreement and Plan of Merger dated May 23, 1995
(the "Agreement") among Insituform Technologies, Inc., a Delaware corporation
(the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI Sub"), and
Insituform Mid-America, Inc., a Delaware corporation ("IMA"), the undersigned
hereby agrees that he or it will not sell, transfer, pledge, hypothecate or
otherwise convey or dispose of or enter into any contract or arrangement for
the sale, transfer, pledge, hypothecation, conveyance or other disposition of
any shares of Class A Common Stock, $.01 par value ("IMA Class A Common
Stock"), of IMA, any shares of Class B Common Stock $.01 par value ("IMA Class
B Common Stock"), of IMA, or any shares of Class A Common Stock, $.01 par value
(the "ITI Common Stock"), of the Company, owned by the undersigned from the
date hereof until the earlier of (i) the termination of the Agreement or (ii)
the date of the first publication of the operating results of the Company
covering at least a 30-day period after the merger of IMA and ITI Sub has been
consummated, without the prior written consent of the Company, except that the
undersigned may convert any shares of IMA Class B Common Stock into shares of
IMA Class A Common Stock prior to the consummation of the transactions
contemplated by the Agreement.

         In order to enable you to enforce the aforesaid covenant, the
undersigned hereby consents to placing stop-transfer orders with the transfer
agents, respectively, of the IMA Class A Common Stock, with respect to any of
the IMA Class A Common Stock registered in the name of the undersigned or
beneficially owned by the undersigned, and with the transfer agent of the IMA
Class B Common Stock, with respect to any of the IMA Class B Common Stock
registered in the name of the undersigned or beneficially owned by the
undersigned, and with the transfer agent of the ITI Common



 
<PAGE>   62
Stock, with respect to any of the ITI Common Stock registered in the name of
the undersigned or beneficially owned by the undersigned.

                                        XANADU INVESTMENTS, L.P.


                                        s/Jerome Kalishman
                                        ----------------------------------------
                                        Jerome Kalishman, General Partner

<PAGE>   1
                                                                      EXHIBIT G



                                                                    May 23, 1995

Interstate Properties
Park 80 West-Plaza Two
Saddle Brook, New Jersey  07663

Dear Sirs:

         In furtherance of the Agreement and Plan of Merger dated as of May 23,
1995 (the "Agreement") among Insituform Technologies, Inc., a Delaware
corporation (the "Company"), ITI Acquisition Corp., a Delaware corporation ("ITI
Sub"), and Insituform Mid-America, Inc., a Delaware corporation ("IMA"), and in
connection with your letter to the Company and IMA dated this date with respect
to the sale, transfer, pledge, hypothecation, conveyance or other disposition of
securities of the Company or IMA, the undersigned hereby commits to use its best
efforts, upon your request, to publish at the earliest practicable date the
operating results of the Company covering the first full calendar month after
the Merger has been consummated; provided, however, that, in the event the
Merger is consummated subsequent to October 31, 1995 and prior to November 30,
1995 such obligation shall be satisfied by the Company's publication at the
earliest practicable date of its operating results for the fiscal year in which
the consummation of the Merger occurs; and provided, further that, in the event
the Merger is consummated subsequent to November 30, 1995, the operating results
of the Company covering such full calendar month after the Merger has been
consummated shall not be published prior to publication of operating results for
such year (which the Company shall use its best efforts to publish at the
earliest practicable date).

         The provisions hereof are not intended, and shall not be construed, to
confer any benefits or rights upon any party other than you and the
undersigned.

                                        Very truly yours,

                                        INSITUFORM TECHNOLOGIES, INC.


                                        By s/James D. Krugman
                                          --------------------------------------

ACCEPTED:

INTERSTATE PROPERTIES


By s/Russell B. Wight, Jr.
  ------------------------
<PAGE>   2


         The undersigned hereby agree that, for purposes of the letters, each
dated this date, with respect to the sale, transfer, pledge, hypothecation,
conveyance or other disposition of securities of the Company and IMA executed to
them by, respectively, Interstate Properties, Steven Roth, Russell B. Wight,
Jr., and David Mandelbaum, the reference to "30-day period" shall be deemed a
reference to the shorter of a 30-day period or a full calendar month; and that
Interstate Properties and Messrs. Wight, Roth and Mandelbaum shall be entitled
to rely hereon.

                                        INSITUFORM TECHNOLOGIES, INC.



                                        By s/James D. Krugman
                                          --------------------------------------

                                        INSITUFORM MID-AMERICA, INC.



                                        By s/Jerome Kalishman
                                          --------------------------------------


ACCEPTED:

INTERSTATE PROPERTIES


By s/Russell B. Wight, Jr.  
  ---------------------------

<PAGE>   3
                                         As of May 23, 1995


Interstate Properties
Park 80 West-Plaza Two         
Saddle Brook, New Jersey  07663

Mr. Steven Roth
Interstate Properties
Park 80 West-Plaza Two         
Saddle Brook, New Jersey  07663

Mr. Russell B. Wight, Jr.
Interstate Properties
Park 80 West-Plaza Two         
Saddle Brook, New Jersey  07663

Mr. David Mandelbaum
Interstate Properties
Park 80 West-Plaza Two         
Saddle Brook, New Jersey  07663

Dear Sirs:

          Reference is hereby made to your letters, respectively, to the
undersigned dated this date with respect to the sale, transfer, pledge,
hypothecation, conveyance or other disposition of securities of the
undersigned, or each of them.  The undersigned each agree that such letters
shall have no force or effect in the event the Merger (as defined in the
Agreement and Plan of Merger dated as of May 23, 1995 among the undersigned and
ITI Acquisition Corp) is not consummated on or prior to January 31, 1996.

          The provisions hereof are not intended, and shall not be construed to
confirm any benefits or rights upon any party other than you and the
undersigned.

                                        Very truly yours,

                                        INSITUFORM TECHNOLOGIES, INC.


                                        By s/James D. Krugman                   
                                          -------------------------------------

                                        INSITUFORM MID-AMERICA, INC.

 
                                        By s/James D. Krugman                   
                                          -------------------------------------



 


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