<PAGE>
                                                                    EXHIBIT 10.1

                   EXECUTIVE SEPARATION AGREEMENT AND RELEASE

         THIS EXECUTIVE SEPARATION AGREEMENT AND RELEASE (the "AGREEMENT") is
made and entered into effective as of June 18, 2004 (the "EFFECTIVE DATE") by
and between INSITUFORM TECHNOLOGIES, INC., a Delaware corporation ("EMPLOYER"),
and Thomas A.A. Cook ("EXECUTIVE").

                              PRELIMINARY STATEMENT

         A. Executive's employment with Employer terminated as of the Effective
Date.

         B. Without any admission as to fault, liability or wrongdoing, and in
order to provide for a smooth transition of the general counsel and corporate
secretary functions of Employer and to avoid the time, distractions and resource
expenditures potentially associated with an involuntary departure, Employer and
Executive desire to resolve all matters relating to or arising out of
Executive's employment by Employer and Executive's termination of employment
with Employer on the terms described below.

         C. Executive is being provided a period of seven (7) days from the
Effective Date (which will be June 25, 2004, to consider the meaning and effect
of this Agreement prior to finally accepting this Agreement. Executive has been
(and hereby is) advised in writing to consult with an attorney prior to finally
accepting this Agreement.

         NOW, THEREFORE, in consideration of the mutual agreements and promises
contained herein and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

         1. RESIGNATION AS EXECUTIVE OFFICER OF EMPLOYER AND ALL AFFILIATES;
EMPLOYMENT TERMINATION. Executive voluntarily resigns all of his executive
officer and director positions and offices with Employer and any of its
subsidiaries and plans as of the Effective Date. These resignations are effected
by means of a separate resignation letter in the form attached to this Agreement
as Exhibit A, signed and delivered by Executive and accepted by Employer. The
employment of Executive by Employer, in any capacity whatsoever, ceases as of
the Effective Date. Executive's status as an executive officer of Employer, and
the accompanying obligations imposed upon executive officers of public companies
by applicable law, regulation, contract and internal company policy also cease
as of the Effective Date. Any and all right or authority of Executive to act as
an agent of Employer, in any manner whatsoever, terminates on the Effective
Date. Employer will pay Executive as soon as practicable after the Effective
Date for all accrued but unpaid compensation due Executive as well as any
accrued but unused vacation time as of the Effective Date.

         2. REVOCATION OF ACCEPTANCE. Executive has the right to consult with an
attorney or attorneys of his choice concerning this Agreement and has been
advised in writing of his right to do so. Executive has until June 25, 2004
(seven (7) days from the Effective Date) to revoke his acceptance of this
Agreement. For Executive to revoke his acceptance of this Agreement, he must
notify the President and Chief Executive Officer, through written notice
delivered to the President and Chief Executive Officer prior to the close of
business on June 25, 2004, of his decision to revoke his acceptance. If
Executive revokes his acceptance prior to the close of business on June 25,
2004, the payments described in this Agreement and the benefits agreed upon will
not be paid or provided and this Agreement shall be null, void and of no force
or effect with respect to either Executive or Employer. In the event of a timely
revocation of acceptance of this Agreement, the resignation of Executive from
his positions as an executive officer of Employer and its subsidiaries and
affiliates as contemplated in Section 1 will not be revoked and will remain in
full force and effect.


                                                        Executive Initials: TAAC

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         3. SEPARATION PAYMENTS AND BENEFITS. In consideration for the
resignation of Executive from all executive officer positions with Employer and
its subsidiaries and affiliates and the other representations, warranties,
covenants and agreements made by Executive and contained in this Agreement,
Employer shall pay the following amounts and provide the following benefits (the
"SEPARATION PAYMENTS AND BENEFITS") under the terms and conditions stated in
this Agreement:

                  (a) REGULAR CASH SEVERANCE PAYMENTS. Employer agrees to pay
Executive a one-time lump-sum payment on or before the 30th day after the
Effective Date equal to One Hundred and Thirty Thousand Dollars ($130,000.00) in
cash.

                  (b) CONTINUATION OF HEALTH, DENTAL, LIFE AND DISABILITY
BENEFITS AND AUTOMOBILE ALLOWANCE. Employer agrees to continue to provide
Executive with health, dental, life and disability benefits equivalent to
Executive's current benefits for Executive and his eligible family members (the
"WELFARE BENEFITS") through the last day of June 2004. If Executive chooses to
continue his health and medical benefits under the Consolidated Omnibus Budget
Reconciliation Act of 1985, as amended ("COBRA") after June 30, 2004, Executive
will be responsible for the payment of such benefits for the remainder of the
period required under COBRA. Unless otherwise modified in a separate letter on
continued employment of Executive by Employer, Executive agrees that the
qualifying event for electing to continue Executive's health and medical
benefits under COBRA is the Effective Date. After the Effective Date, Executive
shall not be entitled to continue his participation in any other benefits
generally available to employees of Employer, including any car allowance,
401(k) plan, cash incentive or bonus plans, stock-based incentive plans or the
like, except as is generally allowable pursuant to the explicit terms and
conditions of such programs or plans.

                  (c) EXERCISABILITY OF STOCK OPTIONS; UNVESTED STOCK AWARDS
FORFEITED. Any vested options that Executive holds unexercised on the Effective
Date will remain exercisable until [JULY 18, 2004], but any options or other
stock awards that are unvested on the Effective Date will be cancelled and
forfeited by Executive to Employer. Executive acknowledges and agrees that he
will remain subject to Employer's insider trading policy, which includes
compliance with the blackout period for the quarter ending June 30, 2004, except
that transactions in the stock of Employer that Executive commenced on or prior
to the Effective Date are specifically not subject to such period.

                  (d) GENERAL. All Separation Payments and Benefits shall be
paid or provided subject to any applicable federal, state and local income tax
or other appropriate withholding requirements as well as the right of Employer
to directly offset any amounts owed by Executive to Employer. Further, the
Separation Payments and Benefits represent all of the compensation (including
vacation and severance pay) to which Executive is, or may be, entitled by virtue
of Executive's employment and separation from employment with Employer. This
Section 3, however, shall have no force or effect if Executive revokes
Executive's acceptance of this Agreement pursuant to Section 2 hereof.

         4. PRIOR AGREEMENTS SUPERSEDED; REPRESENTATIONS AND RELEASES.

                  (a) PRIOR AGREEMENTS, PRACTICES, POLICIES AND PROCEDURES
REGARDING SEVERANCE OR SEPARATION BENEFITS SUPERSEDED. In consideration for all
of the Severance Payments and Benefits to be paid or received by Executive under
this Agreement and subject to Section 2, Executive agrees that any other
agreement between Employer and Executive with respect to severance or separation
payments is terminated as of the Effective Date of this Agreement and any such
agreement or any other severance practice, policy or procedure of Employer is
superseded in its entirety by the terms of this Agreement in all respects.
Executive will have no further rights, and Employer will have no further
obligations, under any such agreement, practice, policy or procedure.


                                                        Executive Initials: TAAC

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<PAGE>

                  (b) REPRESENTATIONS. Executive represents and warrants to
Employer that (i) Executive (A) has not filed any suit, action, claim,
allegation or other proceeding at law or in equity, before any court,
governmental agency, arbitration panel or other forum of any nature (an
"ACTION") with respect to the matters released below or (B) will not prosecute,
and will immediately dismiss with prejudice, any pending Action with respect to
the matters released below; (ii) Executive has not assigned to any other person
or entity any right(s) or claim(s) Executive may have against Employer; (iii) in
deciding to execute this Agreement (A) no fact, evidence, event or transaction
currently unknown to Executive, but which may hereinafter become known to
Executive, shall affect in any way or any manner the final or unconditional
nature of this Agreement; (B) Executive's execution of this Agreement is a
knowing and voluntary act on Executive's part and was not provided in connection
with any exit incentive or other employment termination program offered to any
group or class of employees; (C) Executive has read and fully understands the
terms of this Agreement, including the final and binding nature and effect of
Executive's waiver of rights by execution of this Agreement and was advised in
writing to consult with an attorney before signing the Agreement at the time
Executive first received this Agreement; (D) Executive has been provided with a
reasonable and adequate period of time (and at least seven (7) days) to consider
this Agreement and consult with his attorneys and advisors concerning this
Agreement; and (E) Executive has not been promised anything or provided any
consideration for entering into this Agreement that is not specified in this
Agreement. In addition, Executive hereby represents and warrants that, to the
best of his knowledge, Executive has disclosed to Employer, either on or prior
to the Effective Date, any material violation of federal, state, foreign or
local criminal law or regulation that is applicable to Employer, any threatened
or pending federal, state, foreign or local governmental criminal investigation
against Employer and any practice or policy of Employer that may be unlawful
under applicable federal, state, foreign or local criminal law.

                  (c) WAIVER AND RELEASE. Executive hereby releases, gives up
and waives any and all rights, causes of action, lawsuits and claims for
liability Executive may now or in the future have against Employer, and its
shareholders, directors, officers, employees, agents, affiliates, subsidiaries,
Employer-sponsored benefit plans and associated trusts (including
administrators, trustees and other fiduciaries thereof) and predecessors in
interest, together with their respective shareholders, directors, officers,
employees, insurers and agents (collectively, "RELEASED PARTIES") in connection
with, relating to or arising out of or based upon Executive's employment with
Employer (or any Released Parties) or out of the termination of Executive's
employment with Employer (or any Released Parties), or any promise, agreement,
act, conduct or decision of any of the Released Parties to date. Further,
EXECUTIVE HEREBY VOLUNTARILY, KNOWINGLY, IRREVOCABLY AND UNCONDITIONALLY,
RELEASES, REMISES, ACQUITS AND FOREVER DISCHARGES RELEASED PARTIES of and from
any and all manner of claims, actions, charges, complaints, causes of action,
suits, judgments, demands, injuries, damages and agreements whatsoever, whether
in law or in equity, whether based on contract, statute, tort or strict
liability, any alleged rights or claims arising under the National Labor
Relations Act; Title VII of the Civil Rights Act of 1964, as amended; Sections
1981 through 1988 of Title 42 of the United States Code, as amended; the
Employee Retirement Income Security Act of 1974, as amended (except for claims
under Employer's 401(k) Profit Sharing Plan); the Immigration Reform Control
Act; the Americans with Disabilities Act of 1990, as amended; the Age
Discrimination in Employment Act of 1967, as amended; the Rehabilitation Act of
1973, as amended; the Occupational Safety and Health Act; the Family and Medical
Leave Act; the Missouri Human Rights Act; the Missouri Workers' Compensation
Law; the Missouri Service Letter Statute; other alleged age discrimination or
other employment discrimination, breach of express or implied contract, breach
of the covenant of good faith and fair dealing, wrongful discharge, or any other
alleged violation of federal, state, or local statutory or common law, whether
or not now known or contemplated, which now exist or may hereafter arise from
any matter, fact, circumstance, happening or thing whatsoever occurring or
failing to occur in connection with, relating to or arising out of Executive's
employment with Employer (or any Released Parties) or out of the termination of
Executive's employment with Employer (or any Released Parties). This is not,
however, a release of any claims arising after this date or any right to vested
benefits due Executive under Employer's 401(k) plan or group health or dental
insurance plans based plans based upon service to and ending as of the Effective
Date.


                                                        Executive Initials: TAAC

                                       3
<PAGE>

                  (d) NATURE OF RELEASE. It is expressly understood and agreed
that this Agreement is intended to cover and does cover not only all known
losses and damages but any future losses and damages not now known or
anticipated but which may later develop or be discovered, including the effects
and consequences thereof. It is further expressly understood and agreed that as
against Executive this Agreement may be pleaded as a counterclaim to or as a
defense in bar or abatement of any action taken by or on behalf of Executive.
Executive agrees that neither this Agreement nor performance hereunder
constitutes or should be construed as an admission by Employer or any of the
Released Parties of any violation of any Employer policy, federal, state,
foreign or local law, regulation, common law, or any breach of any contract or
any other wrongdoing of any type, all of which are expressly denied.

         5. COVENANT NOT TO SUE; INDEMNIFICATION. Executive agrees not to enter
into any suit, action or other proceeding at law or in equity (including
administrative actions), or to prosecute further any existing suit or action
that might presently exist, or to make any claim or demand of any kind or nature
against any Released Party, in any such case asserting any claim released by
Executive by Section 4 of this Agreement, other than an action against Employer
to enforce Executive's rights set forth in this Agreement. If Executive enters
into any such suit, action or other proceeding in violation of this Section 5,
Executive shall (i) indemnify, defend and hold the Released Parties harmless
from and against any and all liabilities, obligations, losses, damages,
penalties, claims, action, suits, costs, expenses and disbursements (including
attorneys' fees and expenses and court costs whether or not litigation is
commenced and, if litigation is commenced, during all trial and appellate phases
of such litigation) of any kind and nature whatsoever which may be imposed on,
incurred by or asserted against any Released Party in any way relating to,
arising out of, connected with or resulting from such actions, including any of
the matters released hereunder and (ii) immediately return the Separation
Payments and Benefits (or the value thereof). Employer shall indemnify Executive
to the full extent permitted by Section 145 of the Delaware General Corporation
Law, as amended from time to time, in connection with any action, suit or
proceeding arising by reason of any acts taken or omissions to act occurring
while Executive was an officer and director of Employer or any of its
subsidiaries.

         6. CONFIDENTIALITY; NONSOLICITATION AND NONCOMPETITION.

                  (a) CONFIDENTIALITY. Executive acknowledges that, as General
Counsel of Employer, he served as legal counsel for Employer and has had access
to legally privileged attorney-client communications. Executive agrees that he
will maintain Employer's privilege on all matters in accordance with his duties,
responsibilities and obligations as a licensed attorney and a member of the Bar
of the State of Missouri. In addition, Executive acknowledges the competitive
nature of the Employer's business and agrees and reaffirms that any information
acquired by Executive regarding Employer's business, its finances, costs,
pricing, contracts, customers, prospects, plans, products, manufacturing
methods, technology, legal proceedings, personnel, directors and officers
(whether or not such information is marked confidential) shall be considered the
Employer's confidential information. In furtherance and not limitation of any
prior agreements regarding confidentiality, Executive agrees not to disclose to
anyone (other than Employer), or use for Executive's benefit or the benefit of
any other person (other than Employer), any marketing documents or information,
financial statements, reports, salary information, product cost or price
information, technical information, financial information, manufacturing
methods, technology, any information relating to customers, production,
prospects, bids, proposals or sales or any other information acquired by
Executive regarding Employer or its business, directors, officers and employees
(whether or not such information is marked confidential). Furthermore, Executive
agrees to immediately return to Employer all Employer property and any
information (including any copies thereof) which Executive has received,
prepared or helped to prepare during the course of Executive's employment with
Employer.

                  (b) NONSOLICITATION. In consideration of the Separation
Payments and Benefits, and in furtherance and not limitation of any prior
agreement between Executive and Employer with respect to


                                                        Executive Initials: TAAC

                                       4
<PAGE>

nonsolicitation matters, Executive acknowledges and agrees that, from the
Effective Date through June 18, 2005, Executive will not, directly or indirectly
recruit any employee, sales representative, consultant or other personnel of
Employer or any of its subsidiaries or affiliates (other than secretarial,
custodial and clerical employees) to work for another company or business; nor
will Executive assist anyone else in recruiting or hiring any such employee to
work for another company or business or discuss with any such person his or her
leaving the employ of Employer to engage in a business activity in competition
with Employer or any of its subsidiaries or affiliates. Executive acknowledges
and agrees that, from the Effective Date through June 18, 2005, Executive will
not directly or indirectly (i) solicit or encourage any person firm, corporation
or other business entity to cease doing business, or reduce the level of
business that could be done, with Employer or any of its subsidiaries or
affiliates, or discuss doing so with any such person, firm, corporation or
entity; or (ii) take away or procure for the benefit of any competitor of
Employer or any of its subsidiaries or affiliates, any business of the type
provided by or competitive with a product or service offered by Employer or any
of its subsidiaries or affiliates.

                  (c) NONCOMPETE PERIOD. In consideration of the Separation
Payments and Benefits, and in furtherance and not limitation of any prior
agreement between Executive and Employer with respect to noncompete matters,
Executive agrees that from the Effective Date through June 18, 2005, Executive
will not act as a consultant, advisor, independent contractor, officer, manager,
employee, principal, agent, director or trustee, or provide any services or
advice to, of any corporation, partnership, limited liability company,
association or other entity, or directly or indirectly own more than one percent
(1%) of the outstanding equity of any such entity which is engaged in the
business of rehabilitating, lining, relining, coating, constructing or
reconstructing pipelines, sewers, conduits or passageways anywhere in the world;
or otherwise engage in such business. This does not, however, preclude Executive
from rendering legal services only to any such entity or from working for any
such entity in the capacity of inside legal counsel. Executive specifically
agrees and acknowledges that Employer does business and will continue to seek
and do business in the United States and internationally so the foregoing
geographic scope is reasonable in light of current and presently anticipated
operations of Employer.

                  (d) EQUITABLE RELIEF. Executive acknowledges and agrees that
(i) any breach of this Agreement by Executive, including any breach of the terms
of this Section 6, will cause Employer irreparable injury and damage, (ii) the
provisions of this Agreement are necessarily of a special, unique and
extraordinary nature and (iii) if Executive breaches any such provisions,
Employer shall be entitled, in addition to any other remedies and damages
Employer could recover as a result of any such breach, to obtain equitable
relief, including restraining orders or injunctions, both temporary and
permanent, in order to prevent future violation thereof by Executive or any
person with whom Executive may be affiliated. Executive hereby waives the claim
or defense that Employer has an adequate remedy at law and Executive shall not
claim that an adequate remedy at law exists. Further, Executive waives any
requirement for Employer to post a bond in connection with any action relating
to this Agreement.

                  (e) SURVIVAL. The provisions of this Section 6 shall survive
any termination of this Agreement.

         7. NONDISCLOSURE; NO DISPARAGING REMARKS; NO RE-APPLICATION. Executive
agrees that the terms of this Agreement will not be discussed by Executive with,
or otherwise disclosed by Executive to, any person other than Executive's
attorney, including any present or former employee of Employer, its
shareholders, affiliates, subsidiaries or predecessors in interest. However, the
Executive will be entitled to present a copy of this Agreement, redacted to
delete the financial terms, to a prospective employer with whom he has applied
for employment. Executive agrees that Executive will not disparage Employer or
its directors, officers, employees, agents, consultants, products or services,
or portray Employer or any of its directors, officers, employees, agents,
consultants, products or services in a negative light. Executive agrees not to
re-apply for any employment position with Employer without expressly and
conspicuously listing this



                                                        Executive Initials: TAAC

                                       5
<PAGE>

Agreement on any application for such re-employment. Further, Executive agrees
that Employer shall not be required to give any consideration to such
re-application.

         8. GENERAL PROVISIONS.

                  (a) ENTIRE AGREEMENT. This Agreement incorporates by this
reference the Preliminary Statement hereto. Each party represents and warrants
that any facts relating to such party that are contained in the Preliminary
Statement are true. This Agreement and any agreement, instrument or document to
be executed in connection herewith (as referenced herein) contain the parties'
entire understanding and agreement with respect to the subject matter hereof
(the termination of Executive's employment and directorships with Employer and
its subsidiaries and affiliates, the Severance Payments and Benefits and the
release of any potential related claims). Any discussions, agreements, promises,
representations, warranties or statements between the parties or their
representatives (whether or not conflicting or inconsistent) that are not
expressly contained or incorporated herein shall be null and void and are merged
into this Agreement, except that any confidentiality agreement, noncompete
agreement, invention assignment, stock option agreement or other agreement
between Employer and Executive, expressly covering a party's rights after
termination of employment, shall remain in full force and effect, in accordance
with its terms, after the execution of this Agreement, except to the extent
specified in this Agreement. In case of any conflict between Executive's rights
under any such agreement and this Agreement, the terms of this Agreement will
control.

                  (b) MODIFICATION, AMENDMENT AND WAIVER. Neither this
Agreement, nor any part hereof, may be modified or amended orally, by trade
usage or by course of conduct or dealing, but only by and pursuant to an
instrument in writing duly executed and delivered by the party sought to be
charged therewith. No covenant or condition of this Agreement can be waived,
except by the written consent of the party entitled to receive the benefit
thereof. Forbearance or indulgence by a party in any regard whatsoever shall not
constitute a waiver of a covenant or condition to be performed by the other
party to which the same may apply, and, until complete performance by such other
party of such covenant or condition, the party entitled to receive the benefit
thereof shall be entitled to invoke any remedy available to it under this
Agreement, at law, in equity, by statute or otherwise, despite such forbearance
or indulgence.

                  (c) SUCCESSORS, ASSIGNS AND THIRD PARTY BENEFICIARIES. This
Agreement shall be binding upon, and inure to the benefit of, the parties hereto
and their respective successors and permitted assigns and is freely assignable
by Employer. Except as expressly provided herein, neither this Agreement nor any
rights hereunder may be assigned or transferred, and no duties may be delegated,
by any party hereto without the prior written consent of the other party hereto.
Each subsidiary or affiliate of Employer (and their predecessors, successors and
assigns) shall be a third-party beneficiary of this Agreement, as if such
subsidiary or affiliate was the "Employer" hereunder.

                  (d) CONSTRUCTION. This Agreement shall not be construed more
strictly against one party than against another party merely by virtue of the
fact that this Agreement may have been physically prepared by such party, or
such party's counsel, it being agreed that all parties, and their respective
counsel, have mutually participated in the negotiation and preparation of this
Agreement. Unless the context of this Agreement clearly requires otherwise: (i)
references to the plural include the singular and vice versa; (ii) references to
any person include such person's successors and assigns but, if applicable, only
if such successors and assigns are permitted by this Agreement; (iii) references
to one gender include all genders; (iv) "including" is not limiting; (v) "or"
has the inclusive meaning represented by the phrase "and/or"; (vi) the words
"hereof", "herein", "hereby", "hereunder" and similar terms in this Agreement
refer to this Agreement as a whole and not to any particular provision of this
Agreement; (vii) article, section, subsection, clause, exhibit and schedule
references are to this Agreement unless otherwise specified; (viii) reference to
any agreement (including this Agreement), document or instrument means such
agreement, document or instrument as amended or modified and in effect from time
to time in accordance with the terms thereof and,


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                                       6
<PAGE>

if applicable, the terms hereof; and (ix) general or specific references to any
law means such law as amended, modified, codified or re-enacted, in whole or in
part, and in effect from time to time.

                  (e) GOVERNING LAW. All questions with respect to the formation
and construction of this Agreement, and the rights and obligations of the
parties hereto, shall be governed by and determined in accordance with the laws
of the State of Missouri, which are applicable to agreements entered into and
performed entirely within such State, without giving effect to the choice or
conflicts of law provisions thereof.

                  (f) SEVERABILITY. If any Section (or part thereof) of this
Agreement is found by a court of competent jurisdiction to be contrary to,
prohibited by or invalid under any applicable law, such court may modify such
Section (or part thereof) so, as modified, such Section (or part thereof) will
be enforceable and will to the maximum extent possible comply with the apparent
intent of the parties in drafting such Section (or part thereof). No such
modification or omission of a Section (or part thereof) shall in any way affect
or impair such Section (or part thereof) in any other jurisdiction. If, in the
sole judgement of Employer, a Section (or part thereof) of this Agreement is so
modified or omitted in a manner which eliminates a substantial part of the
benefit intended to be received by Employer hereunder, then Employer may rescind
this Agreement and Executive shall immediately return to Employer any
consideration paid hereunder.

                  (g) CAPTIONS. The captions, headings and titles of the various
Sections of this Agreement are for convenience of reference only, and shall not
be deemed or construed to limit or expand the substantive provisions of such
Sections.

                  (h) COUNTERPARTS. This Agreement may be executed in two or
more counterparts, each of which shall constitute an original, but all of which
together shall constitute a single agreement. A facsimile signature is as good
as an original

         IN WITNESS WHEREOF, the parties have executed this Agreement as of the
Effective Date.

EXECUTIVE:                          EMPLOYER:

                                    INSITUFORM TECHNOLOGIES, INC.,
    /s/ Thomas A. A. Cook
----------------------------
Print Name: Thomas A.A. Cook        By: /s/ Thomas S. Rooney, Jr.
SSN:                                    ----------------------------------------
Address:                            Name: Thomas S. Rooney, Jr.
                                    Title: President and Chief Executive Officer



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                                       7
<PAGE>

                                    EXHIBIT A

                           FORM OF RESIGNATION LETTER


June 18, 2004


Insituform Technologies, Inc.
702 Spirit 40 Park Drive
Chesterfield, Missouri 63005
 Attention: Thomas S. Rooney, Jr.
            President and Chief Executive Officer

Dear Mr. Rooney:

Effective immediately, I hereby resign as Vice President, General Counsel and
Secretary of Insituform Technologies, Inc. (the "Company"). I also resign,
effective immediately, from all other offices and directorships (or similar
positions) of the Company's subsidiaries and affiliates. In addition, I am
terminating my employment with the Company and its subsidiaries and affiliates
effective immediately.

I understand and specifically agree that if I choose to revoke my acceptance of
that certain Executive Separation Agreement and Release (the "Separation
Agreement") pursuant to the terms of Section 2 of that agreement, my resignation
from my offices and directorships and the termination of my employment with the
Company, its subsidiaries and affiliates will not be revoked and will remain in
full force and effect. In the event of such a revocation of the Separation
Agreement pursuant to the Section 2 thereof, the Company agrees to treat my
termination of employment as a termination of employment by Employer without
cause for all purposes.

Very truly yours,



Thomas A.A. Cook

APPROVED AND ACCEPTED:



-------------------------------------
Thomas S. Rooney, Jr.
President and Chief Executive Officer



                                                        Executive Initials: TAAC

                                       8