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                                                                EXHIBIT 10(k)(4)

                               FOURTH AMENDMENT
                                    TO THE
                        ICF KAISER INTERNATIONAL, INC.
                              SECTION 401(K) PLAN



     WHEREAS, the ICF Kaiser International, Inc. Section 401(k) Plan
(hereinafter referred to as the "Plan") was established effective as of March 1,
1989, by ICF Kaiser International, Inc. (hereinafter referred to as the
"Company"); and

     WHEREAS, the Plan was most recently restated as of January 1, 1998; and

     WHEREAS, the restated Plan was amended subsequently on three occasions; and

     WHEREAS, the Company desires to amend the Plan again to comply with recent
tax legislation, to reflect various administrative changes, and to accommodate
certain divestitures;

     NOW, THEREFORE, effective as of April 7, 1999, unless specifically provided
otherwise, the Plan is hereby amended in the respects hereinafter set forth.

     1.   Section 1.6 of the Plan is hereby amended to provide as follows:

          1.6 "Closing" shall mean the consummation of a transaction in which
          the Company disposes of (i) substantially all of the assets used by
          the Company in a trade or business of the Company, or (ii) the
          Company's interest in a subsidiary.

     2.   The last sentence of the second paragraph of Section 1.9 of the Plan
is hereby deleted effective as of January 1, 1997.

     3.   Paragraph (e) of Section 1.12 of the Plan is hereby amended effective
January 1, 1997, to provide as follows:

               (e)  a leased employee who pursuant to Section 414(n)(2) of the
     Code means any person (other than a person who is an employee without
     regard to this Paragraph (e)) engaged in performing services for a Member
     of the Controlled Group (the "recipient") pursuant to an agreement between
     the recipient and any other person ("Leasing Organization") who meets the
     following requirements:

                    (i)  he has performed services for one or more Members of
               the Controlled Group (or for any other "related persons"
               determined in accordance with Section 414(n)(6) of the Code) on a
               substantially full-time basis for a period of at least one year;

                    (ii) such services are under the primary direction or
               control of the recipient; and
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                    (iii)  he is not participating in a "safe harbor plan" of
               the Leasing Organization. (For this purpose a "safe harbor plan"
               is a plan that satisfies the requirements of Section 414(n)(5) of
               the Code, which will generally be a money purchase pension plan
               with a nonintegrated company contribution rate of at least 10% of
               compensation and which provides for immediate participation and
               full and immediate vesting).

          A person who is a leased employee shall also be considered an employee
          of a Member of the Controlled Group during such period (and solely for
          the purpose of determining length of service for vesting purposes, and
          shall also be considered to have been an employee for any earlier
          period in which he was a leased employee) but shall not be a
          Participant and shall not otherwise be eligible to become covered by
          the Plan during any period in which he is a leased employee.
          Notwithstanding the foregoing, the sole purpose of this Paragraph (e)
          is to define and apply the term "leased employee" strictly (and only)
          to the extent necessary to satisfy the minimum requirements of Section
          414(n) of the Code relating to "leased employees.

     4.   Section 1.18 of the Plan is hereby amended effective January 1, 1997,
to provide as follows:

          1.18 [Reserved]

     5.   Section 1.20 of the Plan is hereby amended effective January 1, 1997,
to provide as follows:

          1.20 "Highly-Compensated Employee" shall mean any Employee of the
          Company or a Member of a Controlled Group for a Plan Year who:

               (a)  during the immediately preceding Plan Year, received
          compensation (as defined in Section 4.3(b)(ii) of the Plan without
          regard to Sections 125, 402(e)(3) and 402(h)(1)(B) of the Code) in
          excess of $80,000 (such dollar limitation shall be adjusted
          automatically in accordance with the maximum amount permitted under
          Section 414(q) of the Code); or

               (b)  during such Plan Year or during the immediately preceding
          Plan Year owned directly or indirectly 5% or more of the Company or a
          Member of a Controlled Group (so that he is a "5% owner" as defined in
          Section 416(i)(1) of the Code);

          A former Employee shall be treated as a Highly Compensated Employee if
          such Employee was a Highly Compensated Employee when such Employee
          separated from service or such Employee was a Highly

                                       2
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          Compensated Employee at any time after attaining age 55.
          Notwithstanding the foregoing provisions of this paragraph, the sole
          purpose of this Section 1.17 is to define and apply the term Highly-
          Compensated Employee strictly (and only) to the extent necessary to
          satisfy the minimum requirements of Section 414(q) of the Code
          relating to "highly-compensated employees." This Section 1.17 shall be
          interpreted, applied and, if and to the extent necessary, deemed
          modified without formal amendments of language, so as to satisfy
          solely the minimum requirements of Section 414(q) of the Code.

     6.   Section 1.26 of the Plan is hereby amended effective January 1, 1997,
to provide as follows:

          1.26 "Non-Highly Compensated Participant" shall mean any Participant
          who is not a Highly Compensated Participant.

     7.   Section 1.38 of the Plan is hereby amended effective January 1, 1997,
to provide as follows:

          1.38 [Reserved]

     8.   Section 2.5 of the Plan is hereby amended to provide as follows:

          2.5  Qualified Military Service and Compliance with Uniformed Services
               -----------------------------------------------------------------
          Employment and Reemployment Rights Act. Notwithstanding any provision
          --------------------------------------
          of the Plan to the contrary, effective as of December 12, 1994,
          contributions, benefits, and service credit with respect to Qualified
          Military Service shall be provided in accordance with Section 414(u)
          of the Code.

     9.   Article II of the Plan is hereby amended by the addition of Section
2.6 at the end thereof to provide as follows:

          2.6  Cessation of Coverage of Certain Participants. Effective as of
               ---------------------------------------------
          the date of the Closing with respect to the sale of the Environment
          and Facilities Management Group ("EFM Group") of the Company to The IT
          Group, Inc., coverage under the Plan shall be closed to any individual
          employed by, or at a facility of, the EFM Group and effective as of
          the date of the Closing with respect to the sale of the stock of ICF
          Consulting Group, Inc. ("ICF Consulting Group") to CM Equity Partners,
          L.P., CMEP Coinvestment ICF, L.P. and various individuals, coverage
          under the Plan shall be closed to any individual employed by, or at a
          facility of, ICF Consulting Group.

     10.  Section 4.4 is hereby amended effective January 1, 1998, to provide as
follows:

                                       3
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          4.4  Limitation on Benefits.
               ----------------------

               (a) Incorporation of Section 415 of the Code.  The provisions set
                   ----------------------------------------
          forth in this Section 4.4 are intended solely to comply with the
          requirements of Section 415 of the Code and shall be interpreted,
          applied, and if and to the extent necessary deemed modified without
          further formal language so as to satisfy solely the minimum
          requirements of said Section. For such purposes, the limitations of
          Section 415 of the Code are hereby incorporated by reference and made
          part hereof as though fully set forth herein, but shall be applied
          only to particular Plan benefits in accordance with the provisions of
          this Section 4.4, to the extent such provisions are not consistent
          with said Section 415. The limitations contained in this Section 4.4
          shall be applicable only with respect to benefits provided pursuant to
          defined contribution plans and defined benefit plans specified in
          Section 415(k) of the Code.

               (b) Definitions.  For purposes of this Section 4.4, the following
                   -----------
          definitions shall apply in addition to those set forth in Article I:

                   (i)    The term "Annual Additions" shall mean the amount
               defined in Section 415 (c)(2) of the Code.

                   (ii)   The term "Annual Benefit" shall mean the benefit
               amount defined in Section 415(b)(2)(A) of the Code as adjusted
               pursuant to the provisions of Section 415(b)(2)(B), (C), (D), and
               (E) of the Code.

                   (iii)  The term "Compensation" shall mean compensation as
               defined in Section 415(c)(3) of the Code.

                   (iv)   The term "Defined Benefit Fraction" for any Limitation
               Year beginning prior to January 1, 2000, shall mean the fraction
               defined in Section 415(e)(2) of the Code.

                   (v)    The term "Defined Contribution Fraction" for any
               Limitation Year beginning prior to January 1, 2000, shall mean
               the fraction defined in Section 415(e)(3) of the Code.

                   (vi)   The term "Employer" shall mean the Company and all
               Members of a Controlled Group; provided, however, that for
               purposes of applying the limitations of this Section 4.4 with
               respect to Limitation Years after December 31, 1999, "50 percent"
               rather than "80 percent" shall be used in determining Member of a
               Controlled Group defined under Section 414(b) and Section 414(c)
               of the Code.

                                       4
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                    (vii)   The term "Excess Amount" shall mean the excess of
               the Participant's Annual Additions for a Limitation Year over the
               Defined Contribution Maximum Permissible Amount.

                    (viii)  The term "Highest Average Compensation" shall mean
               the average Compensation for the three consecutive calendar years
               during which the Participant was an active Participant in the
               Plan and had the greatest aggregate Compensation from the
               Employer.

                    (ix)    The term "Limitation Year" shall mean a calendar
               year or such other 12-month period elected by the Company
               pursuant to regulations and rulings under Section 415 of the
               Code.

                    (x)     The term "Defined Contribution Maximum Permissible
               Amount" shall mean Annual Additions of a Participant which do not
               exceed the lesser of (i) $30,000 (adjusted in accordance with
               regulations prescribed by the Secretary of the Treasury for
               increases in the cost of living), or (ii) 25 percent of such
               Participant's Compensation paid for such Limitation Year as set
               forth in Section 415(e)(1) of the Code. If a short Limitation
               Year is created because of an amendment changing the Limitation
               Year to a different 12-month consecutive period, such Annual
               Additions shall not exceed $30,000 multiplied by a fraction, the
               numerator of which is the number of months in the short
               Limitation Year and the denominator of which is 12.

                    (xi)    The term "Defined Benefit Maximum Permissible
               Amount" shall mean the Annual Benefit of a Participant which does
               not exceed the lesser of $90,000 or 100 percent of the
               Participant's Highest Average Compensation as set forth in
               Section 415(b)(1) of the Code.

                    (xii)   The term "Projected Annual Benefit" shall mean the
               annual retirement benefit of a Participant attributable to
               Employer contributions which would be payable to such Participant
               under a plan based on the assumptions that he continues his
               employment as a Participant until the Social Security Retirement
               Age and that his Compensation for the Limitation Year continues
               at the same rate until the Social Security Retirement Age, and on
               the basis of the federal Social Security Act as in effect on the
               last day of the Limitation Year. A Participant's "aggregate
               Projected Annual Retirement Benefit" shall include his Projected
               Annual Benefit, if any, under any other defined benefit plan
               maintained by the Employer.

                                       5
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                    (xiii)  The term "Social Security Retirement Age" shall mean
               the age used as the retirement age under Section 216(l) of the
               federal Social Security Act, without regard to any age increase
               factor and as if the early retirement age under Section 216(l)(2)
               were 62.

               (c)  Limitations on Allocations Under the Plan. Notwithstanding
                    -----------------------------------------
          any other provision of the Plan to the contrary, the amount of Annual
          Additions which may be credited to the Participant's Account for any
          Limitation Year shall not exceed the lesser of the Defined
          Contribution Maximum Permissible Amount or any other limitation
          contained in the Plan. If the Annual Additions to the Account of a
          Participant in any Limitation Year would otherwise exceed such amount,
          the Excess Amount shall be disposed of by reducing the Salary
          Deferrals of a Participant and corresponding matching Employer
          contributions and forfeitures otherwise allocable to the Participant's
          Account for the Limitation Year. Amounts deemed to be forfeitures
          under this Paragraph (c) shall be held unallocated in a suspense
          account established for the Limitation Year and shall be applied
          against the Employer's contribution obligation for the next following
          Limitation year (and succeeding Limitation Years, as necessary). If a
          suspense account is in existence at any time during a Limitation Year,
          all amounts in the suspense account must be allocated to Participants'
          Accounts (subject to the limitations set for in this Section 4.4 )
          before any further Employer contributions may be made to the Plan on
          behalf of Participants. If a suspense account is in existence at any
          time during a Limitation Year pursuant to this Section 4.4, it will
          not participate in the allocation of the investment gains and losses
          on the Plan's assets.

               (d)  Limitation for Multiple Defined Contribution Plan
                    -------------------------------------------------
          Participation. If a Participant is covered by any other qualified
          -------------
          defined contribution plan (whether or not terminated) maintained by
          the Employer concurrently with the Plan, and if the Annual Additions
          for the Limitation Year would otherwise exceed the amount that may be
          applied for the Participant's benefit under the limitation contained
          in Section 4.4(c), such excess shall be reduced by first returning any
          employer contributions made with respect to the Participant under an
          employee stock ownership plan and then by returning the Salary
          Deferrals made on behalf of the Participant for the Limitation Year
          under this Plan and corresponding matching Employer contributions and
          the income attributable thereto as provided in Section 4.4(c). If the
          limitation contained in Section 4.4(c) is still not satisfied after
          returning all of such contributions, then the Employer contributions
          and forfeitures for the Limitation Year under any other plans that
          have been contributions and forfeitures for the Limitation Year under
          such other plans that have been allocated to the Participant shall be
          reduced and disposed of as provided in any such other plans.

                                       6
<PAGE>

               (e)  Limitation for Defined Benefit Plan Participation. For
                    -------------------------------------------------
          Limitation Years beginning prior to January 1, 2000, if a Participant
          in the Plan is also covered by a qualified defined benefit plan
          (whether or not terminated) maintained by the Employer, in no event
          shall the sum of the Defined Benefit Fraction and the Defined
          Contribution Fraction exceed 1.0 in any Limitation Year.

               (f)  Scope of Limitations. The limitations contained in
                    --------------------
          Paragraphs (c), (d), and (e) of this Section 4.4 shall be applicable
          only with respect to benefits provided pursuant to defined
          contribution plans and defined benefit plans described in Section
          415(k) of the Code and all such defined contribution plans (whether or
          not terminated) of the Employer shall be treated as one defined
          contribution plan and all such defined benefit plans (whether or not
          terminated) of the Employer shall be treated as one defined benefit
          plan.

     11.  Sections 4.5 and 4.6 of the Plan are hereby deleted effective January
1, 1998, in their entirety.

     12.  Article V of the Plan is hereby amended effective January 1, 1998, to
provide as follows:

                                   ARTICLE V

                             TOP-HEAVY PROVISIONS
                             --------------------

          5.1  Applicability. Notwithstanding any other provision to the
               -------------
          contrary, in the event the Plan is deemed to be a top-heavy plan for
          any Plan Year, the provisions contained in this Article V with respect
          to vesting and contributions made by the Employer shall be applicable
          with respect to such Plan Year. In the event that the Plan is
          determined to be a top-heavy plan and upon a subsequent determination
          date is determined to no longer be a top-heavy plan, the vesting and
          the contribution provisions in effect immediately preceding the Plan
          Year in which the Plan was determined to be a top-heavy plan shall
          again become applicable as of such subsequent determination date.

          5.2  Top-Heavy Definitions. Notwithstanding the definitions set forth
               ---------------------
          in Article I, the following definitions shall be applicable to this
          Article V.

               (a)  The term "Compensation" shall have the meaning set forth in
                              ------------
          Treas. Reg. Section 1.415-2(d).

               (b)  The term "Determination Date" shall mean for any Plan Year
                              ------------------
          subsequent to the first Plan Year, the last day of the preceding Plan
          Year and for the first Plan Year of the Plan, the last day of that
          Plan Year.

                                       7
<PAGE>

               (c)  The term "Employer" shall mean the Company and all Members
                              --------
          of a Controlled Group.

               (d)  The term "Key Employee" shall mean any Employee or former
                              ------------
          Employee (and the beneficiaries of such Employer) who at any time
          during the Plan Year and any of the four preceding Plan Years was an
          officer of the Employer with annual compensation greater than 50
          percent of the dollar limitation under Section 415(b)(1)(A) of the
          Code, an owner (or considered an owner) under Section 318 of the Code)
          of one of the ten largest interests in the Employer with compensation
          greater than 100 percent of the limitation under Section 415(b)(1)(A)
          of the Code, a 5 percent owner of the Employer, or a 1 percent owner
          of the Employer with annual compensation of more than $150,000.

               (e)  The term "Permissive Aggregation Group" shall mean the
                              ----------------------------
          Required Aggregation Group of plans plus any other plan or plans of
          the Employer which, when considered as a group with the Required
          Aggregation Group, would continue to satisfy the requirements of
          Section 401(a)(4) and 410 of the Code.

               (f)  The term "Present Value" shall mean for purposes of
                              -------------
          computing present value calculations in determining the Top-Heavy
          Ratio, present value calculations based on the actuarial assumptions
          as stated in the applicable plan.

               (g)  The term "Required Aggregation Group" shall mean (a) each
                              --------------------------
          tax qualified plan of the Employer in which at least one Key Employee
          participates or participated at any time during the determination
          period (regardless of whether the plan terminated), and (b) any other
          tax qualified plan of the Employer which enables a plan described in
          clause (a) to meet the requirements of Section 401(a)(4) or 410 of the
          Code.

               (h)  The term "Super Top-Heavy Group" with respect to a
                              ---------------------
          particular Plan Year shall mean a Required or Permissive Aggregation
          Group that, as of the Determination Date, would qualify as a Top-Heavy
          Group under the definition in Paragraph (j) of this Section 5.2 with
          "90 percent" substituted for "60 percent" each place where "60
          percent" appears in such definition.

               (i)  The term "Super Top-Heavy Plan" with respect to a particular
                              --------------------
          Plan Year shall mean a plan that, as of the Determination Date, would
          qualify as a Top-Heavy Plan under the definition in Paragraph (k) of
          this Section 5.2 with "90 percent" substituted for "60 percent" each
          place where "60 percent" appears in such definition. A plan is also a
          "Super Top-Heavy Plan" if it is part of a Super Top-Heavy Group.

                                       8
<PAGE>

               (j)  The term "Top-Heavy Group" with respect to a particular Plan
                              ---------------
          Year shall mean a Required or Permissive Aggregation Group if the sum,
          as of the Determination Date, of the present value of the cumulative
          accrued benefits for Key Employees under all defined benefit plans
          included in such group and the aggregate of the account balances of
          Key Employees under all defined contribution plans included in such
          group exceeds 60 percent of a similar sum determined for all employees
          covered by the plans included in such group.

               (k)  The term "Top-Heavy Plan" with respect to a particular Plan
                              --------------
          Year shall mean the Plan if any of the following conditions exist:

                    (i)   If the Top-Heavy Ratio for the Plan exceeds 60 percent
               and the Plan is not part of any Required Aggregation Group or
               Permissive Aggregation Group of plans.

                    (ii)  If the Plan is a part of a Required Aggregation Group
               of plans but not part of a Permissive Aggregation Group and the
               Top-Heavy Ratio for the group of plans exceeds 60 percent.

                    (iii) If the Plan is a part of a Required Aggregation Group
               and part of a Permissive Aggregation Group of plans and the Top-
               Heavy Ratio for the Permissive Aggregation Group exceeds 60
               percent.

               (l)  The term "Top-Heavy Ratio" shall mean:
                              ---------------

                    (i)   While the Employer maintains one or more defined
               contribution plans (including any simplified employee pension
               plan) and the Employer has not maintained any defined benefit
               plan which during the 5-year period ending on the Determination
               Date has or has had accrued benefits, the Top-Heavy Ratio for the
               Plan alone or for the Required or Permissive Aggregation Group,
               as appropriate, is a fraction, the numerator of which is the sum
               of the account balances of all Key Employees as of the
               Determination Date (including any part of any account balance
               distributed in the five-year period ending on the Determination
               Date), and the denominator of which is the sum of all account
               balances (including any part of any account balance distributed
               in the five-year period ending on the Determination Date), both
               computed in accordance with Section 416 of the Code. Both the
               numerator and denominator of the Top-Heavy Ratio are adjusted to
               reflect any contribution not actually made as of the
               Determination Date, but which is required to be taken into
               account on that date under Section 416 of the Code.

                    (ii)  While the Employer maintains one or more defined
               contribution plans (including any simplified employee pension
               plans)

                                       9
<PAGE>

          and the Employer maintains or has maintained one or more defined
          benefit plans which during the five-year period ending on the
          Determination Date has or has had any accrued benefits, the Top-Heavy
          Ratio for any Required or Permissive Aggregation Group as appropriate
          is a fraction, the numerator of which is the sum of account balances
          under the aggregated defined contribution plan or plans for all Key
          Employees, determined in accordance with subparagraph (i) above, and
          the present value of accrued benefits under the aggregated defined
          benefit plan or plans for all Key Employees as of the Determination
          Date, and the denominator of which is the sum of the account balances
          under the aggregated defined contribution plan or plans for all
          participants, determined in accordance with subparagraph (i) above,
          and the present value of accrued benefits under the defined benefit
          plan or plans for all participants as of the Determination Date, all
          determined in accordance with Section 416 of the Code. The accrued
          benefits under a defined benefit plan in both the numerator and
          denominator of the Top-Heavy Ratio are adjusted for any distribution
          of an accrued benefit made in the five-year period ending on the
          Determination Date.

               (iii)  For purposes of subparagraphs (i) and (ii) above, the
          value of account balances and the present value of accrued benefits
          shall be determined as of the most recent valuation date that falls
          within or ends with the 12-month period ending on the Determination
          Date, except as provided in Section 416 of the Code for the first and
          second plan years of a defined benefit plan. The account balances and
          accrued benefits of a participant (1) who is not a Key Employee but
          who was a Key Employee in a prior year, or (2) who has not performed
          services for the Employer maintaining the Plan at any time during the
          5-year period ending on the Determination Date will be disregarded.
          The calculation of the Top-Heavy Ratio, and the extent to which
          distributions, rollovers and transfers are taken into account will be
          made in accordance with Section 416 of the Code. Deductible employee
          contributions shall not be taken into account for purposes of
          computing the Top-Heavy Ratio. When aggregating plans the value of
          account balances and accrued benefits will be calculated with
          reference to the Determination Date that falls within the same
          calendar year.

          (m)    The term "Valuation Date" shall mean, for purposes of computing
                           --------------
     the Top-Heavy Ratio, the Determination Date.

     5.3  Top-Heavy Minimum Allocation Rules.  The following Top-Heavy Plan
          ----------------------------------
     minimum allocation rules shall apply:

                                       10
<PAGE>

          (a) Except as otherwise provided in Paragraph (b) and (c) below, the
     Employer contributions and forfeitures allocated on behalf of any
     Participant who is not a Key Employee shall be the lesser of 3 percent of
     such Participant's Compensation or in the case where the Employer has no
     defined benefit plan which designates the Plan to satisfy Section 401 of
     the Code, the largest percentage of compensation allocated with respect to
     a Key Employee for the Plan Year.  Tax-Deferred Contributions cannot be
     used to satisfy the minimum contributions for non-Key Employees under
     Section 416 of the Code.  Furthermore, in making the determination of the
     percentage at which contributions are made for the Key Employee with the
     highest percentage, Tax-Deferred Contributions on behalf of Key Employees
     shall be taken into account.

          (b) The provisions in paragraph (a) shall not apply to any Participant
     who is not actively employed as an Employee by the Employer on the last day
     of the Plan Year for which the minimum allocation is to be made.

          (c) The provisions in paragraph (a) shall not apply to any Participant
     to the extent the Participant is covered under any other plan or plans of
     the Employer, and by the terms of such plan or plans it is provided that
     the minimum allocation or benefit requirements applicable to Top-Heavy
     Plans shall be met in such other plan or plans. If such other plan is, or
     if one of such other plans is, a defined benefit plan maintained by the
     Employer, and such plan is a Top-Heavy Plan, the minimum benefit
     requirements applicable to Top-Heavy Plans shall be met under such defined
     benefit plan as provided therein, to the extent such benefit can be
     provided under such plan or plans. If such other plan is, or if one of such
     other plans is, a defined contribution plan maintained by the Employer, and
     such plan is a Top-Heavy Plan, the minimum allocation requirements shall be
     met under such plan, except as may be otherwise provided in such other
     plan. The application and administration of the minimum allocation or
     benefit requirements for Top-Heavy Plans shall be satisfied in a manner so
     as to only satisfy the minimum allocation/benefit requirements as
     permissible and so as to avoid any duplication of minimum
     allocation/benefits for non-Key Employees, as provided under Section 416 of
     the Code.

     5.4  Top-Heavy Vesting Schedule.  A Participant shall be entitled to the
          --------------------------
     vested interest in his Account attributable to Employer contributions
     calculated in accordance with the provisions of Article IV (or, if greater,
     in accordance with the provisions of Section 5.3) determined in accordance
     with the following schedule if greater than under Article III:

                                       11
<PAGE>

            Years of Service            Vested Percentage
            ----------------            -----------------

            Less than 2                      0%
            2 but less than 3               20%
            3 but less than 4               40%
            4 but less than 5               60%
            5 but less than 6               80%
            6 or more                      100%

     If the Plan becomes a Top-Heavy Plan and subsequently ceases to be such,
     the vesting schedule set forth above shall continue to apply in determining
     the rights to benefits of any Participant who had at least three years of
     Service as of December 31 in the last Plan Year in which the Plan was a
     Top-Heavy Plan.  For other Participants, such schedule shall apply only to
     that portion of their Account that became vested under the vesting schedule
     set forth above as of such December 31.

     5.5  Top-Heavy Compensation Limitation.  The annual compensation of any
          ---------------------------------
     Participant to be taken into account under the Plan during any Plan Year in
     which the Plan is determined to be a Top-Heavy Plan shall not exceed the
     limitation on Compensation set forth in the second paragraph of Section
     1.9.

     5.6  Top-Heavy Plan/Benefit Limitations.  In any Plan Year beginning prior
          ----------------------------------
     to January 1, 2000, in which the Plan is a Top-Heavy Plan, the denominators
     of the defined benefit fraction and the defined contribution fraction (as
     such terms are used in applying the benefit limitation provisions of
     Section 415 of the Code) shall be computed using 100 percent of the dollar
     limitation instead of 125 percent.

     13.  The first sentence of Section 6.1 of the Plan is hereby deleted and
four sentences are substituted in place thereof to provide as follows:

     The Company shall cause at least three investment funds to be established
     and maintained at all times.  Each such fund shall be diversified and have
     different risk and return characteristics from the other Funds.  Any fund
     which invests in investments with restrictions regarding funds to which
     investment transfers may be made or to which a minimum investment period is
     applicable shall not be considered as one of such requisite three
     investment Funds.  The Plan is intended to constitute a plan described in
     Section 404(c) of ERISA and DOL Regs. Section 2550.404c-1 and insofar as
     the Plan complies with said Section 404(c), Plan fiduciaries shall be
     relieved of liability for any losses which are the direct result of
     investment instructions given by Participants.  Notwithstanding the
     foregoing, to the extent that Section 404(c) of ERISA is not applicable,
     Participants shall be named fiduciaries with respect to the investment of
     their Accounts.

     14.  Section 8.1 is hereby amended effective January 1, 1997, to provide as
follows:

                                       12
<PAGE>

     8.1  Distribution at Required Beginning Date.  Notwithstanding any other
          ---------------------------------------
     provision of the Plan to the contrary, on and after January 1, 1997,
     payment of a retired or former Participant's benefit shall commence not
     later than the earlier of:

               (i)  the 60th day after the end of the Plan Year in which the
          latest of the following dates occurs: (i) Participant's Normal
          Retirement Date, (ii) the tenth anniversary of the date on which the
          Participant first became a Participant, and (iii) the date of the
          Participant's retirement or other termination of employment; or

               (ii) the April 1 following the calendar year in which the later
          of the following dates occurs: (i) the date on which the Participant
          attains 70-1/2, or (ii) the date on which the Participant retires
          (except for a Participant who is a 5% owner, as defined in Section
          416(i)(1)(B) of the Code, the date determined under this Paragraph (d)
          shall be April 1 of the calendar year following the calendar year in
          which the Participant attains age 70-1/2 without regard to the date of
          the Participant's retirement.

     All payments required under this Article VIII, shall be determined and made
     in accordance with the regulations under Section 401(a)(9) of the Code,
     including the minimum distribution incidental benefit requirements of
     proposed Treas. Reg. (S)1.401(a)(9)-2, if applicable.  Any non-retired
     Participant (other than a 5% owner) who has attained age 70-1/2 and who is
     receiving payment of his benefit while employed by a Member of a Controlled
     Group, may elect in writing in the manner, time, and form required by the
     Company to terminate payment of his Plan benefit otherwise payable after
     January 1, 1997, until after his retirement under the terms of the Plan in
     effect at such time.  Any non-retired Participant (other than a 5% owner)
     who attains age 70-1/2 in 1997 or 1998, may elect in writing in the manner,
     time, and form required by the Company to defer payment of his Plan benefit
     until after his retirement pursuant to the terms of the Plan in effect at
     such time.  Notwithstanding the foregoing, the spouse of any Participant
     who so elects to terminate receiving Plan benefits which are being paid in
     a qualified joint and survivor annuity (within the meaning of Section
     417(b) of the Code) must consent to such election and acknowledge the
     effect of the election.  If such a Participant does not make such an
     election or if the Participant is a 5% owner, payment of his Plan benefit
     shall be made or shall continue to be made to him pursuant to the
     provisions of this Section 8.3 in effect prior to January 1, 1997.  For
     purposes of Section 417 of the Code, any recommencement of benefits under
     this Section 8.3 shall be considered a new annuity starting date.

15.  Paragraph (b) of Section 8.3 of the Plan is hereby amended to provide
as follows:

                                       13
<PAGE>

               (b) Lump Sum.  Except as provided in Section 8.3(c) and (d), a
                   --------
          Participant's Account shall be distributed in one or more payments
          within one calendar year, as soon as practicable after his separation
          from service. The Committee shall direct the Trustee to distribute to
          a Participant or his Beneficiary any amount to which the Participant
          or his Beneficiary is entitled under the Plan in one lump sum payment
          in cash, except that with respect to distribution from the ICF Kaiser
          Stock Fund, the Committee may direct the Trustee to distribute to a
          Participant or his Beneficiary any amount to which the Participant or
          his Beneficiary is entitled under the ICF Kaiser Stock Fund in one
          lump sum payment in whole shares of qualifying employer securities
          (with the value of any fractional share paid in cash), cash, or a
          combination of both, at the election of the Participant; provided,
          however, that the distribution of any such cash payment shall be made
          not later than two months after the date that distribution of Company
          Stock would have occurred and shall be determined as of the value of
          Company Stock on such date.

     16.  Paragraph (d)(2) of Section 8.3 of the Plan is hereby amended
effective January 1, 1997, to provide as follow:

          (d)(2) Notwithstanding any other provision of the Plan to the
          contrary, any rejection, or revocation of a rejection, of the
          automatic election of the qualified joint and survivor annuity shall
          be made only within the 90-day period prior to the Participant's
          annuity starting date. Within a reasonable period of time prior to the
          annuity starting date, the Company shall provide each Participant with
          a written explanation of (1) the terms and conditions of the qualified
          joint and survivor annuity and its financial effect on his retirement
          benefit; (2) the Participant's right to waive such joint and survivor
          annuity; (3) the rights of the Participant's spouse regarding consent
          as described above in subparagraph (ii); and (4) the right to make and
          the effect of, a revocation of an election to waive the automatic
          qualified joint and survivor annuity. Such explanation shall be
          provided at least 30 days prior to distribution unless the Participant
          (with any applicable spousal consent) waives such 30-day requirement
          and distribution commences more than 7 days after such explanation is
          provided.

     17.  Paragraph (e) of Section 8.3 of the Plan is hereby amended effective
January 1, 1998, to provide as follow:

               (e) Alternative Form of Benefit for Amounts Attributable to
                   -------------------------------------------------------
          Benefits Transferred From the Georgia A. Wilson & Associates, Inc.
          -----------------------------------------------------------------
          Retirement Plan (the "Georgia Wilson Plan"). A Participant whose
          -------------------------------------------
          Account is credited with benefits from the Georgia Wilson Plan may
          elect to receive the portion of his Account attributable to such
          benefits from the Georgia Wilson Plan in payments over a period
          certain in monthly,

                                       14
<PAGE>

          quarterly, semiannual, or annual cash installments, which period shall
          not extend beyond the Participant's life expectancy (or the life
          expectancy of the Participant and his designated Beneficiary).

     18.  Article IX of the Plan is hereby amended effective March 17, 1999, to
provide as follows:

                                  ARTICLE IX

                     ADMINISTRATION AND CLAIMS PROCEDURES
                     ------------------------------------

          9.1 Authority of the Company. The Company shall be the Plan
              ------------------------
          administrator for purposes of ERISA and the Code and shall have the
          authority and the power to perform the functions conferred upon it
          herein, subject to the limitations hereinafter set forth. The Company
          shall have the sole right to interpret and construe the Plan, and to
          determine any disputes arising thereunder, subject to the provisions
          of Section 9.3. In exercising such powers and authorities, the Company
          shall at all times exercise good faith, apply standards of uniform
          application, and refrain from arbitrary action. The Company may employ
          such attorneys, agents, and accountants as it may deem necessary or
          advisable to assist it in carrying out its duties hereunder. The
          Company is hereby designated as a "named fiduciary" of the Plan as
          such term is defined in Section 402(a)(2) of ERISA. The Company may
          allocate any of its responsibilities for the day to day operation and
          administration of the Plan to any person or persons employed by it. In
          addition, the Company, by action of its Board of Directors, may
          designate a person other than itself to carry out any of such powers,
          authorities or responsibilities which are retained by it or granted to
          it by this Article IX.

          9.2 Action of Company. Any act authorized, permitted, or required to
              -----------------
          be taken by the Company under the Plan, which has not been allocated
          or delegated in accordance with Section 9.1, may be taken by a
          majority of the members of the Board of Directors of the Company,
          either by vote at a meeting, or in writing without a meeting. All
          notices, advices, directions, certifications, approvals, and
          instructions required or authorized to be given by the Company under
          the Plan shall be in writing and signed by either (a) a majority of
          the members of the Board of Directors of the Company, or by such
          member or members as may be designated by an instrument in writing,
          signed by all the members thereof, as having authority to execute such
          documents on its behalf, or (b) a person who becomes authorized to act
          for the Company in accordance with the provisions of Section 9.1.
          Subject to the provisions of Section 9.3, any action taken by the
          Company which is authorized, permitted, or required under the Plan
          shall be final and binding upon the Company and the Trustee, all
          persons who have or who claim an interest under the Plan, and all
          third parties dealing with the Company or the Trustee.

                                       15
<PAGE>

          9.3 Claims Review Procedure. Whenever the Company decides for whatever
              -----------------------
          reason to deny, whether in whole or in part, a claim for benefits
          filed by any person (hereinafter referred to a the "Claimant"), the
          Plan administrator shall transmit to the Claimant a written notice of
          the Company's decision, which shall be written in a manner calculated
          to be understood by the Claimant and contain a statement of the
          specific reasons for the denial of the claim and a restatement
          advising the Claimant that, within 60 days of the date on which he
          receives such notice, he may obtain review of the decision of the
          Company in accordance with the procedures hereinafter set forth.
          Within such 60-day period, the Claimant or his authorized
          representative may request that the claim denial be reviewed by filing
          with the Plan Administrator a written request therefor, which request
          shall contain the following information:

               (a) the date on which the Claimant's request was filed with the
          Plan administrator; provided, however, that the date on which the
          Claimant's request for review was in fact filed with the Plan
          Administrator shall control in the event that the date of the actual
          filing is later than the date stated by the Claimant pursuant to this
          paragraph (a);

               (b) the specific portions of the denial of his claim which the
          Claimant requests the Plan administrator to review;

               (c) a statement by the Claimant setting forth the basis upon
          which he believes the Plan administrator should reverse the Trustee's
          previous denial of his claim for benefits and accept his claim as
          made; and

               (d) any written material (offered as exhibits) which the Claimant
          desires the Plan administrator to examine in its consideration of his
          position as stated pursuant to paragraph (c).

          Within 60 days of the date determined pursuant to paragraph (a) of
          this Section 9.3, the Plan administrator shall conduct a full and fair
          review of the Company's decision denying the Claimant's claim for
          benefits. Within 60 days of the date of such hearing, the Plan
          administrator shall render its written decision on review, written in
          a manner calculated to be understood by the Claimant, specifying the
          reasons and Plan provisions upon which its decision was based.

          9.4  Indemnification. In addition to whatever rights of
               ---------------
          indemnification the members of the Board of Directors of the Company,
          or any other person or persons to whom any power, authority, or
          responsibility of the Company is delegated pursuant to Section 9.1,
          may be entitled under the articles of incorporation, regulations, or
          by-laws of the Company, under any provision of law, or under any other
          agreement, the Company shall satisfy any liability actually and
          reasonably incurred by any such person or persons, including expenses,
          attorneys' fees, judgments, fines, and

                                       16
<PAGE>

          amounts paid in settlement, in connection with any threatened,
          pending, or completed action, suit, or proceeding which is related to
          the exercise or failure to exercise by such person or persons of any
          of the powers, authority, responsibilities, or discretion provided
          under the Plan, or reasonably believed by such person or persons to be
          provided hereunder, and any action taken by such person or persons in
          connection therewith.

          9.5  Administrative Expenses.  The fees of the Trustee and all other
               -----------------------
          administrative expenses of the Plan and Trust shall be paid by the
          Trustee from the assets of the Trust unless the Company, in its
          discretion, elects to pay any such fees and/or expenses.

          9.6  Voting of Company Stock in the ICF Kaiser Stock Fund.  Each
               ----------------------------------------------------
          Participant or Beneficiary who has shares of Company Stock allocated
          to his Account shall be a named fiduciary with respect to the voting
          of Company Stock held thereunder and shall have the following powers
          and responsibilities:

               (a) Prior to each annual or special meeting of the shareholders
          of the Company, the Company shall cause to be sent to each Participant
          and Beneficiary who has Company Stock allocated to his Account and
          invested in the ICF Kaiser Stock Fund under the Plan a copy of the
          proxy solicitation material therefor, together with a form requesting
          confidential voting instructions, with respect to the voting of such
          Company Stock as well as the voting of Company Stock for which the
          Trustee does not receive instructions. Each such Participant and/or
          Beneficiary shall instruct the Trustee to vote the number of such
          uninstructed shares of Company Stock equal to the proportion that the
          number of shares of Company Stock allocated to his Account and
          invested in the ICF Kaiser Stock Fund bears to the total number of
          shares of Company Stock in the Plan for which instructions are
          received. Upon receipt of such a Participant's or Beneficiary's
          instructions, the Trustee shall then vote in person, or by proxy, such
          shares of Company Stock as so instructed.

               (b) The Company shall cause the Trustee to furnish to each
          Participant and Beneficiary who has Company Stock allocated to his
          Account and invested in the ICF Kaiser Stock Fund under the Plan
          notice of any tender or exchange offer for, or a request or invitation
          for tenders or exchanges of, Company Stock made to the Trustee. The
          Trustee shall request from each such Participant and Beneficiary
          instructions as to the tendering or exchanging of Company Stock
          allocated to his Account. Each Participant and Beneficiary who does
          not instruct the Trustee with respect to the tendering or exchanging
          of Company Stock allocated to his Account shall be deemed to have
          decided not to participate in any such tender or exchange offer. The
          Trustee shall provide Participants and Beneficiaries with a reasonable
          period of time in which they may consider any such tender or exchange
          offer for, or request or invitation for tenders

                                       17
<PAGE>

          or exchanges of, Company Stock made to the Trustee. Within the time
          specified by the Trustee, the Trustee shall tender or exchange such
          Company Stock as to which the Trustee has received instructions to
          tender or exchange from Participants and Beneficiaries.

               (c) Instructions received from Participants and Beneficiaries by
          the Trustee regarding the voting, tendering, or exchanging of Company
          Stock shall be held in strictest confidence and shall not be divulged
          to any other person, including officers or employees of the Company,
          except as otherwise required by law, regulation or lawful process.

     19.  The first sentence of Section 10.1 of the Plan is hereby amended
effective March 17, 1999, by the deletion of the phrase "and the Committee".

     20.  The second sentence of Section 10.3 of the Plan is hereby amended
effective March 17, 1999, by the deletion of the phrase "the Committee and".

     21.  The third sentence of Section 10.3 of the Plan is hereby amended
effective March 17, 1999, by the deletion of the phrase "or Committee".

     22.  The first sentence and third sentence of Section 10.4 of the Plan are
hereby amended effective March 17, 1999, by the deletion of the phrase "and
Committee".

     23.  The term "Committee" is hereby deleted effective March 17, 1999,
throughout the Plan and the term "Company" is hereby substituted in place
thereof.


          Executed this 8th day of April, 1999.

                                                ICF KAISER INTERNATIONAL, INC.



                                                 By:  /s/ Timothy P. O'Connor
                                                      --------------------------

                                                 And: Senior Vice President and
                                                      --------------------------
                                                      Chief Financial Officer
                                                      --------------------------

                                       18