<PAGE>   1




                       SECOND LOAN MODIFICATION AGREEMENT


     This Second Loan Modification Agreement ("this Agreement") is made as of
August 7, 1997 by and among Fleet National Bank (the "Bank") (the Bank being the
successor by merger to Fleet National Bank of Massachusetts, said Fleet National
Bank of Massachusetts being formerly known as "Shawmut Bank, N.A."), GZA
GeoEnvironmental Technologies, Inc., a Delaware corporation ("GZA"), GZA
GeoEnvironmental, Inc., a Massachusetts corporation ("GZA Associates"), GZA
Drilling, Inc., a Massachusetts corporation ("GZA Drilling"), GZA Remediation,
Inc., a Massachusetts corporation ("GZA Remediation"), GZA Securities Corp., a
Massachusetts corporation ("GZA Securities"), Delta Geotechnical Services, Inc.,
a Massachusetts corporation ("Delta"), Grover Enterprises, Inc., a Massachusetts
corporation ("Grover") and Goldberg Zoino Associates of New York, P.C. ("GZA New
York") (GZA, GZA Associates, GZA Drilling, GZA Remediation, GZA Securities,
Delta, Grover and GZA New York being hereinafter referred to collectively as the
"Borrowers" and individually as a "Borrower"). For good and valuable
consideration, receipt and sufficiency of which are hereby acknowledged, the
Borrowers and the Bank act and agree as follows:

     1.   Reference is made to: (i) that certain Revolving Credit and Term Loan
Agreement dated as of February 28, 1994 among Shawmut Bank, N.A. and the
Borrowers, as amended (as so amended, the "Loan Agreement"), the Bank having
succeeded by merger to the rights of Shawmut Bank, N.A. thereunder; (ii) that
certain $5,500,000 face principal amount promissory note dated February 28, 1994
(the "1994 Line of Credit Note") made by the Borrowers and payable to the order
of Shawmut Bank, N.A.; (iii) those promissory notes (collectively, the "Term
Notes") made by GZA (or, in certain cases, GZA and another Borrower) which have
heretofore been issued and may hereafter be issued pursuant to Section 1.02(B)
of the Loan Agreement (the Borrowers hereby representing and agreeing that the
obligations of those Borrowers named in each such Term Note are joint and
several), the Bank having succeeded by merger to the rights of Shawmut Bank,
N.A. under said Term Notes; (iv) those certain guaranties (collectively, the
"Guaranties") executed and delivered in favor of Shawmut Bank, N.A. by each of
the Borrowers pursuant to clause (iii) of Section 3.01(b) of the Loan Agreement,
the Bank having succeeded by merger to the rights of Shawmut Bank, N.A.
thereunder; and (v) that certain $5,500,000 face principal amount promissory
note of even date herewith (the "1997 Line of Credit Note") made by the
Borrowers and payable to the order of the Bank. The Loan Agreement, the 1997
Line of Credit Note, the Term Notes and the Guaranties are hereinafter
collectively referred to as the "Financing Documents".

     2.   The Bank hereby waives the Event of Default under the Loan Agreement
which consists of GZA's failure to comply, as at August 31, 1996, with paragraph
(b) of Section 4.08 of the Loan Agreement (the Cash Flow Coverage test);
provided that this waiver is limited to said paragraph (b) and does not extend
to any other provision of the Loan Agreement, nor does it apply as at any other
date.


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     3.   The Loan Agreement is hereby amended:

          a.   By providing that all references therein to the "Lender" will be
deemed to refer to Fleet National Bank, having a place of business at One
Federal Street, Boston, MA. 02211.

          b.   By deleting from the first sentence of Section 1.01(A) of the 
Loan Agreement the words "in an aggregate principal amount not to exceed at any
time outstanding the sum of Five Million Five Hundred Thousand Dollars
($5,500,000)" and by substituting in their stead the following:

          "; provided that such Line of Credit Loans will be limited in
          aggregate principal amount so that the total Revolving Credit
          Liabilities (hereinafter defined) will never exceed $5,500,000"

          c.   By inserting into the third sentence of Section 1.01(A) of the 
Loan Agreement, immediately after the words "by the Lender", the following:

          "(except as otherwise provided below with respect to LIBOR Loans)"

          d.   By inserting into the last sentence of Section 1.01 of the Loan
Agreement, immediately after the words "except that the Converted Loan", the
following:

          "made at the Expiration Date"

          e.   By inserting into the first sentence of Section 1.01(B) of the 
Loan Agreement, immediately after the words "to the Borrowers", the following:

          "(such Term Loan being made either to GZA singly or to GZA and another
          Borrower jointly and severally)"

          f.   By providing that all references in the Loan Agreement to the 
"Corporate Base Rate" will be deemed to refer to the Prime Rate (hereinafter
defined) of Fleet National Bank.

          g.   By deleting from Section 1.01(C) of the Loan Agreement the words
"`Expiration Date' means July 31, 1996" and by substituting in their stead the
following:

          "`Expiration Date' means July 31, 1999"

          h.   By deleting from Section 1.01(D) of the Loan Agreement the words
"`Maturity Date' means July 31, 2000" and by substituting in their stead the
following:

          "Maturity Date' means July 31, 2004"


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          i.   By deleting in its entirety Section 1.03 of the Loan Agreement 
and by substituting in its stead the following:

          "SECTION 1.03. FIXED RATE LOANS; BORROWING MECHANICS.

          (a)  DEFINITIONS. As used in this Agreement, the following terms have
               the following respective meanings:

          `Adjusted COF Rate' - As defined in Section 1.03(b) below.

          `Bank Certificate' - A certificate signed by an officer of the Lender
          setting forth any additional amount required to be paid by the
          Borrowers to the Lender pursuant to Sections 1.03(b) and 1.03(f)
          and/or 1.03(g) of this Agreement, which certificate shall be submitted
          by the Lender to the Borrowers in connection with each demand made at
          any time by the Lender upon the Borrowers with respect to any such
          additional amount, and each such certificate shall, save for manifest
          error, constitute conclusive evidence of the additional amount
          required to be paid by the Borrowers to the Lender upon each demand. A
          claim by the Lender for all or any part of any additional amount
          required to be paid by the Borrowers may be made before and/or after
          the end of the Interest Period to which such claim relates or during
          which such claim has arisen and before and/or after any payment
          hereunder to which such claim relates. Each Bank Certificate shall set
          forth in reasonable detail the basis for and the calculation of the
          claim to which it relates.

          `Business Day' - Any day which is not a Saturday, nor a Sunday nor a
          public holiday under the laws of the United States of America or The
          Commonwealth of Massachusetts applicable to a national bank; provided
          however that if the applicable provision relates to a LIBOR Loan, then
          the term `Business Day' shall not include any day on which dealings
          are not carried on in the London interbank market or on which banks
          are not open for business in London.

          `COF Loan' - Any Term Loan which bears interest at an Adjusted COF
          Rate.

          `Eurocurrency Liabilities' - Has the meaning assigned to that term in
          Regulation D of the Board of Governors of the Federal Reserve System
          (or any successor), as in effect from time to time, or in any
          successor regulation relating to the liabilities described in said
          Regulation D.


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          `Eurodollar Interest Rate' - For any Interest Period relating to a
          LIBOR Loan, an interest rate per annum, expressed as a percentage,
          determined by the Lender pursuant to the following formula:

                  *EIR  =     LIBOR    +    ERI
                         -------------
                         [1.00  -  RR]

                         Where EIR  = Eurodollar Interest Rate
                         LIBOR   =  See definition of LIBOR
                         RR         = Reserve Rate
                         ERI        = Eurodollar Rate Increment

                  *EIR and each component thereof to be rounded upwards to the
                  next higher 1/8 of 1%

          `Eurodollar Rate Increment' - One and one-half percent (1.5%) per
          annum.

          `Fixed Rate Loan" - Any Loan which is a LIBOR Loan or a COF Loan.

          `Floating Rate' - As defined in Section 1.03(b).

          `Floating Rate Loan' - Any Loan which bears interest at the Floating
          Rate.

          `Impositions' - All present and future taxes, levies, duties,
          impositions, deductions, charges and withholdings applicable to the
          Lender with respect to any Fixed Rate Loan, excluding, however, any
          taxes imposed directly on the Lender's income and any franchise taxes
          imposed on it by the jurisdiction under the laws of which the Lender
          is organized or any political subdivision thereof.

          `Interest Payment Date(s)' - As to each LIBOR Loan, the last day of
          the Interest Period applicable thereto; provided that if any such
          Interest Period for a LIBOR Loan is more than one month, then there
          will be multiple Interest Payment Dates for such LIBOR Loan, the first
          of which shall be on the 30th day of such Interest Period, with a
          subsequent Interest Payment Date to occur at the end of each 30-day
          period thereafter and on the last day of such Interest Period. As to
          each COF Loan, the Interest Payment Date will be the last day of the
          Interest Period applicable thereto.


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          `Interest Period' - As to each LIBOR Loan, the period commencing with
          the date of the making of such LIBOR Loan and ending one, two or three
          months thereafter, as the Borrowers may select; provided that (A) any
          such Interest Period which would otherwise end on a day which is not a
          Business Day shall be extended to the next succeeding Business Day
          unless such Business Day occurs in a new calendar month, in which case
          such Interest Period shall end on the immediately preceding Business
          Day, (B) any such Interest Period which begins on a day for which
          there is no numerically corresponding day in the calendar month during
          which such Interest Period is to end shall end on the last Business
          Day of such calendar month, and (C) no Interest Period may be selected
          which would end after the Expiration Date. The Interest Period for
          each COF Loan will be a period of 30 days commencing on the date of
          the making of such COF Loan and ending on the date occurring 30 days
          thereafter; provided, however, that (A) each such Interest Period
          which would otherwise end on a day which is not a Business Day shall
          end on the immediately succeeding Business Day and (B) no such
          Interest Period may be selected which would end after the Maturity
          Date.

          `LIBOR' - With respect to each Interest Period for a LIBOR Loan, that
          rate of interest per annum (rounded upward, if necessary, to the
          nearest 1/8 of 1%) at which deposits in United States Dollars are
          offered to the Lender, for delivery on the first day of the applicable
          Interest Period, in the London interbank market at 10:00 a.m. London
          time, two Business Days prior to the first day of the applicable
          Interest Period for a term equal to the term of the LIBOR Loan
          requested for such Interest Period and in an amount substantially
          equal to the principal amount of the relevant LIBOR Loan. The Lender
          shall give prompt notice to the Borrowers of LIBOR as determined for
          each LIBOR Loan and such notice shall be conclusive and binding,
          absent manifest error.

          `LIBOR Loan' - Any Line of Credit Loan which bears interest at a
          Eurodollar Interest Rate.

          `London' - The City of London in England.

          `Prime Rate' - That interest rate per annum announced by the Lender
          from time to time as its `prime rate', it being acknowledged that such
          rate is merely a reference rate, not necessarily the lowest, which
          serves as the basis upon which effective rates of interest are
          calculated for obligations making reference thereto.


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          `Revolving Credit Liabilities' - At any time, the sum of (i) the
          principal amount of all Line of Credit Loans then outstanding, plus
          (ii) all then undrawn amounts of letters of credit issued by the
          Lender for the account of any Borrower, plus (iii) all amounts then
          drawn on any such letter of credit which at said date shall not have
          been reimbursed to the Lender by the Borrowers.

          `Reserve Rate' - The aggregate rate, expressed as a decimal, at which
          the Lender would be required to maintain reserves under Regulation D
          of the Board of Governors of the Federal Reserve System (or any
          successor or similar regulation relating to such reserve requirements)
          against Eurocurrency Liabilities, as well as any other reserve
          required of the Lender with respect to the LIBOR Loans. The Eurodollar
          Interest Rate shall be adjusted automatically on and as of the
          effective date of any change in the Reserve Rate.

          Any defined term used in the plural preceded by the definite article
          shall be taken to encompass all members of the relevant class. Any
          defined term used in the singular preceded by `any' shall be taken to
          indicate any number of the members of the relevant class.

          (b) INTEREST RATES. Except as provided below in this Section 1.03(b),
          interest on all Loans will be payable (subject to the provisions of
          the Notes for default rate interest) at a fluctuating rate per annum
          (the `Floating Rate') which shall at all times be equal to the Prime
          Rate as in effect from time to time (but in no event in excess of the
          maximum rate permitted by then applicable law), with a change in such
          rate of interest to become effective on each day when a change in the
          Prime Rate becomes effective. Subject to the conditions set forth
          herein, the Borrowers may elect that any Line of Credit Loan will be
          made as a LIBOR Loan. Such election shall be made by the Borrowers
          giving to the Lender a written or telephonic notice received by the
          Lender within the time period and containing the information described
          in the next following sentence (a `LIBOR Borrowing Notice'). The LIBOR
          Borrowing Notice must be received by the Lender no later than 10:00
          a.m. (Boston time) on that day which is two Business Days prior to the
          date of the proposed borrowing and must specify the amount of the
          LIBOR Loan requested (which shall be $250,000 or an integral multiple
          thereof), whether the Interest Period is proposed to be one month, two
          months or three months and the proposed commencement date of the
          relevant Interest Period. Any LIBOR Borrowing Notice shall, upon
          receipt by the Lender, become irrevocable and binding on the
          Borrowers, and the Borrowers shall, upon demand and receipt of a Bank
          Certificate from the Lender 

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          with respect thereto, forthwith indemnify (and shall be jointly and
          severally obligated to indemnify) the Lender against any loss or
          expense incurred by the Lender as a result of any failure by the
          Borrowers to obtain or maintain any requested LIBOR Loan, including,
          without limitation, any loss or expense incurred by reason of the
          liquidation or redeployment of deposits or other funds acquired by the
          Lender to fund or maintain such LIBOR Loan. Each LIBOR Loan will be
          due and payable in full (if not required to be repaid earlier pursuant
          to the terms of this Agreement) on the last day of the Interest Period
          applicable thereto. The principal amount of any such LIBOR Loan so
          repaid may be reborrowed as a new LIBOR Loan to the extent and on the
          terms and conditions contained in this Agreement by delivery to the
          Lender of a new LIBOR Borrowing Notice conforming to the requirements
          set forth above in this Section (and any LIBOR Loan not so repaid and
          not so reborrowed as a new LIBOR Loan will be deemed to have been
          reborrowed as a Floating Rate Loan). Notwithstanding any other
          provision of this Agreement, the Lender need not make any LIBOR Loan
          at any time when there exists any Event of Default under this
          Agreement or any event or circumstance which, with the giving of
          notice or the passage of time or both, could become an Event of
          Default.

          Each Term Loan will be made (as GZA may designate in writing) either
          to GZA singly or to GZA and another Borrower, jointly or severally.
          Subject to the conditions set forth below, the relevant Borrower or
          Borrowers may request that any Term Loan be made as a COF Loan (or, if
          a Term Loan is already outstanding as a Floating Rate Loan, that same
          be converted into a COF Loan). Any such request must be received by
          the Lender not later than 10:00 A.M. (Boston time) two Business Days
          prior to the date of the proposed borrowing (or if the relevant Term
          Loan is already outstanding, the date on which the Adjusted COF Rate
          is proposed to take effect). Each such request must include the
          principal amount of any proposed COF Loan, must identify any
          outstanding Term Loan as to which an Adjusted COF Rate is requested
          and must state the date on which such COF Loan is proposed to be made
          (or, if relating to an outstanding Term Loan as to which an Adjusted
          COF Rate is requested, the date on which such Adjusted COF Rate is to
          take effect). Following each request for a COF Loan, the Lender will
          endeavor to offer a proposed Adjusted COF Rate at a rate determined as
          provided below and under conditions for acceptance determined by the
          Lender in its sole discretion. The relevant Borrower or Borrowers may
          elect to accept such offer in the manner and within the time period
          specified in such offer. Any 


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<PAGE>   8

          such acceptance shall be irrevocable on the part of such Borrowers.
          Upon such acceptance, the interest rate payable with respect to the
          subject Term Loan shall be fixed (subject to adjustment as provided in
          this Agreement) for the Interest Period specified in the Borrowers'
          request and at the rate communicated by the Lender as its proposed
          Adjusted COF Rate. Any proposed Adjusted COF Rate offered under this
          paragraph will be a rate per annum equal to the sum of (i) two percent
          (2%) per annum plus (ii) the COF Rate (defined below) for the
          applicable Interest Period (expressed as a per annum rate); provided,
          however, that the Adjusted COF Rate shall in no event exceed the
          maximum rate permitted by applicable law. The `COF Rate' shall be
          determined by the Lender in its discretion for the purpose of any
          proposed Adjusted COF Rate offered under this Section and, in this
          determination, the Lender will attempt to reflect the cost of
          obtaining funds at fixed rates from the sources hereinafter provided.
          The Lender may base the COF Rate for the purpose of computing a
          proposed Adjusted COF Rate on any (or any combination of) recognized
          sources of available funding for transactions of this type, including,
          but not limited to, the interbank market, the domestic and European
          certificate of deposit market and sales of commercial paper. The COF
          Rate for purposes of this computation shall in any event include
          adjustments for the costs of maintaining reserves, insurance
          (including, without limitation, assessments by the Federal Deposit
          Insurance Corporation), taxes, hedging and other costs which may be
          incurred by the Lender with respect to the applicable sources or
          sources of funding, all as determined by the Lender in its reasonable
          discretion. The source or sources of funding utilized for the
          computation of the proposed rate shall be selected by the Lender at
          its sole discretion for offering to the Borrowers, and no Borrower
          shall have any claim against the Lender with respect to computation of
          any proposed Adjusted COF Rate. If any Borrower is dissatisfied with
          any proposed Adjusted COF Rate, the Borrowers' sole remedy with
          respect thereto shall be not to accept such proposed Adjusted COF Rate
          within the applicable time period, and thus not to borrow the proposed
          Term Loan (or, in the case of any outstanding Term Loan, to continue
          such Term Loan as a Floating Rate Loan). Notwithstanding the foregoing
          provisions hereof, the Lender need not offer a proposed Adjusted COF
          Rate for any period of time with respect to which the Lender, in its
          sole discretion, determines that there are no recognized sources of
          funding available to it for such time period or principal amount or
          that the cost of funds with respect thereto would be unreasonably
          high. If any one or more of the Borrowers shall accept a proposed
          Adjusted COF Rate offered hereunder and 


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<PAGE>   9


          shall then fail for any reason to borrow the COF Loan to which such
          offer related, the Borrowers shall, upon submission by the Lender of a
          Bank Certificate with respect thereto, forthwith indemnify the Lender
          (and shall be jointly and severally obligated to indemnify the Bank)
          against any loss or expense incurred by the Lender as a result of any
          such failure by the Borrowers, including, without limitation, any loss
          or expense incurred by reason of the liquidation or redeployment of
          deposits or other funds acquired by the Lender to fund or maintain the
          requested COF Loan. Each Adjusted COF Rate accepted hereunder will
          remain in effect through the last day of the Interest Period
          applicable thereto. At the end of such Interest Period, the relevant
          Borrower or Borrowers may request, subject to all of the terms and
          conditions contained in this Agreement, that a new Interest Period
          commence with an Adjusted COF Rate to be offered and accepted as
          provided above or that such Term Loan become a Floating Rate Loan (and
          any COF Loan as to which a new Adjusted COF Rate is not so offered and
          accepted for a new Interest Period will be deemed to have become a
          Floating Rate Loan). Notwithstanding any other provision of this
          Agreement, the Lender need not make any COF Loan at any time when
          there exists any Event of Default under this Agreement or any event or
          circumstance which, with the giving of notice or the passage of time
          or both, could become an Event of Default.

          (c) REPAYMENTS. The Borrowers may repay, at any time, without penalty
          or premium, the whole or any portion of any Loan which is a Floating
          Rate Loan. The Borrowers may repay the whole or any portion of any
          Loan which is a Fixed Rate Loan; provided that (i) the Borrowers give
          the Lender not less than two (2) Business Days' prior written notice
          of their intent so to repay, (ii) the Borrowers pay all interest on
          the Fixed Rate Loan (or portion thereof) so repaid accrued to the date
          of such repayment, (iii) any voluntary repayment of a LIBOR Loan shall
          be in a principal amount of $250,000 or an integral multiple thereof
          and (iv) if the Borrowers for any reason make any payment with respect
          to principal of a Fixed Rate Loan prior to the last day of the
          Interest Period applicable thereto, the Borrowers shall forthwith pay
          (and shall be jointly and severally obligated to pay) all amounts
          owing to the Lender pursuant to the provisions of Section 1.03(f) with
          respect to such Fixed Rate Loan.

          (d) INTEREST PAYMENTS. The Borrowers will pay interest on the
          principal amount of the Loans outstanding from time to time, from the
          date hereof until payment of the Loans in full and the 


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          termination of this Agreement. Interest on Floating Rate Loans will be
          payable monthly in arrears on the first day of each month. Interest on
          each Fixed Rate Loan will be paid in arrears on each of the Interest
          Payment Date or Dates applicable thereto. In any event, interest on
          the Line of Credit Loans shall also be paid on the date of payment of
          the Line of Credit Loans in full and interest on each Term Loan shall
          be paid on the date of payment of such Term Loan in full (and, if such
          Term Loan is being converted from being a Floating Rate Loan to a COF
          Loan, on the date of such conversion). Interest on Floating Rate Loans
          shall be payable at the Floating Rate. The rate of interest payable on
          any LIBOR Loan will be the Eurodollar Interest Rate applicable
          thereto. The rate of interest payable on any COF Loan shall be the
          Adjusted COF Rate applicable thereto. All interest, fees, other
          amounts and other amounts payable under this Agreement and/or under
          any note now or hereafter evidencing the Loans will be calculated on
          the basis of a 360-day year for the actual number of days elapsed.

          (e)  RATE DETERMINATION PROTECTION. In the event that:

               (i) the Lender shall determine that, by reason of circumstances
          affecting the London interbank market or otherwise, adequate and
          reasonable methods do not exist for ascertaining the Eurodollar
          Interest Rate which would otherwise be applicable during any Interest
          Period, or

               (ii) the Lender shall determine that:

               (A) the making or continuation of any LIBOR Loan has been made
               impracticable or unlawful by (1) the occurrence of any
               contingency that materially and adversely affects the London
               interbank market or (2) compliance by the Lender in good faith
               with any applicable law or governmental regulation, guideline or
               order or interpretation or change thereof by any governmental
               authority charged with the interpretation or administration
               thereof or with any request or directive of any such governmental
               authority (whether or not having the force of law); or

               (B) LIBOR will not, in the reasonable determination of the
               Lender, adequately and fairly reflect the cost to the Lender of
               funding the LIBOR Loans for such Interest Period

               then the Lender shall forthwith give notice of such determination
               (which shall be conclusive and binding on the 

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               Borrowers) to the Borrowers. In such event, the obligations of
               the Lender to make LIBOR Loans shall be suspended until the
               Lender determines that the circumstances giving rise to such
               suspension no longer exist, whereupon the Lender shall notify the
               Borrowers.

          (f)  PREPAYMENT OF FIXED RATE LOANS. The following provisions of this
          Section 1.03(f) shall be effective only with respect to Fixed Rate
          Loans: If, due to acceleration of or demand with respect to any Loan
          or due to voluntary prepayment or due to exercise of rights and
          remedies against collateral or due to any other reason, the Lender
          receives payment of any principal of a Fixed Rate Loan on any date
          prior to the last day of the relevant Interest Period, the Borrowers
          shall, upon demand and receipt of a Bank Certificate from the Lender
          with respect thereto, pay (and shall be jointly and severally
          obligated to pay) forthwith to the Lender all amounts required to
          compensate the Lender for losses, costs or expenses which it may have
          incurred and may reasonably incur as a result of such payment,
          including, without limitation, any loss or expense incurred by reason
          of the liquidation or redeployment of funds acquired by the Lender to
          fund or maintain such Fixed Rate Loan.

          (g)  INCREASED COSTS; CAPITAL ADEQUACY.

               (i) If the adoption, effectiveness or phase-in, after the date
          hereof, of any applicable law, rule or regulation, or any change
          therein, or any change in the interpretation or administration thereof
          by any governmental authority, central bank or comparable agency
          charged with the interpretation or administration thereof, or
          compliance by the Lender with any request or directive (whether or not
          having the force of law) of any such authority, central bank or
          comparable agency:

               (A) shall subject the Lender to any Imposition or other charge
          with respect to any Fixed Rate Loan or the Lender's agreement to make
          Fixed Rate Loans, or shall change the basis of taxation of payments to
          the Lender of the principal of or interest on any Fixed Rate Loan or
          any other amounts due under this agreement in respect of the Fixed
          Rate Loans or the Lender's agreement to make Fixed Rate Loans (except
          for changes in the rate of tax on the over-all net income of the
          Lender); or

               (B) shall impose, modify or deem applicable any reserve, special
          deposit, deposit insurance or similar requirement (including, without
          limitation, any such requirement imposed by 


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<PAGE>   12


          the Board of Governors of the Federal Reserve System, but excluding,
          with respect to any Fixed Rate Loan, any such requirement already
          included in the applicable Reserve Rate) against assets of, deposits
          with or for the account of, or credit extended by, the Lender or shall
          impose on the Lender or on the London interbank market any other
          condition affecting any Fixed Rate Loans or the Lender's agreement to
          make Fixed Rate Loans

          and the result of any of the foregoing is to increase the cost to the
          Lender of making or maintaining any Fixed Rate Loan or to reduce the
          amount of any sum received or receivable by the Lender under this
          Agreement or under any related note with respect to any Fixed Rate
          Loan by an amount deemed by the Lender to be material, then, within 30
          days following the Borrowers' receipt of a Bank Certificate from the
          Lender with respect thereto, the Borrowers shall pay (and shall be
          jointly and severally obligated to pay) to the Lender such additional
          amount or amounts as the Lender certifies to be necessary to
          compensate the Lender for such increased cost or reduction in amount
          received or receivable.

               (ii) If the Lender shall have determined that the adoption or
          phase-in after the date hereof of any applicable law, rule or
          regulation regarding capital requirements for banks or bank holding
          companies, or any change therein after the date hereof, or any change
          after the date hereof in the interpretation or administration thereof
          by any governmental authority, central bank or comparable agency
          charged with the interpretation or administration thereof, or
          compliance by the Lender with any request or directive of such entity
          regarding capital adequacy (whether or not having the force of law)
          has or would have the effect of reducing the return on the Lender's
          capital with respect to its agreement hereunder to make Loans or with
          respect to any Loan (whether or not then subject to any COF Rate or
          Eurodollar Interest Rate) to a level below that which the Lender could
          have achieved (taking into consideration the Lender's policies with
          respect to capital adequacy immediately before such adoption,
          phase-in, change or compliance and assuming that the Lender's capital
          was then fully utilized) by any amount deemed by the Lender to be
          material: (A) the Lender shall promptly after its determination of
          such occurrence give notice thereof to the Borrowers; and (B) the
          Borrowers shall pay (and shall be jointly and severally obligated to
          pay) to the Lender as an additional fee from time to time, within 30
          days following the Borrowers' receipt of a Bank Certificate with
          respect thereto, such amount as the Lender certifies to be the amount
          that will compensate it for such reduction. A Bank 


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<PAGE>   13


          Certificate given by the Lender claiming compensation under this
          Section shall be conclusive in the absence of manifest error. Such
          certificate shall set forth the nature of the occurrence giving rise
          to such compensation, the additional amount or amounts to be paid to
          the Lender hereunder and the method by which such amounts are
          determined. In determining any such amount, the Lender may use any
          reasonable averaging and attribution methods.

               (iii) No failure on the part of the Lender to demand compensation
          on any one occasion shall constitute a waiver of its right to demand
          such compensation on any other occasion and no failure on the part of
          the Lender to deliver any Bank Certificate in a timely manner shall in
          any way reduce any obligation of the Borrowers to the Lender under
          this Section.

          (h)  ILLEGALITY OR IMPOSSIBILITY. Notwithstanding any other provision
          of this Agreement, if the introduction of or any change in or in the
          interpretation or administration of any law or regulation applicable
          to the Lender or the Lender's activities in the London interbank
          market shall make it unlawful, or any central bank or other
          governmental authority having jurisdiction over the Lender or the
          Lender's activities in the London interbank market shall assert that
          it is unlawful, or otherwise make it impossible, for the Lender to
          perform its obligations hereunder to make LIBOR Loans or to continue
          to fund or maintain LIBOR Loans, then on notice thereof and demand
          therefor by the Lender to the Customer, (i) the obligation of the
          Lender to fund LIBOR Loans shall terminate and (ii) the Customer shall
          prepay in full all affected LIBOR Loans within five (5) Business Days
          and, in any event, on or prior to the last day on which such LIBOR
          Loans may legally remain outstanding."

          j.   By adding to Section 1.04(A) of the Loan Agreement, at the end 
hereof, the following:

          "Letters of credit may be issued from time to time for the account of
          the Borrowers under the Lender's then customary documentation at the
          written request of the Borrowers; provided that (i) all of the
          conditions to advance contained in Article III shall have been
          satisfied as at the date of such issuance, and (ii) at the date of
          such issuance, and after giving effect thereto, the Revolving Credit
          Liabilities will not aggregate in excess of $5,500,000. The Borrowers
          hereby authorize the Lender, without further request from any
          Borrower, to cause the liability of any Borrower or Borrowers to the
          Lender for reimbursement of funds drawn under 


                                      -13-

<PAGE>   14


          any letter of credit issued by the Lender to be repaid from the
          proceeds of a Line of Credit Loan to be made hereunder. The Borrowers
          hereby irrevocably request that such Line of Credit Loans be made."

          k.   By deleting in its entirety paragraph (a) of Section 4.08 of the
Loan Agreement (the Minimum Net Worth test) and by substituting in its stead the
following:

          "Maintain Minimum Net Worth, measured as at the end of each fiscal
          quarter of GZA, of not less than $21,000,000."

          l.   By deleting from paragraph (d) of Section 4.08 of the Loan 
Agreement (the Working Capital test) the words "Ten Million Dollars
($10,000,000)" and by substituting in their stead the following:

          "$15,000,000"

          m.   By deleting from the definition of "Cash Flow Coverage" appearing
in Section 4.08 of the Loan Agreement the words "Unfinanced Capital Expenditures
and".

          n.   By adding to Section 7.01 of the Loan Agreement, at the end 
thereof, the following:

          "All representations, covenants and agreements of the Borrowers
          contained herein will be deemed the joint and several obligations of
          the Borrowers, whether or not expressly so stated herein."

          o.   By changing the Bank's notice address, pursuant to Section 7.06 
of the Loan Agreement, to the following:

          "Fleet National Bank
          One Federal Street, 4th Floor
          Boston, MA  02211
          Attention:  Thomas F. Brennan, Vice President"

          p.   By deleting in its entirety Exhibit A to the Loan Agreement and 
by substituting in its stead Exhibit A in the form attached hereto.

          q.   By deleting in its entirety Exhibit B to the Loan Agreement and 
by substituting in its stead Exhibit B in the form attached hereto. Said Exhibit
B in the form attached hereto will be used for all future Term Loans.

          r.   By modifying Exhibit C to the Loan Agreement (i) to take into 
account the changes made by the foregoing provisions of this Agreement as to the
identity and address of the 

                                      -14-

<PAGE>   15

Bank, (ii) by replacing the words "Corporate Base Rate" with the words "Prime
Rate", and (iii) by replacing the words "Fixed Rate" with the words "Adjusted
COF Rate".

          s.   By modifying Exhibit E to the Loan Agreement to take into account
the above-described change as to the identity of the Bank.

          t.   By deleting in its entirety Exhibit F to the Loan Agreement and 
by substituting in its stead Exhibit F in the form attached hereto.

     4.   Each presently outstanding Term Note is hereby amended:

          a.   By providing that the "Lender" described therein is Fleet 
National Bank, having an office at One Federal Street, Boston, MA 02211.

          b.   By providing that all references therein to the "Corporate Base 
Rate" will be deemed to refer to Fleet National Bank's "Prime Rate", as defined
above in this Agreement.

          c.   By providing that all references therein to a "Fixed Rate" will 
be deemed to refer to the "Adjusted COF Rate", as defined in this Agreement.

          d.   By providing that the provisions of the Loan Agreement (as 
amended by this Agreement) relating to the method of determination of an
interest rate for Term Loans (as defined in the Loan Agreement), to the
prerequisites for borrowing a Term Loan, to the time for payment of interest of
any Term Loan and to the additional amount, if any, payable upon any prepayment
of principal of any Term Loan, will be deemed to supersede any inconsistent
provisions of the existing Term Notes.

     5.   Whenever in any Financing Document, or in any borrowing request,
certificate or opinion to be delivered in connection therewith, reference is
made to a "Loan Agreement" (or, in the case of a request for a Term Loan, to the
"Agreement"), from and after the date hereof same will be deemed to refer to the
Loan Agreement, as hereby amended.

     6.   In order to induce the Bank to enter into this Agreement, the 
Borrowers further jointly and severally represent and warrant to the Bank as
follows:

          a.   The execution, delivery and performance of this Agreement, the 
     1997 Line of Credit Note and each Term Note to be delivered hereafter have
     been duly authorized by each Borrower by all necessary corporate and other
     action, will not require the consent of any third party and will not
     conflict with, violate the provisions of, or cause a default or constitute
     an event which, with the passage of time or the giving of notice or both,
     could cause a default on the part of any Borrower under its charter
     documents or by-laws or under any contract, agreement, law, rule, order,
     ordinance, franchise, instrument or other document, or result in the
     imposition of any lien or encumbrance on any property or assets of any
     Borrower.

                                      -15-

<PAGE>   16


          b.   Each Borrower has duly executed each of this Agreement and the 
     1997 Line of Credit Note and has delivered same to the Bank.

          c.   Each of this Agreement and the 1997 Line of Credit Note is the
     legal, valid and binding obligation of the Borrowers, enforceable jointly
     and severally against each of the Borrowers in accordance with its
     respective terms. Each Term Note now outstanding is (and each Term Note
     hereafter issued will be) the legal, valid and binding obligation of the
     Borrower or Borrowers named therein, enforceable against each of them in
     accordance with its terms.

          d.   The representations and warranties made in the Loan Agreement
     continue to be correct as of the date hereof, except as supplemented and/or
     modified on the attached supplemental disclosure schedule.

          e.   Giving effect to the waiver set forth in Section 2 above and to
     certain prior written waivers, the covenants and agreements of the
     Borrowers contained in the Loan Agreement (as amended hereby) have been
     compiled with on and as of the date hereof.

          f.   Giving effect to the waiver set forth in Section 2 above and to
     certain prior written waivers, no event which constitutes or which, with
     notice or lapse of time, or both, could constitute, an Event of Default (as
     defined in the Loan Agreement) has occurred and is continuing.

          g.   No material adverse change has occurred in the financial 
     condition of the Borrowers from that disclosed in the financial statements
     of GZA as at February 28, 1997, heretofore provided to the Bank.

     7.   Except as expressly affected hereby, the Loan Agreement and each of
the other Financing Documents remains in full force and effect as heretofore.
Each Borrower hereby agrees that the respective Guaranty heretofore given by
such Borrower (i) remains in full force and effect, (ii) runs to the benefit of
Fleet National Bank and (iii) includes, as obligations guaranteed thereunder,
the Loan Agreement (as amended by this Agreement), the 1997 Line of Credit Note,
the existing Term Notes (as amended by this Agreement) and all future Term
Notes.

     8.   Nothing contained herein will be deemed to constitute a waiver (other
than the express written waiver set forth in Section 2 of this Agreement) or a
release of any provision of any of the Financing Documents. Nothing contained
herein will in any event be deemed to constitute an agreement to give a waiver
or release or to agree to any amendment or modification of any provision of any
of the Financing Documents on any other or future occasion.


                                      -16-
<PAGE>   17


     Executed, as an instrument under seal, as of the date and year first above
written.


                                 FLEET NATIONAL BANK


                                 By: /s/ Thomas F. Brennan
                                    --------------------------------------------
                                    Name: Thomas F. Brennan
                                    Title: VP



                                 GZA GEOENVIRONMENTAL
                                 TECHNOLOGIES, INC.


                                 By: /s/ Joseph P. Hehir
                                    --------------------------------------------
                                    Name: Joseph P. Hehir
                                    Title: Chief Financial Officer and Treasurer


                                 GZA GEOENVIRONMENTAL, INC.


                                 By: /s/ Joseph P. Hehir
                                    --------------------------------------------
                                    Name: Joseph P. Hehir
                                    Title: Treasurer


                                 GZA DRILLING, INC.


                                 By: /s/ M. Joseph Celi
                                    --------------------------------------------
                                    Name: M. Joseph Celi
                                    Title: President

                                 GZA REMEDIATION, INC.


                                 By: /s/ M. Joseph Celi
                                    --------------------------------------------
                                    Name: M. Joseph Celi
                                    Title: President


                                      -17-
<PAGE>   18


                                    GZA SECURITIES CORP.


                                    By: /s/ Joseph P. Hehir
                                       -----------------------------------------
                                       Name: Joseph P. Hehir
                                       Title: Treasurer


                                    DELTA GEOTECHNICAL SERVICES, INC.


                                    By: /s/ Joseph P. Hehir
                                       -----------------------------------------
                                       Name: Joseph P. Hehir
                                       Title: Treasurer


                                    GROVER ENTERPRISES, INC.


                                    By: /s/ M. Joseph Celi
                                       -----------------------------------------
                                       Name: M. Joseph Celi
                                       Title: President


                                    GOLDBERG ZOINO ASSOCIATES OF NEW YORK, P.C.


                                    By: /s/ Richard M. Simon
                                       -----------------------------------------
                                       Name: Richard M. Simon
                                       Title: President




                                      -18-
<PAGE>   19






                        SUPPLEMENTAL DISCLOSURE SCHEDULE
                    [To be provided by Borrowers, if needed]




<PAGE>   20



                                    EXHIBIT F
                                    ---------

                           EMPLOYEES OF GZA AUTHORIZED
                       TO REQUEST LINE OF CREDIT ADVANCES
                       ----------------------------------


     [To be provided by GZA]


                           OFFICERS OF GZA AUTHORIZED
                              TO REQUEST TERM LOANS

     [To be provided by GZA]


                        OFFICERS OF BORROWERS AUTHORIZED
                              TO EXECUTE TERM NOTES


           Borrower                        Authorized Signatory (Name and Title)
           --------                        -------------------------------------

GZA GeoEnvironmental Technologies, Inc.       [To be provided by Borrowers.]

GZA GeoEnvironmental, Inc.                    [To be provided by Borrowers.]

GZA Drilling, Inc.                            [To be provided by Borrowers.]

GZA Remediation, Inc.                         [To be provided by Borrowers.]

GZA Securities Corporation                    [To be provided by Borrowers.]

Delta Geotechnical Services, Inc.             [To be provided by Borrowers.]

Grover Enterprises, Inc.                      [To be provided by Borrowers.]

Goldberg-Zoino Associates of New York, P.C.   [To be provided by Borrowers.]



                                      -20-

<PAGE>   21
                                                                       Exhibit A


                                 PROMISSORY NOTE


$5,500,000.00                                             Boston, Massachusetts
                                                                 August 7, 1997

     FOR VALUE RECEIVED, the undersigned GZA GeoEnvironmental Technologies,
Inc., a Delaware corporation ("GZA"), GZA GeoEnvironmental, Inc., a
Massachusetts corporation ("GZA Associates"), GZA Drilling, Inc., a
Massachusetts corporation ("GZA Drilling"), GZA Remediation, Inc., a
Massachusetts corporation ("GZA Remediation"), GZA Securities Corp., a
Massachusetts corporation ("GZA Securities"), Delta Geotechnical Services, Inc.,
a Massachusetts corporation ("Delta"), Grover Enterprises, Inc., a Massachusetts
corporation ("Grover") and Goldberg Zoino Associates of New York, P.C. ("GZA New
York") (GZA, GZA Associates, GZA Drilling, GZA Remediation, GZA Securities,
Delta, Grover and GZA New York being hereinafter referred to collectively as the
"Borrowers" and individually as a "Borrower") hereby jointly and severally
promise to pay to the order of FLEET NATIONAL BANK (the "Bank") the principal
amount of Five Million Five Hundred Thousand and 00/100 ($5,500,000.00) Dollars
or such portion thereof as may be advanced by the Bank (or may have heretofore
been advanced by the Bank or any corporate predecessor thereof) pursuant to
Section 1.01(A) of the below-described Loan Agreement and remains outstanding
from time to time hereunder ("Principal"), with interest, at the rate
hereinafter set forth, on the daily balance of all unpaid Principal, from the
date hereof until payment in full of all Principal and interest hereunder. As
used herein, "Loan Agreement" means that certain Revolving Credit and Term Loan
Agreement dated as of February 28, 1994 among the Borrowers and Shawmut Bank,
N.A., as amended (Fleet National Bank having succeeded by merger to the rights
and obligations of Shawmut Bank, N.A. thereunder).

     Interest on all unpaid Principal shall be due and payable monthly in
arrears, on the first day of each month, commencing on the first such date after
the advance of any Principal and continuing on the first day of each month
thereafter and on the date of payment of this note in full, at a fluctuating
rate per annum (computed on the basis of a year of three hundred sixty (360)
days for the actual number of days elapsed) which shall at all times be equal to
the Prime Rate, as in effect from time to time (but in no event in excess of the
maximum rate permitted by then applicable law), with a change in the aforesaid
rate of interest to become effective on the same day on which any change in the
Prime Rate is effective; provided, however, that if a Eurodollar Interest Rate
(as defined in the Loan Agreement) shall have become applicable to all or any
portion of the outstanding Principal for any Interest Period (as defined in the
Loan Agreement), then interest on such Principal or portion thereof shall accrue
at said applicable Eurodollar Interest Rate for such Interest Period and shall
be payable on the last day of such Interest Period. Overdue Principal and, to
the extent permitted by law, overdue interest shall bear interest at a
fluctuating rate per annum which at all times shall be equal to the sum of (i)
two (2%) percent per annum plus (ii) the per annum rate otherwise payable under
this note with respect to the Principal which is overdue (or as to which such
interest is overdue) (but in no event in excess of the maximum rate permitted by
then applicable law), compounded monthly and payable on demand. As used herein,
"Prime Rate" means that rate of interest per annum announced by the Bank from
time to time as its prime rate, it being understood that such rate is merely a
reference rate, not necessarily the lowest, which serves as the basis upon which
effective rates of interest are 


<PAGE>   22


calculated for obligations making reference thereto. If the entire amount of any
required Principal and/or interest is not paid within ten (10) days after the
same is due, the Borrowers shall pay to the Bank a late fee equal to five
percent (5%) of the required payment.

     All outstanding Principal and all interest accrued thereon shall be due and
payable in full on the first to occur of: (i) an acceleration under Article VI
of the Loan Agreement or (ii) July 31, 1999. The Borrowers may at any time and
from time to time prepay all or any portion of said Principal, but, as to LIBOR
Loans (as defined in the Loan Agreement), only at the times and in the manner,
and (under certain circumstances) with the additional payments, provided for in
the Loan Agreement. Any prepayment of Principal, in whole or in part, will be
without premium or penalty (but, in the case of LIBOR Loans, may require payment
of additional amounts, as provided for in the Loan Agreement).

     Payments of both Principal and interest shall be made, in immediately
available funds, at the office of the Bank located at One Federal Street,
Boston, Massachusetts 02211, or at such other address as the Bank may from time
to time designate.

     Each of the undersigned Borrowers irrevocably authorizes the Bank to make
or cause to be made, on a schedule attached to this note or on the books of the
Bank, at or following the time of making any Line of Credit Loan (as defined in
the Loan Agreement) and of receiving any payment of Principal, an appropriate
notation reflecting such transaction (including date, amount and maturity) and
the then aggregate unpaid balance of Principal. Failure of the Bank to make any
such notation shall not, however, affect any obligation of any Borrower
hereunder or under the Loan Agreement. The unpaid Principal amount of this note,
as recorded by the Bank from time to time on such schedule or on such books,
shall constitute presumptive evidence of the aggregate unpaid principal amount
of the Line of Credit Loans.

     Each Borrower hereby (a) waives notice of and consents to any and all
advances, settlements, compromises, favors and indulgences (including, without
limitation, any extension or postponement of the time for payment), any and all
receipts, substitutions, additions, exchanges and releases of collateral, and
any and all additions, substitutions and releases of any person primarily or
secondarily liable, (b) waives presentment, demand, notice, protest and all
other demands and notices generally in connection with the delivery, acceptance,
performance, default or enforcement of or under this note, and (c) agrees to
pay, to the extent permitted by law, all costs and expenses, including, without
limitation, reasonable attorneys' fees, incurred or paid by the Bank in
enforcing this note and any collateral or security therefor, all whether or not
litigation is commenced.

     This note is the Line of Credit Note referred to in the Loan Agreement.
This note is subject to prepayment as set forth in the Loan Agreement. The
maturity of this note may be accelerated upon the occurrence of an Event of
Default, as provided in the Loan Agreement. All obligations of the Borrowers
hereunder and/or under the Loan Agreement are joint and several. This note is
governed by, and shall be construed and enforced in accordance with, the laws of
The Commonwealth of Massachusetts.



                                      -2-
<PAGE>   23


     Executed, as an instrument under seal, as of the day and year first above
written.



CORPORATE SEAL                                 GZA GEOENVIRONMENTAL
                                                  TECHNOLOGIES, INC.
ATTEST:

____________________________                   By:__________________________
Secretary                                         Name:
                                                  Title:


CORPORATE SEAL                                 GZA GEOENVIRONMENTAL, INC.

ATTEST:

____________________________                   By:__________________________
Clerk                                             Name:
                                                  Title:


CORPORATE SEAL                                 GZA DRILLING, INC.

ATTEST:

____________________________                   By:__________________________
Clerk                                             Name:
                                                  Title:


CORPORATE SEAL                                 GZA REMEDIATION, INC.

ATTEST:

____________________________                   By:__________________________
Clerk                                             Name:
                                                  Title:




                                      -3-
<PAGE>   24




CORPORATE SEAL                              GZA SECURITIES CORP.

ATTEST:

____________________________                By:__________________________
Clerk                                          Name:
                                               Title:


CORPORATE SEAL                              DELTA GEOTECHNICAL SERVICES, INC.

ATTEST:

____________________________                By:__________________________
Clerk                                          Name:
                                               Title:


CORPORATE SEAL                              GROVER ENTERPRISES, INC.

ATTEST:

____________________________                By:__________________________
Clerk                                          Name:
                                               Title:



CORPORATE SEAL                              GOLDBERG ZOINO ASSOCIATES
                                               OF NEW YORK, P.C.
ATTEST:

____________________________                By:__________________________
Secretary                                      Name:
                                               Title:




                                      -4-
<PAGE>   25

                                                                       EXHIBIT B
                                                                       ---------

                                 PROMISSORY NOTE



                                                  Boston, Massachusetts

$____________                                     [_________________]



         FOR VALUE RECEIVED, the undersigned [add name of applicable company]
and GZA GeoEnvironmental Technologies, Inc., a Delaware corporation ("GZA")
(said [name of applicable company] and GZA being hereinafter referred to
collectively as the "Borrowers" and individually as a "Borrower") hereby jointly
and severally promise to pay to the order of FLEET NATIONAL BANK (the "Bank")
the principal amount of ($____________) Dollars ("Principal"), with interest, at
the rate hereinafter set forth, on the daily balance of all unpaid Principal,
from the date hereof until payment in full of all Principal and interest
hereunder. As used herein, "Loan Agreement" means that certain Revolving Credit
and Term Loan Agreement dated as of February 28, 1994 among the Borrowers and
Shawmut Bank, N.A., as amended (Fleet National Bank having succeeded by merger
to the rights and obligations of Shawmut Bank, N.A. thereunder).

         Principal will be repaid in [ ] equal monthly installments, each in the
amount of $___________, each such installment being due on the first day of each
month, commencing with the first such date following the date hereof, and
continuing on the first day of each month thereafter until all Principal shall
have been paid in full. Interest on all unpaid Principal shall be due and
payable monthly in arrears, on the first day of each month, commencing on the
first such date after the date hereof and continuing on the first day of each
month thereafter and on the date of payment of this note in full, at a
fluctuating rate per annum (computed on the basis of a year of three hundred
sixty (360) days for the actual number of days elapsed) which shall at all times
be equal to the Prime Rate, as in effect from time to time (but in no event in
excess of the maximum rate permitted by then applicable law), with a change in
the aforesaid rate of interest to become effective on the same day on which any
change in the Prime Rate is effective; provided, however, that if an Adjusted
COF Rate (as defined in the Loan Agreement) shall have become applicable to the
outstanding Principal for any Interest Period (as defined in the Loan
Agreement), then interest on such Principal shall accrue at said applicable
Adjusted COF Rate for such Interest Period and shall be payable on the last day
of such Interest Period. (If the Term Loan represented by this note is being
converted from a Floating Rate Loan (as defined in the Loan Agreement) to a COF
Loan (as defined in the Loan Agreement), interest shall also be paid on the date
of such conversion). Overdue Principal and, to the extent permitted by law,
overdue interest shall bear interest at a fluctuating rate per annum which at
all times shall be equal to the sum of (i) two (2%) percent per annum plus (ii)
the per annum rate otherwise payable under this note with respect to the
Principal which is overdue (or as to which such interest is overdue) (but in no
event in excess of the maximum rate permitted by then applicable law),
compounded monthly and payable on demand. As used herein, "Prime Rate" means
that rate of interest per annum announced by the Bank from time to time as its
prime rate, it being




<PAGE>   26
understood that such rate is merely a reference rate, not necessarily the
lowest, which serves as the basis upon which effective rates of interest are
calculated for obligations making reference thereto. If the entire amount of any
required Principal and/or interest is not paid within ten (10) days after the
same is due, the Borrowers shall pay to the Bank a late fee equal to five
percent (5%) of the required payment.

         All outstanding Principal and all interest accrued thereon shall become
due and payable in full upon an acceleration under Article VI of the Loan
Agreement. The Borrowers may at any time and from time to time prepay all or any
portion of said Principal, but, as to any prepayment of COF Loan, only at the
times and in the manner, and (under certain circumstances) with the additional
payments, provided for in the Loan Agreement. Any prepayment of Principal, in
whole or in part, will be without premium or penalty (but, in the case of any
prepayment of a COF Loan, may require payment of additional amounts, as provided
for in the Loan Agreement).

         Payments of both Principal and interest shall be made, in immediately
available funds, at the office of the Bank located at One Federal Street,
Boston, Massachusetts 02211, or at such other address as the Bank may from time
to time designate.

         Each of the undersigned Borrowers irrevocably authorizes the Bank to
make or cause to be made, on a schedule attached to this note or on the books of
the Bank, at or following the time of making the Term Loan (as defined in the
Loan Agreement) evidenced by this note and of receiving any payment of
Principal, an appropriate notation reflecting such transaction (including date,
amount and maturity) and the then aggregate unpaid balance of Principal. Failure
of the Bank to make any such notation shall not, however, affect any obligation
of any Borrower hereunder or under the Loan Agreement. The unpaid Principal
amount of this note, as recorded by the Bank from time to time on such schedule
or on such books, shall constitute presumptive evidence of the unpaid principal
amount of the Term Loan evidenced by this note.

         Each Borrower hereby (a) waives notice of and consents to any and all
advances, settlements, compromises, favors and indulgences (including, without
limitation, any extension or postponement of the time for payment), any and all
receipts, substitutions, additions, exchanges and releases of collateral, and
any and all additions, substitutions and releases of any person primarily or
secondarily liable, (b) waives presentment, demand, notice, protest and all
other demands and notices generally in connection with the delivery, acceptance,
performance, default or enforcement of or under this note, and (c) agrees to
pay, to the extent permitted by law, all costs and expenses, including, without
limitation, reasonable attorneys' fees, incurred or paid by the Bank in
enforcing this note and any collateral or security therefor, all whether or not
litigation is commenced.

         This note is a Term Note referred to in the Loan Agreement. This note
is subject to prepayment as set forth in the Loan Agreement. The maturity of
this note may be accelerated upon the occurrence of an Event of Default, as
provided in the Loan Agreement. All obligations of the Borrowers hereunder
and/or under the Loan Agreement are joint and several. This note is governed by,
and shall be construed and enforced in accordance with, the laws of The
Commonwealth of Massachusetts.





                                       -2-

<PAGE>   27

         Executed, as an instrument under seal, as of the day and year first
above written.



CORPORATE SEAL                                GZA GEOENVIRONMENTAL
                                              TECHNOLOGIES, INC.

ATTEST:

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





CORPORATE SEAL                                [Applicable Company]


ATTEST:

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





















                                       -3-