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                                                                   EXHIBIT 10.58


Private & Confidential

                       DATED                         2000
                       ----------------------------------

                       GZA GEOENVIRONMENTAL, INC.     (1)

                       CARL BRO GROUP LIMITED         (2)

                                       AND

                       CARL BRO AQUATERRA LIMITED     (3)



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

                                    AGREEMENT

                        FOR THE SALE AND PURCHASE OF THE

                  5,000 "B" ORDINARY SHARES OF (POUND)1 EACH IN

                           CARL BRO AQUATERRA LIMITED

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


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                                    CONTENTS

CLAUSE                              HEADING                             PAGE

1        Definitions and interpretation....................................1

2        Sale of the Sale Shares and the Vendor's title....................3

3        Indemnity.........................................................4

4        Mutual Release....................................................4

5        Consideration for the sale of the Sale Shares.....................5

6        Completion........................................................5

7        Post-Completion matters...........................................5

8        Payments..........................................................6

9        General...........................................................6

10       Applicable law and submission to jurisdiction.....................8

SCHEDULE

1        The Company.......................................................9

2        Completion matters...............................................10

AGREED FORM DOCUMENTS

Officers' resignations (schedule 2 paragraph 1.5)


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THIS AGREEMENT is dated 26TH APRIL 2000 and is made BETWEEN:

(1)  GZA  GEOENVIRONMENTAL,  INC., a company  incorporated under the laws of the
     State of Massachusetts  whose principal place of business is at 320 Needham
     Street, Newton, Upper Falls, Massachusetts 02464, USA ("THE VENDOR");

(2)  CARL BRO GROUP LIMITED,  a company  incorporated  in England (No.  2237772)
     whose  registered  office is at Newton  House,  Newton Road,  Leeds LS7 4DN
     ("THE PURCHASER"); and

(3)  CARL  BRO  AQUATERRA  LIMITED,  a  company  incorporated  in  England  (No.
     2621323),  further  details  of  which  are  set  out in  schedule  1 ("THE
     COMPANY"),

(together "THE PARTIES" and each a "PARTY").

NOW IT IS HEREBY AGREED as follows:

1    DEFINITIONS AND INTERPRETATION

1.1  DEFINED TERMS USED IN THIS AGREEMENT

     In this Agreement, unless the context otherwise requires:

     "CA  1985" means the Companies Act 1985;

     "COMPLETION"  means  completion of the sale and purchase of the Sale Shares
     by the  performance by the Parties of their  respective  obligations  under
     clause 4 and schedule 2;

     "COMPLETION DATE" means the date of this Agreement;

     "HOLDING  COMPANY" means a holding  company (as defined in sections 736 and
     736A CA 1985) or a parent undertaking (as defined in section 258 CA 1985));

     "PURCHASE PRICE" has the meaning given in clause 5;

     "PURCHASER'S  SOLICITORS" means Addleshaw Booth & Co of Sovereign House, PO
     Box 8, Sovereign Street, Leeds LS1 1HQ;

     "SALE SHARES"  means the 5,000 "B" Ordinary  Shares of (pound)1 each in the
     Company held by the Vendor;

     "SECURITY  INTEREST"  means any  claim,  mortgage,  lien,  pledge,  charge,
     encumbrance, equity, hypothecation,  right of pre-emption or other security
     interest or any other restriction or right exercisable by, or in favour of,
     any third party (or an agreement or commitment to create any of them);

     "SHARE TRANSFERS" has the meaning given in paragraph 1.2 of schedule 2; and


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     "SUBSIDIARY"  means a  subsidiary  (as defined by sections  736 and 736A CA
     1985) or a subsidiary undertaking (as defined by section 258 CA 1985).

1.2  TERMS DEFINED ELSEWHERE IN THIS AGREEMENT

     In addition to the terms  defined in clause  1.1,  certain  other terms are
     defined elsewhere in this Agreement (denoted by capitalised words in quotes
     and bold  type).  Each such term  shall  have the  meaning  stated  for the
     purpose of the  provision in which it is defined and, if used  elsewhere in
     this Agreement, where so used, unless the context otherwise requires.

1.3  INTERPRETATION OF WORDS AND EXPRESSIONS USED IN THIS AGREEMENT

     In this Agreement, unless the context otherwise requires:

     (a)  a document  expressed to be "IN THE AGREED FORM" means a document in a
          form which has been agreed by the  Parties at or before the  execution
          of this  Agreement and which has, for the purposes of  identification,
          been signed or initialled by them or on their behalf;

     (b)  references  to a clause or schedule  are to a clause of, or a schedule
          to, this Agreement respectively;  references to this Agreement include
          its  schedules  and  references  in a schedule to a paragraph are to a
          paragraph of that schedule;

     (c)  references to this Agreement or any other document or to any specified
          provision  of  this  Agreement  or any  other  document  are  to  this
          Agreement,  that  document or that  provision as in force for the time
          being and as amended from time to time in accordance with the terms of
          this Agreement or that document, as the case may be; and

     (d)  references to any English legal term for any action, remedy, method of
          judicial proceeding,  legal document, legal status, Court, official or
          any legal concept or thing shall, in respect of any jurisdiction other
          than  England  and  Wales,  be deemed  to  include  what  most  nearly
          approximates in that jurisdiction to the English legal term.

1.4  CONTENTS TABLE AND HEADINGS

     In this Agreement,  the contents table and the descriptive headings to, and
     within,  clauses,  schedules and  paragraphs  are inserted for  convenience
     only, have no legal effect and shall be ignored in the  interpretation  and
     construction of this Agreement.

2    SALE OF THE SALE SHARES AND THE VENDOR'S TITLE

2.1  SALE OF THE SALE SHARES

     The Vendor shall sell to the Purchaser and the Purchaser  (relying,  as the
     Vendor hereby acknowledges, on the representations,  warranties, covenants,
     undertakings


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     and indemnities of the Vendor referred to in this Agreement) shall purchase
     from the Vendor the Sale  Shares.  The Vendor makes no  representation  and
     provides no  warranty,  covenant or  indemnity  other than those set out in
     this Agreement.

2.2  THE VENDOR'S TITLE TO THE SALE SHARES

     The Vendor  shall sell and transfer to the  Purchaser  the Sale Shares with
     full title guarantee and free from any Security Interest.

2.3  TITLE TO SALE SHARES TO PASS ON COMPLETION

     Title to,  beneficial  ownership  of, and any risk  attaching  to, the Sale
     Shares  shall  pass on  Completion  and the Sale  Shares  shall be sold and
     purchased  together  with all rights and  benefits  attached or accruing to
     them at, or at any time on or  after,  Completion  (including  the right to
     receive all  dividends,  distributions  or any return of capital  declared,
     paid or made by the  Company  in  respect  of any such  shares  on or after
     Completion).

2.4  WAIVER OF PRE-EMPTION RIGHTS BY THE VENDOR AND PURCHASER

     Each  of  the  Purchaser  and  the  Vendor  hereby  waives  any  rights  of
     pre-emption  or first  refusal or  similar  rights  conferred  on it by the
     articles of  association  of the Company or otherwise  over any of the Sale
     Shares.

2.5  CAPACITY OF THE VENDOR

     The Vendor warrants, undertakes and represents to the Purchaser that:

     (a)  the  Vendor  has  the  requisite   power  and   authority   under  its
          constitutional documents and otherwise to execute, deliver and perform
          its  obligations  under this  Agreement  and any other  document to be
          executed by it;

     (b)  the execution and delivery of, and the  performance of the obligations
          of the Vendor under,  this Agreement have been duly  authorised by all
          necessary   corporate   action   on  its  part   whether   under   its
          constitutional documents or otherwise; and

     (c)  this Agreement constitutes legal, valid and binding obligations of the
          Vendor enforceable in accordance with its terms.



2.6  SHARE CERTIFICATE

     (a)  The Vendor  confirms  that, so far as it is aware,  no  certificate of
          title to the Sale Shares has been issued to it.

     (b)  The Vendor  further  confirms  that  neither  the Sale  Shares nor any
          certificate of title relating to them has been  transferred,  charged,
          lent,  deposited  or



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          dealt with in any manner affecting the title to them and the Vendor is
          the  person  entitled  to be on the  register  in  respect of the Sale
          Shares.

     (c)  The Vendor  undertakes  to  indemnify  and keep the Company  fully and
          effectively  indemnified  from and against all  actions,  proceedings,
          claims,  damages,  costs, expenses and demands which may be brought or
          made against the Company or suffered or incurred by the Company or for
          which the  Company  may become  liable by reason of the Vendor  having
          undertaken any of the matters referred to in clause 2.6(b).

3    INDEMNITY

     The Purchaser  will defend,  indemnify and hold harmless the Vendor against
     any action, sums, demand, damages, loss or liability arising out of:

     (a)  any professional services rendered by the Company;

     (b)  the employment by the Company of any person;

     (c)  taxes payable by the Company, and

     (d)  any other obligation or liability  arising out of the operation of the
          Company's business, whether or after the Completion Date,

     in each case  arising  out of the  ownership  by GZA of the sale shares and
     excluding any liability  arising as a  consequence  of trading  between the
     Vendor and the Company.

4    MUTUAL RELEASE

     Except as otherwise expressly set forth herein and except for any liability
     arising as a consequence of trading between the parties,  each Party hereby
     releases the other Parties and the officers,  directors,  employees, agents
     and  affiliates  of such  other  Parties  of and from all  actions,  suits,
     damages,  losses,  liabilities  or claims of any character that a releasing
     Party has or may have had against any of the  released  Parties at any time
     to and including the Completion Date.

5    CONSIDERATION FOR THE SALE OF THE SALE SHARES

     The  consideration  for the sale of the Sale Shares shall be the payment on
     Completion by the Purchaser to the Vendor of (pound)210,000  ("THE PURCHASE
     PRICE"), plus interest at the rate of 8.5 per cent per annum applied to all
     outstanding  amounts not paid at Completion  until such amounts are paid in
     full, in cash in accordance with the provisions of clause 8.


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6    COMPLETION

     Completion shall take place at the offices of the Purchaser's Solicitors or
     at such other place as the Parties  may agree on the  Completion  Date when
     the Parties shall comply with all of their  respective  obligations  as set
     out in  schedule  2. The  Purchaser  shall not be obliged to  complete  the
     purchase  of any of the Sale  Shares  unless the  purchase  of all the Sale
     Shares is completed simultaneously.

7    POST-COMPLETION MATTERS

7.1  APPOINTMENT OF THE PURCHASER AS ATTORNEY FOR THE VENDOR

     The Vendor hereby  irrevocably and  unconditionally  appoints the Purchaser
     and any director of the  Purchaser  for the time being acting  severally as
     its lawful  attorney  (and to the complete  exclusion of any rights that it
     may have in such regard) for the purpose of  exercising  any and all voting
     and other rights and receiving any and all benefits and entitlements  which
     may now or at any time after the date of this Agreement  attach to or arise
     in respect of any of the Sale Shares and receiving notices of and attending
     and voting at all  meetings  of the  members of the  Company  (or any class
     thereof) and generally  executing or approving  such deeds or documents and
     doing any such acts or things in  relation to any of the Sale Shares as the
     attorney  may think fit, in each case from  Completion  to the day on which
     the  Purchaser  is entered in the  register of members as the holder of the
     Sale Shares.  For such purpose,  the Vendor hereby authorises and instructs
     the  Company  to send all  notices  in  respect  of the Sale  Shares to the
     Purchaser during such period.

7.2  FURTHER ASSURANCE BY THE VENDOR

     The Vendor shall execute or, so far as it is able, procure the execution of
     all such  documents  and/or do or, so far as it is able,  procure the doing
     of, such acts and things as the Purchaser shall after Completion require in
     order to give effect to the provisions of this Agreement and to give to the
     Purchaser the full benefit of this Agreement or any other such document.

8    PAYMENTS

8.1  PAYMENTS TO THE VENDOR

     Any amounts  payable to the Vendor pursuant to this Agreement shall be paid
     by way of telegraphic transfer to the following account of the Vendor:

         Bank:             Fleet Bank, N.A.
                           1 Federal Street
                           Boston MA 02110

         Sort Code:        011000138

         Account Name:     GZA GeoEnvironmental - Accounts Payable


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         Account No.:      027-890-4909

9    GENERAL

9.1  CONTINUING EFFECT OF THIS AGREEMENT

     All provisions of this Agreement shall, so far as they are capable of being
     performed  or observed,  continue in full force and effect  notwithstanding
     Completion,  except in respect of those matters then already  performed and
     Completion  shall not constitute a waiver of any of the Purchaser's  rights
     in relation to this Agreement.

9.2  ANNOUNCEMENTS

     Save  as (but  only  to the  extent)  expressly  required  by law or by any
     relevant   national   or   supra-national   regulatory,   governmental   or
     quasi-governmental body or authority, all announcements by, of or on behalf
     of the Vendor  relating  to the  subject  matter of this  Agreement  or the
     transaction contemplated by this Agreement shall be in terms to be approved
     in writing by the Purchaser in advance of issue.

9.3  ENTIRE AGREEMENT

     (a)  This Agreement sets out the entire agreement and understanding between
          the  Parties  in  connection  with the sale and  purchase  of the Sale
          Shares and other matters described in them.

     (b)  Without  prejudice to the generality of clause 9.3(a),  this Agreement
          shall supersede as from the date of this Agreement:

          (i)  a  shareholders  agreement  dated 10th  November 1992 between the
               Purchaser, the Vendor and the Company; and

          (ii) a letter  dated 21st October 1999 from Andrew Pajak of the Vendor
               to Roger Pyle of the Purchaser.

9.4  ALTERATIONS

     No purported  alteration of this Agreement shall be effective  unless it is
     in writing,  refers  specifically to this Agreement and is duly executed by
     each Party to this Agreement.

9.5  COUNTERPARTS

     This Agreement may be entered into in the form of two or more counterparts,
     each executed by one or more of the Parties but, taken  together,  executed
     by all and,  provided  that all the  Parties so enter into this  Agreement,
     each of the executed counterparts, when duly exchanged and delivered, shall
     be deemed to be an original, but, taken together, they shall constitute one
     instrument.


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9.6  PAYMENT OF COSTS

     (a)  Subject to clause 9.6(b) each of the Parties shall be responsible  for
          its respective legal and other costs and expenses incurred in relation
          to the  negotiation,  preparation and completion of this Agreement and
          all ancillary documents.

     (b)  The  Purchaser  shall  reimburse the Vendor for  reasonable  legal and
          accounting   costs   incurred   by  the  Vendor  in  relation  to  the
          negotiation,  preparation  and  completion  of the  Agreement  and all
          ancillary documents up to a maximum of $14,600.

9.7  SUCCESSORS AND ASSIGNS

     (a)  This  Agreement  shall be binding  on, and shall enure for the benefit
          of, the successors in title of each Party.

     (b)  Save  as  provided  in  clause  9.7(c),  none of the  Parties  to this
          Agreement  may be entitled  to assign the benefit of any rights  under
          this Agreement.

     (c)  The  benefit  of this  Agreement  shall be  freely  assignable  by the
          Purchaser and, in the event of any such assignment,  all references in
          this  Agreement  to the  Purchaser  shall be  deemed  to  include  its
          assigns.

     (d)  The  Parties  agree  that  any  loss  suffered  by any  member  of the
          Purchaser's Group or any assignee of the Purchaser's rights under this
          Agreement as a result of a breach of any  provision of this  Agreement
          shall  be  treated  as,  and  shall  be  deemed  to be,  a loss of the
          Purchaser.

10   APPLICABLE LAW AND SUBMISSION TO JURISDICTION

     APPLICABLE LAW

10.1 This  Agreement  shall be  governed by and  construed  in  accordance  with
     English law, and all claims and disputes between the parties or any of them
     arising  out  of or in  connection  with  this  Agreement  (whether  or not
     contractual in nature) shall be determined in accordance with English law.

10.2 For the avoidance of doubt, the parties expressly agree if in any court any
     party  argues  that a court  (other  than a court in England and Wales) has
     jurisdiction to determine any dispute or difference  between the parties or
     any of them arising out of or in connection  with this  Agreement  shall be
     determined  in  accordance  with English law, and any right any party might
     otherwise have to rely upon the law of the forum is hereby  irrevocably and
     unconditionally waived.

     SUBMISSION TO JURISDICTION

10.3 Each party submits to the  jurisdiction  of the Courts of England and Wales
     in relation to all claims,  disputes,  differences or other matters arising
     out of or in connection


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     with this Agreement, provided that nothing in this clause shall prevent the
     Purchaser  or the Company in its or their sole and  unfettered  discretion,
     from  commencing  proceedings  against the Vendor in any court of competent
     jurisdiction.

10.4 Each party irrevocably waives any right that it may have:

     (a)  to object to an action being  brought in those  Courts,  to claim that
          the action has been brought in an inconvenient forum, or to claim that
          those Courts do not have  jurisdiction.  The waiver  contained in this
          clause  includes  (without  limitation)  a waiver  of all  formal  and
          substantive  requirements of any otherwise  competent  jurisdiction in
          relation to this clause; or

     (b)  to oppose the  enforcement of any judgment of any court of England and
          Wales  whether  on  any  ground  referred  to  in  clause  10.4(a)  or
          otherwise.

IN WITNESS whereof this Agreement has been entered into as a Deed on the date
specified above.


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                                   SCHEDULE 1
                                   ----------

                                   THE COMPANY
                                   -----------

1    Date of incorporation:          18th June 1991

2    Registered number:              2621323

3    Registered office:              Newton House, Newton Road, Leeds LS7 4DN

4    Authorised share capital:       (pound)10,000   divided   into   5,000  "A"
                                     ordinary  shares of (pound)1 each and 5,000
                                     "B" ordinary shares of(pound)1 each

5    Issued share capital:           5,000 "A"  ordinary  shares  all fully paid
                                     registered in the name of the Purchaser

                                     5,000 "B"  ordinary  shares  all fully paid
                                     registered in the name of the Vendor

6    Directors:                      Andrew Richard Dean
                                     Andrew P Pajak
                                     James Roger Pyle

7    Secretary:                      Paul David Berry

8    Auditors:                       PricewaterhouseCoopers

9    Accounting reference date:      30 June


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                                   SCHEDULE 2

                               COMPLETION MATTERS

1    DOCUMENTS AND OTHER ITEMS TO BE DELIVERED BY THE VENDOR

1.1  The  following  documents  and other items set out in the remainder of this
     paragraph  1  shall  be  delivered  by  the  Vendor  to  the  Purchaser  at
     Completion.

     THE SALE SHARES

1.2  A transfer  in respect  of the Sale  Shares  ("THE  SHARE  TRANSFER")  duly
     executed and completed in favour of the Purchaser.

1.3  Share certificates for the Sale Shares.

     BOARD MINUTES OF THE VENDOR

1.4  Certified  copies  of the  board  minutes  for  the  Vendor  recording  the
     resolution of the board of directors of the Vendor authorising:

     (a)  the sale of the Sale Shares held by the Vendor;

     (b)  the execution of the transfers in respect of such Sale Shares; and

     (c)  the  execution  of  this   Agreement  and  all  relevant   Transaction
          Documents.

     DIRECTOR'S RESIGNATION

1.5  The written  resignation of Andrew P Pajak in the agreed form resigning his
     office as a director of the Company.

2    OBLIGATIONS OF THE VENDOR

     BOARD RESOLUTIONS

2.1  The Purchaser  and the Vendor shall procure that written board  resolutions
     of the Company are passed which:

          Registration of the Share Transfer

     (a)  resolve to register the Share Transfer  (subject only to it being duly
          stamped) notwithstanding any provision to the contrary in the articles
          of association of the Company;

          Resignation of director


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     (b)  approve  the  resignation  of  Andrew  P Pajak  as a  director  of the
          Company; and

          Miscellaneous

     (c)  approve the matters referred in paragraph 4.

     REPAYMENT OF INDEBTEDNESS

2.2  The Vendor  shall repay to the  Company,  or procure the  repayment  to the
     Company of, all  indebtedness  outstanding at Completion from the Vendor in
     respect of trading in the  ordinary  course of business by the Company with
     the Vendor which has become payable in accordance with any terms previously
     agreed by the Vendor and the Company.

3    OBLIGATIONS OF THE PURCHASER

3.1  The  Purchaser  shall  pay  the  Purchase  Price  in  accordance  with  the
     provisions of clause 8.

4    JOINT OBLIGATIONS OF THE PURCHASER AND THE VENDOR

4.1  The Purchaser and the Vendor shall join in procuring that:

     (a)  all existing  bank  mandates in force for the Company shall be altered
          (in such  manner as the  Purchaser  shall at  Completion  require)  to
          reflect the  resignations  and  appointments  referred to in paragraph
          2.1; and

     (b)  the Company  shall repay the loan of  (pound)80,000  made to it by the
          Vendor in full and final  settlement of all and any amounts due by the
          Company,  plus  interest at the rate of 8.5 per cent per annum applied
          to all outstanding  amounts not paid at Completion  until such amounts
          are  paid in full,  to the  Vendor  (other  than  any  trading  in the
          ordinary  course of business by the Company  with the Vendor which has
          not yet become payable in accordance with any terms previously  agreed
          by the Vendor and the Company and which shall be repaid in  accordance
          with existing arrangements).


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<PAGE>   14


EXECUTED and delivered as a DEED    )
by GZA GEOENVIRONMENTAL, INC        )
acting by:                          )
                                           -------------------------------------
                                           Director

                                           -------------------------------------
                                           Director/Secretary



EXECUTED and delivered as a DEED   )
by CARL BRO GROUP LIMITED          )
acting by:                         )
                                           -------------------------------------
                                           Director

                                           -------------------------------------
                                           Director/Secretary



EXECUTED and delivered as a DEED   )
by CARL BRO AQUATERRA LIMITED      )
acting by:                         )
                                           -------------------------------------
                                           Director

                                           -------------------------------------
                                           Director/Secretary


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