Document:

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                                                                   EXHIBIT 10.15

THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 OR
APPLICABLE STATE SECURITIES LAWS AND MAY NOT BE TRANSFERRED, SOLD OR OTHERWISE
DISPOSED OF IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT WITH RESPECT
TO THE SECURITY, FILED AND MADE EFFECTIVE UNDER THE SECURITIES ACT OF 1933 AND
SUCH APPLICABLE STATE SECURITIES LAWS, OR UNLESS THE ISSUER RECEIVES AN OPINION
OF COUNSEL SATISFACTORY TO THE ISSUER TO THE EFFECT THAT REGISTRATION UNDER SUCH
ACT AND SUCH APPLICABLE STATE SECURITIES LAWS IS NOT REQUIRED.

                             OAKHURST COMPANY, INC.

                          SUBORDINATED PROMISSORY NOTE

DATE: JULY 19, 2001                                                      $70,125

OAKHURST COMPANY, INC., a Delaware corporation (together with its successors and
assigns the "Issuer") for value received hereby promises to pay to JOSEPH P.
HARPER, SR., or order (the "Noteholder") by wire transfer of immediately
available funds to an account designated by the Noteholder by notice to the
Issuer, the principal sum of Seventy Thousand One Hundred Twenty-Five Dollars
($70,125), without interest on the Maturity Date (as defined herein) in such
coin or currency of the United States of America as at the time of payment shall
be legal tender for the payment of public and private debts.

1.   Note Register. The Issuer shall keep at its principal office a register
     (the "Register") in which shall be entered the name and address of the
     registered holder of this Note and of all permitted transfers of this Note.
     References to the "Noteholder" shall mean the Person listed in the Register
     as the payee of the Note. The ownership of this Note shall be proven by the
     Register. For the purpose of paying the principal on this Note, the Issuer
     shall be entitled to rely on the name and address in the Register and
     notwithstanding anything to the contrary contained in this Note, no Event
     of Default shall occur under Section 3(c) if payment of principal is made
     in accordance with the name and address contained in the Register. The
     Noteholder may change his address as shown on the Note Register by written
     notice to the Company requesting such change.

2.   Definitions. The following terms for all purposes of this Note shall have
     the meanings specified below. All accounting terms used herein and not
     expressly defined shall have the meanings given to them in accordance with
     generally accepted accounting principles as in effect from time to time.
     The terms defined in this Section 2 include the plural as well as the
     singular.

     (a)  "Acceleration Notice" shall have the meaning set forth in Section
          3(c).

     (b)  "Affiliate" means, with respect to any Person, any other Person
          directly or indirectly controlling, controlled by or under common
          control with, such Person.

     (c)  "Business Day" means any day except a Saturday, Sunday or other day on
          which commercial banks in the State of Delaware are authorized by law
          to close.

     (d)  "Debt" means at any date an amount equal to or greater than $100,000
          of (i) all obligations of the Issuer for borrowed money; (ii) all
          obligations of the Issuer evidenced by bonds, debentures, notes, or
          other similar instruments; (iii) all obligations of the Issuer in
          respect of letters of credit or other similar instruments (or
          reimbursement obligations with respect thereto;) (iv) all obligations
          of the Issuer to pay the deferred purchase price of property or
          services, except trade payables; (v) all obligations of the Issuer as
          lessee under capitalized leases; (vi) all Debt of others secured by a
          Lien on any asset of the Issuer, whether or not such Debt is assumed
          by such Person; and (vii) any guarantee by the Issuer of the payment
          obligation of another Person.

     (e)  A "Default" means any condition or event which constitutes an Event of
          Default or which with the giving of notice or lapse of time or both
          would, unless cured or waived, become an Event of Default.

     (f)  Event of Default" shall have the meaning set forth in Section 3(c).

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     (g)  "Lien" means, with respect to any asset, any mortgage, lien, pledge,
          charge, security interest or encumbrance of any kind in respect of
          such asset. For the purposes of this Note, the Issuer shall be deemed
          to own subject to a Lien any asset which it has acquired or holds
          subject to the interest of a vendor or lessor under any conditional
          sale agreement, capitalized lease or other title retention agreement
          relating to such asset.

     (h)  "Maturity Date" means 5:00 p.m. Eastern Time on the earliest to occur
          of the following dates:

          (i)   July 18, 2005;

          (ii)  The fourth anniversary of the date of the closing of the sale by
                the Issuer of all of its then remaining right, title and
                interest in and to New Heights Recovery & Power, LLC to KTI,
                Inc.; and

          (iii) The Put Payment Date, as that term is defined in the Transaction
                Agreement (defined below.)

     (i)  "Notice of Default" shall have the meaning set forth in Section 3(c).

     (j)  "Person" means any individual, corporation, partnership, firm,
          association, joint venture, joint stock company, trust, unincorporated
          organization or other entity, or any government or regulatory,
          administrative or political subdivision or agency, department or
          instrumentality thereof.

     (k)  "Senior Indebtedness" means indebtedness to any bank or other lending
          institution, including, but not limited to (i) all currently
          outstanding indebtedness of the Issuer to Finova Capital Corporation
          (the "Senior Lender"), as the same may be amended, modified, increased
          or decreased from time to time, by agreement between the Senior Lender
          and the Issuer; (ii) any and all replacements or refinancings of the
          indebtedness to the Senior Lender with one or more other lending
          entities, whether any such refinancing is for a greater or lesser
          amount than the current indebtedness to the Senior Lender; (iii) all
          obligations of the Issuer to Comerica Bank-Texas ("Comerica") under
          the guaranty by the Issuer of the obligations of Sterling Construction
          Company, a Michigan corporation, to Comerica (the "Comerica
          Obligations;") and (iv) any and all replacements or refinancings of
          the Comerica Obligations (whether any such replacement or refinancing
          is for a greater or lesser amount than the amount replaced or
          refinanced) with one or more other lending institutions that is
          guaranteed by, or is the direct obligation of, the Issuer.

     (l)  "Subordinated Note" and "Subordinated Notes" shall have the meanings
          set forth in Section 7.

     (m)  "Transaction Agreement" shall have the meaning set forth in Section
          3(c).

3.   PAYMENT OF PRINCIPAL.

     (a)  Payment Obligation. No provision of this Note shall alter or impair
          the obligations of the Issuer to pay the principal of this Note at the
          place and time, and in the currency, herein prescribed.

     (b)  Prepayment. The principal hereunder shall be subject to prepayment by
          the Issuer at any time without the consent of the Noteholder and
          without premium or penalty. Insomuch as this is a zero coupon note,
          any prepayment of this Note shall be in an amount equal to the net
          present value as of the prepayment date of the principal amount
          hereof, applying an interest rate of twelve percent (12%) per annum.

     (c)  Events of Default and Remedies. In case one or more of the following
          events ("Events of Default") shall have occurred and be continuing:

          (i)   Default in the payment of the principal of this Note as and when
                the same shall become due and payable, at maturity, upon any
                redemption, by declaration or otherwise; or

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          (ii)  failure on the part of the Issuer duly to observe or perform (A)
                any other of the covenants or agreements on the part of the
                Issuer contained herein (other than those covered by clause (i),
                above;) or (B) any material covenants or agreements on the part
                of the Issuer contained in any other agreement between the
                Issuer and the Noteholder, including, but not limited to, that
                certain Transaction Agreement, dated as of July 18, 2001 (the
                "Transaction Agreement"), in either such case for a period of 30
                days after the date on which written notice specifying such
                failure, stating that such notice is a "Notice of Default"
                hereunder and demanding that the Issuer remedy the same, shall
                have been given by registered or certified mail, return receipt
                requested, to the Issuer; or

          (iii) the prepayment of any Subordinated Note in violation of the
                provisions of Section 7 of this Note; or

          (iv)  any event or condition shall occur which results in the
                acceleration of the maturity of any Debt or enables or, with the
                giving of notice or lapse of time or both, would enable the
                holder of such Debt or any Person acting on such holder's behalf
                to accelerate the maturity thereof; or

          (v)   the Issuer pursuant to, or within the meaning of, any bankruptcy
                or insolvency law: (A) commences a voluntary case or proceeding;
                (B) consents to the entry of an order for relief against it in
                an involuntary case or proceeding; (C) consents to the
                appointment of a receiver or custodian of it or for all or
                substantially all of its property; (D) makes a general
                assignment for the benefit of its creditors; or (E) admits in
                writing its inability to pay its debts as the same become due;

     then, subject to the last paragraph of this Section 3(c), set forth below,
     in each case where an Event of Default specified in Section 3(c)(i) through
     3(c)(iv) occurs, the Noteholder, by notice in writing to the Issuer (the
     "Acceleration Notice") may declare the principal hereunder to be due and
     payable immediately, and upon any such declaration the same shall become
     immediately due and payable; provided however, that if an Event of Default
     specified in Section 3(c)(v) occurs, the principal hereunder shall become
     and be immediately due and payable without any declaration or other act on
     the part of the Noteholder.

     Any principal, the payment of which shall become accelerated pursuant to
     this Section 3(c), shall be equal to (i) the net present value as of the
     payment date of the principal amount hereof applying an interest rate of
     twelve percent (12%) per annum less (ii) any prepayments made pursuant to
     Section 3(b), above.

4.   REIMBURSEMENT OF EXPENSES. The Issuer shall reimburse the Noteholder, on
     demand, for any and all costs and expenses, including reasonable attorneys'
     fees and court costs, incurred by the Noteholder in collecting or otherwise
     enforcing this Note or in attempting to do any of the foregoing.

5.   POWERS AND REMEDIES CUMULATIVE; DELAY OR OMISSION NOT A WAIVER OF DEFAULT.

     (a)  No right or remedy herein conferred upon or reserved to the Noteholder
          is intended to be exclusive of any other right or remedy, and every
          right and remedy shall, to the extent permitted by law, be cumulative
          and in addition to every other right and remedy given hereunder or now
          or hereafter existing at law or in equity or otherwise. The assertion
          or employment of any right or remedy hereunder, or otherwise, shall
          not prevent the concurrent assertion or employment of any other
          appropriate right or remedy.

     (b)  No delay or omission of the Noteholder to exercise any right or power
          accruing upon any Default or Event of Default occurring and continuing
          as aforesaid shall impair any such right or power or shall be
          construed to be a waiver of any such Default or Event of Default or an
          acquiescence therein; and every power and remedy given by this Note or
          by law may be exercised from time to time, and as often as shall be
          deemed expedient, by the Noteholder.

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6.   WAIVER OF PAST DEFAULTS.

     (a)  The Noteholder may waive any past Default or Event of Default
          hereunder and its consequences. In the case of any such waiver, the
          Issuer and the Noteholder shall be restored to their former positions
          and rights hereunder, respectively; but no such waiver shall extend to
          any subsequent or other Default or impair any right consequent
          thereon.

     (b)  Upon any such waiver, such Default shall cease to exist and be deemed
          to have been cured and not to have occurred, and any Default or Event
          of Default arising therefrom shall be deemed to have been cured, and
          not to have occurred for every purpose of this Note; but no such
          waiver shall extend to any subsequent or other Default or Event of
          Default or impair any right consequent thereon.

7.   SUBORDINATION.

     (a)  No payment on account of principal of or interest on (i) that certain
          promissory note dated July 3, 2001 in the original principal amount of
          $1,000,000 issued to KTI, Inc.; (ii) this Note; or (ii) any other
          promissory note issued contemporaneously herewith pursuant to the
          Transaction Agreement (each a "Subordinated Note and collectively, the
          "Subordinated Notes") shall be made, and no Subordinated Notes shall
          be redeemed or purchased directly or indirectly by the Issuer (or any
          of its subsidiaries), if at the time of such payment or purchase or
          immediately after giving effect thereto, (x) there shall exist a
          default in any payment with respect to the Senior Indebtedness; or (y)
          there shall have occurred any other default or event of default as
          those terms may be defined in the instrument under which such Senior
          Indebtedness is outstanding (other than a default in the payment of
          amounts due thereon) with respect to the Senior Indebtedness
          permitting the holders thereof to accelerate the maturity thereof, and
          such default or event of default shall not have been cured or waived
          or shall not have ceased to exist.

     (b)  Subject to payment in full of the Senior Indebtedness, the holders of
          the Subordinated Notes shall be subrogated to the rights of the
          holders of Senior Indebtedness to receive payments or distributions of
          the assets of the Issuer made on such Senior Indebtedness until all
          principal and interest on the Subordinated Notes shall be paid in
          full; and for purposes of such subrogation, no payments or
          distributions to the holders of Senior Indebtedness of any cash,
          property or securities to which any holders of the Subordinated Notes
          would be entitled except for the subordination provisions of this
          Section 7 shall, as between the holders of the Subordinated Notes and
          the Issuer and/or its creditors (other than the holders of the Senior
          Indebtedness) be deemed to be a payment on account of the Senior
          Indebtedness.

     (c)  The provisions of this Section 7 are and are intended solely for the
          purposes of defining the relative rights of the holders of the
          Subordinated Notes and the holders of Senior Indebtedness and nothing
          in this Section 7 shall impair, as between the Issuer and any holders
          of the Subordinated Notes, the obligation of the Issuer, which is
          unconditional and absolute, to pay to the holders of the Subordinated
          Notes the principal thereof and interest thereon, in accordance with
          the terms of the Subordinated Notes, nor shall anything herein prevent
          any holders of the Subordinated Notes from exercising all remedies
          otherwise permitted by applicable law or hereunder upon default,
          subject to the rights set forth above of holders of Senior
          Indebtedness to receive cash, property or securities otherwise payable
          or deliverable to the holders of the Subordinated Notes.

     (d)  Upon any payment (including by redemption) which is not a payment in
          full of all of the principal amount and accrued interest of all
          outstanding Subordinated Notes, the aggregate amount of the payments
          shall be allocated to all the Subordinated Notes then outstanding in
          proportion to the amounts of principal and interest due thereunder, so
          that the amount of principal paid under this Note shall bear the same
          ratio to the aggregate principal and accrued interest paid under all
          of the Subordinated Notes as the then outstanding principal then owed
          under this Note (as if the same were then being prepaid pursuant to
          Section 3(b)) bears to the

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          aggregate principal and accrued interest then owed under all
          Subordinated Notes then outstanding.

8.   MODIFICATION OF NOTE. This Note may be modified only with the written
     consent of the Noteholder and the Issuer.

9.   MISCELLANEOUS. This Note shall be governed by and be construed in
     accordance with the laws of the State of New York without regard to the
     conflicts of law rules of such state. The Issuer hereby waives presentment,
     demand, notice, protest and all other demands and notices in connection
     with the delivery, acceptance, performance and enforcement of this Note,
     except as specifically provided herein, and assents to extensions of the
     time of payment, or forbearance or other indulgence without notice. The
     section headings herein are for convenience only and shall not affect the
     construction hereof. THE ISSUER AND THE NOTEHOLDER HEREBY IRREVOCABLY WAIVE
     ALL RIGHT TO TRIAL BY JURY IN ANY ACTION, PROCEEDING OR COUNTERCLAIM
     ARISING OUT OF OR RELATING TO THIS NOTE.

10.  SUBMISSION TO JURISDICTION. The Issuer irrevocably submits to the exclusive
     jurisdiction of the state and federal courts located in the State of
     Delaware, for the purposes of any suit, action or other proceeding arising
     out of this Note. The Issuer further agrees that service of any process,
     summons, notice or document by U.S. registered mail to the Issuer address
     set forth below shall be effective service of process for any action, suit
     or proceeding in the State of Delaware with respect to any matters to which
     it has submitted to jurisdiction in this paragraph. The Issuer irrevocably
     and unconditionally waives any objection to the laying of venue of any
     action, suit or proceeding arising out of this Note in the foregoing
     courts, and hereby and thereby further irrevocably and unconditionally
     waives and agrees not to plead or claim in any such court that any such
     action, suit or proceeding brought in any such court has been brought in an
     inconvenient forum.

IN WITNESS WHEREOF, the Issuer has caused this instrument to be duly executed as
of the date first set forth above.

OAKHURST COMPANY, INC.
2751 Centerville Road -- Suite 3131
Wilmington, Delaware 19803

By: /s/ Robert M. Davies
   -----------------------------
Name:  Robert M. Davies
Title: Chief Executive Officer

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                                                                   EXHIBIT 10.17

                                  AMENDMENT TO
                                     SECURED
                                 PROMISSORY NOTE

         This AMENDMENT TO SECURED PROMISSORY NOTE, is executed as of this 13th
day of July 2001 by and between OAKHURST TECHNOLOGY, INC., a corporation
organized under the laws of the State of Delaware (the "Maker") and ROBERT M.
DAVIES ("Holder").

         WHEREAS, the Maker and the Holder entered into that certain Secured
Promissory Note dated October 18, 1999 in the principal amount of $539,117 (the
"Original Note") secured by that certain Stock Pledge Agreement dated October
18, 1999 (the "Pledge Agreement"); and

         WHEREAS, the Maker and the Holder now desire to amend certain
provisions of the Original Note, including those provisions pertaining to the
principal amount, the maturity date and repayment of said note while leaving the
security for the Original Note in place;

         NOW, THEREFORE, for good and valuable consideration, the sufficiency of
which is hereby acknowledged and agreed, the Maker and the Holder, intending to
be legally bound, do hereby agree as follows:

         1. Maturity Date; Payments. The first, second and third sentences of
the first paragraph of the Original Note are hereby amended and restated to read
in their entirety as follows:

         "FOR VALUE RECEIVED, Oakhurst Technology, Inc., a corporation organized
         under the laws of the State of Delaware (the "Maker"), hereby promises
         to pay to the order of Robert Davies (the "Holder"), having an address
         at 100 First Stamford Place, Suite 600, Stamford, Connecticut 06902, or
         his assigns, the principal sum of six hundred seventy two thousand
         Dollars ($672,003), together with interest on the unpaid principal
         balance of this Note. All principal and accrued but unpaid interest
         shall be due to the Holder on July 3, 2005. The Maker shall pay to the
         Holder in sixteen (16) equal quarterly payments beginning on October
         13, 2001, principal plus accrued interest at a rate of twelve percent
         (12%) per annum; provided, that all such payments shall be made to the
         extent of and out of the available Net Cash Flow and Net Cash Proceeds
         (each as defined below); provided, further, that, to the extent that
         accrued interest and/or principal payments cannot be made on the date
         such are due on this Note, then such interest and principal will, at
         the option of Oakhurst Company, Inc., a Delaware corporation ("OCI"),
         be deferred until sufficient Net Cash Flow or Net Cash Proceeds are
         available; provided, however, that such deferment shall not last past
         July 13, 2005. Any accrued but unpaid interest on this Note shall be
         added to the outstanding principal of this Note for the purpose of
         computing subsequent interest payments.

         "Net Cash Flow" as used hereinabove means (a) the operating cash flow
         of Steel City Products, Inc. ("SCPI") or Sterling Construction Company,
         a Delaware corporation ("Sterling"), to the extent permitted by such
         entities' respective bank

<PAGE>

         lenders to upstream such entities' respective operating cash flows to
         OCI, plus (b) the proceeds from the sale by OCI of any shares of its
         common stock, par value $0.01, plus (c) the proceeds received by OCI
         from the exercise by any holders of stock options, minus (d) any and
         all of the foregoing amounts in (a), (b) or (c) that OCI's Board of
         Directors determines, in its sole discretion, should be reserved for
         payment of OCI's past, present and future corporate overhead expenses.

         "Net Cash Proceeds" means (a) the net proceeds available to OCI from
         the sale of assets of SCPI (other than sales of SCPI's inventory and
         other sales that are made in the ordinary course of business), minus
         (b) any and all of the foregoing amounts in clause (a) that OCI's Board
         of Directors determines, in its sole discretion, should be reserved for
         payment of OCI's past, present and future corporate overhead expenses.

         Net Cash Flow shall be applied in the following order: (1) first, to
         pay, pro rata, accrued interest on (i) this Note as well as any
         promissory notes that result from the sale, assignment or transfer of
         any portion of this Note (collectively, the "Davies First Note") and
         (ii) that certain promissory note in the aggregate principal amount of
         $800,000 issued by OTI to James D. Manning as well as any promissory
         notes that result from the sale, assignment or transfer of any portion
         of said note (collectively, the "Manning Note"); (2) second, to repay,
         pro rata, the remaining principal outstanding on the Davies First Note
         and the Manning Note; (3) third, upon payment in full of all accrued
         interest and outstanding principal on the Davies First Note and the
         Manning Note, to pay, pro rata, accrued interest on (i) that certain
         promissory note in the aggregate principal amount of $250,623 issued by
         OCI to Robert M. Davies as well as any promissory notes that result
         from the sale, assignment or transfer of any portion of said note
         (collectively, the "Davies Second Note") and (ii) that certain
         promissory note in the aggregate principal amount of $136,421 issued by
         OCI to Maarten D. Hemsley as well as any promissory notes that result
         from the sale, assignment or transfer of any portion of said note
         (collectively, the "Hemsley Note"); and (4) fourth, to repay, pro rata,
         the remaining principal outstanding on the Davies Second Note and the
         Hemsley Note.

         Net Cash Proceeds shall be applied in the following order: (1) first,
         to pay, pro rata, accrued interest on the Davies First Note and the
         Manning Note; (2) second, equal amounts of Net Cash Proceeds shall be
         applied to the repayment of the Davies First Note and the Manning Note,
         until all accrued interest and outstanding principal on the Davies
         First Note has been paid in full; (3) third, to repay the remaining
         outstanding principal on the Manning Note; (4) fourth, upon payment in
         full of the Davies First Note and the Manning Note, to pay, pro rata,
         accrued interest on the Davies Second Note and the Hemsley Note; and
         (5) fifth, to repay, pro rata, the remaining principal outstanding on
         the Davies Second Note and the Hemsley Note.

         If any of this Note, the Manning Note, the Davies Second Note or the
         Hemsley Note (individually, a "Transferred Note") are sold, assigned or
         transferred (which

                                       2
<PAGE>

         sale, assignment or transfer shall be in full compliance with
         applicable securities laws) and new notes are issued to reflect such
         sale, assignment or transfer (individually, a "New Note" and
         collectively, "New Notes"), the amount of Net Cash Flow and Net Cash
         Proceeds that would have been applied to the Transferred Note under the
         terms of this Note shall be applied to the New Notes in proportion to
         the total amount of accrued interest or principal, as the case may be,
         owed under the New Notes at the time the computation is made."

         2. Enforceability. To the extent not amended hereby, the remaining
rights, duties, obligations, terms and conditions of the Original Note as well
as the rights, duties, obligations, terms and conditions of the Pledge Agreement
shall remain in full force and effect until the principal and accrued interest
of the Original Note, as amended hereby, is paid in full.

         3. Participation. Maker, Holder and Maarten D. Hemsley hereby agree and
acknowledge that Mr. Hemsley's Participation (as defined in that certain
Participation Agreement, dated as of October 18, 1999, by and between the Holder
and Mr. Hemsley (the "Participation Agreement")) shall be increased to $144,153.
Accordingly, Holder acknowledges that distribution of Net Cash Flow and Net Cash
Proceeds to the Original Note shall be allocated by Holder pro rata, according
to the Participation held in the Original Note by Mr. Hemsley, as amended
hereby.

         IN WITNESS WHEREOF, the undersigned have executed this Amendment to
Secured Promissory Note as of the date first set forth above.

                                        "Maker"
                                        OAKHURST TECHNOLOGY, INC.

                                        By:    /s/ Roger M. Barzun
                                           ------------------------------------
                                        Name:  Roger M. Barzun
                                             ----------------------------------
                                        Title: Vice President
                                              ---------------------------------

                                        "Holder"
                                        ROBERT M. DAVIES

                                                 /s/ Robert M. Davies
                                        ---------------------------------------

CONSENTED AND AGREED TO
BY OAKHURST COMPANY, INC.,
as Guarantor

By:      /s/ Roger M. Barzun
   -------------------------------
        Senior Vice President

CONSENTED AND AGREED TO
BY MAARTEN D. HEMSLEY

     /s/ Maarten D. Hemsley
----------------------------------

                                       3

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