<PAGE>
                                 PROMISSORY NOTE


                                                                 July 19, 1999


      FOR VALUE RECEIVED, the undersigned, National Propane L.P. a Delaware
limited partnership (the "Company"), promises to pay to the order of Columbia
Propane Corporation, ("Lender"), in lawful money of the United States of America
and immediately available funds, the unpaid Principal Amount of each Borrowing
made by the Lender to the Company pursuant to the Loan Agreement, dated July 19,
1999, between the Lender and the Company (the "Agreement"). The Company promises
to pay interest on the unpaid Principal Amount on the Interest Payment Dates and
at the rate or rates provided for on the schedule attached hereto (the
"Schedule"). All Borrowings, including the date thereof, the principal balance,
the interest on the unpaid principle balance, the rate of interest or method of
determining such rate, the maturity date of such Borrowing and the Interest
Payment Dates shall be recorded by the Lender on the attached Schedule. Any
principal or interest not paid when due shall bear interest from maturity until
paid in full at a default rate of interest as specified in the Agreement.

      Upon the happening of an Event of Default other than those specified in
Section 6.0l(6) or 6.0l(7) of the Agreement, the Lender may declare the
Principal Amount and all accrued and unpaid interest on the Note due and
payable. Upon the happening of an Event of Default specified in Section 6.0l(6)
or 6.01(7) of the Agreement, the Principal Amount and all accrued and unpaid
interest shall become and be immediately due and payable without any declaration
or other act on the part of the Lender.

      The Company hereby authorizes the Lender to endorse on the Schedule the
date, amount and maturity date of, and the interest rate with respect to, each
Borrowing evidenced hereby and all payments thereof, provided that the failure
to do so shall not affect the obligations of either the Company or the Lender.
Additional Schedule pages may be attached hereto from time to time by Lender, as
necessary.

      The Company hereby waives presentment, demand, protest and notice of any
kind. No failure to exercise, and no delay in exercising, any rights hereunder
on the part of the holder hereof shall operate as a waiver of such rights.
<PAGE>
      The Company hereby irrevocably constitutes and appoints the Lender and any
officer or agent thereof, with full power of substitution, as its true and
lawful attorney-in-fact with full irrevocable power and authority in the place
and stead of the Company and in the name of the Company or in its own name, from
time to time in the Lender's discretion after the occurrence of an Event of
Default or the Company's failure to provide adequate assurances in accordance
with paragraphs (a) or (b) of Section 4.04 of the Agreement, for the purposes of
carrying out the Agreement, to take any and all appropriate action and to
execute any and all documents and instruments which may be, in the Lender's sole
judgement, necessary or desirable to accomplish the purpose of the Agreement,
including, but not limited to, providing security to the Lender with respect to
the Company's obligations under this Note or the Agreement. The powers conferred
on the Lender hereunder are solely to allow the Lender to protect its interest
in the Company's Property and shall not impose any duty upon the Lender to
exercise any such powers.

      The Lender may assign this Note at any time without the consent of the
Company.

      The terms of the Agreement are incorporated herein by reference. Any
capitalized terms not defined herein shall have the meaning assigned to them in
the Agreement.

      This Note shall be governed by and construed in accordance with the laws
of the State of Delaware.


                                        NATIONAL PROPANE L.P.
                                        -----------------------------
                                                             Company

                                        CP HOLDINGS, INC.
                                        Its General Partner


                                        By: /s/ Thomas E. Perkins, Jr.
                                           -------------------------------------
                                                  Authorized Officer
                                                Thomas E. Perkins, Jr.


                                       2
<PAGE>
                            PROMISSORY NOTE SCHEDULE
               PURSUANT TO THE LOAN AGREEMENT, DATED JULY 19,1999
                                     BETWEEN

                        NATIONAL PROPANE L.P. (BORROWER)
                                       AND
                      COLUMBIA PROPANE CORPORATION (LENDER)

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------------------------
                         NEW ISSUE LONG-TERM DEBT
-------------------------------------------------------------------------
REFERENCE    ISSUE   MATURITY    PRINCIPAL   INTEREST       INTEREST             PREPAYMENT         OUTSTANDING
 NUMBER      DATE      DATE       AMOUNT       RATE       PAYMENT DATES       AMOUNT       DATE      BALANCE
---------------------------------------------------------------------------------------------------------------
<S>        <C>       <C>       <C>           <C>        <C>                <C>           <C>       <C>
    1      07/19/99  07/19/09  $137,997,000  Variable*  Last day of month  $137,997,000  10/19/99  $          0
---------------------------------------------------------------------------------------------------------------
    2      10/19/99  07/19/09  $137,997,000    7.65%       Mar 1/Sep 1                             $137,997,000
---------------------------------------------------------------------------------------------------------------

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

---------------------------------------------------------------------------------------------------------------
                                                                               TOTAL OUTSTANDING:  $137,997,000
---------------------------------------------------------------------------------------------------------------
</TABLE>

*   Variable rate will be Columbia Energy Group operating companies' money pool
    rate.