Exhibit 10.1

ALLONGE TO PROMISSORY NOTE

THIS ALLONGE, made as of September 27, 2007 by The Goldfield Corporation, a
Delaware corporation (the “Borrower”) and consented to by Southeast Power
Corporation (collectively the “Guarantor”); is to be attached to and made a part
of that certain Promissory Note dated August 26, 2005, made by Borrower to
Branch Banking and Trust Company (the “Lender”) in the principal amount of Three
Million and No/100 Dollars ($3,000,000.00) (the “Note”) which Note is as therein
set forth.

WHEREAS, there is due and owing under the above-described Note the principal sum
of 0.00; and there remains Three Million and No/100 Dollars ($3,000,000.00)
available on this line of credit.

WHEREAS, Borrower and Lender desire to amend the Note.

NOW, THEREFORE, the Promissory Note dated August 26, 2005 is amended as follows:

REPAYMENT. Interest only on the outstanding principal balance of the Note shall
be payable monthly, commencing October 26, 2007, and continuing on the same day
of each and every consecutive month thereafter until November 28, 2008, on which
date the entire principal sum outstanding under this Note plus accrued interest
shall become due and payable (the “Maturity Date”).

All other terms and conditions of said Promissory Note remain in full force and
effect.

IN WITNESS WHEREOF, the undersigned has executed this document the year first
above written.

    BORROWER:      The Goldfield Corporation            By:  /s/ Stephen R.
Wherry       
Stephen R. Wherry, Senior Vice President
          GUARANTOR:      Southeast Power Corporation            By:
 /s/ Stephen R. Wherry       
Stephen R. Wherry, Treasurer
          LENDER:      Branch Banking & Trust Co.            By:  /s/ Lori A.
Baldwin         Lori A. Baldwin, Vice President