The public improvement fund may be established and maintained from any or all of the following sources:

    (1)    Appropriations from the general funds when available.

    (2)    The proceeds from bond issues as provided in the charter.

    (3)    Collections of special assessments or special tax bills, and any interest thereon, levied or issued for public work or condemnation of land theretofore paid for out of such public improvement fund.

    (4)    The proceeds from the sale of special tax bills.

    (5)    Any other source permitted by law or provided by ordinance.

(Code 1964, § 14.910)