The ordinance providing for any improvement or the ordinance confirming any assessment roll shall create a special fund to be called local improvement fund district No. ____ into which shall be placed all sums paid on account of such assessment, together with all interest and penalty thereon, and in the event of a sale of bonds by the city all premiums and accrued interest on bonds issued for such improvement. Out of such fund shall be paid the entire cost and expense of such improvement. (Prior code § 13.48.100.)