For the purpose of paying the cost of the public improvements as provided in sections 16-672.01 to 16-672.11, the mayor and city council of any city of the first class, after such improvements have been completed and accepted, shall have the power to issue negotiable bonds of the city to be called storm water sewer district bonds, payable in not exceeding twenty years and bearing interest payable annually, which may either be sold by the city or delivered to the contractor in payment for the work, but in either case for not less than their par value. For the purpose of making partial payments as the work progresses, warrants may be issued by the mayor and city council upon certificates of the engineer in charge, showing the amount of work completed and materials necessarily purchased and delivered for the orderly and proper continuance of the project, in a sum not exceeding ninety-five percent of the cost thereof, and upon the completion and acceptance of the work, a final warrant may be issued for the balance due the contractor, which warrants shall be redeemed and paid upon the sale of the bonds issued and sold as provided in this section. The city shall pay to the contractor interest at the rate of eight percent per annum on the amounts due on partial and final payments beginning forty-five days after the certification of the amounts due by the engineer in charge and approval by the city council and running until the date that the warrant is tendered to the contractor. All special assessments which may be levied upon property specially benefited by such work or improvements in any such storm water sewer district shall, when collected, be set aside and placed in a sinking fund for the payment of the interest and principal of the bonds. There shall be levied annually upon all of the taxable property in the city a tax which, together with such sinking fund derived from special assessments collected, shall be sufficient to meet payments of interest and principal on the bonds as the same become due. Such tax shall be known as the storm water sewer tax, shall be payable annually, shall be collected in the same manner as general taxes, and shall be subject to the same penalties.