Ariz. Rev. Stat. § 48-618
C. The total amount of notes to be issued for any work or improvement shall not be greater than the aggregate of ninety per cent of the contract price and the total estimated amount of incidental expenses. The notes shall be sold at not less than par at either public or private sale. When authorized by the governing body, the superintendent of streets may enter into loan agreements with the purchaser of the notes relative to: