The preliminary fund assessment shall be levied by an ordinance of the governing body. Within thirty days after publication of the levying ordinance the clerk of the city shall serve notice in writing of the amount of each assessment on each of the property owners to be assessed by mailing to his last known address, the names and addresses of such property owners to be obtained from the records of the county assessor or from such other sources as the clerk deems reliable. The notice shall state where and on what terms the assessment must be paid, and that it is a lien upon the property assessed. Within thirty days after the publication of the levying ordinance, the clerk of the city shall prepare, sign, attest with seal of the city, and file for record with the county clerk of the county in which the property is located, a claim of lien for the unpaid amount assessed against each tract or parcel of real property, and penalties or interest which may arise thereon. If the proceeds of such assessments exceed the preliminary expenses, the surplus shall be placed in the general fund of the district and used to pay the cost of the project.