If the board determines that said requested drainage improvement should be undertaken, it shall within ninety days develop a proposed plan for said improvement. This plan shall include:

(1) An estimate of the cost of said improvement;

(2) If the estimate indicates the cost will exceed one thousand dollars, a profile showing elevations of the drainageway before, and the proposed elevations after the completion thereof;

(3) A plat showing the lots and lands that will be benefited by said improvement and the proposed assessment of benefits and award of damages in connection therewith for each owner;

(4) A brief statement showing the nature of said improvement and the place of starting and ending thereof;

(5) A list of the owners of the lands and lots included in said plat together with the addresses as shown in the office of the county treasurer of said county; and

(6) A map showing the location and route of said improvement.