1. When the board of supervisors shall have established a benefited street lighting district, they shall appoint a competent disinterested civil engineer, who shall prepare a preliminary plat showing:

 a. The proper design in general outline of the district.
 b. The lots and parcels of land within the proposed district as they appear on the county auditor’s plat books with the names of the owners.
 c. The assessed valuation of said lots and parcels.
 2. The compensation of such engineer on the preliminary investigation shall be determined by the board of supervisors. The engineer shall file a report with the county auditor within thirty days of the engineer’s appointment. The board of supervisors may extend such time upon good cause shown.