It shall be the duty of such board to act promptly upon all such petitions. Upon the filing of the petition with the county clerk, as provided in section 23-310, the county clerk shall transmit a copy thereof to a competent engineer to be selected by the board, who, together with the board of county commissioners or supervisors, shall, as soon as practicable, inspect the proposed locations. If in the opinion of such board and the engineer such levee, dike, bank protection or current control is necessary or advisable, the board shall cause a survey of the proposed project to be made by such engineer, as herein provided. Such survey shall be primarily for the purpose of aiding the board in determining the necessity or advisability of constructing such project, but shall be a complete survey such as will be required for assessment of its costs. Such survey may extend to other lands than those affected by the proposed project for the purpose of determining the best practical method of protecting an area greater than the originally proposed territory. For the purpose of inspection or surveys the county commissioners, board of supervisors, surveyors, engineers, or their employees may enter upon any lands within the proposed territory, or upon any lands which in their judgment are likely to be affected by the proposed project. The surveyor or engineer shall file his report with the county clerk as soon as possible after being so instructed by the board to make such survey. The report shall include an estimated cost of the work together with a preliminary apportionment of individual assessments.