Tenn. Code Ann. § 7-32-102

When the legislative body of any municipality shall determine to construct any improvement authorized by § 7-32-101, it shall adopt an ordinance that such improvement or improvements shall be made, which ordinance shall describe the nature and extent of the work, the character of materials to be used, the location and the terminal points of the proposed improvements, and the flood plain, streets, alleys, highways, or other public places, or part or parts thereof, on which such improvements are to be made, and which shall direct that full details, drawings, plans, specifications, and surveys of the work and estimates be prepared by the city engineer, or such other person as may be designated in the ordinance; or the legislative body may adopt plans for such work already prepared.