Tennessee Code Title 7. Consolidated Governments and Local Governmental Functions and Entities § 7-84-302

(a) Upon the adoption of the ordinance, the municipality shall proceed to advertise for bids, let the contracts, and construct the improvements under the laws and regulations governing the construction of other improvements within the municipality; provided, that where no detailed plan of improvements has yet been prepared, the municipality shall employ architects and engineers for the drafting of such plan, and, upon approval of such plan, shall thereafter, and within four (4) months time, advertise for bids.

(b) If a municipality acquires improvements from a third party, including a private entity, subsection (a) shall not apply.