Tenn. Code Ann. § 7-33-101

When the legislative body shall have ordered the construction of any improvement in accordance with the terms of chapter 32 of this title, the legislative body shall have the power, for the purpose of providing means to pay that portion of the cost of the improvement not chargeable to the municipality proper, to issue negotiable bonds of the municipality pursuant to the Local Government Public Obligations Law, compiled in title 9, chapter 21 to the amount in par value not exceeding two thirds (2/3) of the estimated cost of any such improvement or improvements, which cost shall, for this purpose, be estimated by the legislative body in the ordinance authorizing the issue of the bonds.