After the contract has been let or after the improvement has been made by the municipal corporation, in the event the governing body elects to have the work done by the municipal corporation, and after the cost for such improvement, which shall include all other expenses incurred by the municipal corporation incident to the improvement in addition to the contract price for the work and materials or in addition to the cost of all materials, labor, machinery, equipment, and services used in the making of each improvement, in the event the work is done by the municipal corporation, has been ascertained, the governing body shall, by resolution, appoint a board of appraisers, consisting of three members, to appraise and apportion the cost and expense of the same to the several tracts of land abutting on the improvement as provided in Code Sections 36-39-4 and 36-39-6.