Mich. Comp. Laws § 41.272
Upon the filing of such application, the commissioners shall proceed to examine the location, and, if they deem the proposed improvement necessary, shall cause a survey thereof and establish grades and make specifications of the kind of improvement suitable for the purpose, and estimates of the cost thereof to be filed with them by a registered engineer. The said commissioners shall also cause a plat to be made of said proposed improvement and of the lands that may be benefited by the proposed improvement. The commissioners may adopt such kind of material, grade and manner of construction as they shall deem best under the circumstances, and shall assume responsibility for proper inspection during the construction of said proposed improvement.
MCL 41.272