The commissioners shall, as soon as practicable after their appointment, and after being duly sworn to perform their duties faithfully and impartially to the best of their abilities, inspect and classify all the lands benefited by the location and construction of the drainage or levee district in a graduated scale of benefits, naming the tract or tracts of each owner and so classifying the tract or tracts, each tract to be numbered according to the benefit received, as provided in §§ 54-12-204 and 54-12-205 by the proposed improvement.