The grades of all streets, alleys and sidewalks in the city shall be as established from time to time by, or at the direction of, the city council. All streets, sidewalks and alleys shall be so constructed as to conform with all grades established pursuant to this section and shall be in accordance with the Illinois department of transportation "Standard Specifications For Highway And Bridge Construction", as amended. (1996 Code § 25-6; amd. 2010 Code)