Before any plat of land wherein any new streets or alleys are opened and laid out within the City limits shall be recommended by the Director of Public Service or approved by Council, such streets and alleys shall, if there are other streets or alleys already laid out adjacent thereto, be a continuation of such streets or alleys, as near as practicable, and all streets and alleys shall be properly defined by stone monuments set in the ground. The streets, alleys and lots so laid out shall be properly figured and numbered so that they can be located from the stone monuments. All streams, watercourses or ditches, if any, shall be accurately laid down on the plat or map, and where the surface of the ground is broken or uneven, the same shall be so indicated by proper topographical delineations.