(a) All sidewalks shall be constructed of good concrete, with a proper rock or stone base, and shall be constructed by capable workers according to modern and improved methods of engineering and construction. All curbs shall be constructed of good concrete by capable workers according to modern and improved methods of engineering and construction. Sidewalks shall be not less than three feet in width.
(b) All sidewalks and curbs shall be of uniform grade with the street or alley abutting thereon, which such grade, if not already established, shall be so established by proper order of Council prior to construction of any sidewalk or curb abutting thereon.