In all cases where the City shall contract for the installation, construction or laying of any cement, concrete or pavement, or any improvements to the streets, alleys, and sidewalks or curbs within the corporate limits of the City, or any improvements wherein solids are necessary for endurance, shall be under the immediate supervision of the City Public Works Director, who shall receive his instructions from the Mayor and City Council. It shall further be a part of this Chapter that in all improvements, works, and buildings, as aforesaid, only standard material and approved methods shall be used in their construction, and none other may be used or allowed. (1980 Code § 9.1.1; amd. 1999 Code)