No person shall without the City's written permission install any substructure, except manholes, vaults, valve casings, culverts and catch basins at a vertical distance less than:
A. Streets: Twenty four inches (24") below the established flow line of the nearest gutter. If the flow line is not established, and a design is not available, then the depth shall be a minimum of twenty four inches (24") below the surface of the nearest outermost edge of the traveled portion of the street.
B. Parkway:
1. Substructure Parallel To Parkway: The minimum depth of any substructure shall be sixteen inches (16") below established gutter grade when the substructure parallels the parkway, "depth" to mean the top of the structure or minimum cover.
2. Substructure At Right Angle To Parkway: The minimum depth of any substructure shall be twelve inches (12") below the top of the established sidewalk or top of curb section when the substructure is at right angles to the parkway, "depth" to mean minimum cover.
3. Other Public Places: The minimum depth of any substructure in any other public place shall be twelve inches (12") below the surface. The City may permit a lesser depth in special cases.
C. Grade Changes: Nothing in this section shall impose a duty upon the excavator to maintain required specifications upon subsequent changes of grade in the surface unless the grade in the substructure interferes with the maintenance of, or travel on, a public street. (1968 Code §10-113; Ord. 74-56; Ord. 85-214; Ord. 01-42)