The minimum cover over any and all pipes or conduits larger than two and one-half inches (21/2") installed within the right of way shall be three feet (3') of earth or imported materials, unless otherwise specified in the permit. Within the public street, the minimum cover of three feet (3') shall be measured from the surface, existing or planned. The city engineer is authorized to permit installation of pipes or conduits where three feet (3') of cover cannot be provided because of topography, structures, or other engineering necessity. (Ord. 994, 5-26-1970)