The following standards shall apply to grading and surfacing of all private parking areas:
A. All new and reconstructed parking lots shall be permanently surfaced with asphalt concrete or portland cement concrete. Private parking areas, and driveways, in the RL, RLM-1, RLM-2, PD-1 and PD-2 districts shall be surfaced with a minimum thickness of four inches of portland cement concrete over compacted native soil. Portland cement concrete or asphalt concrete shall be used in all other districts. The required pavement section shall be reviewed and approved by the city engineer prior to the issuance of grading permits. The determination shall be based upon engineering analysis of the subgrade soils, slope conditions and anticipated traffic loads. All paving materials and installations shall be per city engineer's standards.
B. The minimum acceptable parking lot surface gradients are one percent for asphalt concrete and 0.5 percent for portland cement.
C. The maximum acceptable grades for parking stalls and loading areas is five percent. The maximum acceptable grades for all other paved areas is eight percent.
D. All site and parking lot drainage shall be collected on-site and directed through a drainage system approved by the city engineer. Concentrated drainage shall be carried in concrete gutters, or by other approved methods, per city standards.
E. No driveway ramp shall exceed a rate of grade of (+ or -) twelve percent. A ramp is the area between the public right-of-way and the parking area or any area used strictly as a driveway (no adjacent parking). Differential rates of grade of four percent or greater shall require vertical curves. Differential grades at any chord within a vertical curve shall not exceed four percent. The minimum length of vertical curves shall be eight feet. Minimum chord lengths, where vertical curves are not required, shall be two feet. Back of driveway, at the right-of-way, shall not be modified from the standard slope.
(Ord. 93-03-1152 § 18 (part): Ord. 88-09-1015 § 1 (part))