(A) General.
(1) When possible, existing natural drainage ways, wetlands and vegetated soil surfaces must be used to convey, store, filter and retain storm water runoff before discharge to public waters.
(2) Development must be planned and conducted in a manner that will minimize the extent of disturbed areas, runoff velocities, erosion potential and reduce and delay runoff volumes. Disturbed areas must be stabilized and protected as soon as possible and facilities and methods used to retain sediment on the site.
(3) When development density, topographic features and soil and vegetation conditions are not sufficient to adequately handle storm water runoff using natural features and vegetation, various types of constructed facilities such as diversions, settling basins, skimming devices, dikes, waterways and ponds must be used. Preference must be given to designs using surface drainage, vegetation and infiltration rather than buried pipes and human-made materials and facilities.
(B) Drainage plan(s). All development shall contain provisions for adequate surface or subsurface runoff of storm water and snow melt directed to natural drainageways. A storm frequency of a five-year, 24-hour storm period shall be provided for with no structural flooding or ponding.
(C) Natural drainage. All development shall provide for the continuance of natural drainageways, and structures shall be so constructed as to be one foot above the water level in the drainageway created by a storm of a 100-year return period or a 1% chance of occurrence.
(D) Drainage structures. All drainage structures provided shall be sufficient in size to pass a five-year, 24-hour storm to a natural drainageway and to pass a 100-year, 24-hour storm along a drainage way.
(E) Drainage storage areas. The use of natural or human-made storm water storage areas is encouraged. These areas should be vegetated and designed to naturally lower after a storm.
(F) Filling. No filling of areas inundated by the 100-year, 24-hour storm along drainageways shall be allowed, except by conditional use permit.
(G) Impervious areas. All parking areas, heavy use areas, storage areas and impervious areas shall be designed to allow entrapment of silts and nutrients prior to discharge to a natural drainage way or public water.
(H) Public waters. Newly constructed storm water outfalls to public waters must provide for filtering or settling of suspended solids and skimming or surface debris before discharge.
(I) Erosion. Erosion control measures shall be provided in all areas disturbed during any grading or construction. All areas disturbed shall be covered with topsoils and seeded. Areas subject to concentrated runoff or steeper than three to one shall be sodded, planted with appropriate deep-rooted vegetation or protected with an appropriate mulch cover as directed by the City Engineer.
(Ord. 332, passed 5-19-2008) Penalty, see § 152.999