(A) Risk of damage to property. Stormwater facilities shall be designed to accommodate the 100- year storm six hour duration without increasing risk of damages to other property or to the development itself.
(B) Supporting material. Supporting material such as hydrographs, charts, sketches of areas and subareas, computer output and the like, shall be submitted in a neat and presentable form along with the plans.
(C) Restrictions on method of estimating runoff.
(1) The rational method and its modifications shall only be utilized when the drainage area being studied is less than 20 acres. Its use for the design of parking lots, roof top drainage and other small areas is acceptable and should be utilized.
(2) Unit hydrograph methods may be used on drainage areas up to 1,000 acres.
(3) All soils conservation service models may be used up to 20 square miles.
(4) Izzard’s method may be used up to 1,000 acres.
(5) Variations of these methods and other methods are acceptable within the limitations stated by their authors.
(D) Land use pattern. Factors used in all models shall be based upon the projected land use pattern reflected in the comprehensive plan of the city.
(E) Predevelopment and postdevelopment. The drainage basin or subbasin predevelopment and postdevelopment hydrograph shall be computed and reported. The design of the major and minor systems ponds will be based upon these calculations.
(Prior Code, § 11-8-2) (Ord. 594, passed 8-5-1997)