(A) An adequate system to control the adverse impacts associated with increased stormwater runoff shall be constructed.
(B) The minimum stormwater controls shall require that all developments provide management measures necessary to maintain the post-developed peak discharge at a level that is equal to or less than the pre-developed peak discharge for the design storm. The (m) year storm is defined as a storm event which, over a long period of time, will be equaled or exceeded on the average of once every (m) years.
(C) Site specific facilities shall be designed to restrict stormwater discharge to that generated from the pre-developed site during a five-year storm. The facilities shall be designed to limit the Q5 discharge up through the ten-year storm event. The facility shall be designed to prevent uncontrolled overflow for storms having a frequency of 25 years or less.
(D) Regional facilities shall be designed to allow a maximum controlled discharge of Q5 pre-development through the 25-year storm. The minimum uncontrolled overflow should be based on the 100-year storm.
(E) Site grading and drainage for all sites shall be designed to prevent stormwater from outside of the design area from entering the area.
(F) All conveyance systems for proposed projects shall be analyzed, designed, and constructed for existing tributary off-site runoff and developed on-site runoff from the proposed project. Conveyance systems in residential areas shall be designed to carry a two-year intensity storm. A ten-year intensity storm shall be used to check the hydraulic grade of the pipe system. The hydraulic grade line shall be limited to five inches of water in the gutter.
(G) In commercial and industrial areas, the design storm intensity shall be a storm of five-year frequency, the check intensity for hydraulic grade calculations shall be a ten-year frequency with the hydraulic grade limited to the gutter elevation.
(Ord. 3669, passed - -2001)