(A) It is recognized that with the possible exception of White Lick Creek, the streams and drainage channels serving the town may not have sufficient capacity to receive and convey storm water runoff resulting from continued urbanization. Accordingly, the storage and controlled release rate of excess storm water runoff shall be required for any development, redevelopment and new construction located not outletting directly to White Lick Creek unless downstream improvements are made according to § 155.071 within the town.
(B) The release rate of storm water from development, redevelopments and new construction may not exceed the storm water runoff from the land area in its present state of development. The developer must submit to the Board detailed computations of runoff before and after development, redevelopment or new construction which demonstrate that runoff will not be increased.
(C) These computations must show that the peak runoff rate after development for the 100-year return period storm of critical duration must not exceed the 10-year return period predevelopment peak runoff rate. The critical duration storm is that storm duration that requires the greatest detention storage.
(D) Computations for areas up to and including 200 acres may be based on the rational method; typical runoff coefficients are listed herein. For areas larger than 200 acres, hydrograph techniques and/or computer drainage modeling methods may be used. Hydrograph techniques and computer modeling methods used to determine storm water runoff shall be proven methods, subject to approval of the Board.
(Ord. 1995-10 § V, passed 10-13-1995)