(A) It is recognized that with the possible exception of Fall Creek, the smaller streams and drainage channels serving the town may not have sufficient capacity to receive and convey stormwater runoff resulting from continued development. Accordingly, the storage and controlled release rate of excess stormwater runoff shall be required for any development, redevelopment and new construction located within the town.
(B) The release rate of stormwater from development, redevelopments, and new construction may not exceed the stormwater runoff from the land area in its present state of development, as explained below. The developer must submit to the Town 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 does not exceed the 10 year return period pre-development peak runoff rate, and the peak runoff rate after development for the 10 year return period storm does not exceed the two year return period pre-development 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 100 acres may be based on the Rational Method; typical runoff coefficients are listed herein. For areas larger than 100 acres, runoff hydrograph and routing techniques must be used. Hydrograph and routing techniques used to determine stormwater runoff and detention requirements shall be proven methods, subject to approval of the town.
(Ord. 1999-05, passed 6-8-99)