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Article II. Storm Water and Drainage Facility
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It is recognized that the smaller streams and drainage channels serving Jasper County 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 within Jasper County.

Possible exceptions to the requirement are minor subdivisions and parcelization as described in Chapter 20.60 JCC, Subdivision Types.

The Drainage Board, after thorough investigation and evaluation, may waive the requirement of controlled runoff for minor subdivisions and parcelization.

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.

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 pre-development peak runoff rate. The critical duration storm is that storm duration that requires the greatest detention storage.

Computations for areas up to and including 200 acres may be based on the Rational Method; typical runoff coefficients are listed in JCC 16.10.110. 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. 12-1-97C § 6.]