(A) It is recognized that the watercourses serving the county do not have sufficient capacity to receive and convey stormwater runoff resulting from continued urbanization. Accordingly, the storage and controlled release rate of excess stormwater runoff shall be required for the following instances:
(1) All new business, commercial, and industrial developments more than one acre and up to three acres in size and exceeding 33% impervious surface;
(2) All new business, commercial, and industrial developments over three acres in size;
(3) Developments, as defined above; and
(4) Any new highway, street, or road construction that adds impervious surface over and above the existing condition and in the opinion of the County Surveyor adds significantly to the stormwater runoff so as to require the application of this subchapter.
(B) The release rate of stormwater from developments and redevelopments may not exceed the peak five-year return period stormwater runoff from the land area in its present state of development.
(C) The developer shall submit to the County Surveyor and the County Drainage Board detailed computations of runoff before and after development or redevelopment which demonstrates that runoff will not be increased. These computations shall show that the peak runoff rate after development for the 100-year return period storm of 24-hour duration shall not exceed the five-year return period pre-development peak runoff rate.
(D) The method for computations as applied to this subchapter for development sites shall be approved by the County Surveyor.
(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999