a. The release rate of storm water from development, redevelopment, 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 Department of Planning and Building and Plan Commission detailed computations of runoff prepared by a licensed professional engineer or registered land surveyor before and after development, redevelopment or new construction to demonstrate that runoff will not be increased.
b. 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 2-year return period pre-development peak runoff rate. The critical duration storm is that storm duration that requires the greatest detention storage.
c. Computations for drainage areas up to and including one hundred (100) acres may use hydrograph techniques and/or computer modeling methods. Computer modeling methods shall be used for drainage areas over one hundred (100) acres. Hydrograph techniques and computer modeling methods used to determine storm water runoff shall be proven methods calculated in accordance with the requirements of this ordinance, as amended from time to time, subject to the approval of the Plan Commission after review and recommendation by the Town Engineer.
(Ord. No. 1708, 6-13-07; Ord. No. 1708A, § 1, 4-9-08)