(A) All drainage components must be designed in accordance with the Olathe Technical Specifications and Design Criteria for Public Improvements manual as adopted in the UDO.

(B) Stormwater Detention Standards. The Olathe Technical Specifications and Design Criteria for Public Improvements manual contains the complete requirements for detention facilities. Below are the general requirements for stormwater detention in Olathe:

All development projects larger than one (1) acre must control the rate at which stormwater is released from the developed site in order to mitigate increases in stormwater runoff caused by the development. This must be accomplished through detention facilities, which must be designed to manage stormwater runoff generated by the ninety-nine percent (99%) (one (1) year) and ten percent (10%) (ten (10) year) chance (return frequency) design storms. In watersheds where the City Engineer is aware of known downstream flooding concerns, the City Engineer may, at his or her discretion, require, in addition to the above required design storms, detention of larger storm events up to the one percent (1%) (one hundred (100) year) design storm to provide protection against increases in downstream flooding and stream bank erosion. Detention may be provided through off-site facilities with the approval of the City Engineer in accordance with Section 17.16.050(G).

(C) Easements. Permanent easements for the detention and conveyance of stormwater, including easements of access to structures, must be dedicated to the City. Any restrictions must be clearly indicated on the plat, or recorded through a separate instrument. (Ord. 22-52 § 12, 2022; Ord. 09-25 § 2, 2009.)