30.63A.520 Minimum requirement 4: Preservation of natural drainage systems and outfalls, and provision of off-site mitigation.
When minimum requirement 4 applies pursuant to part 300 of this chapter and no exemption under SCC 30.63A.200 applies, the requirements of this section shall be met.
(1) Natural drainage patterns identified in the stormwater site plan and determined by the currently functioning drainage pattern and patterns occurring over the past 10 consecutive years shall be maintained. Discharges from the project site shall occur at natural locations, to the maximum extent practicable.
(2) The manner by which runoff is discharged from the project site shall not cause off-site drainage impacts, as defined in volume I, chapter 3 of the Drainage Manual. Mitigation of off-site drainage impacts shall be provided pursuant to the requirements of volume I, chapter 3 of the Drainage Manual. In addition, appropriate energy dissipation shall be provided for all outfalls in accordance with the requirements of the EDDS and volumes III and V of the Drainage Manual. (Added by Amended Ord. 10-026, June 9, 2010, Eff date Sept. 30, 2010; Amended by Ord. 15-102, Jan. 11, 2016, Eff date Jan. 22, 2016; Amended by Amended Ord. 21-025, June 16, 2021, Eff date July 1, 2021).