Did you know that the October 2019 Stormwater Ordinance (UDO-Section 9) update includes the requirement for a downstream impact analysis for all Stormwater Plan Submittals? The purpose of the study is to determine if the proposed project will cause any additional unintentional impacts on flooding or channel degradation downstream of the project site.
This analysis requires identification of a point downstream where the impact becomes less than 10% of the total drainage area as well as an analysis of what impact the increased discharge will have between the two locations. Mitigation of that impact is required and a flow easement may be required. For additional details, see Wake County UDO Section 9-22.
