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Wake County Unified Development Code
9-1
Article 9. Stormwater Management
Part 1
General Provisions
9-10
Purpose
The stormwater management regulations of this article establish minimum requirements to address
adverse effects of stormwater runoff associated with new development. Proper management of
stormwater runoff will protect property, control stream channel erosion, reduce flooding, protect
floodplains, wetlands, water resources, riparian and aquatic ecosystems, and otherwise provide for
environmentally sound use of the county’s natural resources.
9-11
Scope
Except as otherwise expressly stated, the stormwater management regulations of this article apply to all
development within unincorporated Wake County outside the extraterritorial jurisdiction and incorporated
boundaries of any municipality.
9-12
Exemptions
The stormwater management regulations of this article do not apply to any of the following development
activities:
9-12-1
Agriculture, forestry, or mining.
9-12-2
Office, institutional, commercial, or industrial development that disturbs a land area of one-
half acre or less.
9-12-3
Any development in which the owner has accrued a vested right. Wake County recognizes
a vested right if either of the following occurred:
(A)
A subdivision plan, site plan, or development permit was officially approved by Wake
County or the State before August 13, 2006 and that plan or permit remains unexpired.
(B)
The landowner otherwise demonstrates a vested right has accrued under North Carolina
Law.
Part 2
Standards for Managing Stormwater Runoff
9-20
Maximum Curve Number after Development
Developers must manage residential runoff so that after development the site will not exceed the
following curve numbers, in accordance with procedures specified in the United States Department of
Agriculture, Natural Resource Conservation Service, Technical Release 55, Urban Hydrology for Small
Watersheds.
Zoning District
Maximum Composite Curve Number, By Soil Group
A
B
C
D
R-80W and R-80
37
60
73
79
R-40W and R-40
41
62
75
80
R-30, R-20, R-15, R-10, R-5, Residential Highway,
Highway District, General Business and Office and
Institutional
43
63
76
81
[Amended on 1/22/2008 by OA 04-07.]