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.

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.

9-12-1

Exemptions. The stormwater management regulations of Part 2 "Standards for Managing Stormwater Runoff" of this Article, found in Article 9-20 "Maximum Curve Numbers After Development" including the 4 subparts thereto: Article 9-20-1 "Precipitation Depth"; Article 9-20-2 "Draw-down Period"; Article 9-20-3 "Stormwater Credits"; and Article 9-20-4 "Stormwater Control Measures," do not apply to any of the following development activities:

(A)

Agriculture, forestry, or mining.

(B)

Office, institutional, commercial, or industrial development that disturbs a land area of one-half acre or less.

(C)

Any development in which the owner has accrued a vested right. Wake County recognizes a vested right if either of the following occurred:

(1)

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.

(2)

The landowner otherwise demonstrates a vested right has accrued under North Carolina Law.

9-12-2

Minor and Minor-Limited Subdivisions. Developers of residential minor or minor-limited subdivisions have the option of meeting the Target Curve Number standards in Sec. 9-20 or limiting the proposed subdivision's impervious surfaces to a maximum of 15 percent. Other applicable stormwater regulations are in addition to this requirement.

[Amended on 10/21/2019 by OA-01-19; Amended on 9/8/2020 by OA-02-20]

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.

[Amended on 1/22/2008 by OA 04-07; Amended on 1/3/2022 by OA-03-21]

9-20-1

Precipitation Depth. Calculations must be based on a precipitation depth of three inches over a 24-hour period.

9-20-2

Draw-down Period. Stored water must be drained over a period of not less than two days or more than five days.

9-20-3

Stormwater Credits.

(A)

Purpose. The purpose of establishing a stormwater credit system is to provide incentives to implement better site design and locate new development in a manner that causes less impact to aquatic resources. Certain development practices reduce the generation of stormwater from the site; thereby reducing the size and cost of stormwater storage. In addition, these practices can provide partial removal of many pollutants. The credit system directly translates into cost savings and better protection of water resources.

(B)

Disconnected Impervious Surfaces. Disconnected rooftops and other disconnected impervious surfaces are encouraged. Runoff from these disconnected surfaces must be spread over pervious areas as sheet flow. As a credit, these disconnected impervious surfaces will be assigned the lower curve number specified by procedures of the United States Department of Agriculture, Natural Resource Conservation Service, Technical Release 55, Urban Hydrology for Small Watersheds.

(C)

Reforestation. The planting of trees/shrubs is encouraged as a means of reducing runoff. As credit for such practices, reforested areas will be assigned the curve number for woods in good condition per procedures in the United States Department of Agriculture, Natural Resource Conservation Service, Technical Release 55, Urban Hydrology for Small Watersheds. Areas planted with trees/shrubs must meet the following standards to qualify for the credit.

(1)

Tree/shrub Density and Spacing. Planted trees or shrubs must meet the minimum density and spacing standards of the United States Department of Agriculture, Natural Resources Conservation Service, as specified in the Field Office Technical Guide for Tree/Shrub Establishment. Existing trees or shrubs may be used towards meeting the planting standard.

(2)

Mulching. An initial application of mulch is required for the area designated for reforestation. Mulching must meet applicable standards of the United States Department of Agriculture, Natural Resources Conservation Service, as specified in the Field Office Technical Guide for Mulching-Temporary Protection of Critical Areas without Seeding. Existing groundcover may be used towards meeting the mulching standard.

(D)

Open Space Subdivisions. Open space subdivisions are encouraged. In applying curve number calculations to such developments, the county may not penalize such subdivisions. Calculations must take into account the lots' proportionate share of right-of-way and permanent open space.

[Amended on 11/21/2022 by OA-02-22]

9-20-4

Stormwater Control Measures.

(A)

Location of Stormwater Control Measures. Stormwater control measures capturing stormwater runoff from multiple lots shall be located in a common area of the development and shall be maintained by a property owners' or homeowners' association.

(B)

Easements.

(1)

The developer must record a document or documents showing a permanent easement for each of the following purposes: drainage, all stormwater control measures, access by Wake County for necessary inspections and enforcement and maintenance access by the private entity (property owners' or homeowners' association) responsible for maintenance.

(2)

The stormwater control measures shall be shown and labeled within the easement. The entire footprint of the stormwater control measure system must be included in the access and maintenance easement.

(3)

The maintenance easement shall be ten or more feet in width, not including lateral or inclined slopes that exceed 3:1 (horizontal to vertical) around the stormwater control measure to provide sufficient room to complete maintenance tasks. The stormwater control measure system may include, but is not limited to: forebay, riser structure, the stormwater control measure device, dam embankment, outlet and emergency spillway.

(4)

The access easement shall extend to the nearest public right-of-way or public easement.

(C)

Setback Requirements—Wastewater System. Stormwater control measures shall be set back from all wastewater system components in accordance with the applicable provisions of the Regulations Governing Wastewater Treatment and Dispersal Systems in Wake County.

[Amended on 10/21/2019 by OA-01-19]

9-21-1

State stormwater management rules that implement the Neuse River Basin Nutrient Sensitive Waters Management Strategy (15A NCAC 02B .0235) apply in both the Neuse and the Cape Fear River Basins and are hereby incorporated by reference.

9-21-2

State stormwater management rules for new development that implement the Falls Reservoir Water Supply Nutrient Strategy (15A NCAC 02B .0277) are hereby incorporated by reference.

9-21-3

State stormwater management rules for new development that implement the Jordan Water Supply Nutrient Management Strategy (15A NCAC 02B .0265, the "Jordan new development rules") are hereby incorporated by reference. These rules shall supersede the Neuse Rules within the Jordan Lake watershed portion of the Cape Fear River Basin.

(A)

Delayed Applicability of the Jordan New Development Rules.

(1)

Pursuant to North Carolina Session Law 2015-241, Section 14.5 (c), local government implementation of rules directed to nutrient management that have previously been temporarily delayed by the North Carolina General Assembly, such as the Jordan new development rules, are delayed an additional three years, which is until August 10, 2020 for the Jordan new development rules.

(2)

Pursuant to North Carolina Session Law 2015-246, local governments, including Wake County, are prohibited from requiring or enforcing compliance with the Jordan new development rules until the delay in local government implementation of the Jordan new development rules, which delay has been mandated through the enactment of legislation by the North Carolina General Assembly, ends.

(3)

The Jordan new development rules shall become effective and enforceable upon the end of all applicable legislative delays.

9-21-4

Copies of related codes, standards and guidelines are on file in the office of the Wake County Department of Environmental Services Water Quality Section.

[Amended by OA 03-12 on 7/2/2012; OA 01-16 on 4/4/2016]

9-22-1

General Standards. A Downstream Impact Analysis must be performed in accordance with the "ten percent rule" using the steps set forth in Sec. 9-23-2 below and a copy of the analysis must be provided with the permit application. The purpose of the Downstream Impact Analysis is to determine if the project will cause any unintentional additional impacts on flooding or channel degradation downstream of the project site. The analysis must include the assumptions, results and supporting calculations to show safe passage of post-development design flows downstream. This analysis shall be performed at the outlet(s) of the site, and downstream at each tributary junction to the point(s) in the conveyance system where the area of the portion of the site draining into the system is less than or equal to ten percent of the total drainage area above that point.

9-22-2

Policies and Procedures. The required steps in the application of the ten percent rule are:

(A)

Using a topographic map, determine the point downstream where the proposed site equals ten percent of the total drainage area, called the ten percent point. Identify all tributary junctions between the downstream site boundary and the ten percent point. All points identified, as well as the outlet of the site, are known as ten percent rule comparison points.

(B)

Using a hydrologic model with existing land uses, determine the pre-Development peak runoff rate (cubic feet per second) for the 10-year design storm event at each comparison point.

(C)

Insert the proposed site design and proposed stormwater control measures (SCM) into the land uses and determine the post-Development peak runoff rate for the 10-year design storm at each comparison point.

(D)

If the post-Development peak discharge rate is equal to or less than pre-Development conditions at all comparison points, no further analysis is required.

(E)

If the 10-year post-Development peak discharge rate is greater than the pre-Development peak discharge rate at any comparison point, then one of the following actions must be taken:

i.

Revise the site plan for the proposed site to incorporate better use of natural features, design additional structural control facilities, reduce impervious cover, or alter timing of peak flows to lower post-Development flows at each comparison point to pre-Development levels.

ii.

Obtain a flow easement from downstream property owners through the ten percent point where the post-Development peak discharge rate is higher than the pre-Development peak discharge rate.

[Amended on 10/21/2019 by OA-01-19]

The Wake County Department of Environmental Services may furnish additional guidance and standards for the proper implementation of the regulations of this Article and may provide such information in the form of a Stormwater Design Manual. Stormwater management practices that are designed, constructed, or maintained in accord with the Stormwater Design Manual must be presumed to comply with these regulations.

[Amended on 10/21/2019 by OA-01-19]

Editor's note— OA-01-19, adopted October 21, 2019, renumbered §§ 9-22 and 9-23 as §§ 9-23 and 9-24.

9-24-1

Calculations Regarding Ponds, Lakes, and Streams. Surface water bodies may not be assigned a curve number for impervious surfaces. Instead such water bodies will be removed from calculations so that developments are not penalized for their presence.

[Amended on 10/21/2019 by OA-01-19]

Editor's note— See editor's note, § 9-23.

The developer is responsible for completing all stormwater improvements in accordance with the requirements of this Article and other applicable ordinances and laws.

9-31-1

Performance Guarantee. The county may not approve a record plat, or in the case of single-lot development not requiring a record plat may not issue a building permit, until those stormwater improvements required of the developer have been completed or a performance guarantee has been provided. Such performance guarantees must comply with the performance guarantee provisions of Sec. 8-22.

9-31-2

As-Built Plans. Upon completion of required improvements, the developer or the developer's representative must submit as-built plans prepared by a licensed surveyor of required stormwater improvements to the Wake County Department of Environmental Services. These plans must indicate whether stormwater improvements were constructed in accordance with the county approved stormwater plan.

[Amended on 10/21/2019 by OA-01-19]

9-32-1

Maintenance Required. All stormwater improvements must be maintained so they will continue to serve their intended functions.

9-32-2

Parties Responsible for Maintenance of Improvements.

(A)

The developer must maintain stormwater improvements until transferred to a property owners' association or lot owner via a Stormwater Agreement. The developer must disclose which party will be responsible for continued maintenance on the record plat and on the stormwater management plan.

(B)

Before improvements are transferred for maintenance to the property owners' association or lot owner, the developer or the developer's engineer or other representative, as authorized by Statute, must certify to the property owners' association or lot owner and to the county that improvements are complete and functioning as designed.

9-32-3

Maintenance Plan.

(A)

The developer must record, and reference on the record plat, a maintenance plan that instructs the property owners' association or lot owner about the annual maintenance tasks and associated costs for at least a 20-year period.

(B)

It will be the responsibility of the property owners' association or lot owner to update the maintenance plan at least every ten years.

9-32-4

Maintenance Agreement.

(A)

The developer must record, and reference on the record plat, a maintenance agreement, or restrictive covenant that sets forth the property owners' association's or lot owner's continuing responsibilities for maintenance, including specifying how cost will be apportioned among lot owners served.

(B)

The maintenance agreement must provide that the association and its individual members are jointly and severably liable for maintenance.

9-32-5

Annual Maintenance Inspection and Report.

(A)

The person or entity responsible for maintenance of any structural and non-structural stormwater control measures installed pursuant to this ordinance shall submit an annual inspection report from one of the following persons providing services only in their area of competence: a qualified registered North Carolina professional engineer, surveyor, landscape architect, soil scientist, aquatic biologist, or person certified by the North Carolina Cooperative Extension Service for stormwater treatment practice inspection and maintenance or other certification as approved by Wake County.

(B)

Annual inspection reports are due by June 30 of each year. The first annual report is due by June 30 following one year after approval of the as-built plan. For structural stormwater control measures located on properties subject to property owners' association agreements, the property owners' association is responsible for collecting and submitting information on all individual lot structural stormwater conveyance measures installed pursuant to this ordinance on an annual basis.

(C)

The inspection report shall contain all of the following: The name and address of the parcel owner, the name and address of the party responsible for maintenance of the stormwater control measure, the name of the subdivision or development, the recorded book and page number of the lot of each structural and non-structural stormwater control measure; a statement regarding whether or not inspected structural and non-structural stormwater control measures are performing properly and are in compliance with the terms and conditions of the approved maintenance agreement required by this ordinance. The report shall include any noted deficiencies, needed maintenance and recommended corrective action. The report shall include the name, contact information, original signature, and seal (if applicable) of the qualified person conducting the inspection.

(D)

All reports shall be on a form provided by or approved by Wake County.

9-32-6

Documents Required Before Plat Approval or Building Permit. All maintenance documents required by this Article must be submitted to the Subdivision Administrator or Environmental Services Stormwater Engineer before record plat approval, and such documents must be referenced on the record plat, or, in the case of single-lot developments not requiring record plats, documentation must be submitted to the Zoning Administrator or Environmental Services Stormwater Engineer before building permit issuance.

[Amended on 10/21/2019 by OA-01-19; Amended on 4/7/2025 by OA-01-25]

9-40-1

Illicit Discharge Definition. Illicit discharges are flows in the stormwater collection system that are not associated with stormwater runoff or an allowable discharge.

9-40-2

Discharge Restrictions. No person shall cause or allow the discharge, emission, disposal, pouring, or pumping directly or indirectly to any stormwater conveyance, the waters of the State, or upon the land in manner and amount that the substance is likely to reach a stormwater conveyance or the waters of the State, any liquid, solid, gas, or other substance, other than stormwater; provided that non-stormwater discharges associated with the following activities are allowed, so long as they do not significantly impact water quality:

(A)

Water line flushing;

(B)

Landscape irrigation;

(C)

Diverted stream flows;

(D)

Rising ground waters;

(E)

Uncontaminated ground water infiltration;

(F)

Uncontaminated pumped ground water;

(G)

Discharges from potable water sources;

(H)

Foundation drains;

(I)

Air conditioning condensation;

(J)

Irrigation water;

(K)

Springs;

(L)

Water from crawl space pumps;

(M)

Footing drains;

(N)

Lawn watering;

(O)

Non-commercial car washing;

(P)

Flows from riparian habitats and wetlands;

(Q)

Dechlorinated swimming pool discharges;

(R)

Street wash water;

(S)

Firefighting emergency activities;

(T)

Wash water from cleaning of buildings; and

(U)

NPDES permitted discharges.

9-40-3

Prohibited Substances. Prohibited substances include, but are not limited to:

(A)

Oil;

(B)

Anti-freeze;

(C)

Chemicals;

(D)

Animal waste;

(E)

Paints;

(F)

Garbage;

(G)

Litter;

(H)

Septic tank and sanitary sewer discharges.

[Amended on 10/21/2019 by OA-01-19]

9-50-1

Stormwater Plan Required. For any development requiring stormwater improvements, no applicant may receive a grading, building or other permit required for land disturbance without first having a county-approved stormwater management plan.

9-50-2

Submittal Procedures. Stormwater management plans must be submitted and reviewed in conjunction with subdivision plans, or, in the case of single-lot developments requiring stormwater management, in conjunction with site plans.

[Amended on 10/21/2019 by OA-01-19; Amended on 4/7/2025 by OA-01-25]

Requests for a variance to the stormwater management standards of this Article must be processed in accordance with the procedures of 19-26.

[Amended on 2/5/2018 by OA 01-17; Amended on 10/21/2019 by OA-01-19]

9-52-1

Authority.

(A)

Pursuant to Section 19-41, any person affected by any decision of the county that relates to interpretation or application of this article may appeal to the Wake County Board of Adjustment.

(B)

Any alleged error of the county in making or refusing to make a decision may be basis for an appeal.

9-52-2

Filing. The appeal must be filed in writing with the Wake County Director of Environmental Services, as defined in Section 10-12, within 30 days of the decision complained of and must specify the grounds for appeal.

9-52-3

Decision-Making Criteria. In acting on appeals, the Wake County Board of Adjustment must determine, by simple majority vote, if the appellant has presented substantial evidence that the county erred and whether the county correctly interpreted the stormwater management regulations of Article 9.

[Amended on 10/21/2019 by OA-01-19; Amended on 4/7/2025 by OA-01-25]

Failure to complete required improvements or failure to maintain improvements so they continue to function as required are violations and subject to a fine of up to $1,000.00 per day and other penalties, remedies, and enforcement powers specified in Article 20.

[Amended on 10/21/2019 by OA-01-19]

Wake County agents and officials have the right to inspect sites to determine whether required stormwater improvements are being installed and maintained in compliance with this ordinance.

[OA 05/05 May 15, 2006; Amended on 10/21/2019 by OA-01-19]