For some areas in Wake County, on-site stormwater devices may be installed when a residential site plan is allowed to exceed the maximum allowable impervious surface coverage on that lot. These areas include the non-critical rural zoning of the Swift Creek Land Management Plan and older subdivision built prior to 2006 that do not have subdivision level stormwater nor the perpetuity statement: "Maximum Impervious Area Square Footage on each Individual Lot will be Stringently Enforced with no Exceptions into Perpetuity." Lots in these subdivisions are not permitted to deviate from the approved impervious on an individual lot basis. If there is no perpetuity statement, individual lot stormwater management may be permitted by application and installation of stormwater treatment.
If you property is eligible for a stormwater deviation permit, Watershed Management staff will contact the applicant to allow for revision of the building plan or for potential stormwater deviation from the impervious requirement. Building permit applications are required to supply a plot plan which includes a scale drawing of the lot and the proposed impervious features (house footprint, driveway, sidewalks, porches, outbuildings, etc.).
Small deviations can be mitigated by the applicant or homeowner; however, large Stormwater Management devices should be designed by qualified professionals. A few solutions are listed below; however, keep in mind that there are many different possibilities for stormwater management.
Refer to the NC DWR Stormwater Design Manual for detailed explanation. However, engineering design is not required for most systems. Permeable pavement is the exception, compliance with the State manual is required.
- Rain Gardens
- Cistern (above ground or underground tanks)
- Rain Barrels
- Infiltration Devices
- Dry detention basins
- Permeable Pavement - requires engineered design
Deviation requirements include:
- Deviation Application and site plan
- Stormwater Deviation Submittal Checklist
- Permit fee ($400)
- Approved stormwater management plan
- As-built survey
- Recorded maintenance document
- Recorded stormwater agreement
- Homeowners Annual Inspection Checklist
To schedule a pre-submittal meeting please contact Watershed Management at 919-856-7436. For additional guidance please review section 4.3.2 of the Stormwater Design Manual.
Apply for Stormwater Deviation through the Permit Portal; also upload a site plan with the stormwater device(s) to your building permit or land use plan; septic review may be required.
Technical support in design of rain gardens and cisterns is available through NC Cooperative Extension.