What areas are regulated?
Special Flood Hazard Areas identified on Flood Insurance Rate Maps (FIRMs) provided by the National Flood Insurance Program arm of the Federal Emergency Management Agency (FEMA), as well as Flood Hazard Soils Areas identified in "The Soil Survey, Wake County, North Carolina," are regulated.
How is this accomplished?
Flood hazard areas must be shown on the record plat of subdivisions as well as on the construction drawings for commercial areas. Encroachments (fill material, roads, buildings, etc., in these areas are discouraged and when allowed must meet rigorous design standards. In addition it must be proven (usually through a flood study prepared at the applicant's expense) that the encroachment does not adversely affect existing or proposed on-site structures or off-site properties.
What if Special Flood Hazard Areas and Flood Hazard Soils Areas coexist along the same stream reach?
The Special Flood Hazard Areas delineation would take precedence and all applicable Flood Insurance Rate Maps (FIRMs) provided by the National Flood Insurance Program arm of the Federal Emergency Management Agency (FEMA).
What soil types are considered to be Flood Hazard Soils?
Soil types designated by the Wake County Soil Survey, see list below.
Soil Map Symbol Name
Afa Altavista fine sandy loam 0 to 4% slopes
Au Augusta fine sandy loam 0 to 4% slopes
Bu Buncombe soils 0 to 2% slopes
Cm Chewacla soils 0 to 2% slopes
Cn Colfax sandy loam 0 to 6% slopes
Co Congaree fine sandy loam 0 to 2% slopes
Cp Congaree silt loam 0 to 2% slopes
Ly Lynchburg sandy loam 0 to 4% slopes
Me Mantachie soils 0 to 4% slopes
Ps Plummer sands 0 to 4% slopes
Ra Rains fine sandy loam 0 to 2% slopes
Ro Roanoke fine sandy loam 0 to 2% slopes
Wh Wahee fine sandy loam 0 to 2% slopes
Wn Wehadkee silt loam 0 to 2% slopes
Wo Wehadkee and Bibb soils 0 to 2% slopes
Wy Worsham sandy loam 0 to 4% slopes
Why do I need a Flood Study?
A flood study must be performed to accomplish the following:
· Ensure flood depths are not increased on neighboring properties.
· Ensure the lowest building level is built above the 1% annual chance flood elevation.
· Determine if flood waters will top the foundation pilings/piers under the house during the 1% annual chance storm. If the foundation will be topped by floodwaters (i.e., natural ground elevation at the building site is below the 1% annual chance flood elevation), a special foundation design is required. The foundation must be designed to withstand the various forces it will be subjected to during the 1% annual chance storm event.
How do I refute the maps if I feel they are inaccurate?
For Flood Hazard Soils Areas, the following rules and procedures apply:
· Areas are exempt with areas less than 5 acres of drainage. (may require Professional Land Surveyor check the drainage area and certify that the drainage area is less than 5 acres.)
· Flood Hazard Soil Boundaries may be modified by a field investigation by a Licensed Soil Scientist. The report of the field investigation shall conclude with a description of the actual soil horizons that were encountered on the site.
· A flood study may be performed by a licensed design professional (professional engineer, landscape architect or surveyor) to delineate the 1% annual chance floodplain. This is the most accurate way to determine the actual flood limits for a floodplain area
Note: The options above are performed at the applicant's expense. Wake County charges fees to review flood studies.
For FEMA-Identified Special Flood Hazard Areas, the following rules and procedures apply:
Flood studies, prepared by a Registered Professional Engineer from field-surveyed information supplied by a Registered Professional Land Surveyor, are generally required.
If the mapping error involves an area of high land that was not reflected on the FEMA FIRM maps, it is possible to correct these errors with the assistance of a Registered Professional Land Surveyor only. Changes to FEMA maps require FEMA approval through a LOMA or Letter of Map Amendment.
As above, the applicant is responsible for the expense of flood studies and LOMAs. There are review fees charged by both FEMA and Wake County for flood studies as well as fees for changes to the FIRM maps, if required.
If I want to build a road, driveway, pond, structure or other encroachment in a flood hazard area, what are the requirements?
With few exceptions, a flood study will have to be prepared at your expense and the appropriate review fees will be charged to you.
A particular lot we're interested in buying has some floodplain area as well as an asterisk (*) on the record plat of the subdivision, and there is a note on the plat, which states that a Flood Hazard Area Use Permit may be needed prior to the issuance of a building permit. Please explain.
Depending on where you site your house (or other structures) on the lot, a Flood Hazard Area Use Permit as well as Pre- and Post-construction Flood Elevation Certifications may be issued. Our policy is to issue these documents when a structure is less than 100 feet off of the floodplain area. A $50.00 review fee is required with the building permit application.
What is a Flood Elevation Certification?
A Flood Elevation Certification is a certificate that is filled out by a Professional Land Surveyor to ensure that the proposed or existing structure is either out of the flood hazard soils area or that the low-ground elevation at the structure’s footprint is above the flood elevation or flood depth in FEMA-mapped floodplains or flood hazard soil areas where a flood study has been performed.
What happens when a Flood Elevation Certificate is required?
Prior to your footing inspection a Registered Professional Land Surveyor will visit the site and check the structure's location on the ground against your site plan. He must then certify that the structure is out of the flood hazard soils area or that the low-ground elevation at the structure's footprint is above the flood elevation or flood depth (in FEMA-mapped floodplains or flood hazard soil areas where a flood study has been performed) on the Pre-construction Flood Certificate. As long as your house is out of the flood hazard soils area or above the FEMA flood elevation or depth, you will be allowed to proceed with your footing. If the surveyor indicates that the house location is in the floodplain, additional requirements will have to be met. The surveyor will fill out the Post-construction Flood Certificate prior to your scheduling a foundation inspection. This is to verify that the home has been constructed where it was proposed and conditions are the same as observed during his first site visit. We currently do not have a charge for the Flood Hazard Area Use Permit or Elevation Certificates, but the surveyor will charge a fee to fill out the Elevation Certificates.
Where would I obtain site specific floodplain information for a property?
Consult our Floodplain Contact List.