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Floodplain Management

Frequently Asked Questions

How do I know in which flood zone a property is located?

Your local government can tell you in which flood zone your property is located.  For unincorporated Charleston County, Awendaw, Kiawah Island, Meggett, and Rockville, contact the Charleston County Planning Department to obtain a flood zone determination.  Flood zone determinations are available for property in other municipalities in Charleston County through the applicable municipality.

Flood Insurance Rate Maps for Charleston County are also available on-line at the Federal Emergency Management Agency (FEMA) map service center.

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Is Charleston County potentially subject to hurricane storm surge flooding?

Charleston County has experienced many hurricanes and other severe storms throughout our history, the most recent of which were Hurricanes Hugo in 1989 and Hurricane Floyd in 1999.  The greatest threat for flooding in the Charleston County area is from storm surge associated with a hurricane from the Atlantic Ocean. 

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What do the flood zone designations on the Flood Insurance Rate Maps mean?

If a property within Charleston County is in one of the following flood zones:

 

Zone A: No base flood elevations determined.
Zone AE: Base flood elevations determined.
Zone AH: Flood depths of 1 to 3 feet (usually areas of ponding); base flood elevations determined.
Zone AO: Flood depths of 1 to 3 feet (usually sheet flow on sloping terrain); average depths determined. For areas of alluvial fan flooding, velocities also determined.
Zone A99: To be protected from 100-year flood by Federal flood protection system under construction; no  base flood elevations determined.
Zone V: Coastal flood with velocity hazard (wave action); no base flood elevations determined.
Zone VE: Coastal flood with velocity hazard (wave action); base flood elevations determined.
Shaded Zone X: Areas of 500-year flood; areas of 100-year flood with average depths of less than 1 foot or with drainage areas less than 1 square mile; and areas protected by levees from 100-year flood.
Zone X: Areas determined to be outside 500-year flood plain.
Zone D: Areas in which flood hazards are undetermined, but possible.

 

 

Additional information regarding flood zones and flood insurance is available from the

National Flood Insurance Program.

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Can all properties in Charleston County get flood insurance?

Federally subsidized flood insurance is available through the National Flood Insurance

Program for most properties located in Charleston County and its inclusive

municipalities.  Damage caused by flooding is not covered by a standard homeowner’s

insurance policy.  A separate flood insurance policy is required for flood peril coverage.

Flood insurance is available for buildings only, contents only, or both buildings and

contents.  Insurance agents or the National Flood Insurance Program  should be

contacted for flood policy information. There is generally a 30-day waiting period for

flood insurance policies to become effective.  Charleston County currently has a few

parcels of land that could potentially be developed located in “Coastal Barrier Resource

Act” protected areas (COBRA  zones). Under Federal law, the National Flood Insurance

Program may not issue flood insurance policies for structures built in COBRA zones.  If

flood insurance is available for structures built in COBRA zones, it will be through a

private insurer.

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What regulations apply to construction-related activities in Flood Zones?
The Charleston County Flood Damage and Prevention Ordinance mandates that certain procedures be followed for construction-related work within properties designated as flood zones on the Charleston County Flood Insurance Rate Maps.  Copies of this ordinance are also available from the Charleston County Building Services Department upon request.

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Is there a limit to how much work can be done to an existing structure in an Flood Zone?

The National Flood Insurance Program requires that if the cost of reconstructing, rehabilitating, adding to, or otherwise improving a structure equals or exceeds 50 percent of the building’s assessed or appraised value, then the building must meet the same construction requirements as a new building.  An improvement of 50 percent or more to a structure is known as a “Substantial Improvement”.  These requirements also apply to buildings that are substantially damaged; however, the value used in making the substantial improvement determination is the pre-damage value of the structure.  In Charleston County and the jurisdictions for which it provides inspection-related services, the values of construction work on building permits taken out on a property during the past five (5) years are included in the determination of a “Substantial Improvement.” This regulation is enforced through the construction permitting process.  Any questions regarding “Substantial Improvements” may be referred to the Building Services Department.

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What are the special requirements for construction in "A, AE, AH, AO, A99" Flood Zones in Unincorporated Charleston County?
Flood Elevation Requirements:
The finished floor of all new and substantially improved residential structures must be elevated to a minimum of one foot above the base flood elevation indicated on the applicable flood insurance rate map.  A flood elevation certificate  indicating this elevation  must be submitted prior to any building inspection except for a foundation inspection.  This certificate must be of the latest version available.

Floodproofing Requirements:
Only non-residential structures in all “A” flood zones may be floodproofed to a minimum of one foot above the base flood elevation in lieu of elevating the finished floor to this elevation. A pre-construction (prior to the plans being released for permit) and an as-built (prior to final building inspection) floodproofing certificate must be completed by a South Carolina registered Architect and/or Professional Engineer for all floodproofed buildings. Construction plans for floodproofed buildings must also be sealed by a South Carolina registered Architect and/or Professional Engineer.

Equipment Elevation Requirements:
With the exception of one electrical outlet and one switch on a Ground Fault Interrupter (as required to meet the National Electrical Code), there may be no electrical wiring, plumbing fixtures, mechanical fixtures, other equipment, appliances, or ductwork located within new or substantially improved structures below one foot above the base flood elevation.  Replacement HVAC systems in all “A, AE, AH, AO, A99” flood zones must be located either at or above the existing finished floor elevation or the base flood elevation, whichever is lower, unless the property is undergoing a “Substantial Improvement,” in which case the HVAC system must be elevated to or above one foot above the base flood elevation.

Construction Materials Requirements:
Per FEMA, only Flood Resistant Materials Technical Bulletin 2 (Class 4 or 5 materials) are permitted to be used below the base flood elevation unless the structure is a floodproofed non-residential structure.  

Flood Control Vent Requirements:
Enclosed areas below the base flood elevation (e.g. garages, sheds, crawl spaces, etc.)  must be provided with flood control vents located and sized in accordance with FEMA requirements (e.g. a minimum of two (2) openings on different walls, located within a maximum of 12 inches of grade, sized at a minimum of one square inch per one square foot of enclosed area, with vents that allow the free-flow of flood waters at all times.  If these specifications are not met, a South Carolina registered Architect or Professional Engineer must certify in writing that the structure is designed to comply with FEMA requirements regarding equilization of hydrostatic and hydrodynamic forces.

Permitted Uses Below Base Flood Elevation:
Permitted uses below the base flood elevation are restricted to those necessary for building access, vehicle parking, and limited storage of yard-related equipment.

Refer to the Charleston County Flood Damage and Prevention Ordinance

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What are the special requirements for construction in "V and VE" Flood Zones in Unincorporated Charleston County?
Lowest Horizontal Member Elevation:
The lowest horizontal structural member of all new and substantially improved structures must be elevated to a minimum of one foot above the base flood elevation indicated on the applicable flood insurance rate map. A flood elevation certificate indicating this elevation must be submitted prior to any building inspection, except for a foundation inspection. This certificate must be of the latest version available.

Plan and Certificate Requirements:
Wall section and foundation plans for structures in “V or VE” flood zones must be designed and sealed by a South Carolina Registered Professional Engineer and/or Architect.  Plans must detail breakaway wall construction, foundation design, and scour depth.   If spread footings are used, the bottom of the footing must be a minimum of 12 inches below the anticipated scour depth at the structure location.  Pre-construction “V-Zone design” and “V-Zone Breakaway wall” certificates must be submitted with the construction plans for review.  As-built “V-Zone design” and “V-Zone Breakaway wall” certificates must be submitted prior to a final building inspection.  Obtain copies of these certificates from the Charleston County Building Services Department.

Equipment Elevation Requirements:
With the exception of one electrical outlet and one switch on a Ground Fault Interrupter (as required to meet the National Electrical Code), there may be no electrical wiring, plumbing fixtures, mechanical fixtures, other equipment, appliances, or ductwork located within new or substantially improved structures below one foot above the base flood elevation. Replacement HVAC systems in “V and VE” flood zones must be located either at or above the existing finished floor elevation or the base flood elevation, whichever is lower, unless the property is undergoing a “Substantial Improvement,” in which case the HVAC system must be elevated to or above one foot above the base flood elevation.

Construction Materials Requirements:
Per FEMA, only Flood Resistant Materials Technical Bulletin 2 (Class 4 or 5 materials) are permitted to be used below the base flood elevation.

Permitted Uses Below the Flood Elevation:
Permitted uses below the base flood elevation are restricted to those necessary for building access, vehicle parking, and limited storage of yard-related equipment. 

Walls Below the Base Flood Elevation:
All walls below the base flood elevation must be designed and certified by a South Carolina registered Professional Engineer and/or Architect to break away from a water load less than that which would occur during the base flood.

Fill Restrictions:
No fill is permitted to be used for structural purposes in “V and VE” flood zones.  Landscaping fill is only permitted if a South Carolina registered Professional Engineer certifies in writing that the fill will not cause wave run-up or deflection.

Obstructions Prohibited:
No obstructions are permitted below the base flood elevation within a structure.  Obstructions  not located within a structure (e.g. permanent planters, elevated swimming pools, elevated tennis courts, certain types of fences, etc.) are also not permitted unless a South Carolina registered Professional Engineer certifies in writing that the obstructions will not cause wave run-up or deflection.

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Where can I get a "flood elevation certificate" to determine the actual elevation of my structure?
For properties located in Unincorporated Charleston County, Awendaw, Hollywood, Kiawah Island,
Meggett, Ravenel, Rockville, and Seabrook Island, the
Charleston County Building Services Department maintains copies of flood elevation certificates for all new construction and substantially improved structures. If your structure was constructed in one of these jurisdictions since 1990, the Charleston County Building Services Department may have an elevation certificate on file for your structure. For structures where an elevation certificate is not available on file, a S.C. Registered Land Surveyor will need to survey the elevation of the structure and complete the flood elevation certificate form. Charleston County does not survey structures for the purpose of completing flood elevation certificates.

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Where can I get information on safety measures for flooding?
The Charleston County Emergency Management Department has information available on safety measures for flooding and other hazard events.  The Federal Emergency Management Agency also maintains an electronic library of resources on flood safety.  The South Carolina Flood Mitigation Program office also provides
information on flood safety.
  It is important to remember to not drive through flooded areas.

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How can I protect my property from flood-related damages?
The Federal Emergency Management Agency maintains an electronic library of reference materials on topics such as retrofitting structures for enhanced flood and hurricane resistance and protecting building utilities from flood damages. The Charleston County libraries also have multiple publications available in their reference sections on protecting property from flood damages. Since Charleston County is subject to hurricanes, measures such as protecting glazed openings in your buliding against high wind damages should also be taken for property
protection.
 

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If someone is dumping trash into the drainage ditches or system in my neighborhood, what should I do?

Charleston County has passed an ordinance prohibiting the dumping of trash, landscape debris or other materials into stream channels, ponds, basins or ditches that regularly carry or store stormwater in the unincorporated areas of Charleston County. These channels are routinely cleaned and maintained by the Charleston County Public Works Department. Residents of Unincorporated Charleston County are encouraged to assist in maintaining the drainage channels and ditches by removing or reporting obstructions (i.e. shopping carts, debris, trash, etc.) at (843) 202-7600. Keeping drainage channels free of obstruction reduces flooding potential in the event of heavy rains.

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If my property has been flooded, what should I do?

First and foremost, make certain the building is structurally sound and is not going to

collapse or cause other physical harm prior to entering a damaged structure. Shut off the

electrical and/or gas service to the structure if there is any possibility that the service is

damaged. Notify all applicable insurance carriers of the damage immediately to begin the

claims process.

 

If your property is one of many damaged by an event, make sure the address of your

property is clearly indicated for inspectors and insurance adjusters.

 

Take photographs of any damaged areas. Secure the property from any additional

damages if possible.  Wait for your insurance company to give you clearance to begin

cleaning up damaged areas.

 

The Federal Emergency Management Agency also has information available online regarding the first steps to take after a flood and about repairing your flooded home.  Be careful to avoid injury during post-event clean-up and salvage operations.  Make sure any contractors you hire to repair your property are licensed or registered  for the type of work they are performing and obtain applicable permits prior to starting work on your property.

 

Licensing and permit information is available from the Building Services Department.

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Does Charleston County have a plan to address preparing for floods and other hazard events?

Charleston County coordinates a regional planning initiative, involving the County and municipalities within Charleston County, in developing and maintaining the Charleston Regional Hazard Mitigation Plan.This plan is updated annually to reflect changes that have occurred during the year.  Anyone who would like to provide input into the Charleston Regional Hazard Mitigation Plan may do so by e-mailing the Building Services Department at buildingservices@charlestoncounty.org, or by calling the department at (843) 202-6930.  The public is also invited to attend committee meetings regarding plan updates.

If you have any questions contact (843) 202-6930

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What if my property contains wetland areas or dunes?
Flood hazard areas in Charleston County may contain wetland areas which serve natural and beneficial functions such as flood moderation, water quality enhancement, ground water recharge, and habitat for wildlife. Beachfront areas may also contain primary ocean front dunes, which serve as buffers against minor wave height fluctuations and beach erosion. Protecting these areas maintains their important functions. Activities that disturb beachfront and saltwater wetlands should not be undertaken without first obtaining permits from the South Carolina Department of Health and Environmental Control Office of Ocean and Coastal Resource Management. Any disturbance of freshwater wetlands requires a permit from the U.S. Army Corps of Engineers and certification from S.C. DHEC’s Office of Ocean and Coastal Resource Management.

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Where can I get real time information on water elevations for streams and rivers in Charleston County?

The United States Geological Survey (USGS) has placed stream gages in rivers and streams that indicate real-time water elevations at the following locations within Charleston County:
 

 

  • Cooper River at Highway 17 – 021720709
  • Cooper River at Mobay N. Charleston 02172053
  • Cooper River at Filbin Creek – 021720677
  • Cooper River at Customs House – 021720711  
  • Turkey Creek at SCDOT Maintenance Yard – 021720646
  • Ashley River near N. Charleston  - 021720869 

For topographic map information please  contact the Building Inspections department

 
These stream gage elevations are to be used for approximations only.  

Always follow emergency instructions that will be broadcast over local television and radio stations through the Emergency Alert System as weather advisories are released or updated by the National Weather Service.  If evacuations are required, it is imperative that you follow instructions.  Street patrols and door-to-door notifications may be used if an evacuation is mandatory.  Generally, residents are given 48-72 hours notice in advance of a hurricane. 

 

Charleston County also uses a telephone notification system for emergency information. For more information and free registration, please visit http://alert.charlestoncounty.org

  

Questions regarding emergency procedures may be directed to the Charleston County Emergency Management Department

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