City of Alexandria, VA
Flood Hazards in Alexandria
As residents of Alexandria, we enjoy proximity to the Potomac River for its beauty and the benefit of recreation. But along with these benefits come natural hazards. Flooding is one of the most common risks to Virginia residents living in floodplains, and in Alexandria approximately 20% of the City is mapped as floodplain. The 100 year floodplain is the area that will be flooded on the average of once every 100 years. It has a 1% chance of being flooded in any given year. Put another way, it has about a 26% chance of being flooded over the life of a 30 year mortgage. Smaller floods have a greater chance of occurring in any year and can still create a significant flood hazard to people and property close to the channel.
Flood Safety Measures
Pay attention to evacuation orders. Listen to local radio or TV stations for forecasts and emergency warnings. Know about evacuation routes and nearby shelters and have plans for all family members on evacuation procedures and where to meet if you are separated during an emergency.
Flood Warning Procedures
Flood warnings are forecasts of impending storms and are broadcast to the public by the NOAA Weather Radio, commercial radio, TV stations, and local emergency agencies. Alexandria has developed a flood warning system to notify residents of impending floods. Warnings will be disseminated by local radio, including stations WTOP, and DC101, and local television stations including NBC4/WRC, FOX5/WTTG, ABC7/WJLA, and CBS9/WUSA. The flood warning system is intended to provide up to one half hour of advance warning of a flood hazard. By paying attention to weather alerts, you will have enough time to protect your property or evacuate. The National Weather Service local forecast office transmits flood advisories, watches and warnings on frequency 162.550 MHz. Anyone with a NOAA Weather Radio can receive this information. The Emergency Alert System (operated by the FCC in cooperation with FEMA and NOAA) allows the public to be notified via commercial radio, cable TV and broadcast TV of emergency messages from the National Weather Service or local civil authorities.
Property Protection Measures
There are several ways you can protect your property from flood damage before the flood occurs. If there is an imminent flood threat, you can take these emergency measures:
You can also make permanent changes to protect a building from flood damage:
The City’s Engineering Department can help you determine which of these methods is most appropriate for your home, and you will need a permit to make permanent retrofits to your building. If you are interested in elevating your home above the flood level, grant funding may be available to cover up to 75% of the cost. More information can be found in Homeowners’ Guide to Retrofitting: Six Ways to Protect Your House from Flooding. Available at www.fema.gov/rebuild/mat/fema312.shtm.
Most homeowners’ insurance policies do not cover a property for flood damage. Since Alexandria participates in the National Flood Insurance Program (NFIP), local insurance agents are permitted to sell everyone (residences and businesses) an NFIP flood insurance policy under the rules and standards set by the federal government. You can purchase an NFIP flood insurance policy, which is separate from your homeowners’ insurance. Any house or business in Alexandria can be covered by a flood insurance policy. The average cost of a flood insurance policy is less than $ 750 per year. Detached garages and other accessory buildings are covered under the policy for the main building on the lot. There are two types of coverage you can purchase:
Don’t wait until the next flood to buy insurance. There is a 30-day waiting period before the NFIP coverage goes into effect. For more detailed information on flood insurance you can go to www.floodsmart.gov. Alexandria is a class 7 CRS (Community Rating System) community, thus entitling its citizens with a standard flood policy to a 15 % discount on their insurance premiums. Those citizens with a preferred risk flood polices (PRP) are receiving a 5% discount on their insurance premiums.
Floodplain Development Permit Requirements
Any development in the floodplain (not just the construction of buildings, but bringing in fill or storage of material) requires a permit. You should first contact the City Engineer in Room 3200 of City Hall, 703.746.4045, to find out exactly what is required.
Any illegal floodplain development should be reported to this office as well. Our Code Administration office, Room 4200 of City Hall, has Elevation Certificates of recent construction on file available to the public upon request. The Code Administration phone number is 703.746.4200.
Substantial Improvement/Damage Requirements
The NFIP and the City of Alexandria requires that if the cost of reconstruction, rehabilitation, additions, or other improvements to a building equals or exceeds 50% of the building’s market value, then the building must meet the same construction requirements as a new building. Substantially damaged buildings must be brought up to the same standards. This means that a residence damaged where the cost of repairs equals or exceeds 50% of the building’s value before it was damaged must be elevated above the base flood elevation (BFE). Before proceeding with repairs or improvements to a damaged structure contact the Department to Code Administration 703.746.4200.
Drainage System Maintenance
The City’s drainage system, including storm drains and streams, is designed to carry away water during a storm and helps prevent floods. Dumping debris, soils erosion, and overgrowth of vegetation can compromise the drainage system. When this happens, flooding occurs more frequently and reaches higher elevations, subjecting otherwise safe properties to unnecessary damage. Dumping waste down storm drains or into streams or other bodies of water is not only bad for the environment, but it is illegal. To keep our drainage systems functioning, do not dump or throw anything into ditches, storm drains, streams or rivers. Keep grass clippings and other debris out of storm drains. This will prevent clogging and loss of stormwater storage capacity.
If you see localized drainage problems call T&ES Maintenance at 703.746.4488. If you see dumping into storm drains, streams, ditches or rivers call T&ES Office of Environmental Quality at 703.746.4065.
Natural and Beneficial Functions
In their natural, undeveloped state, floodplains play an important role in flooding. They allow flood waters to spread over a large area, reducing flood velocities and providing flood storage to reduce peak flows downstream. Natural floodplains and its vegetation act as a filter for runoff and flow creating improved water quality, reducing the amount of sedimentation transported downstream, and minimizing the impurities in the sedimentation. Floodplains can be recharge areas for groundwater and reduce the frequency and duration of low flows of surface water. They provide habitat for diverse species of plants and animals, some of which cannot live anywhere else. Floodplains are particularly important as breeding and feeding grounds. Natural floodplains also moderate water temperature, reducing potential harm to aquatic plants and animals.
The City of Alexandria has designated City park property along many of the City’s waterways and has several areas preserved as open space or park areas located within the floodplains that provide natural and beneficial functions. Four Mile Run Park includes approximately 18-acres of dedicated wetlands in the Four Mile Run floodplain. Fort Williams Park contains dedicated open space in a natural forested environment as well as recently restored natural areas located in the Strawberry Run floodplain. Dora Kelley Park, Brook Valley Park and All Veterans Park contain parklands and dedicated natural areas located within the Holmes Run floodplain. Tarleton Park and Cameron Run Regional Park contains natural open space and park lands in the Cameron Run floodplain.
Flood Zone Information
Alexandria’s low elevation and its proximity to the Potomac River make it susceptible to flooding. Nearly every year, and sometimes several times throughout the year during periods of heavy rain, hurricanes or quick snow melts, residential and commercial properties are threatened with the potential of tidal and wind-driven flooding from the Potomac River and/or low-land flooding, particularly in neighborhoods around Four Mile Run. We encourage residents and business owners to plan for flooding as part of their emergency preparedness planning.
The City of Alexandria has detailed, digital flood hazard maps available. These maps, also known as Flood Insurance Rate Maps (FIRMs), reflect current flood risks, replacing maps that date back to 1991. As a result, you and other property owners throughout the city will have up-to-date reliable information about your flood risk on a property-by-property basis.
Frequently Asked Questions (FAQ)
How will these changes affect you?
FEMA's NFIP Grandfathering Rules:
The new maps help promote public safety.
If you feel there has been an error, you can file a protest or appeal.
When do the maps become effective?
Here’s where to go for more information.
The FEMA Flood Maps are also available for viewing at all Alexandria Public Libraries: http://www.alexandria.lib.va.us/client/home
For more information, please contact:
Transportation & Environmental Services
301 King Street, Room 3200
Alexandria, VA 22314