The Town of Nags Head has received inquiries related to the aftermath of several heavy rainfalls and thought it would be helpful to share the following information.
Why have the recent storms resulted in so much flooding in Nags Head?
There are several factors contributing to the issues property owners are experiencing as a result of recent storms.
The weather station at Nags Head’s Town Hall recorded nearly 15 inches of rain since July 1, 2017, resulting in the town receiving rain on 14 of the first 18 days of July. The rainfall frequency is contributing to elevated groundwater conditions, reducing a “drying out” period, as well as the ability for the Town’s drainage network to recover. Life on a sandbar means living with, and being impacted by, a shallow water table. Typically on, or just below the surface, the water table can rise quickly because every 1 inch of rain results in the water table rising 5 inches, causing groundwater to surface in low-lying areas. Therefore, even several small events can greatly impact our groundwater levels, in addition to the daily tidal changes that also influence groundwater levels.
Significant ponding, as experienced recently, can also occur during rainfall due to limited drainage features and flat topography. In some areas where stormwater drainage systems exist, the system has become disjointed or does not efficiently convey runoff due to filled swales or ditches by property owners.
In addition, homes in low-lying areas constructed below street level can, as it has been documented, experience an increase in the frequency of flooding.
Stormwater Frequently Asked Questions
How does the Town drainage system function?
In Nags Head, stormwater, or rainfall runoff, is primarily managed via infiltration into the surrounding sandy soils. What does not infiltrate is conveyed through 55 miles of drainage infrastructure, one third of which is owned and maintained by North Carolina’s Department of Transportation, including the five ocean outfall discharge points. Therefore, if your property is located on South Virginia Dare Trail, South Croatan Highway, or South Old Oregon Inlet Road, your stormwater systems are owned and maintained by NCDOT. If you see an issue with the stormwater system on any of these streets, please contact NCDOT County Maintenance Engineer Jeff Ryder at 252.473.2990 or jdryder@ncdot.gov.
The outfall discharges are strategically located at low elevations to convey water from Town streets within Nags Head’s watersheds. The majority of this drainage infrastructure was installed in the early 1960’s in response to the Ash Wednesday Storm. No design records for the outfall systems are available, but it has been approximated that the system capacity is less than a 2-yr level of service, or a 2 inch rainfall occurring over a 24-hour period.
What does the Town do to maintain the drainage system?
The Town’s primary responsibility is to manage runoff from its roadways. To keep water off Town streets, Nags Head’s Public Works Department clears all main drainageways prior to storms and monitors drainage flow during and after storms to ensure continued flow. Town employees were working during the recent storms, clearing accumulated debris and litter from our major drainage systems. In the offseason, we conduct maintenance, including removing vegetation and sediment, as well as cleaning storm pipes. Individual drainage improvement projects and repairs have been conducted over recent years in conjunction with the maintenance work. For more information on the Town’s stormwater efforts, visit our web site at nagsheadnc.gov.
Can the Town control flow through the NCDOT outfalls?
No. The ocean outfalls are operated and maintained by NCDOT, in addition to approximately one-third of Nags Head’s existing drainage infrastructure. The outfall pipes have no control mechanisms, such as a flood gate or valve, which regulate the outflow or inflow of water from these systems. The Town has no means or authority to close or provide maintenance to the outfall pipe. For more information on the outfalls, contact NCDOT Bridge Program Manager John Abel at 252.482.1850 or jabel@ncdot.gov.
What can I do, as a property owner, to help reduce flooding?
Respect the stormwater systems already in place by not filling in ditches and keeping them free from debris such as leaves, grass clippings, and trash. These systems help move water off of your property. It is illegal to dump any material, soil, trash, yard waste, debris, etc. into a stream or ditch that would clog or stop the flow of stormwater. Please remove the debris and report any dumping or clogging immediately to the Town’s Public Works Department at 252-441-1122. You can also reduce runoff from your property by collecting rain in rain barrels and cisterns, creating rain gardens, or reducing your non-permeable surface area. To reduce pollution from water ponding over your septic system, participate in the Town’s Septic Health Initiative, which offers property owners incentives to have their septic systems pumped out and inspected regularly. For more information contact Environmental Planner Todd Krafft at 252.441.7016 or Todd.Krafft@nagsheadnc.gov.
Where can I obtain additional information on flood zones?
The Town participates in the National Flood Insurance Program (NFIP) and administers flood regulations designed to protect properties from flooding. Information on flood zones and the National Flood Insurance Program can be obtained at www.floodsmart.gov and http://rfris.nc.gov/fris/. We strongly encourage all property owners to carry flood insurance. For more information on flood zones, base flood elevations, or mitigation measures for your property, contact our Planning and Development Department at 252.441.7016. Additional information is located on Planning and Development section of the Town’s website.
If you would like to obtain additional information regarding either Nags Head’s drainage system or NCDOT’s outfalls, please contact David Ryan, P.E., Nags Head Town Engineer at 252.441.6221 or david.ryan@nagsheadnc.gov.