The National Park Service (NPS) completed a test install on October 31, 2014, of a levee system closure structure at 17th Street constructed by the U.S. Army Corps of Engineers that reduces risk to human safety and critical infrastructure downtown from flooding of the Potomac River.
The intent of the test install was to ensure the closure structure will be erected properly in the event of high water and is also required as part of the Corps’ levee system evaluation.
The closure structure, situated between the Lincoln Memorial and the Washington Monument, is regulated by the Corps and will be operated and maintained by NPS.
The 17th Street closure is a removable structure that can be erected in the event of high water to attach to the floodwalls on both sides of 17th Street and consists of aluminum panels between steel posts. Stone cladding application on the 17th Street floodwall was designed to blend in with the historic landscape of the National Mall. The closure is part of the Potomac Park Levee System and the Washington, D.C. and Vicinity Local Flood Protection Project.
“We work closely with our partners to develop the best strategies we can to reduce flood risk in this critical, densely-populated area,” Corps Commander Col. Trey Jordan said. “However, we stress that it is imperative for the public to know their flood risk and take appropriate actions to mitigate this risk.”
Washington, D.C is susceptible to three types of flooding: Potomac and Anacostia river flooding, coastal storm surge, and interior.
The Corps will perform a levee system evaluation to ensure it meets requirements for certification. The Corps will then provide a positive evaluation report to FEMA that demonstrates the levee system will perform as intended; and NPS can install the 17th Street closure structure, and operate and maintain the levee system as required.
If there is a positive evaluation, FEMA will “accredit” the levee system and eventually issue a revised flood insurance rate map for the District of Columbia. This map will include localized flooding hazards in the Federal Triangle Area, and other vulnerable low-laying areas of the district. The Corps will conduct periodic and annual inspections on the system to ensure authorized protection and to ensure the system is being operated and maintained sufficiently.
According to the District Department of the Environment, completion of the 17th Street closure will help to achieve one of the goals of Sustainable DC—the District Government’s long-term sustainability plan—to make the district more resilient by reducing the risk of flooding to district residents, agencies, and businesses.