Shanon Chader, U.S. Army Corps of Engineers Buffalo District, enters the water to inspect the sea wall on the Fort McNair portion of Joint Base Myer-Henderson Hall May 21, 2014. The waters there are a convergence of the Anacostia and Potomac Rivers, as well as the Washington Channel. The inspection takes place every four years unless an incident, such as a hurricane or an earthquake, occurs that would prompt the need for another inspection.