U.S. Army Corps of Engineers (USACE) Vicksburg District Commander Col. Robert Hilliard (right) speaks with River Operations employees Ed Adcock (center) and Barry Sullivan ahead of the Mat Sinking Unit's deployment July 21. Each year, the Mat Sinking Unit places hundreds of thousands of articulated concrete squares, also known as revetment, along the Mississippi River to protect flood control works, prevent riverbank erosion and provide navigable waterways for commercial transportation.