The U.S. Army Corps of Engineers has launched a massive undertaking: a $4.5 billion project to rebuild wetlands on the disappearing Barren Island in the mid-Chesapeake Bay. Barren and its neighbor, James Island, have withered away to small spits of land. They’ll serve as the long-term site for dredged material from the Port of Baltimore’s shipping channels. Cheryl Costello got a first look at the construction underway that will transform these islands. Watch below: