CARTHAGE, Tenn. — This is a view of Cordell Hull Lock and Dam from high above where the switchyard is located above the Cumberland River here., March 6, 2012. A combined team from the Nashville District and the Hydroelectric Design Center in Portland, Ore., which is the Corps’ national center of excellence for hydroelectric and large pumping plant engineering services, visited the Cordell Hull Dam Switchyard and is performing a district-wide assessment of the switchyards at nine hydropower project sites.