CARTHAGE, Tenn. — Scott D. Cotner (middle), senior electrical engineer at the Hydroelectric Design Center in Portland, Ore., Kevin Florence (right), HDC electrical engineer, and James Graham, senior electrical engineer for the U.S. Army Corps of Engineers Nashville District Engineering Design Group, inspect electrical equipment at the Cordell Hull Dam Switchyard here, March 6, 2012. A combined team from the Nashville District and HDC, which is the Corps’ national center of excellence for hydroelectric and large pumping plant engineering services, is performing a district-wide assessment of the switchyards at nine hydropower project sites.