By Ed Voigt, U.S. The U.S. Army Corps of Engineers oldest dredge is now also one of its youngest. The dustpan dredge Potter, the Corps last and longest-serving steam-powered dredge, helped keep the Mississippi River open to navigation for almost 70 years. Now she is back home at the St. Louis District Service Base after a $20 million repowering project by the district and the Corps' Marine Design Center (MDC). Halter Marine, Inc., of Gulfport, Miss, was the contractor. She departed Halter's New Orleans shipyard Sept. 29 with the same overall profile (minus smokestacks) and capabilities, but with an all-new stern and a diesel-electric power plant. Named for Brig. Gen.