Big ships, a deeper channel / Massport examines dredging project

The Massachusetts Port Authority wants to deepen the 11-mile shipping channel into Boston Harbor to accommodate large cargo ships, a project that would move nearly 60 percent as much earth as the Big Dig. The operator of the Port of Boston and the Army Corps of Engineers are close to finishing a four-year, $4 million study evaluating the economic feasibility of digging down through 5 to 10 feet of clay and rock to deepen the channel to 45 to 50 feet. The project, estimated at about $100 million, would have to be authorized by Congress, because the federal government would pay half the cost.