Duluth port officials are hoping to attract more ships with big cargo.

The Duluth Seaway Port Authority is embarking on its largest infrastructure project since the late 1950s, reconstructing a pier to make an intermodal dock that is equipped to handle heavier cargo.

Officials broke ground Wednesday on the $17.7 million project, $10 million of which came from a U.S. Department of Transportation grant.

The work on the pier's now-vacant docks C and D, in the harbor near the lift bridge, will include constructing a new roll-on/roll-off dock, increasing load capacity, replacing corroded sheet piling and deteriorated wooden dock walls and installing 26 acres of new dock surface. It will also involve dredging the slip to 29 feet and installing road and rail connections.

The dock will join the nearby public marine terminal as a landing spot that welcomes big, wide and heavy pieces of cargo such as mining equipment and wind turbine blades.

"We can basically double our offloading capacity," port authority spokeswoman Adele Yorde said.

Officials said it is the largest project the authority has undertaken since before the opening of the St. Lawrence Seaway in 1959.

The docks were originally erected in the early 1900s with grain silos. Once they were out-of-date and developers weren't interested in them, they were given to the port authority in 1989. The authority began a demolition and environmental cleanup process in 1997, lasting through 2001.

The federal grant awarded in September 2013 is spurring the redevelopment, which is expected to be completed in the fall of 2016.

Pam Louwagie