Submarine Cables Cause Dock Wall Failure at the Port of Milwaukee

The Port of Milwaukee is southeastern Wisconsin's transportation and distribution center for vital quality of life products. The Greenfield Avenue dock wall is located within the Port of Milwaukee along the western edge of the Kinnickinic (KK) River, and at the eastern terminus of Greenfield Avenue in the City of Milwaukee. The sheet pile dock wall serves as an unloading facility for coal which is then distributed to and utilized by three of the region's power plants as a source of fuel. Over a multi-year period the dock wall exhibited a reoccurring sinkhole on the land side of the wall near Greenfield Avenue. The City of Milwaukee desired to build a small park-like area where nearby workers could sit and enjoy the views of the port. Further investigation into the site revealed that submarine cables were installed below the river in the 1950's, and that the cables crossed the river at Greenfield Avenue. The American Transmission Company (ATC) as the owner of the cables was deemed responsible for repair of the dock wall. This paper will discuss the various design alternatives considered for repair of the wall, the final chosen repair alternative, technologies considered to locate the cables, below the channel bottom, and problems encountered during construction of the repairs.