Marine Terminal Dredging and Improvements

Background

Holcim US, (Holcim) a building materials and solutions provider, operates a terminal in Green Bay, WI as a regional cement distribution facility for cement companies throughout northeastern Wisconsin and the upper peninsula of Michigan. The terminal connects customers in the region to cement sourced from Holcim’s Alpena, MI plant. The supply is delivered to the terminal by vessels that operate around the Great Lakes region. Shipping is more efficient than transporting cement by land-based alternatives, thereby reducing the amount of carbon emissions per ton-mile transported.
Foth works with both the Green Bay, WI and Alpena, MI facilities, and many other Holcim facilities nationwide, providing marine and waterfront improvement services including structural inspections, topographic and bathymetric surveys, structural engineering/design, sediment dredging characterization and permitting, construction oversight and grant management support.

From 1996 to 2022, the S.T. Crapo, a cement storage and transfer vessel, was laid up in the Green Bay facility’s slip and used for cement storage and cement transfer from other ships. The ship was towed from the slip in 2022 when it began to take on water. Subsequently, Holcim began construction of numerous on-land cement storage and transfer capabilities and improvements to its mooring structures and slip depth.

Approach

Holcim requested Foth to assess existing site conditions and provide suggestions for structural improvements and slip depths to improve berthing conditions. This work included a structural analysis of the existing mooring structures, a bathymetric survey to inform a dredge prism, development of design drawings for structural improvements and dredging, permitting, bid and construction phase services.

The structural analysis informed the design for the steel pile supported dolphins, gangway platform, and fender system, taking into account wind/wave loading, berthing loads, and soil parameters. A structural model of the bulkhead, including potentially damaged structural elements, was prepared to assist Holcim in making informed decisions regarding capital improvements. Foth supported the project through bidding and construction oversight phases.

The dredging component consisted of deepening the slip and river approach to provide better maneuverability for ships visiting the slip, and to allow for larger loads. Additionally, it provides for some depth clearance for sediment accumulation, therefore lengthening the time before the next maintenance dredge event.

There are two underwater utility crossings located at the site along with restrictive areas related to spudding and material removal in the vicinity of the utility crossings. Foth worked closely with the agencies to ensure that procedures were in place to safeguard the water lines and then worked with the dredge contractor so they had appropriate information to prevent impact to the water lines and protective surface materials. Dredged material was disposed of at the Brown County Dredge Material Rehandling Facility.

All projects had to be carefully coordinated around twice weekly ship deliveries of cement.

Results

The structural improvements are in place and completion of the dredging in the slip and the adjacent reach of the Fox River allows the facility to accommodate fully loaded tug barges with a couple thousand more metric tons of product per trip, improving efficiency and reducing emissions from additional vessel trips.