Marinette’s Menekaunee Harbor Improvement project involved dredging and removal of contaminated sediments and restoration activities within the harbor and along its shorelines. Removed material consisted of sediments that exceeded established contaminant concentration limits (environmental dredge spoils) and sediments that did not exceed established contaminant concentration limits (navigational dredge spoils).
The improvement project dredged the harbor to a navigable depth of 8 feet during historic low lake levels and the non-navigational areas on the eastern side of the harbor were backfilled to provide final water depths of approximately 8 feet for habitat restoration purposes. Clean dredge spoils (termed “beneficial-use fill”) removed from the west side of the harbor were used to bring the east side to the desired restoration depths. A total of 27,130 cubic yards of environmental spoils, 30,680 cubic yards of Navigational Dredging, and 7,700 cubic yards of beneficial re-use fill material was moved within the harbor. All other large trash and debris items were transported to the landfill.
Both mechanical and hydraulic dredging was utilized on this project. Hydraulic dredging was used to complete part of the beneficial-use portion, and mechanical dredging was used for all material disposed of off-site. Mechanical dredging sediment was dewatered by placing, working, and blending the material on a dewatering pad constructed in the staging area. All wastewater was collected and partially treated by an on-site facility and disposed into the sanitary sewer lines to be delivered to the City of Marinette WWTP for final treatment.
Due to the creation of dredge spoils, a containment site was created on the west side of Marinette. This containment site has the capacity to hold up to 54,500 cubic yards of dredge spoils; however, only a volume of 19,200 cubic yards of material was transported to this site from the harbor. In addition, the project included shoreline improvements consisting of 8,400 square yards of riprap installation, and 160 feet of anchored sheet pile wall.
The City of Marinette, in cooperation with the Wisconsin Department of Natural Resources (WDNR), is undertaking a restoration of the Menekaunee Harbor as part of the Great Lakes Restoration Initiative (GLRI). The WDNR provided the City with a $1.1 million dollar environmental repair grant that was matched at 35% ($611,474) by the City. In addition to these funding sources, the WDNR secured a $6.5 million dollar grant from the U.S. EPA’s Great Lakes National Program Office (GLNPO) through the Great Lakes Restoration Initiative (GLRI).