Approximately 16,000 cubic yards of accumulated soft sediment, silt and natural clay were hydraulically dredged from the river and marina to increase the navigable depth by four feet. Geotextile tubes used to dewater the dredged sediment were staged in two municipal parking lots along the river.  The active dredging phase of the project took place in over a two month period; dewatered geotextile tubes were removed from the site approximately 60 days later.  At that time, sediment in the geotextile tubes had dewatered to over 60% dry solids by mass.

Filtrate from the geotextile tubes was directed through erosion control devices and discharged over rip-rap into the river.  A temporary permit for this discharge was issued for the project by the Wisconsin Department of Natural Resources (WDNR).  Under this permit, the filtrate discharge was monitored for total suspended solids (TSS), particle charge and the presence of polymer. All permit levels were met throughout the duration of the project.

Scope of Work

IAI served as the General Contractor on the project, responsible for sediment dewatering and regulatory liaison and reporting.  Dredging was performed by subcontractor.

Equipment Utilized

• 10 inch diameter HDPE geotextile tube header system
• Chemical feed system with VFD controls
• 3,200 lineal feet of 80 foot circumference geotextile tubes
• Telehandler