Media

• Photo gallery
• 13 ABC news story (video)
• WTQL News 11 story (video)

Summary

Infrastructure Alternatives, Inc. (IAI) was the General Contractor for all landside operations on the Ottawa River Remediation project, which was conducted over the course of the 2010 construction and dredging season. The project involved hydraulic dredging of 242,000 cubic yards of contaminated sediment from the Ottawa River to geotextile tubes for dewatering and wastewater treatment. The dredged sediment was pumped by the dredging contractor from the Ottawa River to the Hoffman Road Landfill in Toledo, Ohio, where two separate dewatering pads had been constructed for the purpose of dewatering the dredged sediment. Sediment contaminants included polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs) and heavy metals.

About 16,000 cubic yards of the most contaminated dredged material was regulated by the Toxic Substances Control Act (TSCA), and was pumped to the TSCA dewatering pad for chemical conditioning and dewatering in geotextile tubes. The remaining dredged sediment was not regulated by TSCA and was pumped to a second, non-TSCA dewatering pad where the dredge slurry was injected with polymer, screened to remove debris and coarse grain material, thickened in gravity thickeners and finally, dewatered in geotextile tubes. About 226,000 cubic yards of non-TSCA sediments were dewatered in 41,000 lineal feet of 75 – 85 foot circumference geotextile tubes, stacked six layers high over the terraced non-TSCA dewatering pad.

Storm water from the dewatering pads, clear water from the gravity thickeners and geotextile tube weep water was collected and treated in a temporary on-site wastewater treatment plant (WWTP).  The WWTP design and construction was fast-tracked to accommodate a 1 year dredging schedule.  The WWTP, with 4,000 gpm maximum capacity, was installed in just 32 days. 

Treated water was then discharged back to the Ottawa River under an NPDES permit. Several water treatment processes were incorporated into the on-site WWTP, including: lamella inclined plate clarifiers, multi-media filters and bag filters to remove suspended solids; and Granular Activated Carbon (GAC) adsorption vessels to remove dissolved organic contaminants. The WWTP had a design capacity of 4,000 gallons per minute and treated over 500 million gallons of water during the performance of the Ottawa River Remediation project. No NPDES effluent quality permit violations occurred.

Dewatered TSCA sediment was removed from the geotextile tubes after sufficient dewatering and transported with trucks to a nearby hazardous material landfill. Dewatered non-TSCA sediment was capped in place and will remain in the Hoffman Road Landfill permanently.

Project location

• Toledo, Ohio

Services provided

• Sediment dewatering pads design
• Geotextile tube header design, installation
• Polymer dilution & polymer feed systems installation, operation
• Gravity thickener installation, operation
• Geotextile tube dewatering of 242,000 cubic yards contaminated sediment
• 4,000 gpm wastewater treatment plant design, construction
• Wastewater treatment plant start-up, operation & maintenance
• General conditions for landside activities
• OSHA 40 hour HAZWOPER certified staff
• Site Specific Health & Safety Plan
• Air monitoring & personnel monitoring
• Equipment decontamination & demobilization

Contact us about this project

• E-mail Mr. Paul Stage

Aerial view of Ottawa River Remediation landside operations.  The two separate geotextile tube dewatering pads are shown with filled geotextile tubes stacked in layers over them, along with the gravity thickeners used to thicken the dredged material prior to geotextile tube dewatering, and the wastewater treatment plant used to treat the geotextile tube weep water.

J.F. Brennan Company provided two 31,000 gallon gravity thickeners with shaker screens, which were used to remove debris and clear water from the dredged sediment prior to dewatering in the geotextile tubes.  Inset: Clear water flowing over the gravity thickener weirs.  Weir overflow was treated in the on-site wastewater plant.

Geotextile tubes stacked in the non-TSCA dewatering pad.  By project’s end, about 226,000 cubic yards of PCB contaminated sediment not regulated by the Toxic Substances Control Act had been dewatered in approximately 38,000 lineal feet of geotextile tubes, which were stacked in six layers.

Geotextile tubes in the TSCA dewatering pad.  Ottawa River sediment believed to contain the levels of PCB contamination regulated by the Toxic Substances Control Act was dredged and dewatered separately from non-TSCA sediment.  In total, about 16,000 cubic yards of TSCA regulated river sediment was dewatered in approximately 2,700 lineal feet of geotextile tubes in the TSCA dewatering pad. 

Aerial view of the on-site wastewater treatment plant.  The treatment plant was designed, constructed and operated by IAI.  Treatment processes included solids removal utilizing lamella inclined plate clarifiers, pressurized multi-media filters and bag filters and dissolved organics removal with Granular Activated Carbon (GAC) adsorption.  Inset: Treated water was discharged back into the Ottawa River under an NPDES permit issued by Ohio Environmental Protection Agency.

Featured Sediment Dewatering Projects

Next featured project: Ashtabula River Remediation