Onondaga Lake Cleanup

Location	Onondaga Lake Bottom Subsite of the Onondaga Lake Superfund Site, Syracuse, New York
Contaminants	Solvay waste, including BTEX compounds, chlorinated benzenes, mercury, PAHs, PCBs, PCDD/PCDFs
Services	Geotextile tube dewatering operations and design consultation

Onondaga Lake has undergone a massive remediation effort, involving the removal of 2.2 million cubic yards of contaminated sediment. The contaminated mud was dewatered in geotextile tubes, over a three year period, from 2012 – 2014.

IAI was responsible for operations and maintenance management of the sediment dewatering system, including screening, gravity thickening, polymer injection, geotextile tube dewatering, and water treatment plant influent flow control. Large circumference geotextile tubes were stacked in six layers over the 50-acre Sediment Consolidation Area or SCA. Dredge flow of up to 6,200 gpm (up to 40% solids), plus 600 – 1000 gpm sludge flow from the water treatment plant, was received and processed by the sediment dewatering system.

IAI provided a staff of 25 personnel (on average) to manage, operate and maintain the system, and also provided consultation services during the design and operations phases of the project, including making recommendations for the ultimate configuration and equipment sourcing for the thickening, polymer addition and geotextile tube layout and header systems.

Scope of Work

Design consultation services for gravity thickening, polymer make down and dosing, and geotextile tube dewatering systems
Operate polymer make down and feed system
Operate and maintain shaker screens, gravity thickeners and ancillary equipment
Design and operate the geotextile tube header system
Develop geotextile layout plan and modify plan for changing site conditions
Deploy and operate the geotextile tubes
Control flow of water to project water treatment plant

Equipment Utilized

239,468 lineal feet of geotextile tubes, 75 – 80 feet in circumference
Two 12 inch diameter geotextile tube main header systems, and ninety 6 inch minor headers, constructed of fused HDPE pipe
Three 50,000 gal capacity gravity thickeners with shaker screens
Dry polymer make down and feed system capable of delivering up to 1,200 gpm of polymer solution