Because of discharges from paper mills and other industries, the Lower Fox River in Neenah, Wisconsin, had high concentrations of polychlorinated biphenyl (PCB) contamination. Initial efforts to remediate a 7-mile portion of the river called for dredging 800,000 cubic yards of sediment, dewatering, and landfill disposal. After 1.5 years, it became clear that the project goals could not be met by dredging alone. Foth Infrastructure & Environment proposed and executed an alternative, USD 100 million remedial action plan.
Foth used MicroStation and InRoads to develop, evaluate, and combine hundreds of options for remediation in order to create a systematic site review. The optimized remedy for the site rapidly achieved the project cleanup goals while minimizing costs. The plan focused on dredging areas of the river with the highest sediment PCB concentrations. It included design of protective engineered caps for areas with lesser PCB concentrations, and designated areas with the lowest PCB concentrations to receive a sand cover.
The original all-dredge remedy would have cost USD 150 million and taken 10 years. The optimized remedy shortened the implementation time by nearly five years and hastened ecosystem recovery, resulting in a cost savings of nearly USD 50 million. After remedial action completion, Bentley’s 3D modeling tools in combination with field monitoring activities are used to ensure the sediment caps are intact and performing as designed.
Bentley software played a critical role in the development of a cost-saving solution involving accurate dredge volumes and sediment cap area definitions. Foth was able to use this technology to clearly present the optimized remedy to the regulatory agency and the public while drastically reducing the length of time estimated before the software was deployed. During implementation, the dredging operation was kept to a minimum using the software to provide highly accurate coordinate files.