Estimates of on-going PCB discharge to Lake Michigan from the Lower Fox River range from 300 to 500 pounds annually. Once in the Lake, mitigation and remediation of PCBs becomes exceptionally difficult. Potentially Responsible Parties (PRPs) sought a comprehensive, ecosystem-wide strategy for river restoration.
A multidisciplinary expert panel with expertise in river hydrology and hydraulics, sediment transport, sediment management technologies, and ecology was created by a major PRP. The Johnson Company was selected to support the evaluation of clean-up options and perform pre-design studies for the PCB-contaminated sediments. The Johnson Company also supported the PRPs in natural resource damage (NRD) negotiations with the U.S. EPA and the Wisconsin Department of Natural Resources.
The expert panel recommended placement of an in-situ sub-aqueous cap that, within six to ten years, will permanently isolate the PCB contaminated sediments. This option is in contrast to a dredging remedy that will take twice as long and cause significant ecosystem re-exposure to PCBs during remediation.
Remediation Evaluation
In collaboration with the expert panel, The Johnson Company:
- reviewed all relevant water, biological tissue, and sediment data
- developed an alternative river restoration plan for the River, which incorporated sub-aqueous cap designs and applied the risk management framework proposed by the National Research Council
- estimated integrated sediment PCB exposure for several remedial scenarios, and
- evaluated wastewater loading impacts to the River from a full-scale dredging remedy.
