Cleanup Operations
Sampling and studies on the Lower Fox River started in the early 1970s. These studies indicated PCB contaminated sediment was deposited along the entire length of the river, but primarily in OU1, OU3, OU4 and OU5. The majority of sediment dredged from the river was in OU4.
Remedial Action Objectives (RAOs)
Records of Decision (RODs) are governing documents issued by EPA for the project. The RODs define four Remedial Action Objectives (RAO) for the Lower Fox River cleanup.
RAO 1: Achieve, to the extent practicable, surface water quality criteria for PCBs throughout the Lower Fox River and Green Bay.
RAO 2: Protect humans who consume fish from exposure to contaminants that exceed protective levels (achieve safe exposure for recreational and high-intake fish consumers).
RAO 3: Protect ecological receptors from exposure to contaminants above protective levels (achieve safe ecological thresholds for fish-eating birds and mammals within 30 years following remedy completion).
RAO 4: Reduce transport of PCBs from the Lower Fox River into Green Bay and Lake Michigan (reduce loading to Green Bay and Lake Michigan comparable to loading from other Lake Michigan Tributaries).
Full-scale active remediation of the Lower Fox River began in 2004 in OU1 and has since made its way north and downstream toward the bay of Green Bay (OU5). Active cleanup work was completed in 2020.
PCB cleanup
RODs were issued on the project: the first ROD was in 2002 for OUs1-2, and the second ROD was in 2003 for OUs3-5. In 2007 and 2008, ROD Amendments were issued for OUs2-5 and OU1, respectively. The RODs authorized dredging, capping and sand covering as the remedial action methods. The approved remedy for OUs2-5 was to remediate all sediment with PCBs greater than 1 ppm by dredging, capping and/or sand covering. For OU1, the approved remedy was to remediate sediment to a surface weighted average concentration (SWAC) of less than 0.25 ppm PCBs. See RODs on the Documents page for more information.
Dredging
Dredging on the Lower Fox River uses hydraulic pumps to keep the sediment moving down the pipes to the facility. Three dredges were used, ranging from 8 inches to 12 inches. The 10 or 12-inch dredge is better equipped for thicker sediment and the 8-inch is better for thinner cuts and can more easily access shallow waters as low as 2 feet. Dredge locations are available in the Remedial Action Summary Reports on the Documents page.
Capping
Capping generally takes place along the river where dredging is less feasible. Capping is the placement of specifically designed thicknesses and sizes of sand, gravel and armor stone to permanently contain contaminated sediment in place. All caps are engineered to isolate the PCBs from entering the water and food chain. Cap designs vary by specific site conditions. The image diagram below shows two types of caps used on the project, a 33-inch cap and a 16-inch cap. Cap locations are available in the Remedial Action Summary Reports on the Documents page.
Sand cover is used to reduce PCB concentration below 1ppm, either as a primary remedy or after dredging if low residual PCB concentrations are remaining. The sand effectively reduces the PCB concentration at the surface of the river bottom thereby reducing risk. Special grade sand is spread in a uniform manner to settle evenly on the river bottom.
Landfilling
After dredging and treatment, landfilling was the chosen method of sediment disposal for the project. The Hickory Meadows Landfill in Calumet County was the primary location receiving sediment. The second location was Ridgeview Landfill in Manitowoc County, which is authorized to take higher levels of PCB contaminated sediment.
Vitrification (the process of transforming a substance into glass) was also considered for disposal. A pilot study for vitrification on the project involved melting the contaminated sediment and turning it into a glassy material that could then potentially be used as an aggregate in construction projects. This very high temperature associated with vitrification has shown to effectively destroy the PCBs. Due to the size and cost of the project and the lack of a vitrification facility in Wisconsin, this option was not chosen.
OU1 Cleanup Summary
OU1, the upriver section known as Little Lake Butte des Morts, runs from Lake Winnebago to the Upper Appleton Dam and was in active remediation from 2004 to 2009. In the six years of remedial action, 372,000 cubic yards of sediment were removed and 114 acres were capped. Monitoring of these caps, along with LTM of fish and water, will continue for decades.
The Bureau of Remediation and Redevelopment Tracking System (BRRTS) on the Web (BOTW) provides a detailed background on State Closure of the site and contains the OU1 PCB Cleanup BOTW Site File. To view the file:
- Launch BOTW.
- Using the Search Criteria table, enter 02-71-582406 in the BRRTS No. box.
- Click the site file link to see significant documents to the site, including a PDF of the Continuing Obligations (CO) Packet.
OU2-5 Cleanup Summary
Cleanup efforts began in 2009 on the stretch of the river from Appleton Dam to the bay of Green Bay (Ous2-5). Active remediation was completed in 2020.
Monitored natural recovery (MNR) is the selected remedy for OU2 and most of OU5. Deposit N was an exception to the MNR remedy in OU2 since it was dredged as a demonstration project.
A combination of dredging, capping and sand covering was the selected remedy for OUs3-4 and parts of OU5 near the mouth of the Fox River into Green Bay, where over 6 million cubic yards of sediment were dredged and about 850 acres capped, or sand-covered. Most of the dredged material was removed from OU4. The caps will be monitored for years to come along with long-term monitoring of water and fish.