PCB CONTAMINATED SEDIMENT REMOVAL from the SHEBOYGAN RIVER
This project involved the removal of PCB-contaminated sediments from the Sheboygan River in Sheboygan, Wisconsin. Specific tasks included dredging, dewatering, stabilization, transport and disposal of PCB and PAH impacted sediments, post-dredge confirmation sampling and bathymetric surveys, placement of sand cover, and site restoration.
Crews began the first phase of the project, constructing the sediment processing pad where the dredged material was dewatered and stabilized. After the initial processing pad was complete, the team utilized their patented Sed-Vac process to remove sediment next to a bridge in order to install an air curtain prior to dredging operations. The air (turbidity) curtain was a pipeline that was set on the river bottom and air was pumped from the pipe upward to create a barrier of air to contain sediments from escaping beyond the limits of the dredging and still allow boat traffic through the navigation channel.
The overall remediation process involved dredging contaminated material from the river and loading it onto barges which then transported the material to an off-loading platform. From there the material was moved to a sediment processing pad where it was put through “Grizzlys” with shaker screens to separate the debris material. The sediment would continue through the Grizzly into one of two pug mills to stabilize the material by mixing it with Portland Type III cement. After the material was stabilized, loaders transported it to a stockpile area where it was cured for up to 8 to 12 hours. From there it was loaded into trucks and transported to a designated landfill.
Additionally, this project included handling and treating of approximately 20,000 to 30,000 gallons of barge water per day. A vac truck was used to vacuum the water from the barges and release it into a settling basin. The water was then sent to a sump, treated with a polymer, pumped into clarifier tanks, and processed through bag filters and two carbon filters before being discharged back into the river.
Air monitoring was provided around the perimeter of the processing pad for particulates, WPDES construction site storm water inspections, waste water monitoring and sampling including:
- Total volume discharged daily
- Continuous monitoring of pH and turbidity
- Daily sampling for PCB and PAH
- Weekly sampling for pesticides, total metals, TSS, ammonia as nitrogen, oil and grease, hexavalent chromium, and low level mercury
- Submittal of monthly discharge monitoring report to the State
The team also was responsible for post-dredge confirmation sample processing that included a total of 252 shoreline, DMU grid and TSCA core samples.