Case Study
US EPA Superfund Site — Sergeant Bluff, IA
Floating covers and landfill capping for a former tannery Superfund site contaminated with heavy metals, as part of a comprehensive EPA remediation plan.
The Challenge
Problem
A former tannery had long ceased operation and the site was on the superfund list for remediation. The site was contaminated with heavy metals from the tannery operation and was located near a river, with rainwater carrying contaminants into it. The remediation plan called for capping two landfill areas and installing floating covers on the East and West Aeration Lagoons containing contaminated sludge.
Our Approach
Solution
EFI installed 40 mil HDPE geomembrane caps over contaminated soil areas with geotextile layers and vegetative soil cover. For the two 60,000 SF aeration lagoons, GSE 60 mil HDPE floating covers were installed to seal contaminated sludge in place and prevent rainwater from carrying contaminants into groundwater. The covers were designed to be flooded with rainwater to the spillway elevation, weighted to sink as water was removed.
Outcomes
Results & Metrics
Key Outcomes
- Two 60,000 SF floating covers installed on aeration lagoons
- Two capped landfill areas with HDPE geomembrane
- Contaminated sludge sealed in place
- Groundwater contamination pathway eliminated
- Remediated lagoons now providing waterfowl habitat
- Completed on schedule in late summer 1999
“The floating cover system was the right approach for these lagoons — it sealed the contamination in place without the enormous cost of sludge removal. The site is now functioning as wetland habitat.”
EPA Remediation Project Manager, US EPA Superfund Site
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