Prior to Superfund cleanup actions, acid mine drainage discharges from the Iron Mountain Mine Superfund site in northern California resulted in massive fish kills, impacted municipal and agricultural water supplies, and required use of valuable water resources to mitigate impacts to the Sacramento River. Discharges resulted in deposition of more than 160,000 cubic yards of highly toxic, metals-contaminated sediments in the Spring Creek Arm of Keswick Reservoir, restricting operations of Shasta Dam, reducing peak power generation, and threatening the most productive salmon habitat in the Sacramento River.
The Spring Creek Sediment Removal Project was the first Superfund project funded under the American Recovery and Reinvestment Act of 2009(ARRA), commonly referred to as the stimulus. The scale and technical complexity of the project make the IMM- Spring Creek project a great example for how to remediate other large scale mining projects. The project demonstrated how to address project objectives such as rapid acceleration, local job creation, small business utilization, economic development, and green and sustainable remediation. Major technical elements of the project included hydraulic dredging, treatment using lime neutralization and polymers, conveyance of the dredge slurry over 2 miles, and disposal in a newly constructed confined disposal cell. All project objectives were achieved.
Removal of >96% of metals loading to the Sacramento River—formerly the largest discharger of metals to surface waters in the US—has prevented previously common fish kills and protects runs of salmon, steelhead, and trout, and enabled the restoration of benthic communities in a sensitive ecological environment.