On-site repository construction and restoration of the abandoned Silver Crescent lead and zinc mill site, Shoshone County, Idaho

From the early 1900s through the 1950s the Silver Crescent mine and mill processed lead, zinc, and silver from ore found in the Precambrian metasedimentary rocks of the Belt Supergroup. Approximately 150,000 cubic yards of tailings and waste rock were deposited in the floodplain of Moon Creek less than 2 miles upstream of what is now a residential area. The actively eroding tailings impoundments were a source of heavy metal contamination to the surface and groundwater flowing through the site. The U.S. Forest Service began a CERCLA non-time-critical removal action at the Silver Crescent mine in 1998. Removal action goals included reduction of particulate and dissolved metal loading into Moon Creek and local groundwater. These goals were successfully achieved in part by incorporating the tailings and waste rock dumps into an on-site capped repository. The nearly $2 million Silver Crescent removal action construction phase was completed in late 2000 with the final habitat restoration phase scheduled for completion in 2007.