From the Wet Mountain Tribune (Hal Walter):
The contaminated tailings comprised about 100,000 cubic yards of gravel. An existing depression large enough to hold the tailings was utilized to contain this material. Griswold says lead carbonate is chemically different from lead sulfide found in most mine cleanup situations, so there’s little concern about it leaching into the groundwater. Thus, the depression holding the tailings was not lined.
However, acidic runoff from the surrounding pine forests poses a potential problem. So the next step was to cover the tailings with a thick evaporative cap, including a drainage layer of coarse gravel, topsoil and vegetation. In all, this cap will be about 3 feet thick. The site will be shored up with boulder rip-rap to keep the soil in place and guard against flash floods from Oak Creek. Finally, the topsoil will be seeded with a native grass mix recommended by the Soil Conservation District.
Andy Kagan, owner of Kagan and Son, said a cooperative effort between his company and Tezak Heavy Equipment is supplying the 70,000 tons of material for the cap. About 45,000 tons of gravel was provided from his pit located in Fremont County, and the balance of topsoil will come from another pit 12 miles south of Westcliffe. Tezak is supplying the boulder rip-rap.
More Custer County coverage here.