The Environmental Protection Agency has finalized a plan to cleanup a Superfund mine site on tribal land in southern Arizona.
The EPA says it’ll use reverse osmosis treatment for groundwater contaminated with perchlorate, uranium and sulfate to restore drinking water for residents on the Tohono O’odham Nation.
The Cyprus Tohono Mine Site is about 30 miles south of Casa Grande. The mine waste that contaminated the groundwater was removed in 2008 but a 4-mile-long plume of polluted water remains.
The EPA will pump out and remove contaminants from groundwater after which the water will be returned to the aquifer.
The agency says the cleanup will take 30 years and it’ll monitor the site for another 20 years.
The mine dates from the 1880s but was later the site of large-scale open-pit copper mining. It’s been inactive since 2009.