Nevada, Division of Environmental Protection -- History of Yerington Mine Site

History of the Yerington Mine Site

The Anaconda Mining Company, predecessor of the Atlantic Richfield Company, began mining activities at the Yerington Mine Site in the early 1950's. From 1953 to 1965, operations at the facility consisted of mining the Yerington Pit for copper oxide.

The oxide ores were processed using acid. The copper precipitate was sent off site for smelting. In 1965 the mill and concentrator were built to allow processing of both copper oxide and copper sulfide ores. A copper precipitate was produced from the sulfide ore. Both were shipped off site for further processing.

Tailings were transported and placed in a number of on-site tailings ponds. Other process wastes were evaporated in on-site evaporation ponds. The Anaconda Mining Company sold the property in 1978

Miscellaneous mining and processing continued around the site from 1978 to 1989 at which time Arimetco began its leaching operations. The method used by Arimetco to extract copper from copper oxide ore involved leaching with acid and other solutions, followed by electro plating the copper oxides sheets.

Arimetco built and ran five lined heap-leach pads, where tailings and low-grade ore were phased for leaching. After filing for Chapter 11 bankruptcy in January of 1997, Arimetco continued its copper recovery operations through November 1999. Arimetco abandoned the site in January 2000 leaving the five-leach pads with leach solution still in the system.

Since January 2000, the Nevada Division of Environmental Protection (NDEP) has been managing the mine site to ensure that leach solution are appropriately dealt with. NDEP, with cooperation from other parties, has also made improvement to limit site access and to reduce fugitive emissions.

What's Been Accomplished (to be completed)

Operation and Upgrades to the Groundwater Management System
Fluid Management System
Site Security Upgrades
General Site Clean-up
Covering of Dust-Prone Areas
Closure Scope of Work
Installation of Meteorological Station
Installation of 2 New Groundwater Monitor Wells
Site-wide Groundwater Monitoring

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