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Remedial Investigation Will Outline Necessary Cleanup

U.S. EPA orders ARCO to investigate contamination at Anaconda Mine

The U.S. Environmental Protection Agency on Friday ordered to the Atlantic Richfield Company to begin the comprehensive investigation into determine the nature and extent of contamination at the Anaconda Copper Mine in Yerington, Nev.

The order requires ARCO to conduct a remedial investigation and feasibility study for most of the mine site, a necessary step in addressing imminent and substantial threats from hazardous substances at the former mine. The EPA established the scope of work for the investigation through discussions and coordination with Atlantic Richfield.

"Beginning the comprehensive remedial investigation and feasibility study for this site is the next step toward a thorough cleanup," said Kathleen Johnson, the EPA's Superfund Branch Chief managing this site. "After the feasibility study is complete, the EPA, with assistance from Nevada Department of Environmental Protection and Bureau of Land Management, will select a final remedy and work toward the ultimate clean up."

The EPA's information about this site has developed over several years in cooperation with the NDEP and BLM. The agencies have conducted or overseen a wide array of sampling activities, interviewed former employees and local representatives, and conducted lengthy documentary reviews.

In 2003, the agencies became aware of significant radiological concerns in soil and groundwater, which led to today's order. In December 2004, NDEP sent the EPA a letter requesting that the agency formally assume the lead role at the site and the EPA accepted.

The EPA has removed hazardous substances at several sites. These removal actions include the relining and improvement of the "slot ponds" within the site fluid management system, which will prevent further groundwater contamination and actively begin to reduce the acidic load within the ore heaps. In 2005 the EPA covered 100 acres of mine tailings to prevent the further spread of hazardous dust from blowing off the site and removed 120 PCB-containing transformers from the site. The EPA also constructed a new 4-acre evaporation pond and repaired several other holding ponds to prevent acid mine drainage from seeping into area groundwater.

Anaconda Minerals founded the mine in 1953. Atlantic Richfield acquired Anaconda Minerals in 1977, and continued operations at the mine through 1982. The site occupies approximately 3,468 acres, and includes a lead shop, four mine waste piles and associated ponds with acidic process water, large tailings piles and expansive evaporation ponds. Approximately one-half of the site covers private lands held in fee, with the remaining lands subject to the jurisdiction, custody and control of the BLM.

Source: U.S. EPA