NDEP nears completion of first phase in Anaconda mine site cleanup

The Nevada Division of Environmental Protection, the lead agency overseeing cleanup of the Anaconda Copper Mine Site, nearly has completed the first of three phases before expected site closure in 2029, according to an update during a public meeting in Yerington from officials in December.

Paul Eckert, Abandoned Mine Lands program supervisor of NDEP’s Bureau of Corrective Actions, said the plan’s first phase is to install five fluid management ponds and cap approximately 260 acres for the Anaconda Copper Mine Site (ACMS). The land also has to be recontoured and monitored to prevent groundwater contamination constantly with site activities being completed. This portion of the project overall has signified ACMS’ closure as a whole in reducing, controlling and containing the heap leach pad drain-down fluids – the piles of materials used to help drain sulfuric acid to leach out copper fluids to be taken through an electrowinning process to remove copper – Eckert said.

“We’ve taken over this as our largest project,” Eckert said in his introduction to a crowd of about 60 in Yerington.

The ACMS covers about 3,000 acres, half of which is private land and half is public land managed by the Bureau of Land Management. The Anaconda Mining Co. once conducted open pit mining and the processing of copper ores from 1952 to 1978, with Atlantic Richfield Co. purchasing the site and closing mining and processing operations in 1977. Mining company Arimetco acquired private property in 1989, began remining using stockpiled ore and operated five heap leach pads and an electrowinning plant between 1989 and 1999 and most construction activity has occurred there in the past few years, Eckert said.

But Arimetco filed for bankruptcy in 1997, ceased mining operations the following year and stopped all processing by 1999. Eventually, it abandoned the site without properly shutting down according to Nevada law by 2000 when NDEP assumed oversight of its fluids.

“Once they turned their pumps off, there was nowhere for that extra fluid to go except back into the ponds,” Eckert said. “Then (Environmental Protection Agency) requested regulatory control in the site on the National Priorities List, normally referred to as Superfund, and Nevada provided conditional approval in 2015-16.”

The first phase of the cleanup plan, which NDEP calls its Record of Decision 1/1A in remedial action, includes the reduction, control and containment of the acidic, heap leach pad drain-down fluids, Eckert said. Upgrades to its fluid management system and recapping for its heap leach pads focuses on the construction of five evaporation ponds, which were built in August 2019 and completed in August 2020. These were to recontour and cap more than 260 acres of mine landscape features to protect water quality and constructing stormwater controls, according to a release from NDEP.

The division also is requiring Atlantic Richfield to oversee all identified and possible mine-related groundwater contamination regularly, but Eckert said fluid management is one of the major challenges of the project. This means maintaining pond volume and acreage to allow for an evaporation-transpiration process since the fluid is acidic and dangerous, Eckert said. It’s also important to help minimize potential erosion and maintain structural stability.

“The goal is to get the drainage down so low, there won’t be any fluid there for wildlife to interact with,” he added.

Eckert said the ACMS has been able to establish interlocal agreements with state and local tribes since 2020. Local groups and legislators keep a close eye on what’s happening with the land’s future and its cleanup as efforts continue.

State Sen. Robin Titus, representing District 17 that Lyon County, attended NDEP’s presentation and said she considered the division’s representatives friends for their work on the mine.

“I was encouraged to see that there was actually remediation and progress after years of analysis,” she said. “I also think it is important for the public to know that situations like this can no longer happen. Mining companies must plan for remediation before they can move any dirt.”

Eckert said ongoing conversations with the local tribes and the Nevada State Historic Preservation Office have resulted in a public land memorandum of agreement for two efforts at the ACMS between BLM and SHPO with the tribes, NDEP and Atlantic Richfield as invited signatories. Additionally, the Yerington Paiute Tribe provided cultural monitors to help oversee areas with archaeologists to assist with any proposed disturbance, he said.

This part of the cultural resource planning helps conversations about preserving the land and wildlife connected to the area as workers strive to manage the precipitation and stormwater or isolate the fluids that might be hazardous in the process, Eckert said.

In phase two, the investigation and remedy process portion of the project, the goal will be to examine the extent of the contamination that has occurred in the ACMS, with remedial investigation and risk assessments to be completed in 2023. Eckert said the purpose of this is to ensure there is no potential harm to human or ecological health from mine-related contaminants. A feasibility study will be completed by 2024, a record of decision is planned for completion by 2025 and remedial design and action for phase two is planned from 2025 to 2028.

Eckert added the groundwater contaminants of concern as NDEP looks forward to phase two would be uranium, a radioactive element prevalent in the earth’s crust, and sulfate, or salts of sulfuric acid that had been used in the mining process for the extraction of copper or found in common fertilizers.

Lyon County Commissioner Dave Hockaday and interim County Manager Andrew Haskin attended the presentation. Hockaday said he would like to bring the information back in a separate presentation to the Lyon board.

“Mr. Eckert’s presentation was excellent and very thorough,” Hockaday told the Appeal. “I applaud the amount of work NDEP has accomplished to date. Conveying the information to the general public will take some time and is an important step in the process. I will be requesting a similar presentation be made to the Lyon County Board of Commissioners in 2023, I am certain there are many residents that would like to attend. Even though we will be long gone by the time this area is completely cleared environmentally, I am very happy the work is being done.”

“The Nevada Mining Association is impressed by the work NDEP is doing to remediate the site with costs being paid by responsible parties,” Nevada Mining Association President Tyre Gray said in a statement to the Appeal. “Additionally, we take pride in knowing a cleanup like this will never have to happen again thanks to modern mining regulations, putting environmental, safety, and health concerns at the forefront of operations. Finally, the state holds over $3.5 billion in bonding to ensure closure and reclamation are never again a matter of monetary restraints.”

For information about the cleanup, visit ndep.nv.gov/land/abandoned-mine-lands/anaconda-home.