Anaconda Mine Cleanup
State of Nevada requests deferment of Superfund Listing
On July 31, 2017, the State of Nevada Department of Environmental Protection (NDEP) sent a formal “Request for Deferment” to the US EPA Region 9 for the Anaconda Mine near Yerington, Nevada not to be placed on the Superfund National Priorities List (NPL). This is a dramatic development in the long history of attempted cleanup of this toxic, abandoned mine. Under deferment the site will not receive funds from the federal Superfund program and the State of Nevada would assume lead agency control and responsibility for the cleanup process.
Region 9 EPA has never executed a deferment process, so this would be new for both EPA and Nevada. In other cases of deferment outside of Region 9, sites were smaller and in the early stages of investigation, making deferment for this large, complicated and toxic site unique.
In order for EPA to agree to deferment a number of conditions must be met, including assurance that a CERCLA (Superfund) equivalent feasibility study will be conducted at the Site; that the remedy selected be substantially similar to a CERCLA response; and that appropriate enforcement mechanisms will be in place during cleanup activities at the site. In addition, the state must assure support for Tribal involvement (both the Yerington Paiute tribe and the Walker River Paiute Tribe), as well as other affected community members.
The directly affected communities (those whose health could be affected) first learned of the listing deferment approach in February of 2017. However, the State of Nevada, Atlantic Richfield Corp. (ARC, responsible for most cleanup costs), BLM, and EPA had been discussing deferment in private meetings for at least six months prior to February. Finally, on May 23, 2017 the State of Nevada and EPA organized the first of what would be three roundtable meetings on the deferment approach with other stakeholders.
GBRW participated in all three roundtables, has discussed the situation with the directly affected community, and met with NDEP. We found four main issues that need to be addressed in the final deferment agreements and process.
1. The public engagement process must improve and be responsive to public concerns.
The public learned at the end of June that the State of Nevada and ARC had already signed a preliminary “Framework Agreement” document on June 13, 2017 that formed the basis for how the cleanup will proceed and expresses the tone and priorities and liabilities of the cleanup process (This document will be superseded by a more detailed document currently in draft form, which was publically released). As a result, GBRW found that people in the directly affected community, who are primary stakeholders, do not trust the deferral strategy, since they were left out of early discussions. NDEP must develop a community involvement plan that maximizes transparency with regular updates, allows ample time for document review, and incorporates public comment into the decision making.
At the most recent roundtable on July 17 the Yerington Paiute Tribe requested an as needed 60 day period to review documents under the state lead cleanup scenario. The state responded that a 60 day review period would compromise the cleanup timeline proposed by ARC. A 60 day review period is the law under CERCLA; NDEP must allow as much review time. In addition, EPA conducts government-to-government meetings with the tribes as required by federal law, but no such law exists in Nevada, so Nevada must establish legal MOU’s to address this community and EPA priority.
2. The State of Nevada must demonstrate that it will enforce full cleanup.
Many in the affected community recall that prior to 2000 the State of Nevada did not require sufficient bonding for a portion of this site, and NDEP was unable to get ARC to pay for more than token activities prior to EPA involvement. Under EPA lead, ARC (owned by British Petroleum) has spent more than 100 million dollars in assessment and emergency response cleanups at the site. This has left many in the directly affected community feel that it is a risk to return to state control of the cleanup.
Due to the size, risk, complexity, and history of the site the directly affected community is concerned that only through EPA using its authority under CERCLA will be able to manage the complete cleanup of the mine site. NDEP will need to marshal very large resources to manage and enforce the cleanup process.
3. The agreements between the State of Nevada and Atlantic Richfield Corp. must contain a commitment to aquifer restoration.
The mine contaminated groundwater under the mine boundary and beyond the boundary, primarily to the north. The groundwater has been used for both drinking water and for agricultural irrigation. The goal of the cleanup should to restore the groundwater to those “beneficial” uses. It will likely require decades to clean up to the legal standards required under CERCLA. For example, the Homestake Mining Company Superfund site in Cibola County, New Mexico has a commitment to background level restoration and has been treating the various aquifers since 1989.
The goal of aquifer restoration must be clearly stated in both the deferment agreement between EPA and the State of Nevada and all other agreement documents. The Statement of Work must include a schedule to develop a feasibility analysis for remediation strategies to restore the aquifer.
4. The State of Nevada must require that ARC redraft a realistic site cleanup completion schedule.
The draft deferral agreement puts the site completion date in 2029. The site contains five acid heap leach pads, and there is no example of an acid heap leach facility that has been closed to date. In addition to the acid leach pads, are the waste rock dumps, a pit lake, tailings piles, evaporations ponds, massive topsoil needs, and groundwater that need to be addressed. “Long-term institutional management is likely for many more decades,” according to Dr. Glenn Miller, Professor of Natural Resources and Environmental Science, University of Nevada. For this reason and the need for ample time for public review and input the cleanup schedule must be redrafted.
GBRW and many in the affected community foresee costs for work, like groundwater cleanup, extending past 2029 and will therefore be borne by Nevada citizens. The agreement the State of Nevada is proposing to ARC is without precedent with a serious risk of allowing their responsibility to end on a date even if the job is left undone.
Anaconda Mine Chronology
1907 Empire-Nevada Copper Mining and Smelting Company discover Yerington deposit and operates at Yerington Site from 1918 to 1920.
1941 Anaconda Mining Company acquired the property.
1951 Weed Heights housing community constructed.
1952 The Process Areas and Acid Plant constructed at the Yerington Mine Site.
1952 Mining activities began with stripping of overburden.
1953 First copper oxide ore delivered to the leaching plant.
1961 Concentrator for processing sulfide ore and sulfide tailings dam constructed.
1965 Dump leaching of low-grade copper oxide ore in the W-3 Waste Rock dump began. 1967 Sulfide ore concentrator expanded to double capacity.
1973 Nevada Bureau of Mines and Geology reported on radioactivity at Site (Bulletin 81).
1976 U.S. Geological Survey (USGS) performed a study (report published in 1982) to investigate possible groundwater impact of tailings and brine disposal at the Anaconda Copper Mine Site.
1976 Kilborn/NUS Inc. issued a report to Wyoming Mineral Corporation evaluating the feasibility of a proposed uranium processing facility at the Yerington Site.
1977 ARC purchased Anaconda Minerals, including the Site.
1978 ARC shut down all mining and processing operations.
1979 Unison leased building space in the Process Areas for the purpose of dismantling transformers for disposal.
1979 Anaconda Copper Mine was entered into the Comprehensive Environmental Response, Compensation, and Liability Information System (CERCLIS) database.
1982 The Nevada Division of Environmental Protection (NDEP) issued a Finding of Violation (FOV) to ARC for alleged “unauthorized discharge of pollutants to waters of the state.”
1982 Site, including community of Weed Heights, purchased by Don Tibbals of Tibbals Construction (December 29, 1982).
1983 NDEP personnel and Lyon County Commissioners met to discuss the investigation of groundwater and surface water contamination.
1985 Under an Administrative Order issued by NDEP, ARC constructed the pumpback well system, including five pumpback wells (PW-1 through PW-5) and the associated approximate 23-acre pumpback evaporation pond.
1986 Copper Tek leaching operations were shut down by NDEP. An FOV and Administrative Order were issued to Tibbals in December.
1989 Don Tibbals and Copper Tek sold the Site to Arimetco, effective August 7, 1989, with the exception of the community of Weed Heights and a portion of the oxide tailings area. Copper Tek continued to operate the Yerington Project as an operating subsidiary of Arimetco.
1989 Arimetco began heap leaching and processing operations.
1990 The U.S. Environmental Protection Agency (EPA) conducted a Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) evaluation of the Site.
1991 Unison ended lease agreement and ceased transformer dismantling operations at the former Yerington Mine Site.
1992 Canonie Environmental signed a contract with Arimetco No. 84112-01.001 on June 26 to continue operations and maintenance of the pumpback well system and evaporation ponds, monthly water monitoring, and semiannual water quality sampling.
1993 Arimetco expanded onsite operations and posts a reclamation bond/corporate guarantee totaling $3.5 million as part of its financial assurance for reclamation.
1994 EPA conducted CERCLA prioritization and determined that the Anaconda Copper Mine was eligible for listing on the National Priorities List (NPL) as a Superfund site.
1997 Arimetco filed for bankruptcy protection but continued to operate the mine until January 2000.
1998 The U.S. Bureau of Land Management (BLM) was notified of NDEP concerns of offsite contamination, and NDEP requested BLM to consider the Site as a potential threat to groundwater and expedite steps for remediation.
1998 ARC installed six additional pumpback wells (PW-6 through PW-11) and modified the evaporation pond by partitioning the pond into three cells and adding clay liners.
1998 On December 17, NDEP issued Arimetco a Notice of Noncompliance and Order requiring them to reduce levels of operation down to a care and maintenance level and cease adding new ore and makeup water to the heap leach pads.
1999 ARC completed construction of the upgrades to the pumpback system. The system consists of six pumpback wells, one new monitoring well, and an evaporation pond divided into three cells.
2000 Arimetco abandoned operations at the Site, leaving four operational heap leach pads (HLP) with approximately 90 million gallons of pregnant leach solution (PLS) still in the system. The Site comes under NDEP Emergency Management.
2000 In September, NDEP capped a partially excavated, planned Arimetco Fluids Pond, north of the vat leach tailings (VLT) HLP, with VLT material, to mitigate “red dust” exposed during early construction. The newly scoped VLT pond was not completed.
2000 In October, EPA conducted an expanded Site Inspection, which included collecting groundwater samples from monitoring wells on and around the Site and standing water from a belowground cellar, PLS, tailings, and leachate salts.
2000 ARC upgraded the liner systems in the middle and south Pumpback Well System (PWS) evaporation ponds by installing 60-mil high-density polyethylene (HDPE) over the top of the existing clay liners. The north cell remains lined with the clay liner installed in 1998.
2000 In December, EPA requested Nevada’s position on listing the Site on the NPL.
2001 In January, Nevada responded to EPA’s letter regarding NPL listing and did not support listing.
2001 In March, NDEP capped three areas with VLT material, including (1) an area of calcines that were removed from the solution storage tanks and placed on top of the oxide tailings, (2) areas within the former calcine ditch, and (3) one of the strong fluids storage tanks to mitigate fugitive “red dust” generated on the Site.
2002 In March, NDEP completed capping of the Thumb Pond (the largest of the finger ponds) with VLT material to mitigate “red dust.”
2002 On March 28, a Memorandum of Understanding (MOU) was signed between NDEP, EPA, and BLM regarding coordination and oversight of assessment, characterization, and response activities at the Site. NDEP will coordinate all work to be performed under the October 24 Administrative Order on Consent, consistent with the requirements of the MOU. As parties to the MOU, BLM, and EPA will participate in the review of activities and requirements under this order.
2002 On September 23, NDEP issued an alleged FOV and order to Arimetco requiring that it generate a work plan and schedule for removing and disposing of remaining materials onsite. On October 23, NDEP issued a notice of the failure to comply and took over removal actions.
2003 In January, as part of the Site cleanup and removal action, NDEP arranged for collection and analysis of 400 drums and fluids remaining in the Arimetco solvent extraction (SX) and electrowinning (EW) facilities. The drum and EW removal projects were funded by the State of Nevada, were conducted through SRK Consulting, and have since been reimbursed by ARC.
2004 EPA assumed regulatory control of the Site.
2005 In March, EPA issued ARC a Unilateral Administrative Order Docket No. 9-2005-0011 to continue initial response actions.
2005 In October, EPA personnel conducted a removal assessment to determine issues that should be addressed short term. EPA determined two necessary activities: (1) ridding the Site of polychlorinated biphenyls (PCB) and (2) controlling mine waste containing dust from blowing off the Site.
2006 EPA removed approximately 170 transformers, switches, and containers at the Site that potentially contained unacceptable levels of PCBs.
2006 Using VLT material, EPA capped portions of the sulfide tailings area not previously capped and applied a sealant to other areas on the Site that were determined to be contributing to fugitive dust emissions.
2006 EPA constructed a 4-acre evaporation pond to contain excess drain-down fluids from the Arimetco heap leach fluids management system.
2007 In January, EPA issued ARC a Unilateral Administrative Order Docket
No. 9-2007-0005 to begin the Site wide remedial investigation and feasibility study process.
2007 EPA conducted a removal action to address fluid management issues associated with the Bathtub Pond. Removal actions included removing sediments and liner from the pond, backfilling and grading the pond, and constructing an interceptor trench along the shoulder of the pond.
2008 EPA removed the Mega Pond, two Raffinate Ponds, and the PLS Pond. Removal actions included removing sediments and liner from the ponds and backfilling and grading the ponds.
2008 EPA removed two organic traps (Vaults A and B), excavated kerosene-contaminated soils, and constructed the bioremediation cells on top of the Phase IV Slot HLPs.
2008 EPA approved a minimum 1-year shutdown of the PWS to evaluate its effectiveness and to investigate the shallow and intermediate hydraulic zones underlying northern areas of the Site.
2009 EPA issued ARC an Administrative Order on Consent Docket No. 09-2009-0010 for removal actions and settlement on past EPA response costs.
2010 EPA performed several removal actions, including removing the former Mine Site Administrative Building with asbestos-containing material, removing the tire pile located east of the Process Area, and improving existing security perimeter fencing.
2010 PA completed a Draft Supplemental Remedial Investigation and Human Health Risk Assessment on the Arimetco HLPs and Fluids.
Source:
“Historical Summary Report Anaconda-Yerington Mine Site Yerington, Nevada”
Prepared for:
Contract No. EP-S9-08-04/Task Order No. 012-RSBD-09GU U.S. Environmental Protection Agency
Region 9
75 Hawthorne Street
San Francisco, California 94105
Prepared by:
CH2M HILL, Inc.
50 West Liberty Street, Suite 205 Reno, Nevada 89501
October 2010