The McDermitt and Cordero Mercury Mine sites consist of several non-contiguous locations:  the McDermitt Mine, the Cordero Mine, areas within the town of McDermitt where apparent mine waste has been used as fill, and areas of the Fort McDermitt Pauite Shoshone Reservation (the Reservation) where apparent mine waste has also been used as fill.  The Cordero Mine operated from the 1930s until 1970, and is located on land managed by the BLM and on private land.  The adjacent McDermitt Mine was operated from 1973 until the late 1980s.  The McDermitt Mine is located on private land.  The McDermitt Mine was closed under a permit from the Nevada Division of Environmental Protection (NDEP), and a final closure report was submitted in December, 1994.

The EPA Site Assessment program conducted a Site Inspection in 1988 which recommended no further action.  Upon request from the Fort McDermitt Pauite Shoshone Tribe, EPA Emergency Response conducted an additional site visit in November 2009.  At that time, EPA was notified of the possibility that mine waste had been used as fill at locations within the town of McDermitt and on the Fort McDermitt Paiute Shoshone Reservation.

In September and October of 2010, EPA conducted sampling of areas of red-colored fill located in the town of McDermitt and on the Reservation.  The town of McDermitt straddles the Nevada/Oregon border and numerous areas were identified which contained mercury and arsenic in soil at concentrations which exceeded the EPA Region 9 residential Soil Remediation Goals (SRGs).  Two areas were identified on the Reservation  which contained mercury and arsenic in soil at concentrations which exceeded the residential SRGs.

In June 2011, EPA conducted additional sampling of the mine waste present at the mine site and present in the town and on the Reservation.  The goal of this sampling effort was to evaluate the bioavailability and mineral speciation of the mercury and arsenic.  The USGS provided technical and analytical support to EPA in this effort.

On October 16, 2012, EPA signed an Action Memorandum describing removal activities to be performed.  EPA also issued a Unilateral Order to both Sunoco and Barrick Gold requiring these companies to participate in the cleanup process.  To date, both companies have declined to participate in work under these Orders. 

1.1.2.1 Location

The town of McDrmitt is located roughly 70 miles north of Winnemucca, NV, along Highway 95.  The town straddles the Nevada/Oregon state line.  The Fort McDermitt Pauite Shoshone Indian Reservation is located 3.5 southeast of the town of McDermitt and the McDermitt and Cordero Mines are located 7.2 miles southwest of the town of McDermitt.

1.1.2.2 Description of Threat

Mercury and arsenic are present in calcine material located on school property and on residential property in excess of site specific cleanup standards of 60 mg/kg arsenic and 80 mg/kg mercury.

1.1.3 Preliminary Removal Assessment/Removal Site Inspection Results

Removal assessment results are presented in Removal Assessment reports produced by the START contractor.  These reports are available on the epaosc web page.  The removal assessment documented the presence of mercury and arsenic at levels in excess of the site specific cleanup levels at approximately 40 residential properties.