McDERMITT — When the residents of McDermitt needed fill for roads or driveways, they knew right where to go: the abandoned Cordero mercury mine just seven miles away. The waste ore from the roaster provided plenty of such material for unpaved roads and parking lots.
Mercury was first discovered near the community on the Oregon border in about 1924 and two mines went into production: the Cordero Mine and the McDermitt Mine. By World War II, Cordero was the largest producer of mercury in the state but operations ceased there in 1970.
In 2009, the EPA visited McDermitt at the request of the Fort McDermitt Pauite Shoshone Reservation representatives who expressed concern about possible contaminants from the old mine site.
According to Tom Dunkelman, with EPA’s Emergency Response, it was then the EPA learned the residents of McDermitt and the reservation had been putting calcine from the abandoned Cordero roaster to use … well, everywhere. And they had been doing so for decades.
Unfortunately, the roasting process did not capture all the ore’s mercury content. The waste ore from the roasting process, called calcine, left behind at the mine site still had mercury and arsenic content.
In 2010, the EPA conducted soil tests that indicated areas of McDermitt and the Ft. McDermitt Pauite Shoshone Reservation showed concentrations of mercury and arsenic that exceeded EPA regulations.
The EPA determined some properties with calcine material would have to have it removed and clean fill put in its place. Other properties had calcine in quantities too large to be removed; in those cases it was determined the best course of action was to cap it in place.
Initially some residents balked at having their driveways and landscaping torn up by the EPA. Dunkelman and staff from the EPA held town hall meetings with residents, town officials and representatives from the school district.
As the removal of calcine material from private property was entirely voluntary, initially only 30 residents signed up. Dunkelman did not give up. He continued meeting with residents, even going door-to-door, until all 56 residential properties — including two on the reservation — agreed to the removal of the calcine.
Dunkelman said once work started, and the residents saw the quality of work, the people who had initially declined later agreed to have the calcine from their properties removed and replaced.
Dunkelman said, “The community has been great to work with. From my point of view this has been an excellent project.”
Resident Dale Hartley had the gravel replaced in his driveway. He praised the EPA and contractors for the quality of the work performed and their professionalism.
At the McDermitt Combined School approximately 311, 682 square feet of mine waste required remediation. EPA found calcine material on the east side of the football field, the large parking lot adjacent to the football field, and in areas surrounding the playground.
According to the report issued by Dunkelman, of the 311,682 square feet, 594 cubic yards of mine waste was excavated from 45,958 square feet located near the football field, 247,231 square feet (5.56 acres) of mine waste was capped in place at the school parking lot, and 18,493 square feet of mine waste was capped in place at the school playground.
Additionally, a total of 40,410 square feet of mine waste was capped in place on two unpaved roads in the town of McDermitt. This work was performed in conjunction with the McDermitt General Improvement District.
EPA also provided backfill material to Malheur County, Oregon, in order to cap 25,270 square feet of mine waste at one unpaved road, identified as Margarita Road and located west of U.S. Highway 95.
On the reservation, 25,586 square feet of mine waste was capped in place at one unpaved access road leading to the tribal transfer station.
Ultimately about 10,000 tons of calcine were removed from McDermitt and taken back to Cordero. Another 40,000 tons of calcine were capped in place with clean material.
Funds for the cleanup came from the EPA’s Superfund monies, but Cordero itself has not been identified as being on the Superfund National Priority List.