Twenty Mancos community members attended a presentation on the cleanup and health impacts of an illegal gold mill shut down in town last year.
The 91-page report, released by the U.S. and Colorado Departments of Health, documents heavy-metal contamination at the unpermitted Red Arrow Gold Mill in Mancos, and at a company mine site in the La Plata Mountains.
The cleanup was successful, and health impacts are negated, but health impacts from the mill are unknown for workers.
"Contaminates at the mine and mill sites have been excavated and eliminated," said Dr. Raj Goyal, principal investigator with the Colorado Department of Health.
Of particular concern was the use of mercury to extract gold from ore at the Mancos mill, a practice no longer permitted because of health and environmental dangers.
EPA investigators collected 240 pounds of liquid mercury waste at the mill on Grand Avenue after it was shut down in June, 2013. At the mine site in the mountains, 12 tons of ore was found to have elevated levels of mercury, EPA officials said. Some mercury beads were clearly visible in the soil.
Ore material found at the mill, the mine, and at two locations on private land, were found to have toxic levels of heavy metals, including antimony, arsenic, chromium, copper, lead, and mercury.
The contaminated soil was removed, encased in a form of cement, and sent to certified landfills as far away as Wisconsin, and as close as the Montezuma County landfill. Liquid wastes are awaiting disposal in out-of-state facilities.
Cleanup came in at $230,000, a taxpayer expense, said EPA investigator Craig Myers.
"We're pursuing enforcement options," he said.
Audience members were concerned that groundwater was not tested.
Myers said because the mercury was focused inside the building, the EPA did not feel it was necessary. Soil below the ore piles was excavated.
Myers said natural mercury levels in the soil and mercury emitted for regional power plants would have made groundwater testing difficult.
"With the mercury being vacuumed up from the mill floor and surfaces, doesn't that raise concerns for the workers?" asked Mancos resident Jim Law.
It is thought that up to 10 people worked at the mill, estimated to be in operation between six and 11 months. Whether the workers were tested for mercury poisoning health officials do not know, and the matter is outside the scope of the study.
"We advise them to contact their physicians," said Goyal.
Cleanup officials said tests for airborne mercury came up negative. It is likely mercury vapors were emitted from the unpermitted mill site, the report says, but there is no way of estimating what the concentration was or how far it traveled.
"Based on qualitative evaluation from mercury surveillance, the potential for ambient exposures through inhalation pathways appears to be low," the report states. "Current and future exposures to tailings associated with the unpermitted mill are not likely to harm's people's health."
To view the report go to: https://www.colorado.gov/pacific/site/default/files/dc_eeost-red-arrow-mine-and-millsite.pdf
