SD Mines Researchers Trace Pollution from Historic Northern Hills Mine Tailings Hundreds of Miles Downstream

Students taking part in research on this project include Bryce Pfiefle, the lead author of this paper, who graduated from SD Mines with a master’s degree in geological engineering.

The Black Hills of South Dakota was once home to the largest underground gold mine in North America – the Homestake Mine. Following its closure in 2002, the mine was turned into the Sanford Underground Research Facility. But, newly published research shows evidence of the past mining activities can still be found hundreds of miles downstream.

The history of gold mining in the northern Black Hills dates back about 130 years. During the first to middle part of the 20th century, about 100-million tons of mine tailings went down Whitewood Creek and into the Belle Fourche, Cheyenne and Missouri rivers. Research by a group of scientists, including James Stone, Ph.D., a professor of Civil and Environmental Engineering at the South Dakota School of Mines & Technology, along with others at the USGS Dakota Water Science Center show elevated levels of arsenic and other contaminants in these historic mine tailings.  

“The concentrations in the pore waters and sediments were quite high for arsenic in some sampling sites,” says Stone. 

In the 1980s, mine tailings along Whitewood Creek, found to contain arsenic, mercury and other pollutants, became an EPA Superfund Site. That clean-up project was completed in the 1990s and was reported as successful. This research examined mine tailings further downstream that were not removed.

“The concentrations are high, but the area does not have very many people,” says Stone. The sparse population means little contact with any contamination. He says the SD Mines study ended at the border of the Cheyenne River Reservation and he adds that ongoing studies by other research teams are now underway.

Those studying this problem point out that these contaminated sediments come from historic gold mining and there is still a fair bit of gold left over in the tailings. Mining these historic tailings could be one way to reclaim these streams and remove the contamination.

“There were some companies looking at this potential when the price of gold was high,” says Stone. “However, it’s not an easy fix. The challenge is you might remobilize those contaminants.” 

The research article titled “Arsenic Geochemistry of Alluvial Sediments and Pore Waters Affected by Mine Tailings along the Belle Fourche and Cheyenne River Floodplains” is published in “Water, Air, & Soil Pollution,” a scholarly journal that publishes research form around the world on these topics. 

Last edited 7/20/2018 1:54:58 PM

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