Thousands of contaminated sites exist nationally due to hazardous waste. Nine sites of note exist in South Dakota.
Informally called the Superfund, the 1980 Comprehensive Environmental Response, Compensation and Liability Act allows the Environmental Protection Agency to clean up contaminated sites. Superfund also makes the responsible parties do the clean-up or reimburse the government. When there is no viable responsible party, Superfund gives EPA the funds to clean up contaminated sites.
South Dakota has two current Superfund sites.
Ellsworth Air Force Base covers over 4,850 acres in Meade and Pennington counties. In 1990, EAFB was listed on the EPA’s National Priorities List, in part because of base-related contamination in nearby water wells. Sites include petroleum storage tanks, landfills, fire-training areas, explosive ordnance disposal areas, and radioactive waste sites. Contaminants in soil and groundwater are mostly petroleum products and waste solvents. Soil and groundwater contamination is currently being treated. The Air Force is providing drinking water to private nearby residences. In 2006, the EPA deleted portions of the EAFB Superfund Site from the National Priorities List. All ground water at the site remains on the list. Active treatment and monitoring will continue. The Air Force is investigating the presence of poly- and perfluoroalkyl substances, which were used to practice extinguishing petroleum fires.
The Gilt Edge Mine is southeast of Lead in the northern Black Hills. The area has been mined for gold since the late 1800s. Cyanide leaching, mercury amalgamation, and zinc precipitation were used to recover gold. In 1988, the Brohm Mining Company started re-mining the site. They went bankrupt in 1998. The un-reclaimed site contained 150 million gallons of heavy-metal-laden acid water in three open pits, 3.3 million tons of ore on the heap leach pad, and 12 million cubic yards of acidic waste rock. DENR assumed site maintenance and water treatment operations. In 2000, the site was taken over by EPA’s emergency removal program and put on the National Priorities List. The site is currently under EPA’s Superfund remedial program.
Two South Dakota sites have been taken off of the Superfund list.
Williams Pipeline Disposal Pit was a petroleum terminal in Sioux Falls. The terminal operated a pit used in the 1970s for disposal of storage-tank sludge. The EPA determined that the sediments contained volatile organic compounds, heavy metals, pesticides and polycyclic aromatic hydrocarbons. Groundwater under and near the pit was contaminated. In 1990, the EPA listed the site on the Superfund National Priorities List. The EPA determined there was not an unacceptable risk from site contamination. Thus, the action required was to conduct a minimum of two years of groundwater monitoring for arsenic. The EPA delisted the site from the Superfund priorities list in 1999.
Whitewood Creek flows through Lead and Deadwood. Until 1984 the creek was severely impacted by the discharge from Homestake Mining Company operations. Pollution extended into the Belle Fourche and Cheyenne Rivers and into the Oahe Reservoir. A 1971 EPA study showed that Homestake was daily discharging 312 pounds of cyanide, 240 pounds of zinc, 721 pounds of copper and 2,700 tons of suspended solids, and 9.5 tons of arsenopyrite into the creek system. In 1981, an 18-mile stretch of Whitewood Creek from Whitewood to the Belle Fourche River was proposed for the National Priorities List. Cleanup actions were done by Homestake in the creek’s flood plain. Residential sites were cleaned up to reduce the health risks. In 1994, Lawrence, Butte and Meade counties banned future excavation and construction on tailings remaining along the creek. The site entered the operations and maintenance phase, which required water sampling of the creek, monitoring, a yearly education program, and a five-year review program. The EPA delisted the site from the Superfund priorities list in 1996.
The military has created five notable contamination sites in South Dakota.
The Black Hills Ordnance Depot was created in 1942 in Fall River County. In 1962, the 21,095-acre site was renamed the Black Hills Army Depot. It was used for ammunition, propellants, and chemical toxics. The depot closed in 1967. The city of Edgemont purchased some of the land, and the rest was transferred to the United States Forest Service. Currently, the entire site is used for livestock grazing. In 1981 it was determined that a change in land use, such as housing or crops for human consumption, should be avoided.
In 1942 the federal government leased 341,725 acres on the Oglala Sioux Pine Ridge Indian Reservation. Until the mid 1970s, the Pine Ridge Gunnery Range/Badlands Bombing Range was used for bombing practice and as an artillery impact range. Five unexploded ordnance clearing projects have been done, and environmental monitoring is ongoing.
From 1942 to 1946, the federal government used 7,700 acres in Bon Homme and Yankton counties as the Yankton Air-To-Ground Gunnery Range. Currently, the U.S. Army Corp of Engineers is conducting a site investigation under their military munitions response program to confirm the site is clear of potentially hazardous munitions debris.
In 1942, the federal government acquired 1,803 acres in Union County for use as the Sioux City Precision Bombing Range No. 2. It supported machine gun and bombing practices from the Sioux City Army Air Field. In 1945, the federal government terminated all leases for the site. Currently, the U.S. Army Corp of Engineers is conducting a site investigation under their military munitions response program to confirm the site is clear of potentially hazardous munitions debris. This site file is now closed.
In 1943, the federal government acquired 8,056 acres as a precision bombing range, the Sioux City Precision Bombing Range No. 6. It consisted of around 3,716 acres in Bon Homme County. By the end of 1946, all leases had been terminated. Currently, the U.S. Army Corp of Engineers is conducting a site investigation under their military munitions response program to confirm the site is clear of potentially hazardous munitions debris. This site file is now closed.