Ellsworth Air Force Base: Listed on NPL 8/90
Ellsworth Air Force Base (EAFB) is a U.S. Air Force Air Combat Command installation located 12 miles east of Rapid City. EAFB covers approximately 4,858 acres in Meade and Pennington Counties and includes runways and airfield operations, industrial areas, and housing and recreational facilities. Presently, the 28th Bombardment Wing (B-1B bombers) is the host unit of EAFB.
In 1990, EAFB was listed on the U.S. Environmental Protection Agency's National Priorities List. EAFB is on the National Priorities List in part because of the discovery of base-related contamination in water wells on adjacent private property. Sites include petroleum storage tanks, landfills, fire-training areas, explosive ordnance disposal areas, and radioactive waste sites. Contaminants of concern in soul and ground water are primarily petroleum products and waste solvents. Soil and ground water contamination is currently being treated at several locations using traditional technologies, such as ground water pump-and-treat, soil vapor extraction, and active free product recovery. In addition, the Air Force is providing clean drinking water to private residences adjacent to the Base whose drinking water wells have been contaminated. Innovative in-situ treatment technologies are also being tested, or are planned for the near future. These technologies include the use of materials that will accelerate biological degradation, like soy oil, sodium lactate, and bark mulch.
On December 4, 2006, the Environmental Protection Agency announced its decision to delete portions of the Ellsworth Air Force Base Superfund Site from the National Priorities List. This partial deletion pertains to soil, surface water and sediment at Operable Units 2, 3, 4, 5, 6, 7, 8, 9, 10 and 12. All ground water at the site, designated as Operable Unit 11, and the soil at Operable Unit 1 will remain on the National Priorities List. Active treatment and monitoring will continue for these Operable Units.
For More Information
If you would like detailed information about the cleanup at EAFB, you can review documents at the following locations:
The Administrative Record Building
The EAFB Information Repository
Gilt Edge Mine: Listed on NPL 12/00
About the Site
The Gilt Edge mine is located about five miles east of Lead, in the northern Black Hills. It is a 260-acre, open-pit, cyanide heap leach gold mine that encountered sulfidic ore during mining. After the operator became insolvent the mine was left with acidic, heavy metal-laden water in three open pits. The mine site is in need of acid water treatment and capping acid generating waste rock.
Site Description and History
Mining for gold, copper, and tungsten has been conducted in this small mining district since 1876. About a century ago, a series of small underground mines operated and left behind metal-laden mill tailings in Strawberry and Bear Butte Creeks, which impacted water quality significantly. Early testing by Brohm Mining Corporation's (BMC) predecessor indicated that acid generating material would not be a problem. Therefore, under a state mining permit, BMC, in 1988, began developing two open pits, a large cyanide heap leach pad, and a 12 million cubic yard valley-fill waste rock dump, as well as other operations. During construction and operation, BMC cleaned up a lot of the historical tailings both on and off-site. Mining continued until the permitted reserve was mined out in 1992.
Acid mine drainage was confirmed emanating from BMC's waste dump in 1993. At that time, the state issued BMC a notice of violation and order and required BMC to prepare a mine permit amendment to address the acid mine drainage issue and to increase the reclamation bond. BMC's parent corporation was experiencing financial difficulties at that time, which ultimately resulted in a financial reorganization in Canada in 1993.
From 1993 to 1995, BMC planned for a new mine adjacent to the Gilt Edge mine called Anchor Hill. This mine was to provide the cash flow and construction materials needed to close the Gilt Edge mine. The state permitted the Anchor Hill mine in 1996, but with conditions designed to increase the cash reclamation bond. These conditions increased the cash bond before permitted reserves on private land were mined out in 1997 and mining had to cease again. The remainder of the Anchor Hill project depended on U.S. Forest Service approval because 12 acres of the pit were on U.S. Forest Service land.
Due to appeals of the U.S. Forest Service approval and lack of financing, the company notified the state that it would abandon the property in 1998. Governor William J. Janklow took BMC to the 8th Circuit Court and was successful in getting both a Temporary Restraining Order and Preliminary Injunction issued that prevented BMC from abandoning the mine. Meanwhile, environmental groups sued BMC for alleged violations of the Clean Water Act. In 1999, a creditor that had been providing limited funding to maintain operations at BMC in hopes of getting U.S. Forest Service approval refused to provide additional funding, and BMC's parent filed for bankruptcy in Canada in July 1999.
Governor Janklow averted a discharge of acid water by authorizing the SD Department of Environment and Natural Resources (DENR) to pay for water treatment. In February 2000, Governor Janklow requested that EPA Region VIII propose the site for the Superfund National Priorities List (NPL) and provide immediate emergency response and long-term remedial cleanup. The Gilt Edge site was llisted on the NPL on December 1, 2000.
Sulfide waste rock and exposed sulfide zones in the mine pits generate leachates to surface and ground water which contain heavy metals, including arsenic, cadmium, copper, lead and zinc.
The site is currently on the National Priorities List (Superfund List) and EPA is conducting an EPA fund lead cleanup action at the mine site.
For More Information Contact: