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.
Soil and groundwater contamination was previously treated at several locations using traditional technologies, such as groundwater pump-and-treat, soil vapor extraction, and active free product recovery. Innovative in-situ treatment technologies were also tested. These technologies included the use of materials that accelerate biological degradation, like soy oil, sodium lactate, and bark mulch. In February 2012, an amendment to the Record of Decision for Operable Unit 11 (Basewide Groundwater) was approved which changed the remedy for Basewide groundwater to in-situ reductive treatment (IRT) and monitored natural attenuation (MNA). In addition, The Air Force is providing clean drinking water to private residences adjacent to the Base whose drinking water wells have been contaminated.
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.
The Air Force has recently begun investigations into the potential presence of poly- and perfluoroalkyl substances (PFAS) in soil, groundwater, surface water, sediment, and drinking water at and adjacent to EAFB. PFAS are a class of synthetic fluorinated chemicals used in many industrial and consumer products, including non-stick cookware, stain-resistant fabrics, some food packaging, and in firefighting agents. In 1970, the Air Force, including EAFB, began using these firefighting agents to extinguish petroleum fires. These firefighting agents were released during training, equipment maintenance, and use. In 2016, the Environmental Protection Agency set a drinking water Health Advisory Level of 70 parts per trillion (0.070 Âµg/L) for two PFASs, perfluorooctane sulfonate (PFOS) and perfluorooctoanoic acid (PFOA), individually and combined. Documents of potential interest have been placed on the DENR on-line property search/spills database (Spills/Events Database) under DENR ID Number 2000.170. .
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
The complete, searchable, Administrative Record can also be accessed through the Air Force at the following internet site:
Scroll down the Installation List to Ellsworth AFB, SD
Gilt Edge Mine: Listed on NPL 12/00
The Gilt Edge Mine NPL Site is located southeast of the town of Lead in the northern Black Hills in Lawrence County, South Dakota. The lead agency for the site is the EPA with support from DENR.
The area has been mined intermittently by several owners beginning in the late 1800s for gold. Cyanide leaching, mercury amalgamation, and zinc precipitation among other methods were used to recover gold. Mining activities began at the site in 1876 when the Gilt Edge and Dakota Maid claims were located. Mining continued sporadically until 1916. The Gilt Edge Mining Company was incorporated in South Dakota in 1935; the mine reopened in 1937 and operated until 1941.
In 1988, the Brohm Mining Co. started to re-mine the site and continued until they went bankrupt and abandoned the site on May 29, 1998. When Brohm left the 258-acre open pit, cyanide heap leach gold mine it was un-reclaimed, 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.
The DENR, through legal means, had Brohm Mining Co. continue site maintenance and water treatment until July 1999. DENR assumed operations from July 1999 to August 2000 when the site was taken over by EPA's Emergency Removal Program. The site was placed on the National Priorities List in December 2000 and is currently under EPA Superfund Remedial Program.
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