Record of Decision System (RODS)
ELLSWORTH AIR FORCE BASE
|Site Name:||ELLSWORTH AIR FORCE BASE|
|City & State:||ELLSWORTH AFB SD 57706|
|NPL Status:||Currently on the Final NPL|
|ROD Type:||Record of Decision|
|Media:||soils, surface water, sediments|
|Contaminant:||Benzene, toluene, ethylbenzene, xylene, PAHs, jet fuel.|
Please note that the text in this document summarizes the Record of Decision for the purposes of facilitating searching and retrieving key text on the ROD. It is not the officially approved abstract drafted by the EPA Regional offices. Once EPA Headquarters receives the official abstract, this text will be replaced.
Ellsworth Air Force Base (EAFB) was officially activated in July 1942 as the Rapid City Army Air Base, a training facility for B-17 bomber crews. It became a permanent facility in 1948, and historically has been the headquarters of operations for a variety of aircraft. The Air Force has used EAFB for support, training, maintenance, and/or testing facilities. It is still an active Air Force Base.
The Operable Unit (OU 9) study area consists of the Old Auto Hobby Shop and the surrounding area. OU 9 is approximately 90 acres in size and is located in the south-central section of the Base. A number of different contaminant sources are present within and upgradient of the OU 9 study area which have the potential to impact environmental media at the operable unit. OU 9 consists of roughly equal portions of industrialized and undeveloped areas. Gateway lake is also included as part of OU 9 and is located in the extreme southeast corner of the OU. Groundwater cleanup and the fish-ingestion exposure pathway will be addressed as part of the Basewide groundwater operable unit, OU 11.
The types of potential contaminant source areas at OU 9 include: building operations, underground storage tanks (USTs), the former Quartermaster Gasoline Dispensing Area, the former fuel transfer line, industrial waste lines, jet engine test facilities, and upgradient source areas. There is no known documentation of major spills or releases at OU 9. Small volumes of fuels, oils, and solvents may have been released to the environment over time through incidental spills, leaks, or poor waste handling and disposal practices.
In 1993 and 1994, an extensive Remedial Investigation (RI) field program was conducted to characterize conditions at OU 9. The program included drilling and sampling of boreholes, installation of groundwater monitoring wells, groundwater sampling, geotechnical analysis of soil samples, ecological evaluation, assessment of human health risks, and review and compilation of previous investigations. Collection and laboratory analysis of soil, groundwater, surface water, and sediment samples were included in the RI field program.
Contamination occurred in soils, surface water, and sediments. Soil contamination consisted of organic compounds such as benzene, toluene, ethylbenzene, xylene, polycyclic aromatic hydrocarbons (PAHs), and jet fuels. Sediment contamination consisted primarily of PAHs. Surface water contamination consisted of arsenic, lead, iron, and manganese but were considered to be naturally occurring at the detected concentrations.
|Remedy:||The selected alternative for OU-9 is No Action. Media affected solely by petroleum hydrocarbon contamination will be addressed through State of South Dakota programs for Underground Storage Tank removal and/or petroleum- contaminated soils. Groundwater cleanup and the fish-ingestion exposure pathway will be addressed as part of the Basewide groundwater operable unit, OU 11.|
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