Region 8

Ellsworth Air Force Base

Ellsworth AFB site location map Site Type: Federal Facility Final NPL
City: Ellsworth AFB
County: Meade, Pennington
Street Address: Ellsworth AFB
ZIP Code: 57706
EPA ID: SD2571924644
SSID: 08K1
Site Aliases: None
Congressional District: At Large

What's New?

Updated July 2012

For the first time since sampling began, trichloroethene (TCE) was below the federal drinking water regulatory limit of 5 micrograms per liter (μg/l) in all offsite monitoring wells east of the base in April 2012. Use of the groundwater for drinking may be restored in the affected area after multiple sampling events confirm that concentrations of TCE remain below 5 μg/l. Uses other than drinking water, such as irrigation, have been allowed from wells in this area since a modification to the decision document in April 2011.

Groundwater is currently identified as the only remaining portion of the site requiring further clean up. All surface areas of the site were proposed for deletion from the National Priorities List (NPL) under Superfund in the Federal Register in March 2012. No comments were received. The final notice of partial deletion was published in the Federal Register on May 25, 2012. Routine monitoring and maintenance will continue at deleted portions of the site.

An amendment to the record of decision was signed by EPA in February 2012, which will allow groundwater pump-and-treat systems on-base to be replaced by in-situ reductive treatment, or IRT. IRT involves injecting WesBlend (a mixture of molasses and dechlorinating bacteria) directly into the contaminated groundwater zone. Injections are not taking place off-base.

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Site Description

Ellsworth Air Force Base (EAFB) is a U.S. Air Force Air Combat Command base six miles east of Rapid City, South Dakota, next to the town of Box Elder. EAFB covers about 4,858 acres in Meade and Pennington counties. The base includes runways, airfield operations, industrial areas, housing and recreational facilities. EAFB is surrounded by farming and ranching lands, rural housing and light commercial activities.

military jet taxiing

EAFB began in July 1942 as the Rapid City Army Air Base, a training facility for B-17 bomber crews. In 1948, as part of the 28th Strategic Reconnaissance Wing, it became a permanent facility.

Historically, EAFB has been operations headquarters for a variety of aircraft, as well as the Titan I intercontinental ballistic missile system and the Minuteman missile system. Presently, the 28th Bombardment Wing (B-1B bombers) is the host unit of EAFB.

A half century of military activities left contamination on the base and on private land beyond its boundaries. EPA added EAFB to its National Priorities List (NPL) on August 30, 1990. The Air Force, EPA, and the state of South Dakota have worked as partners to clean up EAFB.

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Site Risk

Studies to identify hazardous substances were conducted in 12 general areas of EAFB, including landfills, a fire protection training area, spill sites, industrial areas and an explosive-ordnance disposal area. The hazardous substances found most often on the base are solvents and jet fuels, located in both soils and groundwater.

Some groundwater contaminants have moved beyond the EAFB boundary to the east and south at low concentrations, but above federal drinking-water standards. Continued use of the contaminated groundwater over long periods for household purposes, particularly as drinking water, could pose unacceptable health risks.

Groundwater is the only remaining media at the site currently requiring further cleanup. All surface areas of the site have been deleted from the NPL.

Media Affected Contaminants Source of Contamination
soil, sediment, surface water, groundwater solvents, jet fuels military activities

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Cleanup Progress

2003 groundwater plume
2006 groundwater plume
2009 groundwater plume
2011 groundwater plume
2012 groundwater plume

There are 12 operable units (OUs) at EAFB and remedies have been selected and implemented for all 12 OUs. These decision documents can be found in the Site Documents section. The Air Force installed cleanup systems to address possible future health risks at these OUs. Construction of cleanup systems is complete at all contaminated areas. The cleanup includes groundwater pump-and-treat systems, bio-dechlorination, landfill covers, soil treatment systems, excavation activities and natural attenuation (lessening). The systems are functioning properly. Beginning in 2007, in-situ reductive treatment (IRT) systems were installed to replace pump-and-treat systems.

EAFB obtains its potable water from the Rapid City municipal distribution system. In past years, EAFB obtained its water supplies from five wells that had been installed into deep bedrock aquifers at the base. These wells were taken out of service and have been abandoned in accordance with South Dakota requirements. Shallow groundwater in the area is typically used for domestic water supplies, irrigation and for livestock watering.

Groundwater contamination has impacted the drinking water wells of some homes to the east and south of the base. In 1999, EAFB completed a water supply line to provide treated water from the Rapid City municipal water system to off-base residents. Water was supplied to off-base residents by EAFB until 2007, when a license for operation and maintenance of the water supply line by the city of Box Elder became active.

The Air Force capped landfills and has enforced institutional controls to prevent unauthorized access to those landfills and to prevent the caps from being disturbed.

Contaminated groundwater is pumped out of the ground and purified to drinking water standards. The treated water is then either discharged to a local drainage, to the EAFB wastewater treatment plant or re-injected into the aquifer. A contaminated groundwater plume extends off-site to the east. Natural attenuation of the remaining contamination is occurring and will continue to be monitored. As of 2012, detections in the offsite plume are below the regulatory limit of 5 μg/l.

An amendment to the record of decision was signed by EPA in February 2012, which will allow groundwater pump-and-treat systems on-base to be replaced by in-situ reductive treatment, or IRT. IRT involves injecting WesBlend (a mixture of molasses and dechlorinating bacteria) directly into the contaminated groundwater zone. Injections are not taking place off-base.

Cleanup of the entire EAFB, including 20 years of groundwater treatment, is expected to cost approximately $80 million. All cleanup activities are being performed by the Air Force. EPA and the state of South Dakota provide regulatory oversight.

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Community Involvement

Community involvement plays an important role in the Superfund process. EPA uses a number of different tools and resources to promote effective, on-going, meaningful community involvement. The goals of the Superfund community involvement program are to:

  • Keep communities affected by sites informed throughout the cleanup process.
  • Provide opportunities for communities to comment and offer their input about site cleanup plans.
  • Facilitate the resolution of community issues tied to a site.

In June 2010, as part of the five-year review, 16 individuals were interviewed and asked for their impressions of how the environmental cleanup work at EAFB is progressing. The interviewees comprised a cross-section of the local community and included four county or municipal employees or elected officials, two local businessmen or developers, two on-base residents and eight off-base residents.

Overall, interviewees said they were aware of the cleanup and seemed satisfied with the progress being made. Eleven people said the effort is going well, and five had no comment or no impression.

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EPA places a high priority on land reuse as part of its Superfund response program mission. The agency tries to select cleanup options that encourage and support future use of a site. EPA uses two fundamental methods to facilitate reuse of Superfund sites:

  • Exploring future uses before the cleanup remedy is implemented, an approach that gives the Agency the best chance of designing cleanup remedies to support the likely future use of a site.
  • Working with landowners and communities to remove barriers not considered necessary for the protection of human health or the environment at those sites where remedies are already in place.

One option for reuse is the siting of clean and renewable energy projects on contaminated (or formerly contaminated) lands. As part of this effort, EPA is evaluating the potential for energy projects on these properties and working with landowners and communities to identify ways to remove barriers to such projects.

EAFB is in continued use as a U.S. Air Force Air Combat Command base.

A renewable energy project is in the early stages on-base. A closed-loop geothermal heat exchange system is in the test phase just north of the Twining Risner groundwater plume. A construction waiver and consultation process which includes the regulators is in place for development in areas where contamination remains.

Ellsworth Air Force Base: Reuse Fact Sheet

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Land Use Controls and Other Institutional Controls

Land use controls are the most common type of institutional control (IC). ICs are administrative or legal controls that help reduce the likelihood for human exposure to contamination. ICs can also help protect the integrity of the remedy. Examples of ICs are:

  • Zoning ordinances.
  • Environmental covenants.
  • Deed notices.
  • Well-drilling restrictions.
  • Building permits.
  • Informational advisories.

Ellsworth is a currently operating Air Force base, home to the B-1B bomber. All remedies are in place at this site, and protectiveness is maintained by several land use controls. A basewide continuing order controls access to remedies and remaining contaminants at closed landfills, clean up areas and areas involved in current groundwater treatment or monitoring. Fences are also present in select areas, with special permit signage, and the base itself is fully fenced from the public for general security.

Continuing Order: Land Use Restrictions at Environmental Restoration Sites, August 5, 2010

Residential and ranch properties on private water supplies exist to the east of the site, where contamination was historically released to groundwater. Alternate water has been supplied to this area and agreements are in place with local landowners restricting use of groundwater until protective conditions have been achieved. Alternate water may no longer be needed, as soon as 2015, based on observed groundwater concentrations in the area.

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Five-Year Reviews

EPA or the lead agency conducts five-year reviews following the start of a Superfund cleanup when contamination is left on the site. These reviews are repeated every five years. We use these reviews to determine:

  • How the remedy is working.
  • If the remedy remains protective of human health and the environment.

The third five-year review of the remedial actions implemented at EAFB was completed in September 2010 by the Air Force, as required by Section 121 of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, also known as Superfund). EPA agreed with all protectiveness statements, issues and recommendations.

The five-year review determined that groundwater remedies at EAFB are in place and operating, and that they protect human health and the environment because contaminated groundwater is contained at the base boundary, high concentration source areas have been identified and are being treated, and because land use controls and alternate water supplies prevent groundwater use.

All existing remedial systems require monitoring and occasional minor modifications. The EAFB environmental flight staff continues to conduct these efforts and ensure that the remedies remain protective of human health and the environment.

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Site Documents

You will need Adobe Reader to view some of the files on this page. See EPA's PDF page to learn more.

Decision Documents

Institutional Controls

Five-Year Review

Update to the Five-Year Review, June 2012

Third Five-Year Review Report (PDF), September 2010 (308 pp, 4.5 MB)


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Patricia Smith
Remedial Project Manager
U.S. Environmental Protection Agency, Region 8
1595 Wynkoop Street (8EPR-F)
Denver, CO 80202-1129
800-227-8917 ext. 312-6665 (toll free Region 8 only)

Site Information Repositories:

The Administrative Record
2125 Scott Drive
Ellsworth AFB, SD 57706-4711

South Dakota Air & Space Museum
2890 Davis Drive, Building 5208
Ellsworth AFB, SD 57706


Joane Lineburg
South Dakota Department of Environment & Natural Resources
Joe Foss Building
523 East Capitol
Pierre, SD 57501-3181


Melody Jensen
Remedial Project Manager
U.S. Air Force
2125 Scott Drive
Ellsworth AFB, SD 57706-4711

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Photo/Video Gallery

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Ellsworth Air Force Base Site at the South Dakota Department of Environment & Natural Resources Exit

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