TCE is a nonflammable, colorless liquid with a somewhat sweet odor similar to ether and a sweet, burning taste. TCE was a common industrial solvent used extensively in the 60s, 70s, and somewhat in the 80s to remove oils and grease from metal parts.

The exact way TCE was introduced in the groundwater is unknown. From historical records and interviews, it is known TCE was used to flush fuel chambers in missiles and to clean other components. It is suspected that TCE was introduced into the groundwater from operation and maintenance by missile site crews disposing of spent TCE and residual RP-1 fuel in the sump below the launch building, which then entered the shallow groundwater and then spread.

At the concentrations found in groundwater, there is little likelihood someone drinking the contaminated water would feel ill immediately. The USEPA has set a standard for public water supplies requiring that drinking water provided to the public have no more than 5 ug/L (micrograms per liter)—or 5 parts per billion—TCE. This standard is set for the protection of human health. Differences in the way TCE is processed by humans and animals have prompted the USEPA to reevaluate the cancer risk of long-term exposure to TCE.

You will not be able to tell on your own if there is TCE in your water. It must be sampled according to scientific standards and sent to an accredited laboratory for analysis. If you have specific concerns, you may contact any of the people at the bottom of this page.

If your water has been tested and contains concentrations of TCE at levels at or above 5 parts per billion, it is recommended that you do not continue to drink or use it for cooking, bathing, or showering. Alternatives for making sure the water you consume is safe include drinking bottled water, or purchasing a home water treatment system to reduce contaminants to safe levels.

Groundwater contamination levels of TCE are highest in the area directly below the Atlas missile launchers. Investigations are focused on determining the extent of contamination. The Army Corps of Engineers have provided bottle water and installed carbon filtration treatment systems on private wells that have been sampled and confirmed to have TCE concentrations above 5 parts per billion. Soil contamination above state and federal guidelines, has not been found at the site and does not pose a health risk to nearby residents.

There have been no detections of TCE found at soil depths between the ground surface and the top of the water table, so exposure to TCE via soil is extremely unlikely. A person could be exposed to TCE by directly consuming contaminated water, however, many precautions are being put in place to prevent this from happening. Exposure via inhalation of volatilized TCE is considered extremely unlikely.

Based on the likelihood that TCE will volatilize, or evaporate, when the groundwater is pumped to stock tanks or reaches streams, will further dilute in streams, and its low toxicity to cattle, it is unlikely that exposure to TCE in water will harm cattle.

TCE is the primary contaminant of concern. Although a few other contaminants were detected in low concentrations directly at the Atlas 4 site, they were only found in areas immediately below the launch sites and have not been detected elsewhere. There is no evidence that these contaminants have spread.

The City of Cheyenne gets some of its water supply from wells near the TCE plume area. Water production wells in the Borie Well Field are connected to a pipeline that transports the water to a central treatment plant. At the treatment plant water is treated to remove all contaminants that may be present (including TCE). Water leaving the treatment plant is tested and meets all requirements under the Safe Drinking Water Act. Some of the Cities’ production wells have detected elevated concentrations of TCE at the well head, however, the water gets treated prior to being distributed to the public.

Water quality is tested before and after it enters the municipal water treatment facility. Water leaving the facility must have TCE well below 5 ppb, a standard that is even stricter than what is required by the USEPA. Testing has consistently determined that there is no TCE contamination in the City of Cheyenne water supply.

The Department of Defense is ultimately responsible for any contamination as a result of prior DOD activity. The US Army Corps of Engineers is tasked to manage and clean up contaminated sites under the Formally Used Defense Sites program.

Cleanup is being funded by the Formerly Used Defense Site (FUDS) program, and is being administered by the US Army Corps of Engineers.

Engineering measures can be taken to remove TCE from groundwater. One such method relies upon aeration, or air stripping. Using this method, the contaminated groundwater would be mixed with air, and the TCE would volatilize out of the water. Other measures, such as the absorption of TCE on carbon filters can also remove TCE from groundwater.

The TCE plume is large and deep, and runs underground for many miles. It would be both physically and financially impossible to remove 100% of the contamination in the soil vapor, saturated soil, and groundwater. However, monitoring wells have been installed throughout the plume area to enable regular testing and evaluation of subsurface water in the future. In addition, TCE can be completely removed by the municipal water treatment facilities before the water leaves the treatment plant and moves through the public distribution lines.

Cleanup at various locations along the contaminated area will take several years. Throughout this process and afterward, regular monitoring and maintenance will take place indefinitely into the future. Water and soil will be routinely tested and monitored for changes. If changes occur, future actions will be taken to ensure the safety of the public and the water supply.

No. The TCE is far below any surface soils that the public might be exposed to. Any future water supplies to this area will provide only uncontaminated water.

US Army Corps of Engineers, Omaha District

Erin Stewart, Project Manager
Tel: (402) 490-9022
Email: erin.a.stewart@usace.army.mil

Wyoming Department of Environmental Quality

John Passehl, Geology Supervisor
Tel: (307) 777-5623

Email: john.passehl@wyo.gov

Cheyenne Board of Public Utilities

Clint Bassett
Email: CBassett@cheyennebopu.org

US Environmental Protection Agency

Rob Stites
Email: stites.rob@epa.gov