Drilling of the UC-3 emplacement borehole UC-3 emplacement borehole site UC-1 Central Mud Pit prior to remediation UC-1 emplacement borehole casing UC-1 Central Mud Pit after remediation
Introduction:
On January 19, 1968, the Atomic Energy Commission (AEC), now known as the U. S. Department of Energy (DOE), detonated a nuclear device with a yield of 200 to 1,000 kilotons at a depth of 3,200 feet below ground surface. The nuclear detonation was conducted in the Hot Creek Valley in central Nevada. This test was named FAULTLESS and was designed to study the behavior and characteristics of seismic signals generated by nuclear detonations and to differentiate them from seismic signals generated by naturally occurring earthquakes. The FAULTLESS event produced an unexpected, large subsidence area with up to 15 feet of vertical displacement along a margin of more than a square mile.
CNTA Site Map
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Radiological contamination of groundwater resulted from the test. Today, scientists and engineers, contracted by DOE, are working to identify the risks where radiological contamination exists in groundwater, predict the movement of the contaminated groundwater, and define the contaminant boundaries or extent of migration of the radionuclides released during testing.

Regulatory Oversight:
The Nevada Division of Environmental Protection (NDEP) Bureau of Federal Facilities provides programmatic and regulatory oversight of federal facilities, including both U. S. Department of Energy (DOE) and U. S. Department of Defense (DoD) facilities, in Nevada.

The Federal Facility Agreement and Consent Order (FFACO), outlines a process to ensure that the DOE and/or the DoD, under the regulatory authority and oversight of the NDEP, identify sites of potential historic contamination, thoroughly investigate these sites, and implement corrective actions based on public health and environmental considerations.

The FFACO specifically covers the following federal facilities in Nevada: the Nevada Test Site (NTS), the Tonopah Test Range (TTR), the Nellis Air Force Range (NAFR), the Central Nevada Test Area (CNTA), and the Project Shoal Area (PSA).

For purposes of investigation and corrective action implementation, the Project Shoal Area and the Central Nevada Test Area are grouped as the Nevada Off-Sites. Each of these two sites is considered a separate Corrective Action Unit (CAU) based on geographic location.

The CNTA:
This Website has been developed by NDEP to improve public access to regulatory and programmatic information at the Central Nevada Test Area, Nevada (CNTA). The CNTA - (MAP) is located approximately 85 miles northeast of Tonopah, Nevada, along U. S. Highway 6 in the north-central part of Hot Creek Valley, Nye County, Nevada. The site was obtained by the Atomic Energy Commission for the purpose of developing potential alternative sites for underground nuclear testing and consisted of approximately 20 separate properties categorized as land withdrawals, land easements, and/or special land-use permits obtained from the Bureau of Land Management (BLM). The CNTA consists of three emplacement boreholes (UC-1, UC-3, and UC-4) - (Diagram) that were to be used for nuclear weapons-related device testing.

CNTA UC-1 casing Although three large emplacement boreholes (UC-1, UC-3, and UC-4) were drilled at the site for nuclear testing, Project FAULTLESS was the only nuclear device detonated. Emplacement boreholes UC-3 and UC-4 were never used and were closed in place in 1974.

Project FAULTLESS, having an announced yield of between 200 and 1,000 kilotons was detonated in emplacement borehole UC-1 on January 19, 1968, at a depth of 3,200 feet below ground surface in zeolitized tuff. FAULTLESS was designed to study the behavior and characteristics of seismic signals generated by nuclear detonations and to differentiate them from seismic signals generated by naturally occurring earthquakes and also to evaluate the usefulness of the site for higher-yield nuclear tests that could not be safely tested at the Nevada Test Site (NTS).

CNTA UC-1 subsidence cracks along the western margin of the sink The FAULTLESS event produced a large structurally controlled sink - (Diagram) with fractures thousands of feet in length. Vertical displacements on these fractures are as much as 15 feet and horizontal displacements are up to 3 feet. The land surface around the device casing subsided some 8 feet as seen in the photo above.

The CNTA is no longer in use for testing purposes. Both radioactive contamination of the deep bedrock around the shot cavity and hazardous waste contamination from the closed mud pits near the surface exist at the CNTA. Groundwater is the most likely transport medium for the deep contamination, however, because of the depth of the contamination (in excess of 3,200 feet) and the remoteness of the site, exposure to humans is unlikely. The Department of Energy decommissioned the site in 1973. Currently, all three CNTA areas are accessible to the public.

The selection of corrective action processes for both surface and subsurface contamination is based on site-specific information and conditions. Surface corrective actions are complete and the surface CAU (CAU 417) is now in the long-term monitoring phase.

The strategy for the subsurface is to characterize groundwater flow and contaminant transport through numerical modeling utilizing site-specific hydrologic data. The contaminant of focus is tritium, because, based on presently available data, it is the most conservative (i.e., remains in solution) and therefore the most mobile of the potential radiological contaminants.

Project Objective - The overall objective of the investigation is to define the hydrologic boundaries encompassing groundwater resources that may be unsafe for domestic or municipal use.

The boundaries will also define the area in which contaminants are expected to remain. It is anticipated that after boundaries have been established a determination can be made that monitoring alone will be acceptable and some form of active contaminant containment system will not be necessary.

The links at the bottom of the page provide more details about ongoing remediation activities at CNTA. For additional information contact Christine Andres, Nevada Division of Environmental Protection - Bureau of Federal Facilities
Mailing Address for Las Vegas Office:

2030 E. Flamingo Rd., Suite 230
Las Vegas, Nevada 89119
Phone: (702) 486-2850
Fax: (702) 486-2863
Bureau Chief: Tim Murphy
Mailing Address for Carson City Office:

901 South Stewart Street, Suite 4001
Carson City, Nevada 89701-5249


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