2010 Groundwater Monitoring Report Central Nevada Test Area, Corrective Action Unit 443 Page: 7 of 36
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This report presents the 2010 groundwater monitoring results collected by the U.S. Department
of Energy (DOE) Office of Legacy Management (LM) for the Central Nevada Test Area
(CNTA) Subsurface Corrective Action Unit (CAU) 443. Responsibility for the environmental
site restoration of CNTA was transferred from the DOE Office of Environmental Management to
LM on October 1, 2006. The environmental restoration process and corrective action strategy for
CAU 443 are conducted in accordance with the Federal Facility Agreement and Consent Order
entered into by DOE, the U.S. Department of Defense, and the State of Nevada. The corrective
action strategy for the site includes proof-of-concept monitoring in support of site closure. This
report summarizes investigation activities associated with CAU 443 that were conducted at the
site from December 2009 through December 2010. It also represents the second year of the
enhanced monitoring network and the 5-year proof-of-concept monitoring period that is intended
to validate the compliance boundary.
2.0 Site Location and Background
CNTA is north of U.S. Highway 6, approximately 30 miles north of Warm Springs in Nye
County, Nevada (Figure 1). The U.S. Atomic Energy Commission (predecessor to DOE)
acquired CNTA in the early 1960s to develop sites for underground nuclear testing that could
serve as alternatives to the Nevada Test Site. Three emplacement boreholes-UC-1, UC-3, and
UC-4-were drilled at CNTA for underground nuclear weapons testing. The initial underground
nuclear test, Project Faultless, was conducted in borehole UC-1 at a depth of 3,199 feet (ft)
(975 meters) below ground surface on January 19, 1968. The yield of the Project Faultless test
was estimated to be 0.2 to 1 megaton. The test resulted in a down-dropped fault block that
extends to land surface (Figure 2). No further nuclear testing was conducted at CNTA, and the
site was decommissioned as a testing facility in 1973.
2.1 Summary of Corrective Action Activities
Surface and subsurface contamination resulted from the underground nuclear test at CNTA.
Contamination at the surface was identified as CAU 417. Surface restoration was completed in
1999, and the remediation activities are described in the Closure Report for Corrective Action
Unit 417: Central Nevada Test Area Surface, Nevada (DOE 2001). Contamination in the
subsurface is identified as CAU 443. The corrective action process for the subsurface CAU 443
has not yet been completed. Site restoration activities associated with CAU 443 are summarized
in the remainder of this section.
A Corrective Action Investigation Plan was developed and approved for CAU 443 in 1999. The
objectives outlined in that document are provided below:
. Determine the characteristics of the groundwater flow system, sources of contamination, and
transport processes, to acceptable levels of uncertainty;
. Develop a credible numerical model of groundwater flow and contaminant transport for the
UC-1 Subsurface Corrective Action Site and downgradient areas; and
. Develop stochastic predictions of the contaminant boundary, at an acceptable level of
uncertainty (DOE 1998).
U.S. Department of Energy 2010 Groundwater Monitoring Report, CNTA, CAU 443
February 2011 Doc. No. 507116
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2010 Groundwater Monitoring Report Central Nevada Test Area, Corrective Action Unit 443, report, February 1, 2011; United States. (https://digital.library.unt.edu/ark:/67531/metadc870352/m1/7/: accessed April 19, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.