Central Nevada Test Area and Project Shoal site Area — The Central Nevada Test Area and Project Shoal site are administered by the Nevada Operations Office. The Central Nevada Test Area is located in south central Nevada, 96 kilometers (60 miles) northeast of the City of Tonopah. The Project Shoal Site is located 48 kilometers (30 miles) southeast of Fallon, Nevada.

The Department of Energy (DOE) used this site for one subsurface nuclear test, Project Faultless, detonated in January 1968. The DOE conducted the test to determine the suitability of the area for additional testing. It also conducted nonnuclear special experiments top determine the behavior of seismic waves. The Central Nevada Test Area is no longer in use. The land surface has been released for unrestricted use while subsurface intrusion restrictions are still in effect.

The Central Nevada Test Area includes radioactive contamination of the deep bedrock around the shot cavity and hazardous waste contamination from the closed mud pits near the surface. Ground water is the most likely transport medium for the deep contamination; however, because of the depth of the contamination (in excess of 976 meters [3,200 feet]) and the remoteness of the site, exposure to humans is unlikely. The DOE decommisioned the site in 1973.

Project Shoal is approximately 30 miles southeast of Fallon. The DOE conducted a nuclear test at the site in October 1963. The purpose of the test was to determine the effect of a nuclear detonation in a granite rock formation and to compare the seismic activity of natural earthquakes with activity from an underground nuclear explosion. A 12-kiloton device was detonated at a depth of 369 meters (1,211 feet). The test was conducted to improve the ability to detect underground nuclear explosions.

At the Project Shoal site, contamination consists of radioactive contamination of the deep granite bedrock and ground water around the shot cavity and in the access drift for the device emplacement. Ground water is the most likely transport medium for the deep contamination; however, because of the depth of the contamination (in excess of 402 meters [1,320 feet]) exposure to humans of the environment from this material is unlikely. The DOE has not confirmed the existence of surface contamination from the abandoned mud pit. Contaminated soil and drill cuttings are reported to have been mixed with clean fill and buried onsite, but the DOW has not confirmed this report.

This estimate assumes the DOE will maintain control of these sites. A definitive future use plan is not complete. However, this report assumes the surface of these sites will be cleaned to a level that permits Open Space use. The subsurface of the sites will be maintained by the DEO as a Controlled Access area. The final future-use designation for these sites will be determined by negotiations between the DOE and the State of Nevada.

The environmental restoration strategy will be to characterise ground water flow and areas of contamination, assess risk, and model contaminant movement away from the shot cavities. The focus will be on tritium, since it is the most mobile of the potential radiological contaminants. The DOE will make maximum use of the existing data, including monitoring data collected from the Long-Term Hydrolic Monitoring program well networks at each area. The Long-Term Hydrolic Monitoring program sampling has been completed annually at Project Shoal and the Central Nevada Test Area since 1972. The Department of Energy and the State of Nevada are currently preparing a Federal Facilities Agreement to govern future activites at these sites.

Assessment activites provide for the evaluation of data collected at the Central Nevada Test Area and the Project Shoal site. Assessment activites at the Central Nevada Test Area and the Prohject Shoal site will be conducted in accordance with the Federal Facility Agreement and Consent Order. Activities at these sites are assumed to consist of characterising the ground-water flow using existing monitoring well and characterising the surface areas using additional field samples and tests. These activities will provide information for generating a risk assessment for each site. Assessment activities at Shoal are assumed to begin in FY 1996. Assessment activities at the Central Nevada Test area are not scheduled to begin until FY 2002.

Waste is due to subsurface nuclear detonations in and around the shot cavities. Until characterisation activites are completed, remediation activities cannot be completely defined.

Surface contamination at the Central Nevada Test Area consists of surface mud pits at the UC-1 and UC-4 areas that contain drilling mud contaminated with medals and diesel fuel. A risk assessment will be conducted to determine the best method for dealing with the mud pits. Low-level and other waste in and around the subsurface shot cavities will not be removed. Surface waste, assumed to comprise approximately 3,850 cubic meters (5,044 cubic yards) of contaminated soil (hazardous waste) will be shipped to an appropriate commercial disposal facility for disposal.

This estimate assumes the shaft at the Shoal Test Area will be sealed. Negotiations are currently under way with the State to determine the best method for dealing with the shaft. Surface contamination at Project Shoal consists of a mud pit in which contaminated soil and cuttings from the post-shot drilling were mixed with clean soil and buried. This estimate assumes the contamination is below regulatory levels of concern and no removal actions will be required. If the areas of potential contamination are not adequately bounded by the present Long-Term Hydrologic Monitoring program networks, or if there are potential exposure pathways not presently monitored, remedial actions may include adding more monitoring wells to the existing network, placing use restrictions on the ground water, excavating surface mud pits, and sealing and abandoning the Shoal shaft.

The Environmental Protection Agency (EPA) is monitoring the Project Shoal site and the Central Nevada Test Area as part of the Long-Term Hydrologic Monitoring program. Monitoring consists of sampling selected ground-water and surface-water collection locations around each site. Sampling requires approximately one week per year per site, plus the analysis of approximately 20 samples per site per year. Modifications to the Long-Term Hydrologic Monitoring program networks and ground-water use restrictions will be documented in a Corrective Action Decision Document. This report assumes assessment and remedial action effort costs will continue to pay for this program.

Environmental Management program costs at the Central Nevada Test Area and Project Shoal site are limited to Environmental Restoration program assessment, remediation, and surveillance and monitoring costs. Both the 1995 and change the cost assumptions regarding needed remedial action. The 1996 life-cycle cost estimate are based on characterization activites that are not complete and which, upon completion, could change the cost assumption regarding needed remedial action. The 1996 life-cycle cost estimate for the two sites $8.2 million. This is about $10 million less than the 1995 estimate for the entire Central Nevada Test Area. However, the 1995 estimate including the Tonopah Test Range activities. The DOE has since transferred Tonopah Test Range activities to the Nevada Test Site, Industrial Sites Category. This change accounts for most of the $10 million reduction in the 1996 estimated life-cycle cost.