Gasbuggy and Gnome-Coach Sites

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The Gasbuggy site and the Gnome-Coach site are administered by the Nevada Operations Office. A more thorough description of the environmental activities managed by the Nevada Operations Office can be found in the Nevada Offsite Program narrative.

Estimated Site Total

(Thousands of Current Year Dollars)
	FY 1996	1997	1998	1999	2000
Environmental Restoration	86	1,155	2,391	5,468	4,394	Grey shaded area reflects annual cost estimates for the first five years of the site BEMR Base Case (as of October 1995) and includes 3% annual inflation, see Readers' Guide.
1996 Appropriation	105			These levels reflect the current estimates for compliance with applicable statutes and agreements (as of March 1996), see Readers' Guide.
1997 Congressional Request		330
(Five-Year Averages, Thousands of Constant 1996 Dollars)
	FY 1996-2000	2005	2010	2015	2020	2025	2030	Life Cycle*
Environmental Restoration	2,474	281	83	44	12	8		14,511
* Total Life Cycle is the sum of the annual costs in constant FY 1996 dollars.

FACILITY MISSION

The Gnome-Coach and Gasbuggy sites were part of the Plowshare program, which was a series of nuclear and conventional tests conducted by the Atomic Energy Commission to explore peacetime uses of nuclear explosives. The Project Gnome test was conducted in bedded salt approximately 31 miles southeast of Carlsbad, New Mexico in December 1961. The purpose of the test was to determine the effects and products of a nuclear explosion in a salt medium. Because the test vented radioactivity into the atmosphere, Project Coach, another experiment scheduled for this location, was canceled.

The Gasbuggy Site, located approximately 88 kilometers (55 miles) east of Farmington, New Mexico, was the location of a single subsurface nuclear test in December 1967. The purpose of the test was to determine whether or not nuclear explosions would stimulate release of natural gas not recoverable by conventional methods. This test was the first joint government-industry gas stimulation experiment.

The Gasbuggy site includes radioactive contamination of the deep bedrock around the shot cavity, contamination of the bedrock from the injection of tritiated water, possible surface contamination from the gas flaring and decontamination activities, and near-surface hazardous waste contamination from the closed mud pits. Ground water is the most likely transport medium for the deep contamination; however, because of the depth of the contamination (in excess of 1,290 meters [4,240 feet]) exposure to humans from this material is unlikely. There has been no confirmation regarding the existence of surface contamination from the gas flaring and decontamination operations or the abandoned drill-back mud pit.

Contamination at the Gnome-Coach site consists of radioactive contamination of the deep bedrock around the shot cavity and the emplacement drift, the location for the disposal of contaminated soil. Contamination is also present in a shallower aquifer from a tracer test that was conducted shortly after the test. Ground water is the most likely transport medium for the deep contamination; however, because the shot cavity is in dry salt, exposure to humans from this material is unlikely. The Department is conducting modeling and field investigations to determine if this is a concern. Surface contamination of this site occurred when the shot vented shortly after the detonation.

FUTURE USE

Preliminary hydrologic studies and ground-water characterization at these sites is in progress; therefore, a definitive future-use plan is not complete. However, this report assumes the surface of the sites will be cleaned to a level that permits a mix of Open Space and Recreational use. The future-use designation for subsurface of the sites will remain Controlled Access. The Department of Energy will maintain control of the subsurface and retain all mineral rights; any disturbance of the subsurface (for example, well drilling, mining, excavation) will require Department approval. The final future use will be negotiated with the State of New Mexico. The Department will maintain both sites under a mix of Industrial, Open Space, and Controlled Access use until remedial action is complete.

ENVIRONMENTAL RESTORATION

Surface contamination at the Gasbuggy site is the result of fallout from the gas flaring and equipment decontamination operations. Surface contamination at the Gnome-Coach site is the result of an unplanned vent at the time of the Gnome test. These areas were reportedly cleaned up during site cleanup and decommissioning in the 1968 to 1969 time frame, but the Department has not confirmed this. The drill-back mud pit at the Gasbuggy site has the potential to be contaminated with low-level waste; however, this assumption has not been confirmed.

The cleanup strategy at both sites will include characterizing ground-water flow and area of contamination, assessing risk, and modeling contaminant movement away from the shot cavities. The focus will be on tritium, since it is the most mobile of the potential radiological contaminants. Attenuation characteristics provide for little migration of other radionuclides. Tritium results will indicate whether other radionuclides should be included in the source evaluation. Maximum use will be made of existing data, including monitoring data collected from the Long-Term Hydrologic Monitoring program well networks.

Major Environmental Restoration Activity Milestones

TASK	COMPLETION DATE Fiscal Year
Gasbuggy
Sample Gas Well Area	1997
Preliminary Site Characterization Report	1998
Risk Assessment Report	1998
Characterize Mud Pits	1998
Long-Term Surveillance and Monitoring	2025
Gnome-Coach
Characterize Surface Contamination	1996
Preliminary Site Characterization Report	1998
Risk Assessment Report	1998
Characterize Ground Water (Tracer Study)	1999
Long-Term Surveillance and Monitoring	2025

ASSESSMENT

Assessment activities provide for continued data gathering and analysis of the Gasbuggy and Gnome-Coach sites in New Mexico. This activity defines the magnitude and extent of surficial contamination and risks associated with that contamination through evaluation of existing information. These activities include characterizing the physical setting and testing areas, defining the occurrence of contamination, and identifying pathways to reach a potential receptor. The risks to receptors will also be calculated using standard risk assessment procedures. If risks exceed acceptable limits, the Department will initiate remedial actions at the New Mexico test sites. Risk assessment activities are not planned to begin until FY 1996.

Activities completed to date include the removal of production tubing at Gasbuggy and completion of a casing integrity test. Ground water has been characterized at Gasbuggy wells, and preliminary hydrologic studies at Gnome-Coach have been completed.

REMEDIAL ACTION

This baseline estimate assumes subsurface waste in and around the shot cavities will not be removed, and long-term monitoring will continue. The surface sites and facilities will be remediated to appropriate levels and the waste treated and disposed of offsite.

Surface contamination occurred at the Gasbuggy site as a result of the gas flaring operation. No cleanup of soils around the flare stack was reported. Surface soils at Gasbuggy around the flare stack will be removed. Site waste in and around shot cavities will not be removed. This estimate assumes 2,926 cubic meters (3,850 cubic yards) of hazardous waste will be shipped to an appropriately permitted commercial facility for disposal. Remedial action at the Gasbuggy site will begin in FY 1999 and is assumed to be complete in FY 2001.

Surface contamination at the Gnome-Coach site resulting from venting of the shot at the time of the detonation may need to be removed. All of this contamination was reportedly cleaned up. This estimate assumes no additional surface cleanup will be required.

LONG-TERM SURVEILLANCE AND MONITORING

Monitoring of the sites began in 1992 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. Costs for this monitoring program are included in the assessment and remediation costs. However, after remedial action is complete, all costs are reflected under long-term surveillance and monitoring.

FUNDING ESTIMATE

The following table presents estimated funding information for the Gasbuggy and Gnome-Coach sites.

COMPARISON WITH PREVIOUS ESTIMATE

Environmental Management costs at the Gasbuggy and Gnome-Coach sites are limited to Environmental Restoration program assessment, remediation, and surveillance and monitoring costs. The 1996 life-cycle cost estimate is $14.5 million, a slight increase over the 1995 estimate of $12.6 million. This increase reflects the application of a three percent annual escalation factor and the adjustment of pre-FY 1996 costs to reflect actual costs through FY 1995.