Rio Blanco and Rulison Sites

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The Rulison and Rio Blanco sites are administered at 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 narrative. The Rulison site is located 22 kilometers (14 miles) southwest of Rifle, Colorado. The Rio Blanco site is located 58 kilometers (36 miles) northwest of Rifle, Colorado.

FACILITY MISSION

The Department conducted the Rulison and Rio Blanco tests under the Plowshare Program, which was a series of nuclear and conventional tests conducted by Atomic Energy Commission to explore peacetime uses of nuclear explosives. The Rio Blanco and Rulison tests were designed to increase natural gas production from low-permeability sandstone. The Project Rulison detonation took place in September 1969 at a depth of 2,568 meters (8,426 feet) in a sandstone formation near Rifle, Colorado. The shot was the second of the gas production stimulation experiments in the Plowshare Program. The Project Rio Blanco test, which was located approximately 36 miles northwest of Rifle, consisted of the nearly simultaneous detonation of three 33-kiloton devices in a 2,130 meter (7,000 feet) well in May 1973. The Rio Blanco test was the third gas production stimulation experiment in the Plowshare Program. Contamination is present as a result of the activities conducted on the sites in conjunction with the gas stimulation testing and gas flaring operations.

At the Rio Blanco site, contamination consists of radioactive contamination of the deep bedrock around the shot cavities; contamination of a deep zone in FCG Well No. 1, in which contaminated water from the production testing and decontamination operations was injected; possible surface contamination from the gas flaring 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 1,500 meters [5,000 feet]), exposure to humans from this material is unlikely. The Department has not confirmed the existence of the surface and near-surface contamination. The Department cleaned up the site in 1976, and all surface contamination was reported to have been shipped to the Nevada Test Site for disposal. However, this cleanup was not well documented and may not meet today's standards.

The Rulison site includes radioactive contamination of the deep bedrock around the shot cavity, 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 2,568 meters [8,426 feet]), exposure to humans from this material is unlikely. There has been no confirmation of the existence of surface contamination from the gas flaring and decontamination operations or the abandoned drill-back mud pit. The site was remediated in 1972 and again in 1976, and all surface contamination was reportedly cleaned up and shipped to the Nevada Test Site for disposal. However, the Department has confirmed additional contamination is present. It consists of diesel fuel and heavy metals in the pre-shot drilling mud pit. The Department is currently in the process of addressing this additional contamination. Surface water and near-surface ground water are the most likely transport mechanisms for the surface contamination; however, no domestic wells use the near-surface aquifer, and the site uses surface water primarily for irrigation.

FUTURE USE

The only negotiations the Department has conducted with the State of Colorado have concerned remediation goals for the pond at the Rulison site. The Department has not completed a definitive plan or an agreement with the State for either Rulison or Rio Blanco. However, this report assumes the surface of the sites will be cleaned to a level that permits Recreational use. The subsurface of the sites will remain Controlled Access. The Department of Energy will maintain institutional 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 Colorado. The Department will maintain both sites under a mix of Industrial, Open Space, and Controlled Access use until remedial action is complete.

ENVIRONMENTAL RESTORATION

The cleanup strategy will be to characterize ground-water flow and area 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. Attenuation characteristics provide for little migration of other radionuclides. However, other radionuclides will be evaluated if tritium migration indicates that they need to 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.

Cost estimates for this report assume subsurface waste in and around the shot cavities will not be removed, and long-term monitoring will continue. Surface remediation activities will depend on the type and quantity of contamination and the available remediation technologies and their effectiveness. This report also assumes hazardous waste will be shipped to a commercial facility for disposal.

Major Environmental Restoration Activity Milestones

TASK	COMPLETION DATE Fiscal Year
Rio Blanco
Preliminary Site Characterization Report	1996
Risk Assessment Report	1999
Work Plan for Assessment/Remediation	1999
Installation of Two Additional Monitoring Wells (Deep Aquifer)	2000
Remediation of Mud Pits	2000
Post-Closure Monitoring Program	2025
Rulison
Preliminary Site Characterization Report	1996
Risk Assessment Report	1996
Remediation of Drilling Effluent Pond	1996
Installation of Two Additional Monitoring Wells (Low-Pressure Zone)	1997
Post-Closure Monitoring Program	2025

ASSESSMENT

Assessment activities will define the magnitude and extent of surficial contamination and the associated risks to human health and the environment through the evaluation of existing information on the two test areas. The evaluation process will include characterization of the physical setting to determine the presence of contamination and identification of pathways to potential receptors. Evaluators will use standard risk assessment procedures to calculate risks to receptors. If risks exceed acceptable limits, the Department will establish the requirements for risk reduction through remediation or other actions.

Completed activities include annual monitoring of the site, sampling the drilling effluent pond at Rulison, dewatering the drilling effluent pond, and stabilizing the sediment in the pond. The stabilized sediment at Rulison has been hauled to the disposal facility. Assessment activities at the Rulison site have found no ground water contamination; however, the mud pit contained approximately 16,000 cubic meters (21,000 cubic yards) of sediment and soil contaminated with metals and petroleum hydrocarbons (hazardous waste). Rio Blanco assessment activities are scheduled to begin in FY 1996. This report assumes results for the Rio Blanco site assessment will mirror those obtained during the Rulison site assessment.

Since 1979, the Department has monitored the surrounding areas of the two sites as part of the Long-Term Hydrologic Monitoring Program. Because ground water has not been impacted by these sites, this program is assumed to continue through the completion of assessment and remedial action (FY 2005). Monitoring consists of sampling from selected ground-water and surface-water collection locations around each site. Sampling requires approximately one week per year per site, plus analyzing approximately 20 samples per site per year. The Department funds the program, and the Environmental Protection Agency operates it under a Memorandum of Understanding. Monitoring required as a result of Resource and Conservation Act closure activities is discussed in the Long-Term Surveillance and Monitoring section below.

REMEDIAL ACTION

Surface contamination at both facilities is the result of fallout from the gas flaring and equipment decontamination operations and near-surface hazardous waste contamination from the closed mud pits. Contamination consists of soil contaminated with metals and petroleum hydrocarbons. This estimate assumes that the remedial action at the sites will include removing the pond sediment from the drilling mud pit at Rulison and removing contaminated surface soils associated with drilling mud at Rio Blanco.

Remediation of the mud pit at Rulison began in FY 1995. Approximately 16,000 cubic meters (21,000 cubic yards) of hazardous waste (contaminated soils) was generated when the sediment was exhumed and stabilized with kiln dust. The waste was staged onsite and then sent offsite to an appropriately permitted commercial disposal facility. All remedial action at this site will be complete in FY 1996.

This report assumes the remedial action at Rio Blanco will be complete in FY 2005. Remedial actions will be based on a risk assessment approach that is determined during the assessment and characterization of the site.

LONG-TERM SURVEILLANCE AND MONITORING

This report assumes post-closure monitoring of the sites will involve yearly monitoring for an assumed duration of 30 years. This report assumes that the approach will comply with the provisions of the Resource Conservation and Recovery Act and will require the installation of two additional wells at each site. However, the Department has not yet negotiated the monitoring strategy with the state.

FUNDING ESTIMATE

The following table presents estimated funding information for the Rio Blanco and Rulison sites.

COMPARISON WITH PREVIOUS ESTIMATE

Environmental Management program costs at the Rio Blanco and Rulison sites are limited to Environmental Restoration program assessment, remediation, and surveillance and monitoring costs. The 1996 life-cycle cost estimate is $6.6 million, a slight increase over the 1995 estimate of $5.1 million. The increase reflects the inclusion of an environmental restoration contingency that was not assumed in the 1995 estimate.