Site Description and History

Regulatory Setting

The Rulison Site is located 8,154 feet above sea level onthe north flank of Battlement Mesa in western Colorado,about 12 miles southwest of the town of Rifle and 8 milessoutheast of the town of Parachute.

On September 10, 1969, the U.S. Atomic EnergyCommission (AEC), a predecessor agency of theU.S. Department of Energy (DOE), detonated a 40-kilotonnuclear device 8,426 feet below the ground surface inan attempt to release commercially marketable quantitiesof natural gas from the fine-grained, low-permeabilitysandstone of the Williams Fork Formation. This was thesecond natural gas reservoir stimulation experiment inthe Plowshare Program, which was designed to developpeaceful uses for nuclear energy. Austral Oil Company ofHouston, Texas, and the nuclear engineering firm CERGeonuclear Corporation of Las Vegas, Nevada, proposedthe project. Those two firms and AEC jointly sponsoredProject Rulison.

The objective of the Project Rulison detonation was tostimulate flow of natural gas through fractures created bythe blast and use the chimney as a collection chamber.The detonation created a roughly spherical cavity esti-mated to be 152 feet in diameter and containing meltedand vaporized rock. The blast also fractured the sur-rounding rock to an estimated radius of 263 feet from thedetonation point. As the cavity cooled, the melted andvaporized rock collected in a puddle at the bottom. Mostof the radionuclides were trapped in this puddle as itcooled and formed into a glassy solid. Shortly after thedetonation, gravity caused the roof of the cavity tocollapse into the cavity chamber. This progressivelyupward collapsing of fractured rock into the cavitychamber formed a chimney of broken rock to an estimatedheight of about 274 feet above the point of detonation.

Following the detonation, a reentry well was drilled intothe top of the chimney to collect data on gas production byburning or “flaring” the natural gas. Four gas-flaring eventswere conducted as part of the production testing and dataevaluation that took place between October 1970 andApril 1971. The first flaring event lasted three days. TheU.S. Public Health Service used this test to calibrateits network of off-site equipment to monitor potentialhealth effects of the production testing. Following theinitial production test, three intermittent gas-flaring testsfollowed. These tests showed that production of natural

gas stimulated by the detonation was less than antici-pated. Although approximately 455 million cubic feet ofnatural gas was produced, elevated levels of radioactivityin the gas made it unacceptable for use at that time.

The federal government holds title to, and DOE is respon-sible for, radioactive and other hazardous materialsgenerated at the Rulison Site. The federal governmentretains control of the subsurface rights beginning at adepth of 6,000 feet within a 40-acre area surrounding thedevice emplacement well, known as surface ground zero.DOE's Office of Legacy Management has responsibilityfor long-term management of the Rulison Site. Regulatoryoversight for the site involves collaboration with theColorado Department of Public Health and Environment(CDPHE) and the Colorado Oil and Gas ConservationCommission (COGCC).

site. Following the decontamination and removal of

Surface Cleanup at the Rulison Site

In July 1972, equipment that was no longer needed atthe site was decontaminated and removed from the

Location of the Rulison, Colorado, Site

FACT SHEET

This fact sheet provides information about the Rulison, Colorado, Site.This site is managed by the U.S. Department of Energy Office of Legacy Management.

Rulison, Colorado, SiteENERGY

LegacyManagement

U.S. DEPARTMENT OF

equipment, the site was left in standby condition until 1976,when the remaining equipment and surface facilities weredismantled, inspected, surveyed for radiation, decontami-nated if necessary, and removed to an off-site location.

Power poles and power lines were left at the site at thelandowner's request. Drilling fluid in the effluent pond wasremoved, and the impoundment structure was left at therequest of the landowner.

Sediment and soil samples collected from the formereffluent pond and areas near the reentry well containedorganic drilling additives in the form of petroleum hydrocar-bons. The corrective action consisted of draining the pondand removing sediments that contained petroleum hydro-carbons in concentrations exceeding the state regulatorylimit. A pond liner was installed before the pond wasrefilled. Eight wells were installed to monitor groundwaterquality and to verify that no contamination was movinginto the groundwater from pond sediments below theliner and from soils in the reentry well area. After eightconsecutive quarters of sampling, no migration of petro-leum hydrocarbons above risk-based trigger levels wasdetected. The monitoring wells were decommissionedaccording to Colorado well abandonment regulations. In1998 DOE provided the Colorado regulators with a SurfaceClosure Report and recommended closure of the RulisonSite surface with no further action. CDPHE agreed andapproved the closure activities.

DOE does not plan to remove the radioactive contamina-tion in or around the test cavity in the deep subsurfacebecause no feasible technology currently exists. Thedetonation occurred in low-permeability natural-gas-bearing sedimentary rock that extends several thousandfeet above and below the test cavity. Aquifers used for

Subsurface Conditions

drinking water and irrigation in the surrounding area are inalluvium and terrace materials that are 6,000 to 9,000 feetabove the detonation point. The geologic formationsbetween the near-surface aquifers and the deep,subsurface detonation point are nearly impermeableand produce little, if any, water.

The nuclear test created a wide variety of radionuclides.Most of these were incased in the glass melt puddle thatformed at the base of the cavity shortly after detonation,greatly reducing their mobility. Some radionuclides thatwere in the gas phase or in water vapor were removedduring production testing of the natural gas. The primarycontaminant of concern remaining in the deep subsurfaceis tritium, a mobile radioisotope of hydrogen. Tritium hasa half-life of 12.3 years and decays to nonradioactivehelium. DOE monitors gas and water vapor from nearbygas production wells for tritium and other contaminantsas a precaution. To date, no test-related radionuclideshave been detected.

Since 1972, the U.S. Environmental Protection Agencyhas monitored groundwater annually at and near theRulison Site as part of a long-term hydrologic monitoringprogram. No radioactive contamination associated withthe Rulison test has been detected in any samples takenfrom the nearby municipal drinking water supply springs,the water supply wells on five local ranches, or the springand three wells on the test site.

DOE has been working with the natural gas industry, Stateregulators, and stakeholders in the development of a long-term monitoring plan for gas wells drilled near the RulisonSite. DOE is committed to long-term monitoring of wellsfor potential contaminates and to protect human healthand the environment.

Long-Term Hydrologic Monitoring Program

Cross Section of the Rulison, Colorado, Site

+8,000 ft

–2,000 ft

+4,000 ft

SeaLevel

Green River Fm.

Wasatch Formation

Mesaverde Group

Mancos Formation

Ohio Creek Formation

Surface Ground Zero

Shot Cavity

0

RE-X Exploration Hole

Cement Plug

Fort Union Formation

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Ele

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tio

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ColoradoRiver

Distance (miles)

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10/05/2011

Institutional Controls

The federal government prohibits drilling and extractingbelow 6,000 feet within a 40-acre zone surrounding surfaceground zero. DOE is conducting subsurface modelingstudies to assess the adequacy of this exclusion boundary.The modeling simulates subsurface conditions of the testcavity, applies hypothetical gas production stresses to theformation (such as fracturing the rock at target depths torelease natural gas), and defines a probable contaminantboundary. Subsurface use restrictions within the RulisonSite boundary will remain in place in perpetuity. A perma-nent monument at surface ground zero bears a plaquewith an inscription denoting the historical significance ofthe site and states that excavation, drilling, and removalof subsurface materials below a depth of 6,000 feet isprohibited without permission of the U.S. Government.

COGCC established two wider boundaries around the site.When a company applies for a permit to drill within a three-mile radius of surface ground zero, COGCC notifies DOE;DOE reviews the application and provides comments.COGCC also established a half-mile boundary aroundsurface ground zero. An application for a permit to drillwithin one-half mile requires a full hearing before thecommission.

Legacy Management Activities

Contacts

The DOE Office of Legacy Management managesthe Rulison Site to ensure that conditions at the sitecontinue to be protective of human health and theenvironment. DOE will conduct annual site inspectionsto verify that no drilling has taken place within theexclusion boundary and will conduct long-termmonitoring of surface water, groundwater, andnatural gas.

Documents related to the Rulison Site are availableon the DOE Office of Legacy Management website at

.

For more information about DOE Office of LegacyManagement activities at the Rulison Site, contact

U.S. Department of EnergyOffice of Legacy Management2597Legacy Way, Grand Junction, CO 81503E-mail:

(970) 248-6070 (monitored continuously), or(877) 695-5322 (toll-free)

http://www.lm.doe.gov/rulison/Sites.aspx

Rulison@lm.doe.gov

Rulison Post-Detonation Cross Section