This baseline risk assessment of ground water contamination at the uranium mill tailings sites near Slick Rock, Colorado, evaluates potential public health and environmental impacts resulting from ground water contamination at the former North Continent (NC) and Union Carbide (UC) uranium mill processing sites. The tailings at these sites will be placed in a disposal cell at the proposed Burro Canyon, Colorado, site. The US Department of Energy (DOE) anticipates the start of the first phase remedial action by the spring of 1995 under the direction of the DOE`s Uranium Mill Tailings Remedial Action (UMTRA) Project. The second phase of the UMTRA Project will evaluate ground water contamination. This baseline risk assessment is the first site-specific document for these sites under the Ground Water Project. It will help determine the compliance strategy for contaminated ground water at the site. In addition, surface water and sediment are qualitatively evaluated in this report.

The Uranium Mill Tailings Radiation Control Act of 1978 (42 USC {section}7901 et seq.), hereafter referred to as the UMTRCA, authorized the US Department of Energy (DOE) to clean up two uranium mill tailings processing sites near Slick Rock, Colorado, in San Miquel County. Contaminated materials cover an estimated 63 acres of the Union Carbide (UC) processing site and 15 ac of the North Continent (NC) processing site. The sites are within 1 mile of each other and are adjacent to the Dolores River. The sites contain concrete foundations of mill buildings, tailings piles, and areas contaminated by windblown and waterborne radioactive tailings materials. The total estimated volume of contaminated materials is approximately 621,300 cubic yards (yd{sup 3}). In addition to the contamination in the two processing site areas, four VPs were found to contain contamination. As a result of the tailings being exposed to the environment, contamination associated with the UC and NC sites has leached into shallow ground water. Surface water has not been affected. The closest residence is approximately 0.3 air mi from either site. The proposed action is to remediate the UC and NC sites by removing all contaminated materials within the designing site boundaries or …

The US Environmental Protection Agency (EPA) has established health and environmental protection regulations to correct and prevent ground water contamination resulting from processing activities at inactive uranium milling sites (52 FR 36000 (1987)). According to the Uranium Mill Tailings Radiation Control Act (UMTRCA) of 1978, 42 USC {section}7901 et seq., the US Department of Energy (DOE) is responsible for assessing the inactive uranium processing sites. The DOE has determined that for Slick Rock, this assessment shall include hydrogeologic site characterization for two separate uranium processing sites, the Union Carbide (UC) site and the North Continent (NC) site, and for the proposed Burro Canyon disposal site. The water resources protection strategy that describes how the proposed action will comply with the EPA ground water protection standards is presented in Attachment 4. The following site characterization activities are discussed in this attachment: Characterization of the hydrogeologic environment, including hydrostratigraphy, ground water occurrence, aquifer parameters, and areas of recharge and discharge. Characterization of existing ground water quality by comparison with background water quality and the maximum concentration limits (MCL) of the proposed EPA ground water protection standards. Definition of physical and chemical characteristics of the potential contaminant source, including concentration and leachability of …

This proposed remedial action plan incorporates the results of detailed investigation of geologic, geomorphic, and seismic conditions at the proposed disposal site. The proposed remedial action will consist of relocating the uranium mill tailings, contaminated vicinity property materials, demolition debris, and windblown/waterborne materials to a permanent repository at the proposed Burro Canyon disposal cell. The proposed disposal site will be geomorphically stable. Seismic design parameters were developed for the geotechnical analyses of the proposed cell. Cell stability was analyzed to ensure long-term performance of the disposal cell in meeting design standards, including slope stability, settlement, and liquefaction potential. The proposed cell cover and erosion protection features were also analyzed and designed to protect the RRM (residual radioactive materials) against surface water and wind erosion. The location of the proposed cell precludes the need for permanent drainage or interceptor ditches. Rock to be used on the cell top-, side-, and toeslopes was sized to withstand probable maximum precipitation events.

A report regarding carnotite resources of the upper group area in San Miguel County, Colorado

A photograph print of Rio Grande Southern (RGS) Ophir station, Galloping Goose #4 or #5 track side.

Discussing deposits of Vanadium and Uranium ore that were discovered in the Egnar-Slick Rock vanadium district during the 1912-23 period of "carnotite" mining.

Report discussing the geology and ore deposits of the Placerville area of San Miguel County, Colorado. "This report is an abstract of a paper with the same title that is planned for publication as a Geological Survey bulletin."

A report regarding uranium deposits of the Urvan Mineral belt.

The following report covers a study of the electrical properties of the Morrison formation in the Uravan mineral belt of the Colorado Plateau province where it is indicated that there is a significant correlation between electrical resistivity and the relative favorability for occurrence of ore. This report presents the measurements of resistivity trends.

Summarizing the data on the uranium-vanadium deposits of the Bull Canyon area in Montrose and San Miguel Counties, Colorado.

The following document contains the 17 figures in relation to the report, Environment of Uranium Deposition in the Bull Canyon Area, Southwestern Colorado.

A study made of the joint patterns in four different formations exposed in Bull Canyon, and of favorable and unfavorable ground in the upper ore-bearing sandstone unit of the Salt Was member of the Jurassic Morrison formation.

Report discussing the contact and weathering of the Burro Canyon formation shales and Dakota sandstone as well as other connections of the Burro Canyon formation.

This report sumarizes the results of the US geological survey exploration in the Bull Canyon district from October 1955 to April 1956

Report discussing the regional geology, geomorphology, structure, mineral deposits, and details of the sedimentary and igneous rocks of the Placerville Quadrangle in Colorado.

A report regarding the areal geology of the Placerville Quadrangle, located in colorado. This report concerns work done on behalf of the division of Raw Materials of the U.S. Atomic Energy Commission.

This report summarizes the general geology of the Slick Rock mining district and the results of drilling done by the U.S. Geological Survey during 1955.

Preliminary geologic map of the Placerville quadrangle, Colorado.

A report regarding development drilling on the Upper Group area, Slick Rock District, San Miguel County, Colorado

A report regarding development drilling in the Ellison-Burro claims area, Slick Rock District, San Miguel County, Colorado

Report outlining development drilling in the Hawkeye Claim Area Slick Rock District, San Miguel County, Colorado, including the geology, ownership, location, and plans for future drilling. Maps of the development drilling area and a summary of assay data, in tabulated form, are also included.

A report regarding development drilling in the Hawkeye claim area, Slick Rock District, San Miguel County, Colorado

A report discussing development drilling on the Long Ridge group of claims, Gypsum Valley district, San Miguel County, Colorado