IS-12 Hydrogeologic and Stratigraphic Data Pertinent to Uranium Mining, Cheyenne Basin, Colorado


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Citation: Kirkham, Robert M., William O’Leary, and James W. Warner. “IS-12 Hydrogeologic and Stratigraphic Data Pertinent to Uranium Mining, Cheyenne Basin, Colorado.” Information Series IS-12. Denver, CO: Colorado Geological Survey, Department of Natural Resources, 1980.


This is a report on natural groundwater contamination near a proposed in-situ uranium mine in Weld County. Stratigraphic, structural, and hydrologic data on uranium-bearing rocks; including analyses from over 100 wells and brief description of uranium mining activities in the Cheyenne Basin, located predominately in Weld County, Colorado. 31 pages. 8 figures. 2 appendices. 1 plate (1:1,000,000). Digital PDF download. IS-12D

Humans are major polluters of the waters of the globe. However, natural groundwater movement also causes significant water contamination globally — including salts, acids, radioactivity, nitrogen, and metals (arsenic, selenium, zinc, lead, iron and manganese). As we attempt to regulate and clean up human pollution of water, it is important to recognize natural water pollution sources in a particular area. Understanding the geology of an area is important to aid in recognizing potential natural sources of water pollution.

Modified from the Abstract:

Recoverable low-grade uranium deposits occur in the Upper Cretaceous Fox Hills Sandstone and Laramie Formation in the Cheyenne Basin, Colorado. One of these deposits, the Grover deposit, had been test mined on a pilot scale using in situ solution mining techniques. A second deposit, the Keota deposit, was in 1980 being licensed for mining using the same techniques. Other uranium deposits exist in this area that could also be solution mined, although open-pit mining could possibly be employed at a few locations in the Cheyenne Basin.

One of the principle environmental impacts of this uranium mining activity is the potential effect on groundwater quality and quantity. In order to fully assess potential groundwater impacts, regulatory agencies and mine planners and operators must be familiar with regional geologic and hydrologic characteristics of the basin.

Many of the 100 sampled wells yield water that exceeds U.S. Public Health drinking water standards for pH, TDS, sulfate, manganese, iron and selenium. Uranium, molybdenum, and vanadium concentrations are also high in many of these wells. These data are included in the appendices.