Hydrologic Assessment: Inactive Uranium Mines
San Juan County, Utah and Montrose County, Colorado
Assessment of surface water resources was a primary component of the La Sal Creek Watershed Project conducted to evaluate impacts resulting from former operation of five uranium mines in eastern Utah and western Colorado. The project was conducted under the direction of the US BLM with US EPA oversight. The mines are located along the Colorado/Utah state line and are upgradient of La Sal Creek and several major tributaries which are used for recreational purposes and as an irrigation source by local residents. In addition, local residents in the vicinity of the mines rely on wells and nearby springs for their domestic water needs.
Water draining from the mines and runoff waters infiltrating the waste-rock dumps are considered primary contaminant source areas of concern, potentially contributing to degradation of La Sal Creek and groundwater resources in the area. Data were gathered for the study by measuring discharge rates in area streams and collecting water samples in nearby reference areas to assess natural background conditions from area springs and seeps, mine drainage channels, La Sal Creek and its major tributaries, and at each of the local residences. In addition, a benthic macroinvertebrate survey was conducted along La Sal Creek and its tributaries, co-located sediment samples were collected at each surface-water monitoring station, pasture grass samples were collected from irrigated fields, and samples of produce were collected from residential gardens and fruit trees. The samples were submitted to an analytical laboratory for analysis of a comprehensive list of metals, inorganics, and radionuclides. Sample results were compared to natural background levels reported for the reference area samples and a streamlined risk evaluation was performed to assess potential threats to human health and the environment. The streamlined risk evaluation utilized risk-based benchmarks established by the US EPA, State of Colorado, and State of Utah and risk management criteria established by the US BLM for mine sites. Results of the evaluation were used to prepare an engineering evaluation/cost analysis document in accordance with removal action requirements set for in the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA).
San Juan County, Utah and Montrose County, Colorado
Assessment of surface water resources was a primary component of the La Sal Creek Watershed Project conducted to evaluate impacts resulting from former operation of five uranium mines in eastern Utah and western Colorado. The project was conducted under the direction of the US BLM with US EPA oversight. The mines are located along the Colorado/Utah state line and are upgradient of La Sal Creek and several major tributaries which are used for recreational purposes and as an irrigation source by local residents. In addition, local residents in the vicinity of the mines rely on wells and nearby springs for their domestic water needs.
Water draining from the mines and runoff waters infiltrating the waste-rock dumps are considered primary contaminant source areas of concern, potentially contributing to degradation of La Sal Creek and groundwater resources in the area. Data were gathered for the study by measuring discharge rates in area streams and collecting water samples in nearby reference areas to assess natural background conditions from area springs and seeps, mine drainage channels, La Sal Creek and its major tributaries, and at each of the local residences. In addition, a benthic macroinvertebrate survey was conducted along La Sal Creek and its tributaries, co-located sediment samples were collected at each surface-water monitoring station, pasture grass samples were collected from irrigated fields, and samples of produce were collected from residential gardens and fruit trees. The samples were submitted to an analytical laboratory for analysis of a comprehensive list of metals, inorganics, and radionuclides. Sample results were compared to natural background levels reported for the reference area samples and a streamlined risk evaluation was performed to assess potential threats to human health and the environment. The streamlined risk evaluation utilized risk-based benchmarks established by the US EPA, State of Colorado, and State of Utah and risk management criteria established by the US BLM for mine sites. Results of the evaluation were used to prepare an engineering evaluation/cost analysis document in accordance with removal action requirements set for in the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA).