Mining operations in the Grand Canyon region create volumes of ore and waste rock which contain elevated levels of uranium and associated trace elements (chemical elements that typically occur in low levels in the environment).
Fluvial transport (movement of material by flowing water in stream channels) of these contaminants from production sites is a concern as the region is susceptible to violent storms and flash flooding which can quickly erode protective barriers and move large quantities of ore or waste rock. Once contaminants leave a production site they may infiltrate water supplies and affect large areas of the environment. Previous incidents of such processes at the Hack mines have been noted.
In order to assess and manage the risks associated with uranium mining, it is critical to understand the transport and storage rates of sediment and uranium within the ephemeral streams of this region.
To address these questions, a historic mining site in Hack Canyon which experienced fluvial erosion of its waste rock deposits during the early 2010s is being studied. Using the uranium from the tailings as a tracer, a 1-dimensional tracer model was created to examine the transport and storage of different sections of the ~40km river (Hack Canyone and Kanab Creek) between the mine and the Colorado River. Samples were collected in 2015 and 2018.
Objectives:
Ongoing
Task 5b: Collect/analyze water and sediment samples from streams and springs Task 12: Surface water monitoring of chemical constituents in drainages with historical and current mining
Adam Benthem
Hydrologist
New England Water Science Center
703.648.5208
abenthem@usgs.gov
