Understanding the chemical makeup of groundwater near a breccia pipe uranium mine before mining begins is critical to determining if mining practices cause a change in groundwater quality in the area. In June of 2017, the USGS installed a well adjacent to the Pinyon Plain (formerly Canyon) uranium mine to monitor the shallow (or perched) groundwater in the area. The perched groundwater system is 1000 feet or more above the regional groundwater system in the area and is at about the same depth as the uranium ore body in the nearby breccia pipe. Additionally, Energy Fuels, the Pinyon Plain Mine (formerly Canyon Mine) operator, maintains a regional groundwater well at the mine site.
The perched and regional groundwater wells are currently sampled by USGS once per year to establish pre-mining groundwater conditions in the shallow and deep groundwater systems. Water is collected from the wells and analyzed for major ions, trace elements (including elements often associated with mineralized breccia pipes such as uranium, arsenic, copper, lead, and others), and isotopes of certain elements that may help determine the age of water in the different groundwater systems (which may change if there are impacts from mining). Water-quality results from both the perched and regional groundwater wells are publicly available through the USGS National Water Information System (see links in “Sources†section below). By monitoring groundwater near the mine during the entire mining lifecycle, we can learn more about the potential for mining impacts on groundwater quality.
Objectives
Sample the perched groundwater observation well during active mining operations, during post-mining reclamation, and after all mining activities have been completed.
Sample the regional groundwater well for as long as permission is granted by the mine operator and/or until the well is abandoned.
Sources
Perched groundwater observation well A-29-03 20CBA1
Regional groundwater well A-29-03 20BCD1
Ongoing
Task 6: Compare water transport mechanisms in mined and unmined breccia pipe
Fred Tillman
Hydrologist
Arizona Water Science Center
520.670.3312
ftillman@usgs.gov
Kimberly Beisner
Hydrologist
Arizona and New Mexico Water Science Centers
505.830.7945
kbeisner@usgs.gov
