Effects of a Potash Mine Roof Fall Observed in Nearby Monitoring Wells

At approximately 5 AM on March 18, 2012, a significant collapse occurred in a potash mine near the Department of Energy's Waste Isolation Pilot Plant (WIPP). The US Geological Survey estimated the event to be magnitude 2.9. Two wells in the WIPP regional groundwater monitoring network experienced oscillatory water level fluctuations greater than 5 feet in response to the event. The changes in water level decayed slowly over several weeks following the event. The potash mine is located in the McNutt Potash zone of the Salado Formation, which is 1000-1400 feet below ground surface (BGS) near the location of the roof fall. The monitoring wells are completed in the semi-confined Culebra Dolomite member of the Rustler Formation, which is 375 feet BGS. The observed response is compared to published well responses to earthquakes and other seismic events. We explore the potential for using the event to characterize aquifer parameters. This research is funded by WIPP programs administered by the Office of Environmental Management (EM) of the U.S Department of Energy. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000