2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 161-5
Presentation Time: 2:25 PM


SMILOWITZ, Michelle, HydroGeo Group, 1165 North Cottage Way, Midway, UT 84049 and MAYO, Alan L., Mayo and Associates, LC, 710 East 100 North, Lindon, UT 82042

Physical hydrogeology data are often inadequate to fully evaluate the impacts of mining operations on non-mine water. In many cases solute and isotopic chemistry provide the insight to resolve difficult and often contentious issues. We present three examples where stable and radiogenic isotopes were used to 1) abrogate a notice of violation (NOV), 2) end the threat of water rights infringement lawsuits, and 3) evaluate leakage of contaminates from ponds.

Case 1 - alleged underground leakage. Colorado issued West Elk mine an NOV alleging in-mine groundwater leaked through a barrier wall into adjacent abandoned workings and that this water discharged to the surface. δ13C, δ2H and δ18O were used in conjunction with geochemical modeling to demonstrate that the water from the mine does not discharge to the surface and the NOV was rescinded.

Case 2 - alleged infringements of surface water rights by in-mine groundwater interception. Most Utah underground coal mines intercept groundwater and this interception has been attributed to declines in spring discharges. Using stable and radiogenic isotopes in conjunction with physical hydrogeology data in the 240 km long Wasatch Range and Book Cliffs, we developed a conceptual model of groundwater flow that describes active and inactive systems. Active zone groundwater flow paths are continuous, responsive to annual recharge and climatic variability, and have groundwater resident times “ages” that become progressively older from recharge to discharge area. This water discharges from thousands of springs and contains appreciable 3H and anthropogenic 14C.

Inactive zone groundwater has extremely limited or no connection with annual recharge. Groundwater may occur as discrete bodies, is encountered 300-700 m bgs, and has δ2H and δ18O compositions distinguishable from near surface groundwater. In general, deep waters have no 3H and mean 14C ages of 500 to 20,000 years (45.9 to 4.9 pmc). Based on this investigation the pending infringement actions ceased.

Case 3 – pond leakage. Evaporation of holding pond water often results in an evaporative δ2H and δ18O signature and leakage of this water will partially impart this signature onto downgradient groundwater. Using pond and up-gradient groundwater as end members the extent of leakage has been evaluated at several locations.