Investigative Methods for Controlling Groundwater Flow to Underground Mine Workings
![]() |
Old mine working from the upper adit at the Elkhorn Mine and mill site near Wise River, MT. |
Mitigation of poor-quality adit discharges tends to fall into three general categories as described in Metesh, Jarrell, and Oravetz (1998):
Treatment and indirect control of adit discharges have been investigated frequently. Metals-laden, acid discharge can continue for many decades, so these methods require a long-term commitment to yearround maintenance and monitoring. Because sites on lands administered by the Forest Service commonly do not have electrical power and have limited access, such treatment is especially difficult.
Adit plugging or grouting can be very effective in reducing or eliminating adit discharge. Often, the two methods are combined. Construction costs are considerable because the work is done within the mine workings. Grouting or plugging active mines nearing closure is often the best approach. Long-inactive mines may have to undergo extensive rehabilitation for safety and for proper application of the grouting or plugging.
![]() |