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Resource Recovery of Flooded Underground Mine Workings
Citation:
Nordwick, S., K. Petritz, K. Manchester, H. Joyce, AND D. R. BLESS. Resource Recovery of Flooded Underground Mine Workings. Presented at National Ground Water Association, Denver, CO, October 02 - 03, 2008.
Impact/Purpose:
To inform the public
Description:
Butte, Montana has been the site of hard rock mining activities for over a century. Over 400 hundred underground mines were developed and over 10,000 miles of underground mine workings were created. During active mining, groundwater was removed from the workings by large-scale pumping. When underground mining ended in 1982, the pumps were turned off and Butte’s mines have been flooding ever since as groundwater returns to pre-mining levels. The waters in the underground mine workings are part of the Butte Mine Flooding Operable Unit, which is a component of the Butte Area/Silver Bow Creek National Priorities List site. Post-mining issues of land and surface utilization now serve to accentuate how important it is to incorporate sustainable development aspects into hard rock mining projects. Redevelopment efforts have included seeding areas that have been capped with vegetation. However, the future of this vegetation is dependent on a limited and costly municipal water supply for irrigation. Alternative water sources like the water in the flooded mine workings could be utilized to sustain this vegetation and reduce stress on the municipal water supply. To characterize the water in the flooded underground mine workings, the Mine Waste Technology Program funded a long-term pumping test on a well at the Belmont mine that intercepts the 600-foot level of horizontal workings. Results indicated that the water had a near neutral pH and elevated concentrations of iron, manganese, arsenic, and zinc that exceed non-agricultural irrigation, discharge standards. Treatability tests were then performed to identify technologies that have the ability to reduce metals concentrations below target irrigation standards in a cost effective manner. The results of the pumping test and treatability tests will be presented and discussed.