TD News, Number 3, 2003 - Internet Web Site: 'http://www.fs.fed.us/t-d' Send an e-mail request for username and password to: 't-d@fs.fed.us'

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Controlling Groundwater Flow to Underground Mines

Extracting the ore from an underground mine site requires a shaft or adit to access the workings or tunnels used to excavate the rock and ore. During the active period of a mine’s life, miners often encountered groundwater that had to be drained. Drainage may continue long after mining has ended, causing serious environmental problems.

Groundwater circulating through a mine interacts with mineral-rich rock exposed by mining. Metal-bearing ore can produce high concentrations of harmful metals in the discharge water. Many mines also contain abundant iron pyrite. Interaction of pyrite, oxygen, and water can produce an acidic discharge. A pyrite content of only a few percent by volume can produce acid for thousands of years. Controlling or stopping groundwater from entering the workings of a mine diminishes the pollution problems associated with abandoned mines. Investigative Methods for Controlling Groundwater Flow to Underground Mine Workings (0371–2801–MTDC) is an MTDC report available electronically at: http://www.fs.fed.us/eng/t-d.php?link=pubs/htmlpubs/htm03712801.

This report, by Phyllis Hargrave and John Metesh of the Montana Bureau of Mines and Geology and Ken McBride of the Bitterroot National Forest, reviews the methods of controlling groundwater flow to underground workings. The first step requires identifying and characterizing the source of both surface and groundwater. Infiltration controls may include grouting from outside the workings, soil or streambed treatment to reduce infiltration capacity, runoff management, and recontouring of natural recharge areas. Two abandoned mines in Montana with typical discharge problems are examined in detail to illustrate the process of mitigating groundwater flow.

Cover for Investigating Methods for Controlling Groundwater Flow.

For more information, contact Charlie Showers, project leader (phone: 406–329–3945; fax: 406–329–3719; e-mail: cshowers@fs.fed.us).


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