drainage, in mining, removal of water seeping into shafts and other underground mine workings from the surrounding ground. Unless seeping water is removed continually, it may endanger haulage and mining equipment, weaken supporting structures, and, in some instances, flood the mine completely. Water in a mine is drained into sumps, or reservoirs, usually excavated below the lowest working level of the mine, and is then removed by pumps. Methods to minimize seepage include the sealing of visible fissures through which water enters and the injection of concrete into the ground surrounding the shafts.
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