LKAB Wassara, the Swedish company that develops and manufactures unique water-powered drill systems for surface and underground operations, noted that there are more than 48,000 dams in the world that have a structural height above foundation of 15 m or more. Most have water seepage problems to some extent, raising the questions of: how many are leaking to a point where rehabilitation is required, and what's the best way to do it? A common method to rehabilitate a dam is to create a seal-a concrete wall or a grout curtain, for example-usually accomplished by drilling boreholes up to 100 m or more deep, then injecting grout into the holes to seal any cavities. This can be done either during construction or later. Older dams may undergo rehabilitation several times.
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