Prevention of seepage in foundations for dams

The theory of seepage in foundations for dams has been treated in numerous articles and publications. The purpose of this paper is not to discuss such theoretical considerations, but to present briefly a number of instances which the writers have encountered in their professional practice, where seepage had actually occurred in existing foundations for dams or has threatened to occur, and likewise to discuss the actual measures which were taken to prevent this seepage or to control it to such an extent that it did not endanger the safety of the dam structure.