Relief Wells for Dams and Levees

Since 1930 a large number of flood control dams and levees have been constructed. Many of them are located on pervious foundations-a practice which would have been considered unsafe in the 1920's. In addition, many of the structures are founded on alluvial deposits which usually grade from fine materials near the ground surface to coarser materials in lower portions of the strata. As a result, the lower parts of the deposits forming the foundations are much more pervious than the upper parts, and deep drainage facilities are necessary for relieving high uplift pressures downstream from the structures to prevent serious and alarming boils and seepage. The writers have studied this problem over a period of years and have developed certain design criteria for systems of relief wells which provide deep drainage.