Dissecting a dam

To determine the source of seepage from a Soil Conservation Service (SCS) high hazard flood prevention dam in New York, a geologic and engineering investigation was made which showed unexplained high permeability in the foundation and embankment and a possibility of voids in the trench drain system. The decision was made to immediately breach this 65 ft high earth fill structure. The drains were intact and were not overloaded; however, they had relatively low permeability. The seepage appearing near the toe of the dam was moving through and under the slide material. The dam was redesigned and reconstructed with higher capacity drains.--Modified journal abstract.