Past performance of Grenada Dam indicates piping of embankment and foundation soils through joints of the collector pipe for the toe drainage system (prior to its replacement with an open paved ditch in 1961) occurred. Also, rainfall erosion tunnels developed on the downstream slope of the dam, primarily in the valley section between sta 105+00 and 145+00, soon after completion of the main embankment in 1949 and continued to develop at a decreasing rate to the present. Based upon laboratory tests conducted on undisturbed soil samples and reservoir water samples obtained in 1973 and 1976, the embankment soil is nondispersive at the surface and dispersive below a depth of about 6 ft. Limited data obtained below the embankment indicate the foundation soil is dispersive at the surface and nondispersive to dispersive with depth. The Australian method of analysis, using the exchangeable sodium percentage of the soil, total ionic concentration of the reservoir (eroding) water, and predominate clay mineral of the soil, indicates both the embankment and foundation soils would be potentially susceptible to dispersive clay piping if Grenada Dam contained cracks or sandy lenses traversing the width of the dam where the reservoir water would have a path of rapid access across the dam. Since piping failure through the embankment or foundation has not occurred, either the dam is free from cracks or sandy lenses traversing the width of the dam, or if cracks are present, the soil is able to swell and seal the flow channels.

Offers a collection of papers, dealing with selected engineering aspects of soil erosion, dispersive clays, and loess. Two papers deal with laboratory studies, while the remainder are case studies. Degrees of erosion are related to soil type, mineralogy, gradation and compacted condition.

The present state of the art of dam engineering has been ronmental, and political factors, which, though important, attained by a continuous search for new ideas and methods are covered in other publications. while incorporating the lessons of the past. In the last 20 The rapid progress in recent times has resulted from the years particularly there have been major innovations, due combined efforts of engineers and associated scientists, as largely to a concerted effort to blend the best of theory and exemplified by the authorities who have contributed to this practice. Accompanying these achievements, there has been book. These individuals have brought extensive knowledge a significant trend toward free interchange among the pro to the task, drawn from experience throughout the world. fessional disciplines, including open discussion of prob With the convergence of such distinguished talent, the op lems and their solutions. The inseparable relationships of portunity for accomplishment was substantial. I gratefully hydrology, geology, and seismology to engineering have acknowledge the generous cooperation of these writers, and been increasingly recognized in this field, where progress am indebted also to other persons and organizations that is founded on interdisciplinary cooperation. have allowed reference to their publications; and I have This book presents advances in dam engineering that attempted to acknowledge this obligation in the sections have been achieved in recent years or are under way. At where the material is used. These courtesies are deeply ap tention is given to practical aspects of design, construction, preciated.