ACKNOWLEDGMENTS. The writer wishes to acknowledge his appreciation of the assist- ance given him by Mr. Jas. D. Schuyler, M. Am. Soc. C. E., Con- sulting Hydraulic Engineer, in reviewing this paper, and in making suggestions of value. Appendix II. contains a list of authors whose writings have been freely consulted, and to whom the writer is indebted the numerous citations in the body of the paper further indicate the obligations of the writer. Introductory CONTENTS. CHAPTER I. CHAPTER II. Preliminary Studies and Investigations CHAPTER III. PAGE Outline Study of Soils. Puddle 12 CHAPTER IV. The Tabeaud Dam, California 17 CHAPTER V. Different Types of Earth Dams 33 CHAPTER VI. Conclusions 63 APPENDIX I. Statistical Descriptions of High Earth Dams 67 APPENDIX II. Works of Reference... ..68 I ILLUSTRATIONS. PAGE Fig. I. Longitudinal Section of Yarrow Dam Site 10 2. Cross-Section of the Yarrow Dam 10 3. Plan of the Tabeaud Reservoir 17 4. Tabeaud Dam Plan Showing Bed Rock Drains ..18 5. Details of Drains . . 18 6. View of Drains 19 7. North Trench 20 8. South Trench . 21 9. Main Central Drain 21 10. Embankment Work 23 11. Dimension Section 26 12. Cross and Longitudinal Sections 27 13. View of Dam Immediately After Completion 29 14. Cross-Section of Pilarcitos Dam 34 15. San Andres Dam 34 16. Ashti Tank Embankment 35 17. Typical New England Dam 40 18. Two Croton Valley Dams Showing Saturation 41 19. Studies of Board of Experts on the Original Earth Portion of the -New Croton Darn 43 20. Studies of Jerome Park Reservoir Embankment 46 21 to 24. Experimental Dikes and Cylinder Employed in Studies for the North Dike of the Wachusett Reservoir 49 25. Cross-Section of Dike of Wachusett Reservoir 49 26. Working Cross-Section of Druid Lake Dam 53 27 to 29. Designs for the Bohio Dam, Panama Canal -55 30. Cross-Section of the Upper Pecos River Rock-Fill Dam 59 31. Developed Section of the San Leandro Dam 59 VI EARTH DAMS CHAPTER I. Introductory. The earth dam is probably the oldest type of dam in existence, The litera- antedating the Christian Era many hundreds of years. ture upon this subject is voluminous, but much of it is inaccessible and far from satisfactory. No attempt will here be made to collate this literature or to give a history of the construction of earth dams, however interesting such an account might be. The object will rather be to present such a study as will make clear the application of the principles underlying the proper design and erection of this class of structures. In no way, therefore, will it assume the character or dignity of a technical treatise. Dams forming storage reservoirs, which are intended to impound large volumes of water, must necessarily be built of considerable height, except in a very few instances where favorable sites may exist. Recent discussions would indicate that a new interest has been awakened in the construction of high earth dams. As related to the general subject of it storage, is with the high structure rather than the low that this study has to do. To the extent that the greater includes the less, the principles here presented are ap- plicable to works of minor importance. Many persons who should know better place little importance upon the skill required for the construction of earthwork embankments, considering the work to involve no scientific problems. It is far too common belief that any ordinary laborer, who may be able to use skillfully a scraper on a country road, is fitted to superintend the construction of an earth dam...