UNITED STATES DEPARTMENT OF AGRICULTURE 



^^ BULLETIN No. 502 ^ 



Jff^ Contribution from Office of Public Roads and Rural Engineering ^ 

 SS^'^^U LOGAN WALLER PAGE, Director 



Washington, D. C. 



PROFESSIONAL PAPER 



April 23, 1917 



THE DRAINAGE OF IRRIGATED SHALE LAND/ 



By Dalton G. Miller, Senior Drainage Engineer, and L. T. Jessup, Junior 



Drainage Engineer. 



CONTENTS. 



Page. 



Introduction 1 



Geological features 2 



Surface topography 3 



Underground water 4 



Alkali 7 



Drainage methods H 



Construction 



Cost data 



Examples of methods . 



Results of drainage 



Conclusion 



20 

 22 

 23 

 38 

 39 



INTRODUCTION. 



Drainage is now recognized as one of the most important problems 

 confronting the farmers of irrigated lands. Drainage methods in 

 the arid regions differ from those in the humid sections, and even 

 with respect to arid land different methods must be used for different 

 types of land. One of the frequently occurring types that require 

 special treatment is the so-called shale land, by which term is meant 

 those lands that are immediately underlain by shale which may or 

 may not outcrop and in which the soil is made up largely of dis- 

 integrated shale. Areas of this type occur in all of the Rocky 

 Mountain States and in some of those immediately adjoining. 



In spite of the fact that shale is classed among the less pervious 

 formations, it becomes an important factor in the movement of under- 

 ground water in those areas where uplifts and displacements have 

 occurred. Investigations by this department have shown that in 

 those sections which have underlying shale near the surface there is a 

 close relation between the shale and the areas of seepage. This rela- 

 tion depends more or less on the topography of the underlying shale, 



^ This bulletin contains information on the drainage of those Irrigated lands of the 

 Rocky Mountain States that are underlain by shale. 



Acknowledgments. — The soil analyses presented in this bulletin were made in the 

 laboratory of the Bureau of Soils, U. S. Department of Agriculture. The analyses of 

 the water samples were made in the water laboratory of the Bureau of Chemistry, 

 U. S. Department of Agriculture. 

 70250°— Bull. 502— 17 1 



