UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1408 
Washington, D. C. 
June, 1926 
STRUCTURES USED IN DRAINING AGRICULTURAL LAND 
By L. T. Jessup 
Associate Drainage Engineer, Bureau of Public Roads 
CONTENTS 
Page 
Introduction 1 
Structures for use with underdrains_ 2 
Manholes 2 
Surface-water inlets 4 
Lamp holes 6 
Cradles 7 
Angle boxes 7 
Lateral connections 8 
Outlets 8 
Crossings under railroads and 
canals 9 
Lumber box drains 10 
Structures for open ditches 11 
Drops and checks 11 
Timber linings in open ditches_ 12 
Page 
Structures for open ditches — Contd. 
Surface-water inlets 14 
Stock guards 15 
Sluiceways and tide gates 15 
Ocean outlets 18 
Bridges and culverts 19 
Flumes and inverted siphons 25" 
Miscellaneous structures 27 
Pump houses 27 
Connections for flushing drains 29 
Relief well connections 30 
Connections for diverting water 31 
Watering places for livestock 31 
Transitions 32 
INTRODUCTION 
A system for the drainage of agricultural lands requires a variety 
of structures in addition to the tile or ditches. To permit cleaning 
underdrains, manholes are used at connections with laterals and at 
changes in alignment. Lamp holes may be installed to facilitate 
inspection. In soft ground and at crossings under railroads and 
canals, cradles and other foundations are used. Open drains sub- 
ject to erosion require checks, drops, and bank protection. 
In the installation of such structures care should be taken to select 
suitable material, to prepare standard plans and specifications, to 
obtain proper locations, and to coordinate the structures with the 
rest of the system. Improper design and location of structures 
introduce defects in drainage systems which decrease their efTec- 
jtiveness. 
A wide variation exists in the design and cost of structures serv- 
ing identical purposes. This bulletin describes the principles of 
design indicated by practice and experiment to be the most satis- 
factory in reduction of cost and of maintenance expenses and in 
increase in the efficiency of drainage systems. 
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