UNITED STATES DEPARTMENT OF AGRICULTURE 
tt BULLETIN No. 724 
Contribution from the Bureau of Public Roads 
SO^^QL LOGAN WALLER PAGE, Director J&P'^&U 
Washington, D. C. PROFESSIONAL PAPER. December 21, 1918 
DRAINAGE METHODS AND FOUNDATIONS FOR 
COUNTY ROADS. 
By E. W. James, General Inspector, Vernon M. Peirce, Assistant Engineer, and 
Charles H. Moorefield, Senior Highway Engineer. 
Page. 
Page. 
Primary soils 
1 
Subdrainage 
28 
Drainage 
3 
Foundations. . 
39 
Design of surface-drainage gutters 
...... 18 
Notes on specifications 
76 
Drop inlets and catch basins 
24 
The first essential feature of an improved road is adequate drain- 
age. It is practically impossible to secure satisfactory results unless 
this feature be given proper attention. Another prime requirement, 
wherever a hard-surfaced road is to be constructed, is that a firm and 
unyielding foundation be provided. The purpose of this bulletin 
is to supply information concerning the proper methods of draining 
roadbeds, constructed of various kinds of soil, under different topo- 
graphic conditions, and also to explain how foundations may be 
designed to suit the soil conditions, the road surface, and the system 
of drainage. Since the quality of the soil has such an important 
influence both on the proper method of drainage and on the proper 
type of foundation to be employed, it is desirable first to discuss 
briefly some of the most important characteristics of the different 
kinds of soils ordinarily encountered in highway construction. 
PRIMARY SOILS. 
The texture and structure are the principal properties of soils that 
determine the manner in which they should be drained and prepared 
for road foundations. These are important because of their effect 
on the permeability and capillarity of soils. For the purpose of this 
discussion, primary soils may be classified as gravel, sand, and clay ; 
but it should be borne in mind that many of the secondary or mixed 
soils, because of their more general occurrence in connection with 
road-building connections, are equally important with these. This is 
especially true of some of the more clearly defined derivative or sec- 
ondary soils such as loam, marl, gumbo, hardpan, etc. Where a soil 
is composed of two different materials, mixed in such proportions 
that its character is decidedly intermediate, it may be designated 
66998°— 18— Bull. 724 1 
