78 BULLETIN 724, U. S. DEPARTMENT OF AGRICULTURE. 
CONSTRUCTION. 
SIDE DITCHES. 
The side ditches, when completed, shall have the general cross section indi- 
cated on the plans, and shall confirm in all respects to the lines and grades 
furnished by the engineer. Where the exact cross-sectional dimensions are 
not indicated on the plans for each particular section of the road, these di- 
mensions will be fixed by the engineer, with a view to providing adequate 
drainage without erosion, and shall be strictly observed by the contractor. 
In making excavations for side ditches care shall be exercised to see that the 
earth is not disturbed below the proposed bed of the ditch, and wherever it is 
necessary to fill in at the sides of a ditch, the material shall be thoroughly 
tamped as it is deposited so that it will offer practically the same resistance to 
erosion as the rest of the ditch bed. The ditch, when completed, shall present 
a smooth uniform bed and shall be kept free from obstructions during all sub- 
sequent stages of the work. 
The material excavated from side ditches will be paid for at the price bid 
for ditch or gutter excavation. 
COBBLE GUTTEES. 
Cobble gutters shall be constructed as shown on the plans or as directed by 
the engineer in writing, and, when completed, shall conform in all respects to 
the required cross section, line, and grade. The method of construction shall 
be as follows : 
TRENCH. 
Along the line of the gutter, as staked out by the engineer, a trench shall be 
excavated to the full width of the gutter and to a depth of 12 inches below the 
gutter grade. When complete, the trench shall be true to line and grade and 
the bottom shall be compacted and firm, and wherever filling is necessary in 
order to bring any part of the trench to the required cross section, the material 
filled in shall be thoroughly tamped. 
FOUNDATION. 
Upon the bottom of the trench, prepared as described above, shall be spread 
a layer of crusher-run stone or gravel, such that when thoroughly tamped and 
compacted it will have a depth of 6 inches. 
After the foundation material is spread to the necessary depth it shall be 
thoroughly compacted, by tamping, or otherwise, until the upper particles are 
not disturbed by men walking on the surface of the foundation. The founda- 
tion, when complete, shall be approximately parallel to the surface of the 
finished gutter. 
SAND BEDDING. 
After the foundation has been prepared as above described it shall be cov- 
ered with a layer of bedding sand. This layer shall have a loose depth of about 
2 or 3 inches as may be required to bring the gutter stones which are bedded in 
it to the required cross section. 
SETTING COBBLES. 
In setting the cobbles those which are largest and most nearly perfect shall 
be picked out and set in the edges and middle row of the gutter. All of the 
