DRAINAGE METHODS FOR COUNTY ROADS. 35 
5. After the tile is finished and the forms removed it should be 
protected from the drying action of the sun and air and kept wet by 
sprinkling for at least seven days. Then the tile should for about 
60 days be left in a protected place before it is used. 
6. The cost of concrete tile depends on the cost of the materials 
of which it is composed and the cost and efficiency of labor. These 
are so variable in different localities that figures of general value 
can not be given. In general, the cost of concrete tile probably would 
average slightly greater for the smaller sizes and slightly less for the 
larger sizes than that of clay tile. 
LAYING THE TILE. 
In laying the tile work should begin at the lower end of the drain 
and proceed up hill when bell tile is used, and, in general, the work 
of excavating, laying and back filling should follow this rule, so 
that the various steps may be taken and the ditch drained at all 
times. To insure that the tile is laid true to grade, it is necessary 
to employ grade stakes, which are usually set by means of an engi- 
neer's level. These stakes should be spaced about 50 feet apart and 
offset sufficiently far from the line of the drain not to be disturbed 
while the ditch is being excavated. The excavation ordinarily is 
carried down to within a few inches of grade with plows, picks, 
shovels, etc., and the bottom of the trench is finished with a tile 
scoop. In handling the scoop great care must be exercised in order 
to bring the bottom of the ditch to a uniform grade and at the same 
time scoop out a properly shaped trench to receive the tile. 
The tile should be laid as the ditch is completed, and each section 
should be turned until the ends fit together closely. Small openings 
at the joints, due to slight unevenness of the ends, are permissible, 
provided they are made to come in the bottom of the tile, but any 
opening more than about ^-inch wide should be covered with a piece 
of broken tile, cement mortar, or heavy tar paper. In the case of 
fine sandy soils, all joints should either be wrapped with cloth or 
tar paper. This is necessary in order to prevent sediment from being 
carried into the tile. Wherever two drains come together, the junc- 
tion should be made preferably by means of T or V branches, be- 
cause, when it is attempted to cut straight sections of tile to fit an 
angle, one section is ver}^ likely to project into the other and cause 
more or less obstruction. In case it is necessary to use straight tile 
on curves the joints should be covered with pieces of broken tile. 
Curves . in a tile drain- always should be as gradual as the location 
will permit, and should be avoided if possible. 
As soon as the tile is laid it should be covered carefully to a depth 
of 5 or 6 inches with loose earth to hold the different sections in 
