22 BULLETIN 502, U. S. DEPARTMENT OF AGRICULTURE. 
— joint surrounded by cinders, gravel, or other suitable material. If, 
in making turns or by reason of an irregularly shaped tile, a crack 
one-fourth inch or more is left, it must be covered securely by broken 
_ tile. All junctions at manholes and branches should be made securely. 
Care must be exercised to prevent sediment from washing into the 
tile, and when each drain is complete it should be free from sand, 
mud, or other obstructions. 
The tile should be hauled and distributed along the line of trench 
all in one operation. They should be hard-burned clay tile of good 
quality, preferably in 2-foot lengths. ‘They should have smooth 
interior surfaces and should be hard burned entirely through, of 
uniform texture, and free from lime or other impurities. No piece 
should vary from a straight line more than one-half inch for a 2-foot 
length. No tile should be used that has a piece broken from either 
end deeper than 14 inches. After the tile are laid they should be 
covered carefully to a depth of at least 6 inches with broken shale, 
gravel, or coarse cinders. 
Relief wells can be installed with a 2-inch auger,'or where hard 
strata are encountered a churn drill can be used. Each well should 
be located so that it will come near the end of a tile; it is then 
connected with the line by chipping out one end of the tile with a 
wrench, so as to leave a hole about 2 inches in diameter over the well. 
All wells must be connected, regardless of whether they ftow or not, 
for they may flow later. 
Where the banks of the trench stand up well, the tile where wells 
are desired should be left with but little aadine over them; after 
the line is completed a tile can be taken up at each of these races 
and the well installed. In this case the wells can be placed directly 
beneath the tile. In trenches where the banks will not stand, it 
becomes necessary to drill the wells as the tile laying progresses, and 
they should be placed a few inches to one side and connected with the 
opening in the tile by placing a half tile over the well. They should 
not be placed directly beneath the tile, for the sediment washing down 
from the construction work above is apt to fill up the weak or non- 
flowing wells. 
COST DATA. 
Where drainage systems have been installed wholly or in part by 
the individual landowners, itemized records of expenses incurred 
generally are not obtainable. However, it is believed that the tracts 
from which the following data were obtained are fairly representa- 
tive of conditions as ordinarily encountered in this type of drainage; 
consequently the unit costs may be assumed to indicate fairly what 
may be expected in excavating in this sort of material by hand 
labor. 
