186 



PRACTICAL DRAINAGE 



properly matched and beveled at the lower ends to insure 

 a tight lit. The sheeting may be driven by means of a 

 heavy maul and may be removed with a three-legged 

 derrick and a special grabhook. 



"If the soil in the bottom of the completed trench is so 

 soft that it will not support a man's weight, wooden racks 

 or cradles should be laid under the tile to keep it in line 



FIG. 28. DRAINAGE MACHINE WITH THE DIGGING WHEEL ABOVE 

 THE GROUND. 



and on grade. If conditions are exceedingly bad it often 

 is advisable to use sewer pipe in place of drain tile, as the 

 bells aid in keeping the line intact. Second quality sewer 

 pipe is suitable and generally may be purchased at about 

 the same price as drain tile. Under ordinary conditions, 

 however, the use of sewer pipe is not recommended, since 

 the cost of freight and hauling is higher than for drain 

 tile and it is heavier and more difficult to handle. Also, 

 in stable ground it is necessary to dig out places for the 

 bells, which considerably increases the cost of trenching. 



