90 



LAND DRAINAGE 



cient to continue to move the particles. If, then, in a line 

 of tile the fall were lessened at some point, it might happen 

 that considerable quantities of this silt would accumulate 

 at the point of change. Sometimes this happens to the 



FIG. 33. Silt-basin built of brick. 



extent that the tile is clogged. Means should be pro- 

 vided, therefore, to prevent such a contingency. 



120. Silt-basins. To prevent the clogging of tiles 

 by the accumulation of silt, chambers or openings, such 

 as are illustrated by Figs. 33, 34, and 35, are established 

 at intervals along the tile drain. They are commonly 

 called silt-basins. These are placed wherever in a line 

 of tile the grade is changed from a higher to a lower 

 rate of fall, and especially where it is evident that the 



