80 



LAND DRAINAGE 



112. Outlet. The point at 

 which the main discharges its 

 water is called the outlet. The 

 efficiency of a tile system and the 

 expense of installing will depend 

 very much on the location and 

 construction of the outlet. The 

 outlet may discharge its water 

 into any natural water-way or 

 stream, ravine or drainage ditch. 

 Generally it should be so located 

 that the main shall extend 

 through the lowest portion of 

 the area to be drained, and so 

 that it may be placed with the 

 least amount of digging and 

 have the fewest possible angles 

 in its course. This outlet should 

 be so situated that the ordinary 

 outside water should not stand 

 as high as the bottom of the tile. 



113. Depth of tile drain. It 

 is desirable that tile drains shall 

 lie, generally, not less than three 

 feet below the surface. Occa- 

 sionally a farmer is met who 

 believes that tile drains should 

 be laid as deep as four feet. 

 Waring favored a depth of four 

 feet. According to Elliott, 4 

 to 4J feet is deep, 3 feet is 



FIG. 27. A combination of the sys- 

 tems shown in Figs. 24 and 25. 



