302 Ground Water, Wells and Farm Drainage. 



laterals and the least distance between them is about 

 feet. 



FIG. 120. Drainage system of 80 acres. Double lines, mains; single lines, 

 laterals. Numbers give length and diameter of tile. (After C. G. 

 Elliott. 



376. Outlet of Drains Much care should be exercised in 

 selecting the location for, and in placing, the outlet. It 

 should if possible have a free outfall as shown at A, !Fig. 

 121, rather than to end beneath water as at B. 



FIG. 121. A, proper outlet for drain; B, improper outlet; C, proper junc- 

 tion of lateral witb main; D, improper junction. 



To avoid injury from freezing in cold climates the last 

 10 to 16 feet of the main should end in glazed sewer tile or 

 in the glazed drain tile; and the outlet should be guarded 

 with masonry and covered with a grating to keep out ani- 

 mals. 



