196 



FARM DEVELOPMENT 



in order to remove the volume of flood water or rainfall. 

 The minimum grade for tile drains is usually considered 

 as about 2 inches to the 100 feet. Generally, tiles need 

 not be laid at a less grade than 4 to 6 inches fall to the 

 100 feet. 



The size of tiles to be used is important, because drains 

 which are too small to carry a given amount of water 

 at a given grade will not drain off the water rapidly 

 enough to avoid injuring the crops, and the use of tiles 

 larger than necessary is a waste of money. The amount 

 of rain which annually falls in a locality, the flood water 

 received by the wet area from surrounding lands, the 

 distance apart of the drains, the presence or absence of 

 seepage or spring water in the subsoil, the character of 

 the subsoil, the amount of fall, or grade, given the drain, 

 and sometimes other considerations, make the problem 

 a complicated one. In the notes under Figure 84, the 

 sizes of tiles to be used in the various main and branch 

 drains there mapped are specified, together with the 



Main I, from 1 to 12, has a grade of 4 inches per 100 feet; and 4-inch tiles are used 

 from 1 to 11, and from 10 to 12, also from 12 to 13. Branches 11, 12 and 13 have 

 grades of 4 inches per 100 feet, and 3 -inch tiles are used. 



Main 2 and its branches are all laid at a grade of 8 inches per 100 feet. A 6-inch 

 tile is used from 2 to 21, 5-inch from 21 to 211, 4-inch tiles from 21 to K, and 211 

 to M, and 3 -inch tiles thence to the upper ends of the two branch drains. 



Main 3 has a 6-inch grade to K, thence 10 inches. Sizes tiles used: 6-inch, 3 to 

 32, and 3-inch beyond K. Branch 32 and sub-branch 321 have a grade of 8 inches, 

 and 322 a grade of 8 inches to F, and 12 inches from F to the upper end. Sizes used: 

 5-inch on 32 to 321, 4-inch on 321 to S and 322 to F; 3-inch above F and S. Branch 

 31 and sub-branch 311 have a grade of 6-inch to P and E and beyond 10 inches or 

 more. Sizes used: 4-inch, 31 to 311; beyond, 3-inch. 



Main 4 and its branches, 8-inch grade; 4-inch tile 4 to 41, and beyond 3-inch tiles. 



Main 5: Grade 5 to X, 3 inches, 5-inch tile; grade X to upper end (springy hill- 

 side). 10 inches, 4 -inch tile. 



Main 6: Grade 6 to 62, 10 inches, tiles 4-inch; grade branches 61 and 62, 8 inches, 

 tiles 3-inch. 



Main 7: Grade 10 inches, tile 5-inch; branch 71, grade to L, 6 inches, and beyond 

 12 inches or more; tiles 4-inch from 71 to L, and beyond L 3-inch; branch 72, grade to 

 M. 8 inches, and beyond 10; tiles 4-inch from 72 to M, and 3-inch beyond. 



Main 8: Grade, 16 inches; size, 3-inch. 



Main 9:. Grade to R, 10 inches; tile, 5- inch; grade R to S, 6 inches tile 4-inch- 

 grade beyond S, 12 inches; tile, 3-inch; branch 91, grade, 8 inches; tile, 91 to C 4- 

 inch; C to upper end, 3-inch. 



Main 10: Grade 10 to 101, 10 inches; beyond, 14 inches; branch 101, grade, 36 

 Inches or more (the upper end tapping a spring with considerable water) ; tiles, 10 to 

 101, 8-inch, beyond 3-inch; tiles, 101 to F, 6-inch, beyond 4-inch. 



Main II: Grade to B, 18 inches, beyond B 20 inches; tiles, 11 to B, 4-inch, beyond 

 B 3-inch. 



Main 12: Grade 12 to 121, 20 inches, beyond 121, 24 inches; tiles 12 to 121, 4-inch; 

 beyond 122, 3-inch; branch 121, grade 36 inches; tile, 3-inch. 



