THE PRACTICE OF UNDERDRAINING 



TO secure satisfactory results careful 

 study should first of all be given 

 to the best manner of laying out a 

 system of drains, the aim being to secure 

 the greatest fall, the least outlay for tile, the 

 least amount of digging, and the most per- 

 fect drainage. 



Tile. — For underdraining there is noth- 

 ing better than the ordinary round drain tile. 

 The size to be used can only be decided by 

 a study of the conditions under which the 

 drain is to work. They should be large 

 enough to carry off in twenty-four to forty- 

 eight hours the surplus water, from the 

 heaviest rains, but it is important that they 

 should not be too large, as the cost of under- 

 draining is governed largely by the size of 

 the tile used. It may be mentioned that the 

 capacity of the round water pipes is in pro- 

 portion to the squares of their diameters. 

 That is, under the same conditions, a two- 

 inch pipe will carry four times as much 

 water and a three-inch pipe nine times as 

 much water as a one-inch pipe. In fact, 

 the larger pipe will carry even more than 

 this proportion, because of the greater fric- 

 tion in the small pipe. In ordinary cases 

 five or six inch tile are recommended for the 

 lower part of a main drain and four-inch 

 for the upper portion : for the branches 2^/2 

 to 3-inch are preferable. 



Depth and Distance Apart. — It is sel- 

 dom necessary to lay drains more than four 

 feet below the surface, and in most cases 

 two and a half to three and a half feet will 

 be found sufficient. The proper distance 

 between branch drains depends on the quan- 

 tity of water to be carried and the nature of 

 the subsoil. In general practice the lines of 

 tile are usually placed from fifty to one hun- 

 dred feet apart. In a tenacious clay soil, 

 however, thirtv feet would not be too close. 



Digging the Drain. — The drain may be 

 opened up in the first place by passing three 

 or four times along the same track with an 

 ordinary plow. Then the subsoil may be 

 broken up with a good strong subsoil plow. 

 In this way the earth may be loosened to a 

 depth of two feet or more and thrown out 

 with narrow shovels. The bottom of the 

 drain should be dug with narrow draining 

 spades made for the purpose. The ditch 

 should be kept straight by means of a line 

 stretched tightly near the ground and about 

 four inches back from the edge. In ordi- 

 nary cases the ditch need not be more than 

 a foot wide at the top and four to six inches 

 at the bottom, the width of course increas- 

 ing in proportion to the depth of the drain 

 and the size of the tile. 



Grading. — As a rule drains should be 

 given as much fall as possible, and the grad- 

 ing should not be less than two inches in one 

 hundred feet, if this can be secured. Care- 

 ful leveling is necessary to ensure a uniform 

 fall throughout the course of a drain. As 

 a simple method for this purpose, one of 

 our leading authorities recommends the 

 ditcher to use several cross-heads made from 

 strips of inch boards, three or four inches 

 wide The length of the standard varies 

 according to the depth of the drain. A 

 cross piece about two feet long is nailed on 

 the top of the standard. These cross- 

 heads are then placed along the line of the 

 ditch so that the cross pieces are in line. 

 The proper grade is ascertained by the use 

 of the ordinary spirit level. When ready 

 to lay the tile a standard should be set at the 

 bottom of the drain and marked in line with 

 the top of the cross heads ; this will, by test- 

 ing every few feet, give a true grade for the 

 tiles. 



Laying the Tile. — When the bottom of 



