44 



If in excavating the ditch earth of cUfferent grades is found, it will 

 be best to throw that which is coarsest by itself, as such earth is best 

 suited to fill immediately around and above the tile. In clay sands or 

 soils made up very largely of silt and extremely fine sand, it will often 

 be profitable, if the distance which it must be carted is not too great, 

 to haul coarse sand or fine gravel in order to fill in immediately about 

 and above the tiles. If soil made up either of quicksand or fine silt be 

 placed next the tiles it is almost certain to wash in at the joints. In 

 all cases where the bottom is quicksand, or soft and treacherous in 

 character, it will be best to place slabs or boards in the bottom of the 

 ditch and to lay the tiles on these. In laying the tiles the utmost care 

 should be taken to make as close joints as possible. Considerable 

 security against the entrance of silt and fine sand is secured by care- 

 fully covering the joints between tiles. For this purpose tenacious 

 sods, placed with the grass side against the tile, are often effective. 

 Other materials which prove effective are stri|DS of tarred paper, about 

 two or three inches wide and long enough to reach around the tiles, 

 or similar strips of burlap, — old fertilizer sacks cut or torn up answer 

 this purpose admirably. 



As soon as possible after the tiles are laid the earth should be filled 

 in, for until this work is complete there is danger of serious damage 

 through washing and caving should excessive rains occur. Care should 

 be taken in filling to compact the earth thoroughly, and to round it up 

 immediately over the line of the drain. 



Many authorities recommend putting in silt basins at the junction 

 of laterals with main drains and at points where there is a change in 

 direction. In the writer's experience such basins add considerable to 

 the expense, and are in many cases somewhat difficult to keep in 

 repair. He does not, moreover, regard them as essential, and would 

 advise putting them in only at important points in the system. The 

 simplest method of making a silt basin is to use vitrified sewer pipe 

 set with the lower end about one foot below the level of the tile. The 

 drains are led into and out of it through holes of suitable size, which 

 may easily be cut through the sides of the pipe. A second length of 

 pipe may be set over the first if the depth requires, but the author 

 would advise against carrying such wells to the surface. He would 

 have the upper end of the well at least a foot below the surface of the 

 ground. This must be covered to exclude the earth which will be filled 

 in above it, and for this purpose either a cast-iron cover or a flat stone 

 will be best. 



The location of a well may be marked by a stake driven beside it, 

 or it may be indicated on a plan, which, indeed, it is always wise to 

 make and preserve for future reference whenever underdrains are put 

 in. 



