156 LAND DRAINAGE 



sand by his own weight sufficiently to bring it even with 

 or a little below the bottom of the ditch when it is com- 

 plete ; or if his weight is not sufficient, he may remove a 

 portion of the sand and then place his weight upon the 

 shield and lower it little by little to the bottom of the 

 ditch. With a tile scoop, the bottom of the ditch can 

 then be properly formed and the tile laid in place. The 

 shield is then lifted and moved ahead sufficiently to pre- 

 pare the bottom for the next section. It would not be 

 difficult to make a shield of wood that could be operated 

 in much the same way. 



Where the ditch is deep and the quicksand is found to 

 stand to some height above the bottom of the ditch, 

 planks or boards should be used to hold the banks from 

 falling in and great care should be taken to avoid accidents 

 from caving. 



206. Protection to joints against quicksand. When 

 tile is laid in quicksand or in very fine ordinary sand or 

 silt, it is usually necessary to provide some means to pre- 

 vent the fine particles from entering the tile through the 

 joints. It is sometimes recommended that marsh hay 

 be laid over the tile before any soil is introduced into 

 the ditch. Strips of strong building paper are sometimes 

 laid over the joints before the earth is introduced. An 

 inch or more of top soil or fine clay, laid over the joints, 

 will prove fully as satisfactory as grass or paper, and much 

 more enduring. 



207. Boggy and springy places. Sometimes in laying 

 tile through muck soils, springs are discovered which cause 

 such a degree of softness in the muck at the bottom of 

 the ditch that it is very difficult to lay the tile with any 

 degree of evenness. In such cases it is recommended by 

 successful drainage engineers that the ditch be dug 



