DRAINAGE 23! 



countries, there are extensive areas where the cost of 

 diking would be only a small fraction of the increased 

 value of the reclaimed land. Back water gates are often 

 necessary where diking and draining are combined. 

 Where fresh water is kept off the land by means of 

 dikes, a system of irrigation often can readily be intro- 

 duced in combination with the drainage. 



Open drains should be kept free from obstructions, such 

 as grass, growing weeds and weeds blown in from sur- 

 rounding fields. The accumulations which arise from 

 banks caving in, or from earth or material washed into 

 the ditch by water or blown in by the wind, as dust from 

 plowed lands, should be early removed, since obstructions 

 of this kind tend to accumulate still more of similar ma- 

 terials. The grade should be kept uniform that any 

 sediment coming into the running water may be carried 

 on to the outlet. Thus, in a ditch carrying considerable 

 water, a slushing device which will stir up the loose 

 mud and help the water carry it forward is sometimes a 

 practical means of clearing the ditch. In some cases a 

 device with shovels, as those from a common cultivator, 

 will answer. A broad board faced with a steel cutting 

 edge and held upright by means of a tongue or by han- 

 dles, is sometimes used. This kind of a device will not 

 work well except where there is current enough to carry 

 the dirt forward, as finely divided particles, in the water. 

 Much depends upon the kind of soil also. Some kinds 

 of fine clay may thus be carried off rapidly in the water. 



Tile drains should be inspected occasionally. The 

 outlet should be visited to learn whether the water is 

 running freely. In cases where portions of drains have 

 been laid through quicksand, which may filter in and fill 

 the tiles, or where for other special reasons clogging is 

 feared, investigations are occasionally necessary to see 

 that all parts of the drains are carrying away the sur- 

 plus water. Silt wells, or even peep holes, aid in this 



