DRAINAGE 301 



small slough is connected into one of these passages by- 

 means of a well, the water will flow downward and escape. 

 There is no practical method of determining on the surface 

 where to sink a well, how deep to go, or what the final 

 results will be. The conditions in a water supply and a 

 drainage well are reversed. In the former the fine sand 

 and silt are drawn up and ejected by the pump, tending 

 to make the flow freer with use; but in the latter the silt 

 and fine sand carried in the drainage waters are carried 

 backward into the strata, and the continuous action of the 

 water pushing outward from the well compacts and solidi- 

 fies the material and in a short time it is closed to the pass- 

 age of water. The well then ceases to operate as a drain. 

 The drainage of large areas of surface water into under- 

 ground strata is objectionable from the standpoint of 

 sanitation, as there is danger of contamination of the water 

 supply. 



FINAL MAP 



On the completion of a farm drainage system, a plat 

 should be made showing the location and size of all 

 drainage work completed. This is not as important for 

 open ditches as for tile drainage. In a few years' time 

 it may be impossible to determine on the surface where 

 the tile was laid, and when the land is sold the purchaser 

 may demand a plat showing the underdrainage system. In 

 many soils it is costly work to plat a tile drainage system 

 that has been laid for several years, and there is always an 

 uncertainty as to the exact location and size. Real estate 

 men recommend, in drained areas, filing with the county 

 recorder a certified plat showing underdrainage on individual 

 farms. 



BIBLIOGRAPHY 



Elliott, Charles G. Engineering for Land Drainage. John Wiley & 



Sons. 

 Elliott, Charles G. Practical Farm Drainage. John Wiley & Sons. 

 Jeffrey, Joseph A. Text-book of Land Drainage. Macmillan. 

 Parsons, John L. Land Drainage. Myron C. Clark Publishing Co. 



