102 



DOMESTIC WATER SUPPLIES FOR THE FARM 



Corrosion of pipes is also frequently an irritating feature of 

 driven wells, even galvanized pipes being at times attacked with 

 great rapidity. The remedy is discussed in the chapter on 

 Special Problems. 



Advantages and Disadvantages of Jet Wells. - - The chief ad- 

 vantage of the jet or jetting process of sinking wells is its extreme 

 rapidity, the water current and drill cooperating in loosening the 

 material ahead of the casing and permitting the latter to be sunk 

 more rapidly than by any other method. Wells of 400 to 500 

 feet in depth are sometimes sunk, cased and cleaned in two days. 

 The chief disadvantage is probably the fact that it requires a 

 previous supply of water to operate, a supply that in desert 

 regions is by no means always available. Other advantages and 

 disadvantages are indicated below. 



Well sunk by jet process. 



Advantages. 



Disadvantages. 



Rapid in soft materials; operates continuously. 



Cheap compared with hydraulic, hydraulic ro- 

 tary, and drilling methods. 



Supplies inexpensive and readily obtainable. 



Adapted to incoherent materials, such as sand, 

 not capable of standing alone. 



Affords fair records and samples of materials 

 penetrated. 



Other advantages similar to those of driven 

 wells. 



Limited to soft materials. 



Requires more apparatus than driven wells; requires skilled 



labor. 



Requires previous supply of water. 

 Small water seams not readily recognized. 



Draws from single water bed. 



Requires strong water beds due to absence of storage facili- 

 ties; seeps can not be utilized. 

 No storage capacity. 

 Usually limited to small diameters. 

 Satisfactory only in wells of moderate depth. 

 Slow response to rainfall as compared to shallow dug wells. 

 Corrosion and incrustation of pipes. 



Taste of water due to solution of iron by corrosive waters. 

 Difficulty of cleaning. 



Location of Jet Wells. - - The jetting process is particularly 

 adapted to the finer types of unconsolidated deposits, such as 

 sands, etc., the materials of which are easily displaced and lifted 

 by the water current. It has been extensively used in the coastal 

 plain deposits along the Atlantic, in many inland glacial deposits, 

 and in some of the alluvial valleys of the West, especially in 

 California. 



In general, the statements made as to the location of driven 

 wells apply equally to jet wells, since the two forms of wells are 



