12 



l-ri.l.KTIX 495, U. S. DEPARTMENT OF AGRICULTURE. 



ARTESIAN 





l"i<;. 6. — Deep-well pump in casing to per- 

 mit Installation of pump below ground- 

 water level. 



bearing stratum is intercepted. 

 Care should be exercised to case 

 off strata having a weak flow if 

 strata having stronger flow are 

 encountered in the same well, 

 because water may be forced out 

 of the well into the weak strata 

 so that they will be a source of 

 loss rather than gain. Each 

 water-bearing stratum should be 

 tested before the final casing is 

 sunk, so that the well screens can 

 be properly located and propor- 

 tioned in size and mesh. 



SCREENING WATER. 



A difficult factor to control in 

 many water supplies for spray 

 irrigation is the clogging of noz- 

 zles and pipe lines by sediment, 

 moss, lime, or other matter. This 

 is true especially with the over- 

 head system, where many small 

 nozzles must be kept clean. The 

 most desirable place to remove 

 clogging matter is before the 

 water enters the suction pipe of 

 the pumping plant. Screens of 

 different forms are placed in the 

 " turning unions " at the feed 

 end of each lateral, but these 

 screens can remove only a small 

 amount of material before they 

 in turn must be cleaned. Sands 

 from wells or other sources may 

 be collected to a certain extent 

 by placing in the main pipe line 

 an enlarged chamber similar to 

 a pressure tank, where the veloc- 

 ity is checked and the sand 

 grains settle out. Under extreme 

 conditions it may be necessary to 

 reservoir well waters and re- 

 pump after settling. Bucket- 

 type screens for installation in 



