454 TuiRTiL'Tii Annual Rkport 



Engineer in 1916. Since that time the Irrigation Engineer has de- 

 signed the general layout for the 4000 acres of irrigable land, the 

 water-supply development, the distribution system, the works for 

 flood protection, and various minor agricultural engineering works. 

 This connection has provided the opportunity for demonstrating 

 many ideas advocated by the irrigation department, and has made 

 possible the preparation of Bulletin 86, which is the first general 

 treatise on cement pipe. 



WATER SUPPLY FOR YUMA MESA EXPERIMENT 



STATION 



A water-supply system for the irrigation of the Citrus Investi- 

 gations Station on the Yuma Mesa has been designed, and all ma- 

 terial required has been ordered. Much care has been given to 

 making this an ideal system ; and, according to the custom in the 

 past in connection with water-supply development on Experiment 

 Station farms, a description of the system will be made a matter 

 of record. 



The water supply is derived from the east main canal in the 

 Yuma Valley and is elevated to the Mesa by pumping through a 

 long pipe line. Power is available from the Somerton transmission 

 line by means of a branch line one mile in length. An Allis-Chal- 

 mers direct-connected pumping unit, consisting of a 5 inch, Type S, 

 double-suction pump and a 40 horsepower, 440-volt, 3-phase, 60- 

 cycle, 6-pole motor will be set in a dug pit 45 feet from the canal 

 and slightly lower than the water level in the canal, so that the 

 pump will always be primed. The switchboard and starting box 

 will be on the ground floor above the pump. The suction pipe is 

 of 8 inches diameter and there will be an 8-inch gate-valve on each 

 side of the pump. The combined efficiency of pump and motor is 

 guaranteed to be 63 percent. The over-size motor is required by 

 the location in a pit and in a hot climate. 



The pipe line to the Mesa is 1050 feet long. Standard spiral 

 steel pipe with flanged joints was first selected, but later the design 

 was changed to use redwood machine-banded stave pipe. The steel 

 pipe would have several advantages, ease of installation, freedom 

 from troubles, and high salvage value, but the stave pipe is of lower 

 first cost and will give direct opportunity to study the behavior 

 and life of this type of construction. On account of the short 

 supply and high cost of steel, it would be of great moment if the 

 characteristics of wood pipe were such that it could be recom- 

 mended for water lines, particvilarly those under high head or 



