Othkk L'sks of Ckment PlI-K 163 



Frequently, too, canals and ditches have to be carried acr(»ss 

 and beneath rivers. The Woodruff (Arizona) canal intersects the 

 Little Colorado River three times. The Flowinjj^ Wells ditch is 

 carried under the Santa Cruz River in an inverted siphon 3200 feet 

 long. 



It is evident that conduits for these purposes should have weight 

 or be anchored down w^th piling, and they should have great bend- 

 ing strength, as portions of them may be undermined during floods. 

 Some form of reinforced concrete pipe should be used. The amount 

 of steel reinforcement can be varied to meet the requirements and 

 although the pipe line should be buried beyond the probable reach 

 of floods, yet if a portion is undermined by the scour or is subjected 

 to lateral pressure, the longitudinal reinforcement will be very ef- 

 fective in maintaining the stability of the line. 



For that portion of the line safely outside of the river bed plain 

 cement pipe will be adequate. 



DOMESTIC SUPPLY PIPK LINES 



The excellent characteristics of machine-made pipe suggest an- 

 other use for it. In view of the almost prohibitive price of cast- 

 iron and wTought-iron pipe at the present time, it may be prac- 

 ticable to substitute cement pipe, in some cases reinforced, in cases 

 where the internal pressure is less than 20 pounds per square inch. 

 Twelve-inch cement pipe of an extra rich mixture, extra thick, and 

 containing some steel reinforcement can be made in Tucson for 

 about one-sixth the cost of standard W^ I. pipe of the same diameter 

 and capacity. Under favorable conditions the cement pipe will not 

 deteriorate, while iron pipe does. The only disadvantage on the 

 side of the cement pipe, probably, is the great danger from water 

 hammer, but this could be obviated by careful designing. In small 

 villages, mining camps, cantonments, and for farm homes much 

 cement pipe could be employed economically. 



