WOOD PIPE FOR CONVEYING IRRIGATION WATER. 33 



For replacing 280 feet 40-inch pipe, January, 1911. 



Item. 



Cost. 



Cents 

 per foot. 



Hauling staves, 78 ton-miles, 137.30 



Excavating and tearing down 



Relaying 



Superintendence 



Piling old lumber 



Lumber, 6.7 M., at S2S 



Total 



$29.30 



41.00 



81.90 



30.00 



9.00 



187. 60 



10.4 

 14.4 

 29.3 

 10.7 

 3.3 

 67.0 



378. 80 



135.1 



DURABILITY OF WOOD PIPE AND FACTORS AFFECTING IT. 



" How long will it last ? " is a question asked perhaps of tener than 

 any other in the discussion of wood pipe. It was the common ques- 

 tion during the early years of its manufacture, and it is common 

 to-day after the experience of more than 30 years of extensive use. 



The failure of wood pipe is in general due either to decay of the 

 wood or corrosion of the bands, though wearing out of the wood is 

 also under certain conditions a matter upon which the life of a pipe 

 may depend. The range of variability with reference to these points 

 in the life of the pipes that have been built has been such as to demon- 

 strate conclusively that how long any pipe will last can not be accu- 

 rately predicted without a thorough knowledge of all the conditions 

 involved. 



Sufficient time has not yet elapsed to show the life of some of the 

 earliest continuous stave pipes that were built, while others have 

 endured but from 5 to 12 years. In support of the foregoing state- 

 ment specific data bearing upon the durability of a number of pipe 

 lines, several of which were inspected by the writer, are given in the 

 following pages. 



In writing of the first continuous stave pipe built in the West, at 

 Denver, in 1884, S. Fortier states x — 



The pipe was laid in a portion of its length about 15 inches above the 

 hydraulic gradient. Native pine, whose durability under unfavorable condi- 

 tions is from three to five years, composed the staves, and in the portion of 

 the line referred to the pipe was never more than two-thirds full of water. 

 The top staves decayed rapidly. In the fall of the year (1889) the Denver 

 Water Co. had bands loosened and the staves from the upper arc removed 

 without shutting off the water. It was then found that the lumber was per- 

 fectly sound up to the surface of the water in the pipe, and in the next stave 

 above on either side, whereas the remaining staves which the water could 

 not reach by capillary attraction or otherwise were rotten. 



A part of this line, lying close to the river, under conditions where 

 both exterior and interior are kept wet, was said to be still in use 

 in 1912. 



iAnn. Amer. Soc. Irrig. Engin., 1892-93, p. 11. 



