DTTILDIN'C; COXSTRUCTION 



lOI' 



the canals where seepage losses were greatest, these localities ha\nng first 

 been determined by current meter measurements. 



The losses in the canal system for ign with 43 miles of canals and lat- 

 erals in operation and only i mile concrete lined was 51. i per cent, an aver- 

 age of 1.2 per cent per mile. The loss for 1915 was 20.4 per cent with 76 

 miles of canals and laterals in i-^peration, or an average of 0.27 per cent per 

 mile. It is estimated that the further lining for 5 i/^ miles which will be 

 completed before this year's (1016) irrigation season commences will reduce 

 the losses to less than 13 per cent. 



In the original designs most of the canals were built with i on i I/2 

 slopes on the upper portions of the project and i on 2 side slopes on the 

 lower or sandier portions. A friction factor of n =0.025 was ^^sed for the 

 unlined canals, while « =0.015 was found to be safe for concrete lining. 

 The canals as already built and in operation were generally too large for 

 lining without back filling. A concrete lining i^ inch thick was decid- 

 ed upon with a backfill of sand and gravel of at least 3 inches on the bot- 

 tom and side slopes. According to the size of the canal- in some places, 

 the backfill re juired was 4 to 8 inches and sometimes as much as 2 feet. 



The writer describes in detail the methods followed in carrying out 

 the work. Altogether, 134 000 lineal feet of canal were lined and they 

 re luired 7500 cu. yards of concrete. 



The following table gives some data concerning the work done and 

 its cost per cubic 3 ard and per lineal foot. 



Part of the lining has been in use for four seasons and has given good 

 service and shows no signs of wear. No trouble has been experienced on 

 account of expansion or contraction injuring the lining even when the 

 canal is dry during hnlf the time in summer. 



