41 



by placing flatwise 2 inch by 4 inch timbers across the slopes at the dis- 

 tance desired and with a straight edge tamp and level the earth between. 



It is important to remove all deposits of vegetable character and the 

 sides and bottom must be well settled to prevent the cracking of the lining. 

 It is well to run water in the diteh before the ditch is prepared and lined. 



The placing of the concrete should follow the trimming as soon as pos- 

 sible and if the channel is dry it should be thoroughly moistened by sprink- 

 ling. The concrete lining is built in alternate strips or panels. To place 

 the concrete wooden guide pieces of the thickness of the lining are laid 

 across the side slopes at the required distance apart which may be 3 feet 

 or more. The concrete is spread between these studdings and raked to 

 about a uniform thickness, tamped and made smooth and level by means 

 of a straight edge resting on the guide timbers. The floor is finished in 

 the same manner. Fig. 34 shows the completed canal. 



Cost of concrete linings. 



The cost of concrete lining varies a great deal with the accessibility of 

 the canal, the material through which the canal is cut, the planning of the 

 work, the efficiency of the construction force, the price of labor and 

 material. 



The cost of lining with forms is given by the following examples. 



The Anaheim Union Water Company of southern California, which has 

 many miles of concrete lined canal, obtained the following unit cost for 

 1,000 feet of a canal 9 feet wide at the top, 6 feet wide at the bottom and 

 3 feet deep, lined with average thickness of concrete of about 3 to 3 1 /& 

 inches, with the corner at the bottom made thicker. 



170 barrels of cement at $2.70 ......................................... $ 460.00 



170 cubic yards of gravel at 65c ........................ . .............. 110.00 



Labor of backfilling using earth form .................................. 254.00 



Labor of placing with concrete form .................................. 212.00 



$1,036.00 



Cost oer lineal foot, including backfilling-, $1.036. 

 Cost per square foot, including- backfilling, $0.0818. 



For 4,070 feet of a smaller canal 2% feet wide at the top, 1 foot wide at 

 the bottom and l 1 /^ feet deep, lined with 2 inches thickness of concrete, 

 the cost was: 



Total cost 

 Material. for 



4070 feet. 



180 barrels of cement at $2.40 .......................................... $432.00 



180 cubic yards of gravel at $1.25 ................................. . ..... 225.00 



Total labor for backfilling, mixing and placing concrete ................. 270.06 



$927.06 



Cost per lineal foot, including backfilling, $0.228. 

 Cost per square foot, including backfilling, $0.0526. 



The wages paid were: 



$1.75 per day for men using earth form and backfilling. 



$2.00 per day for men mixing and placing concrete. 



$3.00 per day for foreman. 



These costs include only the cost of materials in the concrete and the 



