CONCRETE LINING FOR IRRIGATION CANALS. 69 



faces with straight-edges. The sides and bottom were tamped 

 lightly with wooden tampers and sprinkled before the lining was 

 applied. The section lined has a bottom width of 11| feet, side 

 slopes of 1 J to 1, and a wetted perimeter of 26^ feet. 



The three mixers used were operated on planks in the bottom of 

 the ditch in advance of the work. With each mixer there was a 

 crew of about 25 men and in addition a finishing crew of 5 or 6 men 

 to dress the earth surfaces immediately ahead of the mixer. One 

 rock crusher was also operated, the crushed rock being hauled an 

 average of 2 miles. Most of the sand was procured from pits along 

 the fine of the canal and was used without screening. The fining 

 was laid in 8-foot sections If inches thick, with strips of building 

 paper in the joints between the sections. Four hundred feet of 

 lining was considered a good day's work for a crew. 



A 1:3:4 mixture of concrete was used for most of the fining, but 

 on one section a 1 : 4 mortar applied 1 inch thick was considered just 

 as good as the thicker fining of concrete, besides being much easier 

 to apply. 



The fining in gravel sections leaked considerably the first season, 

 presumably because allowed to dry too rapidly on account of lack 

 of water for keeping it moist after laying. In work that was done 

 the following year this difficulty was obviated by allowing a small 

 amount of water to flow in the ditch soon after lining, using check 

 dams to prevent its interference with construction. Men wearing 

 rubber boots then waded along and with shovels or buckets threw 

 water upon the side slopes at frequent intervals to keep the concrete 

 wet while setting. Where lining had been placed on moistened sand, 

 the results were better than in the sections through gravel, there 

 being no perceptible leakage. Conditions in the gravel portion 

 improved with the first year's use of the lined section, after which 

 the seepage was considerably lessened. 



The various items of cost secured are as follows: 



Cost of lining canal of Lower Yakima Irrigation Co. 



Laborers per day of 10 hours, without board $2. 50 



Man and team per day, without board 4. 50 



Contract price per square foot for mixing and laying concrete . 025 



Cement per barrel x 3. 10 



Sand per cubic yard, approximately .50 



Total cost of lining, per square foot . 065 



Total cost of lining 9, 064. 49 



During February and March, 1911, the company placed additional 

 lining, using practically the same methods above described, except 



1 This doss not include an 8-mile haul over heavy roads. 



