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For the ordinary conditions in British Columbia the following thickness 

 of concrete lining and side slopes should be used. For a canal 2 to 4 feet 

 deep excavated in an ordinary firm soil which will stand naturally on a 

 slope not flatter than 1 or 1 y 2 horizontal to 1 vertical, use a concrete lining 

 not less than 3 inches thick built on a slope of ^horizontal to 1 vertical, or 

 a lining not less than 2 inches thick built on a slope of 1 horizontal to 1 

 vertical. For loose soil which will stand naturally on a slope of 2 or 3 

 horizontal to 1 vertical use a 3 inch lining placed on a slope of 1 vertical 

 to 1 horizontal. For canals 12 to 18 inches deep use a minimum thickness 

 of 2 inches. 



When side slopes of % horizontal to 1 vertical are used, the form of 

 cross section requiring the least concrete will have a bottom width equal 

 to 94-100 of the square root of the area in square feet and a depth equal to 

 76-100 of the square root of the area. When the side slopes are 1 horizontal 

 to 1 vertical, the bottom width and depth will be 61-100 and 74-100 respec- 

 tively of the square root of area. 

 Shrinkage and expansion. 



No matter what the thickness is, unless the concrete is reinforced with 

 steel, or expansion joints provided, cracks are to be expected because of the 

 contraction or shrinkage in the winter. These cracks will usually be fine 

 cracks occurring at more or less regular intervals and the leakage through 

 them will be small and often silt up. For better appearance and to dis- 

 tribute the cracks at uiform intervals, the lining shoud be laid in sections 

 or strips 6 to 8 feet long. 

 Effect of frost. 



Frost should have no effect on the lining if the soil is well drained. But 

 when the soil contains water, freezing will produce heaving of the soil which 

 will not be resisted even by thicker linings than those recommended. 

 Usually a canal which must be lined is located where the water drains too 

 readily from the soil, but if the canal is located where water is liable to 

 collect behind the lining, a drain should be provided. The drain should be 

 a 3 or 4 inch tile placed below the floor of the canal lining in a trench 12 

 inches deep, located along the center line of the canal and the tile covered 

 preferably with loose rock, gravel, sand, or other porous material. To dis- 

 charge the water collected cross drains should be placed every 400 or 500 

 feet or wherever there is a drainage channel. The tile may be omitted and 

 the trench filled entirely with rock or gravel but this is not as efficient. 

 Method of construction of concrete linings. 



The details of construction in lining canals usually vary with the ideas 

 and judgment of the men in charge of construction. There are two general 

 methods of construction. 



The first method of construction requires forms behind which the con- 

 crete is placed. The second method requires no forms, the concrete being 

 spread on the bottom and sides of the canal much in the same manner as 

 for sidewalk work. The first method is used when the side slopes are 

 steeper than 1 horizontal to 1 vertical. The second method is used for side 

 slopes of 1 to 1 or flatter. 



Construction of concrete lining by means of forms. 



This method has been used by the Fruitlands Irrigation and Power Com- 

 pany, near Kamloops, by the Kelowna Irrigation Company and the South 

 Kelowna Irrigation Company. It has also been used extensively on a num- 



