39 



For these conditions it may be advisable to use expansion joints spaced 

 about 12 feet apart and omit all other joints. However, the writer believes 

 that the soil can be thoroughly settled by running water in the excavated 

 canal prior to the construction of the lining. The expansion joint, if de- 

 sired, could be made by imbedding in the edges of the adjacent section a 

 metal tongue about 4 inches wide! This tongue may be of galvanized iron 

 well painted with oil to prevent adhesion of the concrete. 

 Method used near Kelowna by Kelowna Irrigation Company. 



The method was very similar to the one described above. The main 

 difference was that no separate earth forms were used. The concrete forms 

 were placed in position in the excavated ditch and galvanized iron metal 

 plates were put outside of the concrete form and held away from it by 

 pieces of timber of the thickness of the lining (Pig. 31). The earth back- 

 filling was placed against these plates and the concrete was poured in be- 

 tween the plates and the concrete forms. The plates and pieces of timber 

 were pulled out as fast as the concrete was poured in. 



The above methods of lining by means of forms are limited to side slopes 

 steeper than 1 to 1, because when using a wet mixture even with side slopes 

 between % to 1 and 1 to 1, the forms will tend to raise. Bolting the forms 

 together will help to "keep them in position. 

 Construction of concrete lining without forms. 



This method of construction has not been used in British Columbia but 

 it is used extensively on irrigation canals in California and other states 

 where concrete lining was necessary. It is the method to use for side slopes 

 of 1 to 1 or flatter and is well adapted to large canals. While the first 

 method is usually preferable for new canals on side hills, because steeper 

 side slopes can be used, the second method may be preferable in the valley 

 or in level land and especially in loose sandy soil which will stand naturally 

 on slopes of 2 horizontal to 1 vertical or more. 



The method used in preparing the excavated earth canal for the lining 

 and in applying the concrete lining varies. One of the best methods which 

 has been used by the Gage Canal Company of Riverside, California, is 

 as follows: 



Preparation of earth canal (Fig. 32). Place the grade stakes 20 feet 

 apart along one side of the ditch at a distance of 1 foot from the top of the 

 sloping side. Hold a level rod or cross section rod across the ditch with one 

 end resting on the grade stake, set the corresponding grade stake on the 

 other side and put the bottom stakes in position by measuring down from 

 this rod. By means of these stakes the bottom is cut to grade. To trim 

 the side slopes, iron strips 1 inch wide, % inch thick and of suitable length 

 are driven edgewise in the sloping sides 3 feet apart, and extending up and 

 down the slopes. The lower ends of these bars are placed in line by means 

 of a line stretched between the bottom grade stakes and the proper slope 

 is given to the bars by using a specially constructed slope level, which con- 

 sists of a wooden rod on which a level bubble is placed, the bubble coming 

 to the center when the rod is on the desired slope. The iron bars when in 

 position, are guides for a sharp iron straight edge with which all irregu- 

 larities are shaved off and hollow places filled in and well tamped. 



A modification of this method would be to locate the top and bottom 

 grade stakes by means of a templet of the same form as the finished ditch, 

 the templet being equipped with a plumb bob or spirit level will indicate 

 when it is in position (Fig. 33). Then stretch longitudinal lines between 

 the stakes and grade approximately to these lines and finish the dressing 



