THE IRRIGATION AGE. 



171 



moved the larger irregularities, tamping the sides and 

 bottom; then the smooth finishers brought the surface 

 exactly true. 



Method of Lining. The cement men usually fol- 

 lowed the finishers, about a half day later. If the earth 

 had dried, it was usually well sprinkled. Wooden strips 

 iy^ inches in width, % inch thick, and equal in length 

 to the width of the sloping sides, were placed flatwise 

 on the slopes. They were placed 3 feet apart, and 



The cost of this class of work, including prepara- 

 tion of the slopes and bottom, and their lining, varies 

 from 3% to 4 cents per square foot. 



The Riverside Water Company has plastered a 

 large portion of its water channels in a very similar 

 manner, the cost being nearly the same. 



The Jurupa canal is lined with cement plaster; the 

 thickness of the lining, however, is only 14 to ^ inch. 

 (Fig. 8.) The earth ditch was not brought to" grade 



Fig. 7 Gage Canal, lined with cement mortar. 



served as guides to a straight edge which assured a uni- 

 form thickness of %-inch mortar. 



The mortar was mixed on top of the bank in gal- 

 vanized iron portable mixing boxes, and spread uni- 

 formly between the wooden strips on the slopes. With 

 the straight edge as a guide, all irregularities were re- 

 moved, and the mortar was finally compacted with the 

 trowel. After the slopes had been lined the bottom lin- 

 ing was put on. A good lining % inch in thickness was 



as accurately, nor the sides finished as smoothly, as for 

 the Gage Canal Company. The water channel was 

 trimmed approximately with shovels; the sides and 

 bottom were then sprinkled and the mortar spread with 

 trowels to a uniform thickness as nearly as possible. 

 The cost of this lining was not obtainable, but very sim- 

 ilar work used by the Escondido Irrigation District for 

 some of its channels cost from 15 to 20 cents per square 

 yard, or from 1.66 to 2.22 cents per square foot. 



Fig. 8 Jurupa canal, lined with cement mortar. 



thus obtained. The bottom width of the canal varies 

 from 5 to 10 feet, and the side slopes are 1 on 1, the 

 depth being 3% to 4 feet. (Fig. 7.) The lining is 

 extended on each side of the top of the slope to a dis- 

 tance of 5 inches. 



The plaster is composed of one part of good Port- 

 land cement to four parts of clean sharp sand. 



A smaller ditch near Hemet, the Little Valley 

 ditch, 2 feet wide at the bottom, iy 2 feet deep, with 

 side slopes of 1 on 1, was lined with cement mortar 

 plaster 1 inch thick on the bottom, and % inch thick 

 at the sides. The composition of the mortar for the 

 bottom was one part of California cement to four parts 

 of sand ; for the sides it was one part of cement to six 



