240 



THE IRRIGATION AGE. 



LINING OF DITCHES AND RESERVOIRS TO PRE- 

 VENT SEEPAGE LOSSES. 



BY PROF. B. A. ETCHEVERRY, BERKELEY, CAL. 



(Continued.) 



PUDDLED CLAY LINING. 



This method of lining had not been used to any 

 extent in the irrigated districts investigated, and the 

 writer could not learn of any systematic work of the 

 kind. 



The cost of this lining would depend o'n the dis- 

 tance the clay would have to be hauled and the ease with 

 which it can be loaded, and on the way the clay is 

 applied. 



Under the best conditions, clay being close at hand, 

 easily loaded and applied cheaply, would be very sat- 

 isfactory and efficient in stopping seepage. Probably 

 the cheapest method of applying the clay would be to 

 spread it on the bottom and slopes when the clay is soft 

 and moist, or if it can not be obtained in that condition, 

 to spread it after the ditch has been wetted thoroughly 

 by damming up the water and then draining it out; 

 or to spread it dry and then fill the canal and drain the 

 water out. After the clay has been spread as uniformly 

 as practicable, the canal could be fenced in, and cattle 

 or, better, sheep could be driven in the fenced area ; 

 they could be fed along the ditch and in this way would 

 tramp the puddle thoroughly. 



The cost of such a lining would be mainly the cost 

 of the clay; for a lining 4 to 6 inches thick this cost 

 would probably not exceed 1 to 1^ cents per square 

 foot. 



EXPERIMENTS TO DETERMINE RELATIVE EFFICIENCY OF 

 CANAL LININGS AS REGARDS SEEPAGE. 



The purpose of these experiments was to deter- 

 mine the relative efficiency of canal linings, as regards 

 seepage only, and not to compare the resistance of the 

 lining to the cutting or erosive force of running water. 



For this purpose twelve ditches closed at both ends 

 were excavated in earth of uniform texture, that they 

 might all be under the same conditions. These ditches 

 were lined with the different materials used in California 

 for the lining of irrigating canals. After the ditches 

 were excavated and lined daily measurements were taken 

 to determine the rate of seepage, and from these the 

 relative efficiency was obtained. 



LOCATION AND POSITION OF DITCHES. 



The site chosen for the experiments is in Stanislaus 

 County, near Modesto, on the University experimental 

 farm, about 3% miles east of the town. Lateral Xo. 

 1 of the Modesto Irrigation District ran near the south 

 end of the ditches and was the source of water supply 

 for the experiments. 



The soil is a fine sandy loam and is very homo- 

 geneous to a depth of 2 feet : below this some hardpan 

 was found in the north end of the ditches. This hard- 

 pan only occurred in small quantities and was in a soft 

 condition. It could be plowed and removed with 

 scrapers. It is to be regretted that a site with a more 

 sandy soil was not available, as the results might have 

 been more conclusive. 



The ditches were parallel and ran north and south, 

 at right angles to Lateral No. 1. (Fig. 13.) The south 

 ends of the ditches were at approximately the same dis- 



tance from this lateral, so that the seepage from it, 

 if any, would aifect each ditch equally. 



A wooden flume built with Ixl2-inch redwood 

 lumber, running parallel to the lateral and along the 

 south end of the ditches, carried the water from the 

 lateral to the ditches; a gate in the flume was provided 

 for each ditch. 



The ditches were at the same elevation, that the ef- 

 fect of underground water might be equal, and were all 

 21/0 feet deep, with side slopes of 1^2 n 1> an( i a bot- 

 tow width of 2 feet. A side slope of 1^4 on 1 was used 

 because the wet earth in the unlined ditches and the 

 puddle in the puddled ditch would not stand on a 

 steeper slope, and mainly because of the difficulty of oil- 

 ing the slopes if they had been steeper. The length of 

 the ditches at the top was 50 feet, the ends having also 

 a slope of 1% on 1 ; the bottom length was 421/2 feet. 

 The top bank width was 4% feet, making a depth of 14 

 feet between the ditches, center to center. 



METHOD OF CONSTRUCTION. 



The site was not exactly level. It was thought best 

 to make it so, that the ditches might be more nearly 

 under the same conditions. The land was irrigated 

 and plowed and the earth from the higher part of the 

 plot was removed with Fresno scrapers and carried off 

 the site. The ditches were all in cut. After the sur- 

 face was made level, the grade stakes were located and 

 the excavation of the ditches begun. Each ditch was 

 plowed deeply and the earth removed at first with 

 Fresno scrapers, but as the bottom was reached the 

 smaller scrapers (scoop scrapers) were used. In this 

 manner the ditches were excavated roughly to the re- 

 quired cross-section. The total volume of excavation 

 was approximately 500 cubic yards and the total cost 

 was $95, or at the rate of 19 cents per cubic yard. 



LININGS TO BE USED. 



The linings which it was thought advisable to try in 

 the experiment were: 



1. Cement concrete similar to that used by the 

 Santa Ana Water Company and the Anaheim Water 

 Company. 



2. Cement mortar and cement plaster 1 inch thick, 

 as used around Eiverside by the water companies 

 (Jurupa, Gage, and Riverside) and in several other 

 localities in southern California. 



3. Cement lime concrete. It was thought that the 

 addition of some lime to take the place of part of the 

 cement in the concrete similar to No. 1 would perhaps 

 make the concrete more water tight. and also slightly 

 cheaper in some localities. 



4. Puddle. 



5. Road oil in various proportions per square yard 

 of surface and also as a mixture of oil and gravel. The 

 extensive use of oil and its success in road oiling when 

 properly used, especially in southern California, where 

 in many cases the oiled streets are almost as good and 

 even in a few cases better than asphaltum, made it ad- 

 visable to try oil in several ways. 



For a good oiled road, a good foundation and a 

 well-rolled wearing surface are necessary. The quantity 

 of heavy road oil necessary should not exceed li/o gal- 

 lons to the square yard. 



For canal lining, the conditions are somewhat dif- 

 ferent from those found in road construction. A good 

 foundation is not necessary. It is impracticable to roll 



