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Show LOSS OF CANAL WATER Too Steep Grades Are Sometimes Responsible for Leaks. When Ditches Are Built Through Gravelly Soils Seepage Losses Are Naturally Heavy Unless Measures Are Taken to Prevent. There is not an irrigating canal in this country from which there is not more or less loss of water in transit. These losses are generally spoken of as caused by seepage and evaporation. However, it has been demonstrated that the evaporation losses as compared com-pared to those caused by seepage are so light that they may be disregarded. The loss by seepage unusually occurs from the character of the soil through which the canals run, says the Denver Field and Farm. When this is a finely divided sandy loam such as occurs in many places the losses from this cause are generally light, but when the canals are built through soils which are very gravelly or perhaps nearly pure gravel the seepage losses are natur Uy very heavy unless strenuous stren-uous measures are adopted to prevent them. In other places much water Is lost along parts of the canals where tha excavation has been through seamy basaltic rock or decomposed sandstone. sand-stone. Too steep grades sometimes are responsible for much seepage. This condition Is found on some of the smaller early ditches built through gravelly soil. We have heard it argued that when the water is to be conducted conduct-ed through gravel or a porous formation forma-tion it should go fast, but in canalB built on this theory the velocities ars such as to prevent silting of the channels chan-nels and thus actually promote seep-age. seep-age. In the construction of canals many fills are made across short gullies gul-lies or depressions, where to follow the contour of the land would necessitate necessi-tate wide detours; and frequently the upper banks are either omitted or destroyed de-stroyed which allows the water to Bpread out over the land above the canal and form lakes. In cases where the fills are of considerable con-siderable height quite large areas of land are sometimes flooded and below such lakes are invariably found heavy seepage losses, large enough often to run in small streams away from the canal. To prevent these losses the upper banks of the canals have been built up so as to prevent the formation forma-tion of the lakes. On the canals where the difficulty Is due to gravelly soil it has been the practice to some extent to excavate a foot or so below grade and then fill in with clay or fine material, so as to form a puddle. The clay is tamped in the bottom, and then the bottom and sides are plastered several inches thick with a mortar formed of the clay in plastic state. This is then covered with a layer of gravel to prevent washing. The results of this work are quite satisfactory, but it is difficult to find suitable clay for the purpose and cement ce-ment has to be used which is more expensive ex-pensive but considerably more durable. dur-able. Some measurements have been made on our canals to learn the extent of seepage, but on the smaller ditches it is almost impossible to get any reliable re-liable results on account of the numerous numer-ous diversions which there Is no satisfactory sat-isfactory means of measuring; and If ' these are shut off along a stretch two or three miles long, the extra water will cause such a rise in the canal below be-low as to be dangerous. The loss often oft-en amounts to fifty per cent, and this is more than any business can stand. |