UNIVERSITY OF CALIFORNIA PUBLICATIONS. COLLEGE OF AGRICULTURE. AGRICULTURAL EXPERIMENT STATION, BERKELEY, CALIFORNIA. LINING OF DITCHES AND RESERVOIRS TO PREVENT SEEPAGE LOSSES. By ELWOOD MEAD AND B. A. ETCHEVERRY BULLETIN No. 188. (Berkeley, Cal., June, 1907.) SACRAMENTO: w. w. shannon ■:::::: superintendent state printing 1907. BENJAMIN IDE WHEELER, Ph.D., LL.D., President of the University. EXPERIMENT STATION STAFF. E. J. WICKSON, M.A., Acting Director and Horticulturist. E. W. HILGARD, Ph.D., LL.D., Chemist. W. A. SETCHELL, Ph.D., Botanist. ELWOOD MEAD, M.S., C.E., Irrigation Engineer. C. W. WOODWORTH, M.S., Entomologist. R. H. LOUGHRIDGE, Ph.D., Agricultural Geologist and Soil Physicist. (Soils, Alkali.) M. E. JAFFA, M.S., Nutrition Expert, in charge of the Poultry Station. G. W. SHAW, M.A., Ph.D., Agricultural Technologist, in charge of Cereal Stations. GEORGE E. COLBY, M.S., Chemist. (Fruits, Waters, Insecticides.) RALPH E. SMITH, B.S., Plant Pathologist and Superintendent of Southern California Pathological Laboratory and Experiment Stations. A. R. WARD, B.S.A., D.V.M., Veterinarian and Bacteriologist. E. W. MAJOR, B.Agr., Animal^ Industry. F. T. BIOLETTI, M.S., Viticulturist. (Grapes, Wine, and Zymology.) H. M. HALL, M.S., Assistant Botanist. H. J. QUAYLE, A.B., Assistant Entomologist. JOHN S. BURD, B.S., Chemist, in charge of Fertiliser Control. C. M. HARING, D.V.M., Assistant Veterinarian and Bacteriologist. E. H. SMITH, M.S., \ H. J. RAMSEY, M.S., ( Assistant Plant Pathologist. T. F. HUNT, B.S., \ R. E. MANSELL, Assistant in Horticulture in charge of Central Station Grounds. G. R. STEWART, B.S., Assistant in Chemical Laboratory. , Assistant in Soil Laboratory. RALPH BENTON, B.S., Assistant in Entomology. LUDWIG ROSENSTEIN, Laboratory Assistant in Fertilizer Control. ALFRED TOURNIER, Assistant in Viticulture. HANS C. HOLM, Student Assistant in Zymology. A. J. GAUMNITZ, M.S., Assistant in Cereal Laboratory. J. C. BRADLEY, A.B., Assistant in Entomology. D. L. BUNNELL, Clerk to the Director. JOHN TUOHY, Patron, ) „,..,*. m , > Tulare Substation, Tulare. J. T. BEARSS, Foreman, ) J. W. MILLS, Horticultural Assistant in Southern California, Riverside. J. W. ROPER, Patron, ) „ _, . . ~. „ > University Forestry Station, Chico. E. C. MILLER In charge, ) ROY JONES, Patron, 1 University Forestry Station, Santa Monica. N. D. INGHAM, Foreman,. ) VINCENT J. HUNTLEY, Foreman of Calif ornia Poultry Experiment Station, Petaluma. The Station publications (Reports and Bulletins), so long as available, will be sent to any citizen of the State on application. LININGS OF DITCHES AND RESERVOIRS TO PREVENT SEEPAGE LOSSES, INTRODUCTION. The water which sinks into the soil from ditches and reservoirs is one of the chief sources of waste in irrigation. In gravelly soils, or where ditches cross gypsum strata, the losses sometimes amount to more than half the total flow. Measurements on a large number of ditches, made by the Office of Experiment Stations, show an average loss on main canals of about one per cent for each mile that water is carried; on laterals the loss amounted to between 11 and 12 per cent per mile ; while on some California canals the loss in a single mile was 64 per cent.* The water which escapes is often worse than wasted. It collects in the lower lands, fills the soil, drowns the roots of trees and plants, brings alkali to the surface, and is a prolific breeding place for mosquitoes. On large and costly aqueducts or important storage works, linings of cement, concrete, or asphaltum may be employed without the expense being prohibitive. But the great bulk of these losses occur on lateral ditches and small storage basins where some simpler and cheaper method of making the surface impervious to water must be found; and if ditches can be lined with this substitute by methods which can be carried out by farmers or unskilled laborers, a great improvement in irrigation practice and a marked increase in the duty of water will be brought about. Muddy water soon silts up muddy ditches, but where the water is clear seepage losses are likely to be permanent and some sort of lining to stop this becomes an important matter. As water drawn from wells or reservoirs is always clear, methods of preventing seepage are live problems where water is pumped or stored. Measurements made in 1906 on a storage reservoir having a surface of 10,000 square feet showed a seepage loss of 1,000 cubic feet per day. The reservoir is filled by a windmill and this loss was 10 per cent of the average quantity pumped each day — a loss too heavy to be borne. The problem of this reservoir owner is the problem of hundreds of irrigators. Unless this * Bulletin 158, U. S. Office of Experiment Stations, pp. 36-37. 386 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. leak in the reservoir can be stopped, the attempt to irrigate by pump- ing will be a failure ; but the owner can not afford the expense needed to line the reservoir with concrete or asphalt, because the value of the water stored will not justify this expense. Puddling has been tried, but there is not enough clay in the soil, and no other material or process has been tried sufficiently to make it safe for him to adopt it. His problem is, therefore, to find some cheap and valuable material or some process which he can utilize at small cost which will make the reservoir hold water. There are an unusual number of raw materials found in California which promise well, and the richness of the mineral wealth of the arid region leaves little doubt that other things besides cement and clay will come into use to prevent the leakage of reservoirs and ditches. The purpose of this investigation is to determine what is the relative merit and expense of both those expedients which have been tried and those which seem worthy of a trial. The investigation was undertaken by the California Experiment Station, which was assisted at the outset by the U. S. Office of Experi- ment Stations, which furnished part of the money expended. This bulletin gives the results of the first year's work and is only a progress report. The investigation will be continued on a more extended scale during 1907. The investigations and experiments of 1906 were carried out by Prof. B. A. Etcheverry, of the University of California, whose report follows. Elwood Mead. LINING OF DITCHES AND RESERVOIRS. 387 INVESTIGATIONS AND EXPERIMENTS, By B. A. ETCHEVERRY. Examination of Lined Ditches in Southern California. — About 1880 all surface waters iu southern California were being diverted and used. The heavy profits derived from irrigation and the rapidly increasing price of orange land since then caused a -great demand for additional water. The development of the country depended on water, which was, and is even more so at present, the most important question for that locality. All available water supply must be developed and all waste prevented. This meant the rapid development of underground waters by wells and tunnels and the storage of flood waters, and explains the large number of wells yielding probably a good deal more water than the flow of surface water in midsummer. It was here naturally that the loss of water due to seepage was first felt. Every drop of water saved meant increased prosperity. The value of water increased rapidly after 1880. Water valued at $30 per miner's inch in 1880 had a value of $300 January, 1883, and $720 in 1888. This naturally meant better use of water and a higher duty of water. The duty of water increased to one miner 's inch for four or five acres, and has still increased until at present this duty for some of the best citrus lands is one miner's inch for ten acres. Most of the improvements for economy of water and for the decreased loss in transportation were started after 1880. • Canals were first paved to prevent seepage and erosion ; and to permit the use of an economical section. This paving was then improved upon by paving and cementing. Plastering with cement mortar and the use of concrete for lining came into use soon after. At about the same time the use of steel or cement pipes was intro- duced. They have since become much in favor in southern California, when the volume of water to distribute is not large, and have to a great extent replaced the smaller open ditch. While for these parts of southern California there is no doubt but what the use of cement in some form will always be the most generally used material for canal lining, it is expensive and its use is only justi- fiable where the value of water is very high, or where excessive seepage must be stopped. 388 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. For districts where water is plentiful the seepage loss may not be of so much consideration, or at least not so great but that a concrete lining would be prohibitive. The canals or even the laterals of these districts carry several times more water than the largest canals of southern California. The lining, if concrete were used, would have to be stronger and the cost large. Other considerations besides seepage must, however, be studied before one can decide whether it will be beneficial to line the water channels, and other linings should also be investigated. A good lining should fulfill the following requirements: (1) It should stop seepage; (2) It should prevent gophers and squirrels from burrowing through the banks; (3) It should prevent vegetation; (4) It should prevent scouring; (5) It should not be easily damaged by the tramping of cattle and by the action of the weather. No doubt concrete will answer for all these requirements, but cheaper linings in many cases will be more economical. It was mainly to inquire into this that these investigations were undertaken, in May, June, July, and August, 1906. These investigations include first a journey around some of the irri- gated districts of California to learn the different types and methods of lining canals in use, their cost and detail of construction. CANAL LININGS USED IN CALIFORNIA. Naturally the best types of canal linings are in southern California, very little having been done in other parts of the State. A study of the various types shows that they can be classified as follows : (a) River boulders set in lime mortar and pointed with cement mortar. • (&) River boulders or cobbles placed behind a wooden form and cemented together with cement mortar rammed between the cobbles. (c) Cement concrete from 3 to 6 inches thick. (d) Cement mortar plaster y 2 to 1 inch thick. (e) Heavy road-oil. (/) Clay puddle. RIVER BOULDERS SET IN LIME MORTAR AND POINTED WITH CEMENT MORTAR. This method has been extensively used in the San Bernardino Valley. Good examples of this type are seen in Redlands, Crafton, Highlands, and San iVrnardino. This type of lining was probably introduced in L882 to 1883, when the Ontario Colony Enterprise, receiving its water liom the San Antonio Canon, paved its canal, LINING OF DITCHES AND RESERVOIRS. 389 bottom, 6 feet wide at the top, and 2 1 / 1 > feet deep, with rocks laid in hydraulic lime water and plastered over with cement mortar. This lining was 8 inches thick and cost about 60 cents per lineal foot, or about 6 cents per square foot, which is very much cheaper than the average cost per square foot of this type of work since then. This low cost is probably accounted for by the cheap Chinese labor used at that time, the rate being $1.25 per day; also the small cost of the lime, $1 a barrel, and the rock not having to be handled at great distance. The cement plaster was mixed in the proportion of one part of cement to three parts of sand with lime water. The bottom was finished with a FIG. 1. New Bear Valley Water Company's Canal ; lined with cobbles set in lime mortar and pointed with cement. thin coating of cement and sand in equal quantities. The lime mortar was one part of lime to five parts of sand. This type of lining, while largely used since then, is now employed mainly where repairs are necessary. Accurate data as to cost and details of construction are difficult to obtain. A great deal of this work has been replaced with pipes. The new Bear Valley Water Company and also the Crafton Water Company have good examples of this construc- tion. The ditch known as the Highlands Ditch, and the Old Redlands Ditch, known as the South Fork Ditch, both diverting water from the Santa Ana River, are paved and cemented. While parts of these ditches were first paved with cobbles or rocks without the use of lime or cement mortar, or paved with cobbles or rock faced with cement mortar without the use of lime mortar, the more recent type of construction consists mostly of cobbles laid in lime mortar and pointed or faced with cement 390 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. mortar. The method of construction used by the Bear Valley Water Company is as follows: The ditch is excavated to a definite cross-section, this cross-section being of such size that after receiving a lining of about 1 foot in thick- ness it will be the required finished cross-section. After the excavation, mold frames with boards are used to guide the lining work; between the mold boards and the sides is a space of 1 foot which is the thickness of the lining. Into this space a layer of cobbles about 1 foot in thick- ness is built, with the interstices filled with small stones ; a grout formed of one part of lime to seven parts of clean, sharp sand is then poured in and tamped in order to fill all voids. The lining of the sides is IH^* fe^g— J** %^ % ^** ■■■■■-■:.- ■ 4*. * '*> \ < . FIG. 2. Hemet Land and Water Company's Canal ; lined with cobbles set in cement mortar. built up in this manner in consecutive layers 1 foot at a time. The bottom is usually paved before the sides, the mold frame resting on .the bottom. The lining is generally allowed a few days to harden, then the mold boards are removed and the cement plaster put on. This plaster is a mixture of one part cement to three parts of clean sand and is applied about % inch thick, giving a smooth surface. The size of the ditch thus lined was 2% to 3 feet wide at the bottom, about 4 feet deep, and side slopes of about 1 on 4. (Fig. 1.) The approximate cost was 15 cents a cubic foot. The price of labor and materials was as follows: Cement, $3.75 a barrel; lime, $1.30 a barrel ; ordinary labor, $2 per nine-hour day; masons, $3.50 to $4 per eight- hour day. The method used by the Grafton Water Company was very similar. LINING OF DITCHES AND RESERVOIRS. 391 The ditch was excavated with scrapers and shovels. No form was used for lining ; the sides and bottom were put in by line, the cobbles being placed to line and grade in lime mortar, the interstices between cobbles being filled and chinked. The surface was evened off by forcing in cement mortar with a trowel, and a coating of this cement mortar about ] /2 inch thick covered the sides and bottom. The rock lining was about 1 foot in thickness. This work was done in 1893, thirteen years ago, and was limited to the intake canal (one mile long) of the Grafton Water Company. According to one of the former directors of the FIG. Method of lining the Ffemet Land and Water Company's Canal. company no repairs have been made during these thirteen years. The work is still in good condition. The average cost of this class of lining would probably be about 13 cents per square foot. While substantial and satisfactory, a stronger and not much more costly is the next class described. RIVER BOULDERS OR COBBLES SET IN CEMENT MORTAR. A good example of this work is a section 3Vi» miles long on the main canal of the Hemet Land and Water Company. One mile of this canal has a bottom width of 4 feet, a depth of 3 feet, and a top width of 7 feet. (Fig. 2.) The remaining 2% miles have a bottom width of 3 feet, a top width of 6 feet, and a depth of 3 feet. 392 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. The canal was excavated with scoop scrapers and shovels. No form was used in the excavation," the cross-section being finished, ready for the lining, by the shovelers. After the excavation, the banks were well moistened by letting the water into the excavated canal and holding it by earth dams. When the banks were thoroughly wet the water was drained out and the lining put on. The lining consists of cobbles, most of them not less than 6 inches in dimension, placed in the cement mortar. The bottom was constructed first, the cobbles being laid in the bed of cement mortar and the space between cobbles well filled in and finished smooth and to grade. This cement mortar for the bottom consisted of one part of cement to four parts of clean river sand. A little lime was added to this mortar. Closely following the lining of the bottom came the lining of the sides. (Fig. 3.) For this, mold frames and mold boards were used. The frames were placed 5 feet apart and so constructed that the mold boards were held in place against the frames by a %-inch iron rod. The mold boards could be put in one at a time, and one section 20 feet in length was finished at one time. The mold frames having been put in position and the lowest mold board placed on each side, a layer of cement mortar was spread on the bottom ; in this mortar were embedded cobbles, another layer of mortar put on top of these cobbles, then successive layers of cobbles and mortar until the side lining was completed for the section. Mold boards were put on as the lining was built up. The mixture was also tamped during construction to assure the filling of all spaces between cobbles. The ingredients used for the mortar in this lining of the sides were one part of cement to six parts of river sand. After the forms were removed the sides and bottoms were finished with a very thin wash of neat cement. The cost of cement was $3 a barrel, delivered on the grounds. The cobbles were close at hand. The cost of labor was $1.75 for common labor per nine-hour day and $3.50 for masons per nine-hour day. The total contract price for excavating and lining the ditch was $25,000, or an approximate cost of 13 cents per square foot, for the lining. CEMENT CONCRETE. The best examples of this kind of construction are seen south of Los Angeles near Orange, Santa Ana, and Anaheim. In this vicinity two irrigation companies, both diverting water from the Santa Ana River, afford good illustrations of this efficient lining. These two companies are the Anaheim Water Company and the Santa Ana Irrigation Company. The Anaheim Water Company lias Lined its main canal and laterals LINING OF DITCHES AND RESERVOIRS. 393 with a thickness of concrete varying from 4 inches for the larger canal to 2 inches for the smaller laterals. The work of lining has been done very thoroughly and with great care. If the canal is an old earth ditch it is prepared for the lining and carefully finished as described below. A/ossf #J r/A, */*//■ flarfh Form //? place Concrete form PUtsy-^mu/Z 7?ZT '/OUJ I// J OJ (y,Q/ £pJ / f O rf^vz/i / (7° "/-!..?) Z/PP nj / U ^°/D y>u.o^Ay^&c/ ?uo//o6 y 7) / /£> ") (S ' U /Lt ■// ou) / ouj f^V_ o C/?st>/ Is-^x/ s-u 0// oS^f £)/ r X AVdf^ E ■ / (9 °J r ) / J*^-? put, j ,q /> Djf-f joA Sy sad ?uo/ /0 6 */, ZJ />Q fa od/ J 1*5 N fSu./u // ou ) Y/ Jr J gallons per square yard. No. 7. Clay puddle, 3% inches thick. No. 8. Earth (no lining). No. 9. Cement mortar, 1 inch thick. No. 10. Cement concrete, 2% inches thick. No. 11. Earth (no lining). No. 12. Cement lime concrete, 2y 2 inches thick. It will be noticed that arranging the ditches as above, there are eight ditches lined and four earth ditches with no lining. Each earth ditch has an adjacent lined ditch on each side, so that in case the seepage from the four earth ditches was unequal, the seepage in the lined ditches FIG. 15. Method of using templet to finish trenches. could be compared with the seepage from the adjacent (or nearest) earth ditch. The lined ditches would also be affected more nearly equally by the seepage from the earth ditch. METHOD OF FINISHING DITCHES. After the excavation with teams the ditches were finished by hand in the following manner (Fig 14) : Pieces of timber, 2 inches by 3 inches, were placed at the center of the banks between ditches, and extending parallel to them from one end of the ditch to the other; these pieces of timber were placed in the banks and made level. The top of these timbers was at the same level as the banks. Frames or templets were built, as illustrated, of the same size as the finished ditch, ready for the lining. Four of these frames were used, the same one being used for the four earth ditches and for the ditches where the oil was sprinkled 410 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. on the slopes and bottom. A second form was used for the cement mortar lined ditch ; this form was larger than the previous one, allowing 1 inch for the lining. The third form was made large enough so that the ditch finished with this form, after being lined with a 2%-inch lining, would be of the same cross-section as the earth ditch. The fourth form was used where the ditch was to be lined with a 3 1 /2 -inch lining. These frames were used in the following manner (Fig. 15) : Begin- ning at one end the frame was placed in the ditch and the side slopes and bed were cut down until the top piece of the frame would rest on the two pieces of timber on the banks. The frame was then moved forward on these guides and the cross-section was cut down with spades to the proper size. The slopes were finished first and the earth cut from the slopes was removed with a scoop scraper. The cost of finish- ing was about 1 cent per square foot. METHOD OF LINING. No. 1. The oil was heated to a temperature of about 180° Fahr., at which temperature it would flow easily. This heated oil was mixed with the gravel in the proportion of one part of oil to eight parts of gravel by volume. The mixing was done with rakes and. the mixture was very uniform. The sides were lined first. Pieces of timber 3% inches thick were placed on the slopes at right angles to the axis of the ditch, about every 10 feet. The oil-gravel mixture was carried in wheelbarrows and dumped on the slopes between these timbers. A straight edge about 12 feet long, extending from one timber to the other and worked up and down the slope, regulated the thickness of the lining to 3^ inches. The mixture was tamped while being placed in position. No. 3. This ditch was lined in exactly the same manner. The mixture used contained one part of heavy Bakersfield oil to six parts of gravel. The thickness of the lining was only 2y 2 inches; the slope timbers being therefore 2% inches thick instead of 3% inches thick, as for No. 1. No. 4. This ditch was lined with the same heavy oil. The oil was heated to a temperature of 180° Fahr., and was sprinkled or poured on the slopes with a 3-gallon watering pot, with the rose sprinkler flattened so as to throw a flat stream or sheet of oil on the side of the ditch. The oil was applied mostly on the top of the slope, and as it ran down the slope it was gradually absorbed by the ground — some of it reaching the bottom. An excess of oil accumulating at the bottom was dragged up the slopes by using a stick about 8 feet in length to which a 2-foot piece of timber was nailed, at right angles, at one end, and to this piece was nailed a couple of sacks to be used as a mop. If the oil LINING OF DITCHES AND RESERVOIRS. 411 is not applied in large quantities at once, but instead several successive light applications are made, it will not be found necessary to use this mop. The oil was not raked in; the object sought for was to have the oil form a thoroughly saturated crust ; while if it was raked or plowed in r the oil may have been disseminated through too thick a layer to form a water-tight crust. No. 6. The sixth ditch was sprinkled with lighter oil in exactly the same manner as the fourth ditch, using 2% gallons per square yard. No. 7. The seventh ditch was lined with clay puddle. The clay was difficult to obtain, having to be hauled about three miles, which made it very costly. The clay contained fine silt and sand. It was sprinkled with water, and when soft was hauled in wheelbarrows and applied in the same manner as the oil-gravel mixture. The thickness of the lining was Sy 2 inches. No. 9. The ninth ditch was lined with cement mortar, composed of one part of cement to five parts of gravel. The lining being 1 inch thick, the scantlings or guides placed on the slopes were only 1 inch thick. No. 10. This ditch was lined with cement concrete 2% inches thick, composed of one part of cement to seven parts of gravel and crushed rock, in equal quantities. No. 12. The twelfth ditch was lined with cement lime concrete 2y 2 inches thick, composed of % part of cement, % part of lime, and seven parts of gravel and crushed rock in equal quantities. Before lining with cement mortar, cement concrete, and cement lime concrete, the slopes and bed of the ditches were well wetted by sprink- ling. These three linings were also kept wet for several days after the construction. The oil ditches had been finished about ten days before the water was turned into them. This was necessary for the oil to soak in well and also for the lighter volatile parts of the oil to evaporate. The water was first turned in on July 23, 1906, and observations were then started. METHOD OF OBSERVATION. The ditches were filled each morning to a depth of 2 feet (approx- imately), the measurements being taken as soon as filled. Measure- ments were again taken late in the afternoon and also the next morning before refilling the ditches. The instrument used to take the measure- ments consisted of a wooden post, 2 inches by 3 inches, which was driven firmly in each ditch at the south end. The top of the post was about 3 feet from the bottom of the ditch. A right-angle screw hook, with the shorter arm filed to a point, was screwed into the post. The depth from 412 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. the bottom of the ditch to the end of the hook was 2 feet. This served as a guide in filling the ditch, each ditch being filled as nearly as possible up to this hook. For an exact measurement a piece of steel about 5 inches long, % inch thick, and % inch wide, was screwed at the top of the post and at right angles to it. This piece of steel projected about :2 inches beyond the post and its upper edge was beveled. This edge was the index from which the measurements were taken. (Fig. 146.) The measurements being taken with a plumb-bob attached to a steel tape, the steel tape was placed next to the index and the plumb-bob lowered until the point of the bob touched the water. Accurate measurements could thus be taken to % of a hundredth of a foot (.005 foot) . Evaporation. — The evaporation was determined by means of a gal- vanized iron tank placed at the north end of the ditches, between ditches No. 6 and No. 7. Measurements were taken in the morning and in the afternoon in the same manner as for the ditches. From the observations taken beginning with the 23d and extending until the 28th of July, it was found that the lining of ditches No. 1 and No. 3 was entirely unsatisfactory, as the seepage in them was larger Than in the earth ditches with no lining. It is probable that the water percolated through this lining and was carried away through gopher and squirrel holes under the lining. In the earth ditches gopher and squirrel holes were found, but could be stopped ; but this oil and gravel mixture had sufficient strength not to break through where the holes were, and they could not be discovered. From the observations during these few days it was found that the seepage in all four earth ditches was almost identical, so it was decided to sprinkle oil on two of these earth ditches, using in both cases less oil than was used on ditch No. 4. The gravel-oil mixture was removed from No. 1 and this ditch was used as an earth ditch. Ditch No. 3 was not changed; measurements on this ditch were continued, but it did not improve. The ditches after July 28th were allowed to dry and after the changes were made were in the following order: New Order of Ditches. No. 1. Earth (no lining). No. 2. Heavy oil sprinkled, 2% gallons per square yard. No. 3. Heavy oil and gravel, one part of oil to six parts of gravel {21/2 inches thick). No. 4. Heavy oil sprinkled, 3% gallons per square yard. No. 5. Earth (no lining). No. 6. Thin oil, 2% gallons per square yard. No. 7. Puddled clay, 3% inches thick. LINING OF DITCHES AND RESERVOIRS. 413 No. 8. Heavy oil sprinkled, 3% gallons per square yard. No. 9. Cement mortar, 1 inch thick. No. 10. Cement concrete, 2% inches thick. No. 11. Earth (no lining). No. 12. Cement lime concrete, 2% inches thick. The table accompanying this report (see page 414) refers to the ditches after they had been changed. The water was again turned into the ditches on August 6th, but because of a serious break in the main canal of the irrigation system, the water could not be obtained again until August 28th. Observations were again begun and were taken until September 10th, a period of fourteen days. For the first four days the results were not very uniform; probably because some of the ditches had held water much better than the others during the interval when no water was available for filling them. The rates of percolation per hour given in the table are the rates of percola- tion for the last ten days. This rate of percolation is computed from the readings taken each day. The seepage and. evaporation for each ditch, from the time the ditch is filled to the time when the level of the water is measured next morning just before filling, give the total seepage and evaporation for that time. Subtracting from this the loss in level due to evaporation gives the loss due to seepage. This quantity divided by the number of hours in which this loss occurred gives the rate of percolation or seepage in feet per hour. Consulting the table, it will be noticed that the rates of percolation for the three earth ditches were very nearly equal. However, in com- paring the seepage from the lined ditches with the seepage from the earth ditches, the relation is obtained by making the comparison with the nearest earth ditch. The efficiency of a ditch is the ratio between the rate of percolation for the earth ditch and the rate of percolation for the adjacent lined ditch ; or, efficiency = rate of percolation for earth ditch over the rate of percolation for lined ditch. The larger this ratio the more efficient or water-tight is the lining. From the mean sinkage or mean percolation of the several ditches is computed the percentage of saving due to the lining in each case. This saving indicates the probable percentage of water saved from the loss which would take place if the ditch was not lined. The experimental cost per square foot of the lining is the actual cost at which the work was done. It does not include the cost of finishing and preparing the ditch for the lining. This cost was about 1 cent per square foot. The actual cost per square foot for work on a larger scale would naturally be somewhat smaller. The cost given in the table is estimated 414 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 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CD O ^ • B " ; S» ; arc) i— Actual cost of lining per sq. ft * Cement concrete, 3 inches thick .0046 7.17 86.6 Cents. 83 Cents. 7.5 Cement lime concrete, 3 inches thick .0114 2.90 65.5 8.3 7.5 Cement mortar _ _. .. .0121 2.73 63.3 3.88 3.25-3.50 Heavy oil, 3§ gallons per square yard .0176 2.02 50.4 120 1.20 Clay puddle, 3i inches thick .0185 1.78 47.8 3.90 1.20 Heavy oil, 3 gallons per square yard ... .0220 1.50 38.0 1.00 1.00 Heavy oil, 2^ gallons per square yard .0239 1.37 27.3 .77 .77 Thin oil, 1\ gallons per square yard .0329 f .0329 1 1 .0355 \ 1.08 7.3 1.00 .80 Earth (no lining) 1.00 0.00 ,.0330 J ♦Excluding the preparation of the ditch. (Last two columns.) While there is no doubt but that cement concrete is the most efficient as regards seepage, it is also the most expensive, being more than six times the cost of the heavy oil lining (3% gallons per square yard), which saves 50.4 per cent of the water which would seep were the ditch not lined. This saving with the concrete ditch is 86.6 per cent, or 1% times as large. Where water is very valuable there is no doubt but that the concrete ditch is more permanent and economical. But where the water is not so scarce and a little waste will do no damage, the expense of lining the ditch with oil may be justified, while a more expensive lining would be impracticable. LINING OF DITCHES AND RESERVOIRS. 417 The question will come up : * * Is it economical to use oil on a ditch to save 50 per cent or less of the water which is being lost in ditches not lined?" Perhaps there is a great deal of water, and in many irrigated districts the waste of water seeping from the canals and laterals while- large is small compared with the larger waste due to over-irrigating the fields and to poor methods of irrigation. These conditions will no> doubt better themselves as California becomes more settled and the water is more economically used and more valuable. But even under the present conditions the advantage of lining a canal is not alone the decrease in seepage ; other factors should be considered, as mentioned in the first part of this paper. (1st) The prevention of growth of vegeta- tion is an important item and is quite an expense, when in most cases, the ditch or lateral must be cleaned out several times during an irriga- tion season, (2d) The resistance to scouring, on which depends the velocity which the water can be given. (3d) The prevention of squirrels and gophers from burrowing into the banks and bottom of ditches. That oil will prevent vegetation and the burrowing of animals on the banks and bottom of the ditch is clearly shown by the example near Lemoore, previously mentioned. That oil will prevent scouring to a great extent and will allow a muck higher velocity of flow of water than the earth ditch may be expected, when we consider its resistance to wave action at the Ivanhoe Reservoir,, and the resistance of oiled roads to cutting under the action of running water. This toughness of oil lining was also noticed in filling the ex- perimental ditch each morning. When the water carried by the wooden flume discharged into each ditch through the gate it had a fall of at least one foot. It was difficult to prevent the sloping ends of the earth and puddle ditches from being badly cut up by the erosive force of the falling water. These ends had to be well protected with heavy canvas, and even the erosion could not be altogether prevented. The ditches, lined with oil resisted the erosion and showed no cutting, although they were not protected with canvas. A letter from the superintendent of the Modesto Irrigation District, dated January 21, 1907, states that the ditches were examined by him after the recent heavy rainfalls. The banks of the earth ditches were badly washed where the water ran in ; the clay puddle was slightly so, but the oiled ditches showed absolutely no sign of wash. The oil linings are all hard and firm and scratch almost like concrete. This resistance to erosion will permit in a saving of cross-sectional area due to the possibility of giving the water an increased velocity. The higher velocity will prevent the deposition of silt to a great extent and there will be a consequent decrease in the cost of operation and maintenance. 418 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. The puddle lining in the experiment showed a saving in seepage nearly equal to the heavy oil lining when 3% gallons of oil per square yard was used, and a greater saving than the other oil linings. This puddle lining, whose thickness was 3% inches, would, no doubt, if made thicker, be more efficient than any of the oil linings as regards seepage ; but clay puddle when wet becomes very soft and will not resist the erosive force of the flowing water unless the velocity is very small. It will not prevent the growth of weeds. For these reasons it is probably not as efficient for canal linings as oil. But where clay is plentiful it would be preferable for reservoir lining. The slopes should, however, be protected against the erosive action of the waves by the use of cobblestones or other protection. The use of oil in lighter quantities, while not very efficient in pre- venting seepage, will no doubt prevent the growth of vegetation, as illustrated by the example of the ditch near Lemoore. In this case only 1% gallons per square yard was used and this quantity has been sufficient to prevent vegetation. Cement mortar plaster, so extensively used in southern California, showed a saving in seepage water of 63 per cent. Better results were expected, and it is probably safe to expect a greater saving where good work is done, especially where the work is constructed in cold weather. This lining had to be applied when the temperature in the field was probably 110° or over. The cement mortar was mixed in small quantity and quickly applied. As soon as the setting had started the lining was sprinkled and covered with wet canvas, but even with these precautions better work could be done in cooler weather. This plaster, while very efficient and economical on small ditches, would not be of sufficient thickness and strength to be used on the larger canals and laterals of larger irrigation systems, where a thick- ness of from 2 to 4 inches would no doubt be successful.