UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA CIRCULAR 304 March, 1926 DRAINAGE ON THE FARM WALTER W. WEIR A well built, substantial, concrete outlet protection for a tile drain. • FOREWORD This circular is intended to cover the principles and methods of drainage of wet lands in California and is applicable to those parts of the state which do not require the special considerations essential in the drainage of lands where alkali is a factor. UNIVERSITY OF CALIFORNIA EXPERIMENT STATION NEED FOR DRAINAGE Almost every farm contains some land that could be improved and made to produce more or better crops by some type of drainage. This, rather than the presence of swamps, ponds or springs, usually deter- mines the need for drainage. Good slopes or even hillsides do not necessarily insure adequate natural drainage, although such slopes will greatly facilitate the correction of poor drainage conditions. The greatest need of drainage, however, occurs in flat, level areas or basins which are made up largely of heavy-textured soils or soils having relatively impervious subsoils. Fig. 1. — A typical poorly drained grain field showing patches where the grain has been drowned out or stunted. BENEFITS OF DRAINAGE There are many benefits to be derived from drainage. The most obvious is the removal of ponds and the drainage of swamps to permit the growth of crops where it would otherwise be impossible. Land of this type, however, constitutes only a small proportion of the area which could be improved. Most of the land that would be benefited by drainage can be farmed and some crop obtained without drainage. Figure 1 shows a poorly drained grain field in which part of the grain has been drowned out. Drainage would improve the granu- lation or tilth and improve the aeration of such land and raise its temperature during the early season, and thus promote early develop- Circ. 304] DRAINAGE ON THE FARM ment of the crops. It would also very materially lessen the effects of drought during the dry season and by quickly removing the excess of water from wet places permit entire fields to be planted or cultivated at one time. Other benefits follow, such as the more rapid development of useful microorganisms, which accelerate chemical reactions and increase the availability of plant food elements there is less danger from frost injury; and the plants are rendered less susceptible to disease or parasitic injury. Drainage does not remove any water which is in a form available for use by the plants. It removes only the free water existing in the soil in excess of that necessary to wet it to capillary capacity. The removal of this excess water increases the mass of soil wetted with only capillary or available water. There are few useful plants which will thrive with their roots in saturated soil. ENGINEERING ASSISTANCE Too much stress can not be laid on the advisability of securing reliable engineering advice before installing a drainage system. The owner rarely has the training or experience which will enable him to design and construct the best and most economical system. The designing of large comprehensive drainage systems, involving the organization of drainage districts or cooperation among a number of owners, is usually conceded to require the services of an engineer, but no less ability is often required to properly design and lay out a system involving only a few hundred feet of drain. Good engineering advice is cheaper than poor drains. The careful engineer makes a survey not only of surface conditions to determine the direction in which drains should run and the fall available, but also carefully examines the subsoil with a soil auger to assist in determining the best location of a drain, its depth, and the proper spacing between drains. To determine the proper size of a drain for the slope and the amount of water to be removed also requires study and com- putation. THE OUTLET No system of drainage will prove entirely satisfactory or give the maximum results without a good and adequate outlet. The first step in planning for drainage is to ascertain the suitability of the outlet. If a channel which will provide free flow for the discharge of the proposed system can not be found one must be provided. This may require very careful planning to use most advantageously all available fall. To secure an outlet it will often be necessary to cooperate with 4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION a neighbor or obtain permission to cross other property. The ideal outlet provides a free flow from the main drain at all times and allows the construction of the main drain at a good depth. (See cover picture. ) This does not imply, however, that unless an outlet meeting all of the ideal requirements can be secured, the proposed drainage project must be abandoned. Under certain conditions the main drains may be submerged for short periods during storms without serious damage. In the drainage of tidal marshes the outlet is frequently through tide gates which are closed for several hours each day, yet satisfactory drainage is provided. Fig. 2. — Open drains waste valuable land, harbor weeds and injurious insects and require considerable maintenance. TYPE OF DRAIN There are two general types of drains, each of which may be modified in many ways to suit local conditions. These are the open drain, or drainage ditch, and the covered drain, or buried conduit. Covered drains are usually of tile. The type of drain selected for any particular place depends upon the requirement to be met and the wishes of the owner. Open Drains. — Open drains have an advantage over tile where large quantities of surface water are to be removed rapidly, as for instance, providing an outlet for run-off from a hillside during a heavy rain, or as an outlet for a large tile drain. Where large areas Giro. 304] drainage on the farm 5 are drained and the land is not of great value, the ditch is most frequently used because it carries a large amount of water more economically than tile. On the other hand, open drains constructed across a field are at best unsatisfactory and, if deep enough to ade- quately drain the subsoil, they require a considerable area of land, which might otherwise be farmed. Often a combination of tile and open ditch is used. In this case a broad shallow ditch carries off flood waters while beneath it a tile line completes the work by draining the subsoil. Open drains may be a source of danger to stock unless properly fenced; harbor obnoxious weeds, plant diseases and rodents; and require consistent maintenance to be always fully efficient. Figure 2 illustrates a badly obstructed open drain. 1 Natural System Intercepting System Gridiron System Herring Bone System Fig. 3. — Various arrangements of drains. Frequently drainage systems as actually constructed involve a combination of two or more of these arrangements. Tile Drains. — Tile drainage offers the most efficient and permanent method of draining land. The tile are placed underground where they do not interfere with cultivation and when properly laid require very little attention to keep them in operation. Although it is neither good engineering nor good farming to be ignorant of the exact location of underdrains, many farms are being successfully drained year after year by tile, the location or even the presence of which may not be known to those who operate the farms. Tile drains lend themselves to more variation in design than do open drains because of the fact that they do not interfere with culti- vation. In general there are four arrangements (see Figure 3) which can be used either in the true form or in combination. There is no best arrangement for all conditions. Each field must be surveyed and studied to determine its own particular needs. 6 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION SURVEY AND PLANS When the outlet has been decided upon, a complete survey should be made of each area that requires drainage. This survey should include all areas which will have a common outlet whether it is intended to drain them at this time or not. If only a portion of the work is to be done at one time, it should be planned with the future extensions in view. If this is not done, some portion of the work, usually the main drain, may be found inadequate to care for additional areas when they are added. As a drain is constructed, its location should be noted exactly on the plan. It is not sufficient to rely on the original plan, which is made before construction begins, for frequently minor and sometimes major changes are made during construction. All survey notes and plans should be carefully preserved, as the time may come when they will be badly needed. DESIGN OF OPEN DRAINS For areas up to 160 acres, drains should be designed to remove about one surface inch from the tract in twenty-four hours. If water reaches the tract from other sources, the entire contributing area should be considered rather than merely the area it is proposed to drain. For larger tracts the main drain may be designed for a run-off of only three-fourths inch in twenty-four hours. Conditions of tilth, topography, and soil are determining factors in the rapidity and amount of run-off. In a gently sloping field in good tilth, the soil will retain much more water than in barren or untilled fields or in those having greater slopes. The size of ditch required to carry a given amount of water is dependent upon the slope or grade and, to a less extent, upon the shape of its cross-section ; the shape is deter- mined by the kind of soil through which the ditch passes. In ascertaining the size of an open drain required to carry a given quantity of water on a given grade, Elliott's formula for open drains has been found satisfactory and because of its simplicity is more convenient to use than some others, which may under certain con- ditions be slightly more accurate. -v ax iy 2 f P where v=velocity in feet per second a=area or cross-section of drain in feet p— wetted perimeter in feet f =fall in feet per mile Q=quantity in cubic feet per second CIRC. 304] DRAINAGE ON THE FARM 7 When the velocity is found the quantity of water carried "Q" is obtained from the following formula : Q=av An open drain should be deep enough and wide enough to carry the maximum flow without overtopping its banks, and to carry the normal flow well below the general ground surface. The banks of the ditch should be .sloped to such an extent as to prevent, as far as possible, any caving when they are wet. In clay the side slopes may be as steep as one-half foot horizontal to one foot vertical, while in sandy soils it may be necessary to make the slopes as flat as two or more feet horizontal to one foot vertical. The excavated material should be placed some distance from the edge in order to prevent it from slipping back into the drain. A safe rule to follow for ditches under twenty feet in top width is to place excavated material so that the berm, or strip of land between the edge of the ditch and the toe of the waste bank, is equal to one-half the top width of the ditch. Team and scraper ditches are sometimes used where surface water accumulates in considerable quantities and the drain is required simply to remove it quickly. Drains of this nature are expected to be dry most of the time and are so dug as to be of least hindrance to cultivation and cropping. In many cases cultivation is continued over such drains. Open drains dug by hand are necessarily limited to rather small ditches, seldom over three or four feet wide on top and four or five feet deep. Ditches of this type cause the least inconvenience when located along fence or property lines. Figure 4 illustrates the relation between depth, side slopes and width of berm for a hand dug ditch in heavy soil. The banks of open drains, at the points where surface water enters, must be protected so as to prevent erosion, which not only destroys the banks and wastes land but also fills up the drain and impairs its efficiency. Surface water may be admitted to an open drain through a box or culvert under the waste bank. When properly constructed, such a box will be a protection against washing of the ditch bank. UNIVERSITY OF CALIFORNIA EXPERIMENT .STATION CONSTRUCTION OF OPEN DRAINS Open drains are constructed in three ways: by machinery, with teams and scrapers, and by hand. There are several types of exca- vating machinery for digging open drains ; these vary in size from the large floating or dragline dredge capable of excavating drains up to 100 or more feet in width, to the excavator which will dig a drain three or four feet in width. For farm drains, however, only the smaller types of excavators are used, and these only on the larger farms, or where several farmers unite in a general plan of drainage. When drains are constructed during the dry season, teams may be used. Ditches excavated in this way are necessarily limited to rather shallow, broad drains in soils stable enough to permit the driving of teams over them. Digging drains by hand is feasible only when they are small enough to allow the excavated material to be disposed of without rehandling. mm ^P^fe* 3 3 ' Berm lilt ; Fig 4. — A type of hand dug ditch suitable for heavy soils. MAINTENANCE OF OPEN DRAINS Open ditches require a considerable expenditure for maintenance. It is this item that makes the final cost of open drains equal to or above that of underdrains. In order to maintain the efficiency of a ditch, it is necessary to clean it at least once each year. Brush and weeds that are certain to grow during the dry season must be removed, caving banks must be repaired, and all obstructions such as temporary fences, rubbish, etc., removed before the we1 season begins. After a year or two it may be necessary to reexcavate in order to maintain the desired depth. If these things are not done, conditions may soon become as bad as they were before the ditch was constructed. The cost of maintenance, of course, varies with the amount of excavation and repair work necessary; in a few years it may amount to a con- siderable proportion of the first cost. ClRC. 304] DRAINAGE ON THE FARM DESIGN OF TILE DRAINS Location.— The location of the main drain will be controlled largely by the position of the outlet, the size, shape and slopes of the area to be drained and the location and depth of the laterals. On the other hand, the location and depth of the main drain will have much to do with the location, cost and efficiency of the lateral drains. Usually the main drain follows the lowest of the natural depressions with submains following the minor depressions. In the natural system as illustrated in figure 5, this is all the drainage that is required. In the foothill areas, the intercepting system is most frequently employed. Where the water comes from springs or seepage areas at the base of a hill or is known to be moving in a definite direction, a drain located either directly through the spring or just at the upper edge of the damaged land usually intercepts the water before it has reached the land it is desired to improve. In an intercepting drain sometimes the variation of a few feet one way or the other will mean success or failure. Where springs are to be drained, it is essential that their exact location be determined. A diligent use of the soil auger may reveal interesting facts regarding subsoil conditions in such areas. Where a regular system of drains, such as the gridiron or herring bone, is required, considerable study is often necessary in order to plan a lateral system to suit the drainage requirements and at the same time be economical. One point to be observed is the elimination of all unnecessary "double drained" areas. Where two drains join there is always an area from which drainage water might flow into either drain. In Figure 5 the area around the junction of laterals C and B with the main drain may be said to be "double drained." A drainage system using the minimum amount of tile consistent with efficiency is usually the cheapest. Depth. — The depth, spacing and size of tile drains are related and interdependent subjects. The proper depth for tile varies some- what with the texture of the soil. In sandy soils the depth may be greater than for clay since the water moves more freely in sand than in clay. Deep drains in a clay soil will lower the water table farther than shallow ones, but it usually requires more time after a storm for them to function. It is well known that drainage is more effective and shows greater results after two or three years than it does the first. In medium textured soils, drains from three and one-half to four and one-half feet deep are most satisfactory. Four feet is prob- 10 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION -r s Circ. 304] DRAINAGE ON THE FARM 11 ably the most efficient average depth, though a very impervious subsoil or rock may make a smaller depth necessary. The greater the depth of drained soil, the greater will be root penetration, feeding area, available plant food supply and drought resistance of the crop. Spacing. — The texture of the soil also influences the spacing or distance between laterals. Since in heavy soils the movement of water is retarded by the fineness of the soil particles, in such soils it is necessary to place drains closer together to obtain a certain degree of drainage than in a lighter soil. T " T ; ' T N \fy / y \ \ \^^/ / \ \ \ \ \ X \ry / / / Fig. 6. — The relation between depth and spacing of tile and the area affected. Other things being equal, the greater the depth of drainage, the wider the spacing. Figure 6 illustrates this point. In soils ranging from a sand to a sandy loam, drain lines may be placed from 150 to 300 feet apart ; while in heavy silts and clays it may be necessary to place the lines as close together as thirty or forty feet. Experience with soils of the same texture in the same locality is the best guide for spacing. Tile drains spaced as far as 150 feet apart and 3^ feet deep have given satisfactory drainage in some instances in California where the soils are quite heavy. Grade. — The more fall that can be secured, other things being equal, the more rapid will be the drainage and the smaller the tile necessary to carry a given amount of water. The necessity for accu- rately determining the grade on which tile are to be laid should be emphasized. This is especially true when the grades are fiat. It is not so important that any particular grade be secured, but it is important that the grade, whatever it is, be known and that the tile be carefully laid to conform to it. More than one grade is frequently used on long tile lines. This is known as a "broken" grade. Whenever a grade is flattened, it must be compensated for by an increase in the size of the tile. Whenever possible, the grade should be made 12 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION steeper as the outlet is approached. Such a condition is a reasonable assurance that particles of soil which may enter the line will be carried on to the outlet instead of settling in the line with the danger of clogging it. It more often happens that grades must be flattened toward the outlet, because of the topography of the land. A fall of one foot per thousand feet, or a grade of 1/10 of 1 per cent, is about as fiat as it is advisable to use, although some successful drains have less. A grade of 2 to 5 feet per thousand feet is very satisfactory for tile lines and very little difficulty will be encountered either in construction or maintenance where this can be secured. It is sometimes said that one drain "draws" better than another or that the "draw" is of such and such a distance. Actually drains do not draw at all in the sense that they pull or suck the water from the soil. Underdrains serve only as collecting channels or outlets for the water which reaches them by gravity. If one field drains farther back from the lines of tile than another, it is because the soil conditions are such that there is a more ready lateral movement of the underground water to the tile in one case or that the tile is of insufficient capacity to remove the water as rapidly as it reaches it in the other. Discharge or Run-off. — The size of tile necessary to drain a tract of land is based on two considerations, the fall or grade on which the tile can be laid, and the amount of water or run-off which it is necessary to carry. The grade can be quite accurately determined, but the run-off is not so easily obtained. Drains are usually spoken of as having a capacity to remove in twenty-four hours some definite amount (%, ] /2 or 1 inch) in depth of water from the area to be drained. The amount of water which will reach the drains in a given time is dependent upon the character of the soil, the intensity and duration of rainfall, the size of the area, and, to some extent, the shape of the area. In clay soils, water reaches the tile more slowly than in sand; therefore, the tile may be smaller in clay, although during the season as much water may be removed from one soil as from the other. Open drains, especially those designed to take care of surface fiow, must be built of a size capable of handling the maximum run-off. At times this may amount to a considerable proportion of the heaviest rains. It sometimes happens in the coast sections of California that a steady rain lasting for several days will be followed by a very heavy down- pour, most of which will run off as surface water. In normal years this may occur once or twice during the winter season. CIRC. 304] DRAINAGE ON THE FARM 13 For tile drains the maximum twenty-four hour rainfall is not so important as the maximum duration of any one storm. Long continued rains which permit the water to penetrate into the soil rather than flow from the surface usually cause the greatest discharge in tile systems. It is seldom that underdrains are necessary which have a larger twenty-four hour carrying capacity than one-half to five-eighths inch in depth from the area drained, although occasionally a run-off of 1 inch may be obtained. For large areas the rate of run-off at the outlet is smaller than for small areas. The same is true for long, narrow areas as compared to areas more nearly square, because water from the more distant sections does not reach the outlet unti] after that from nearer points has passed on. The amount of water to be carried in a drainage system can not be exactly foretold as each case presents its own local peculiarities and experience is the best guide. An approximate estimate of the discharge is necessary for a general guide, however, and the figures given will serve as a basis for such an estimate. Size of Tile. — When the maximum amount of water to be carried has been decided upon and the grade upon which the drain can be constructed is known, the size of the ditch or tile necessary is largely a matter of computation. There are a few general principles, how- ever, which do not conform strictly to the mathematical computation of tile size. It is never advisable to use tile smaller than four inches in diameter, even for short laterals; in fact, some tile factories have discontinued the making of drain tile less than four inches in diameter. Even with the greatest care irregularities in the grade or laying of the tile are sure to occur. A slight irregularity in a line of small tile has a much more serious effect on its efficiency than does a similar irregularity in a line of larger tile. Four- and six-inch tile (preferably six-inch) may ordinarily be used for lateral drains 1000 feet or less in length. Six- and eight-inch tile may be used for submains and the upper ends of mains. Some factories make the intermediate sizes, five- and seven-inch, which can of course be used in their proper places. Except for small areas, it is not necessary to make the capacity of the main drain equal to the combined capacities of the laterals. Lateral drains are seldom required to carry their full capacity; in fact, a drain that runs full for a considerable time may safely be considered too small. 14 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION The difference between the cost of a drainage system using four- inch tile and of one using six-inch tile for laterals, lies almost entirely in the cost of the tile itself, which is seldom more than 30 or 35 per cent of the entire cost of the system. The smallest trench that it is practicable to dig by the methods usually employed in California will be large enough for six or even eight-inch tile. There is not enough difference in weight between a four-inch and a six-inch tile Fig. 7. — Diagram for computing the size of drain tile when certain are known. (After Yarnell and Woodward.) factors ClRC. 304] DRAINAGE ON THE FARM 15 to add materially to the cost of laying, and the cost of backfilling will be the same in both cases. Furthermore, incidental expenses do not increase in direct proportion to the size of tile used. To be of the highest efficiency, the tile must be of sufficient size to remove all surplus water before the crops are injured, even after the heaviest rainfall in a continued wet period. The diagram shown in figure 7 was prepared by D. L. Yarnell and S. M. Woodward, and used by them in U. S. Department of Agricul- ture Bulletin 854 as a means of determining the size of tile necessary when certain facts are known. For example, suppose the estimated run-off is % inch in 24 hours from an area of 70 acres and the available fall is two feet per thousand (or .2 foot per 100), what size will the main drain need to be? In the third column on the right above the title "R=%" will be found the area "70"; a horizontal line through this' point intersects a vertical line through ".2" found on the bottom border of the table at a point just below the line sloping upward to the right marked " 12, ' ' which represents the tile diameter. Thus a tile 12 inches in diameter will be required. At the same time it can be noted that the discharge from this tile will be slightly under 2 cubic feet per second (left hand border), and the velocity of flow will be approximately 2y 2 feet per second (line sloping upward to the left). The use of a diagram saves a great deal of computation. The method used in computing the formula for this diagram is fully described in the bulletin referred to. Kinds of Tile. — There are two kinds of tile available for drainage work in California, namely, clay tile and concrete tile. Both are used extensively, sometimes on the same system, and both are proving satisfactory when they have been well made from good material. Clay tile is made in sizes varying from four inches to twenty-four or thirty inches in diameter, although some factories do not carry regular stocks in sizes greater than eighteen inches. For the large sizes, sewer pipe is sometimes used. There is no objection to this other than it may be more expensive. Clay tile should be straight, well burned and free from defects. Soft or porous tile, either in clay or concrete should be discarded as defective. Water enters a tile line at the joints between the separate tile lengths and does not pass through the walls of the tile itself. Any tile which is so porous that water will pass through the walls is defective and should be treated as such. Concrete tile can usually be obtained in a larger assortment of sizes than clay. Concrete tile should be true to form, hard, dense 16 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION I 06 < w g ClRC. 304] DRAINAGE ON THE FARM 17 and thoroughly cured. Home-made tile is likely to be inferior in quality and its use should be discouraged unless the builder has a good knowledge of the principles of concrete construction. It is safer to purchase tile from a reliable manufacturer. Reliable and established manufacturers of both clay and concrete tile are thoroughly familiar with the "Standard Specifications for Drain Tile of the American Society of Testing Materials" and make a product which they guarantee to meet those specifications. The engineer or tile user should insist upon actual tests being made if there is any doubt whatever as to its quality. Specifications requiring tile to be made either of clay or concrete are not in themselves assur- ance that a good quality will be obtained. CONSTRUCTION OF TILE DRAINS Before any work is done, the lines along which the tile are to be laid should be staked out and plainly marked. This is usually done by setting a ' ' guard " or " marker ' ' stake each fifty feet or one hundred feet upon which the distance from the outlet is shown. Close to each of these stakes another, known asa " hub " or " grade stake ' ' is driven so that its top is flush with the ground surface. (See figure 8.) It is from this latter stake that measurements of depth or "cut" are made. This stake must not be disturbed in any way until the tile is laid and tested. The required depth at each stake is either recorded on the marker stake or furnished the workman in the form of a table or profile. The nearer edge of the trench is laid off by the workman parallel to and about 9 inches from the line of stakes. This line should be marked with a stretched cord or by shovel marks on the ground so as to insure a straight trench. Digging the Trench. — If there is much work to be done, a trench- ing machine may be used. For the type of drains described in this paper, the wheel type of trencher is the most common, but these machines are too expensive for the individual farmer to purchase. In some sections of the state, drainage contractors can be found who own trenchers and construct drains for others at a stated price per foot or rod. A light ladder-type ditcher can be purchased as an attachment for the Fordson tractor. This machine, however, is rather expensive for the small farmer unless he contemplates doing work for others. Machine trenching is usually cheaper than hand trenching and has the great advantage of being more rapid. In figure 9 can be seen a wheel-type excavator at work. 18 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION Fig. 9. — Drainage contractors use excavators which dig trenches rapidly and accurately and usually at a less cost than the work can be done by hand. For hand dug trenches, one of the tile spades shown in figure 10 is the most satisfactory where the ground is moist. This tool, however, is not very common in California. Often work is done during the dry part of the year when it is necessary to use a pick to loosen the soil. Work done at this time, however, is more expensive than when done at a time when the more convenient tools can be used. Digging should always start at the outlet so that any water that is encountered Fig. 10. — Tools used in constructing tile drains by hand. Circ. 304] DRAINAGE ON THE FARM 19 can drain away. Even when the ground is dry at the time of digging the trench, it is best to begin at the outlet. The trench, unless dug by machinery, should be finished to within an inch or so of the bottom before the grade line is set. With machine dug trenches a skilled operator can dig very close to grade at a single operation. Establishing Grade. — It is very essential that tile be laid true to the established grade. When tile drains become clogged or silted up it is very probable that they were not laid absolutely true to grade. Fig. 11. — Measuring down from an overhead cord to make sure that the completed trench is everywhere seven feet from the line. (Courtesy of Inter- national Harvester Co.) An easy method of determining the true grade at all points along the line is to stretch a light stout cord on cross-bars directly over the trench and at some chosen distance, say 7 feet above the bottom. The cross-bars are located at the stakes which have been set by the engineer. The bars are placed at a distance above the grade stake equal to the difference between 7 and the "cut" or depth of trench at that point. A cord stretched across a number of bars so placed will everywhere along its length be 7 feet above the true bottom of the trench, which can easily be determined by measuring down from the cord at any point (see figure 11). Care should be taken to see 20 UNIVERSITY OF CALIFORNIA- — EXPERIMENT STATION that the cord is supported at intervals to prevent its sagging. When the grade cord is set the almost completed trench can be finished with a shovel and tile scoop. Laying Tile. — It is presumed that the tile has already been dis- tributed along the line within easy reach from the trench. Small tile can be placed from the bank with a tile hook, as shown in figure 12. They should be placed end to end as closely as they will lie in the trench. Tiles will occasionally be found whose ends are not exactly square, but by turning them slightly they can be made to fit closely. t*H "V* Fig. 12. — Laying small tile with a tile hook from the top of the trench. (Courtesy of International Harvester Co.) Tile larger than about 8 inches in diameter are placed by hand from the bottom of the trench, as they are too heavy to conveniently handle with the tile hook, and those over 18 inches in diameter are lowered into the trench with a block and tackle. Tile should receive a final inspection just before laying, as some may be damaged after they are brought to the field. A single tile that fails after being placed may destroy the usefulness of the entire line above it. It is better to discard a good tile occasionally than to put in a single poor one. As soon as the tile is in position, a little earth cut from the side of the trench will prevent its rolling out of line. After each 50 or 100 feet of tile is laid and at the end of each day's work, the tile laid CIRC. 304] DRAINAGE ON THE FARM 21 should be covered with earth to a depth of three or four inches so as to protect it from injury or dislocation by falling stones or chunks of earth. Sometimes in heavy soil, the first backfill or ' ' blind- ing, ' ' as it is called, is done with soil from the surface containing some sod or grass. A little straw, gravel, or rock may be used in order to keep heavy clay from packing too closely about the tile. If quick- sand is encountered, these substances may be effectively used to prevent its entrance into the tile. These precautions, however, are necessary only in unusual circumstances. Fig. 13. — Backfilling a tile trench with slip scraper. Backfilling. — If the tile are to be inspected by the engineer, such inspection should be done just before they are covered. The filling of the trench can be accomplished in several ways. In places where the work is crowded, such as in an orchard or around buildings, the back- filling can best be done by hand with shovels. In the open field the soil is usually plowed into the trench. A long doubletree is provided so that one horse or one team is on each side of the trench. This method requires from two to three men and steady teams. Small slip or four-horse Fresno scrapers are sometimes used, in which case the team works on the opposite side of the trench from the scraper. (See figure 13.) Power operated backfillers are too expensive for the average farmer to own, but they are very desirable for the drainage contractor. All of the earth excavated from the trench should be replaced; otherwise there will be a depression along the line when the soil settles. 22 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION BOX DRAINS Box drains may be used when lumber can be secured at a reason- able price and tile is very expensive. The installation of box drains is similar in every respect to that of tile, and the same care should be used. (See figure 14). Redwood lumber is much more durable than pine or fir and should be used for all underground work in Fig. 14. — Box drains in place and ready for backfilling in a Placer County pear orchard. b c Fig. 15. — Types of lumber box drains. California. It is reasonable to expect redwood boxes to last for ten or twelve years; if kept wet during the entire year, they will last much longer. In all cases, however, where lumber is used for under- ground work its life can be lengthened by treating with creosote. Simple forms of boxes are shown in figure 15. The lumber for the smaller box (a) should run lengthwise. The sections may be from twelve to sixteen feet long if the trench will remain open for that Circ. 304] DRAINAGE ON THE FARM 23 distance. The top is nailed tightly to the sides, but the bottom is held away from the sides by short pieces of lath placed at intervals of three or four feet. In boxes with interior dimensions greater than eight inches square, two-inch lumber should be used and the top and bottom put on crosswise (b). In large boxes for main drains, the lumber for the top, bottom, and sides should all run crosswise. The bottom pieces should be separated so that when the lumber becomes wet and swells it will not close all openings for the water. The use of box drains without bottoms is not advisable, as the water is likely to undermine the sides and cause the box to settle. Furthermore, any roughness of the bottom of the trench will reduce the capacity of the drain. Fig. 16. — Surface inlets with screens. STRUCTURES Surface water should not be allowed to enter directly into a tile line unless some provision is made to exclude sand, dirt, sticks, and other rubbish. Figure 16 shows two methods of screening surface water before it enters a drain. One consists of a concrete box with an open bottom resting on a bed of stones which covers the tile. Water enters the box near the top through wire screens. The wire screens keep large particles, such as leaves and sticks, from entering the box and the stone filter removes sand and finer particles from the water before it enters the tile line. The other device is made from sewer pipe through which the water passes to enter the line. A heavy iron grating covered with small stones will prevent the entrance of any- thing, except the water. If there is a considerable quantity of water, the stone filter should extend over a greater length of tile than shown. 24 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION The types of screen shown in this figure admit water readily to the tile line, but when placed in open fields are an obstruction to cultivation. It is good practice to install silt boxes at intervals along a tile drain to catch and retain any silt that may enter the line. These boxes So// \. s~2*6*3'-3- Fig. 17. — Combination manhole and silt -box w ith cover. (After D. G. Miller.) may be made of lumber, concrete or brick. A very satisfactory com- bination silt-box, manhole and observation well of lumber is shown in figure 17. It is inadvisable to construct silt boxes so small that they can not be readily entered and cleaned. They should be placed at points where the grade changes to a natter one, or where there are abrupt changes in the direction of the line. The junction of two lines is easily effected through such a box, although in the gridiron or Circ. 304] DRAINAGE ON THE FARM 25 herring bone system of drains it would not be advisable to place a box at each junction. The outlet of a tile drainage system, unless very favorably located, should be protected by some device which will prevent the tile from washing out or becoming injured or displaced. The outlet protection may be made of lumber, stone, brick, or concerte, the design depending upon the conditions which exist at the outlet. In any case care should be taken to secure a good foundation and anchorage so that the structure will not be undermined. Figure 18 shows an outlet pro- tection for small tile, and the illustration on the front page of this circular shows a more elaborate outlet for a large main drain. The construction material used in making silt wells may also be used for outlet protections. Fig. 18. — Timber outlet protection for small tile. MAINTENANCE OF TILE DRAINS Properly installed tile drains require very little maintenance. The silt boxes should be inspected frequently during the first year and at regular intervals thereafter, and should be kept free from silt. The covers of silt boxes should be kept closed and locked at all times. (See figure 19.) Tumble weeds, rabbits, and squirrels may enter the silt boxes and obstruct the tile lines unless this precaution is observed. Soil will not seal the joints and prevent the entrance of water into the tile lines under ordinary conditions. There need be but little fear of the roots of fruit trees growing into a tile line unless the tile carries water when the surrounding soil is dry. Such a condition 26 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION would exist when the drain taps a spring which flows long after the surrounding area has become dry. Cottonwood and willow trees, however, should not be allowed to grow within fifty feet of a tile line, as they are water loving trees and frequently cause serious trouble. Should a tile line become obstructed in any way, silt boxes located at frequent intervals will aid materially in locating the obstruction. A number of devices have been developed for cleaning sewers which can be used for drain tile. These may also be found useful during construction, especially if the tile is laid in a wet, muddy trench. Fig 19. — A manhole made from large concrete tile and having a metal cover securely fastened with a heavy chain and padlock. The most common form of tile cleaner is one whose several sections can be joined together when the rods are held at right angles, but can not be unhooked when extended. These rods may be used with or without any of the various attachments such as an auger, wire brush, hoe, or spiral cutter. A very simple brush can be made by wrapping a piece of leather belting around a cylindrical rod, the belting first having been driven full of wire nails of such a length that the completed brush will not quite fill the tile. Care must be exercised not to use fixtures that may become detached or will catch on the tile. Two hundred and fifty feet or more of rod can be operated in a straight tile line. Circ. 304] DRAINAGE ON THE FARM 27 COST OF DRAINAGE The matter of cost is probably the most important item in drain- age ; upon this depends the feasibility of any undertaking. The engineer who has planned a system should be able to estimate the cost of it very closely. Unless the details of construction are known, how- ever, only general and approximate cost data can be given. There are only a very few factories on the Pacific Coast which manufacture clay drain tile exclusively, most of it being made to order or as a side line by clay products factories. Cement tile plants are more numerous, as practically the same equipment is used for the manufacture of drain tile as for irrigation pipe. TABLE 1 Clay Concrete Size Price per foot Weight per foot Price per foot Weight per foot 4 5c to 8c 7 5c to 8c 9 6 8c to 13c ny 2 8c to 13c 18 8 14c to 22c 193^ 14c to 18c 27 10 20c to 30c 32 18c to 26c 36 12 28c to 38c 40 25c to 35c 42 14 35c to 51c 50 33c to 42c 64 16 45c to 60c 60 40c to 55c 85 18 60c to 90c 100 65c to 75c 102 20 90c to $1.10 138 75c to 90c 120 22 $1.25 to SI. 55 150 90c to $1.10 145 24 $1.60 to $1.90 165 $1.10 to $1.25 170 26 $2.00 to $2.50 200 $1.50 to $1.75 210 28 $2. 50 to $3. 00 235 $1.90 to $2. 50 250 30 $3. 00 to $3. 50 265 $2.50 to $3 00 277 Tile are sold by the foot or the 1000 feet, with discounts on car lots. Tile, both clay and concrete, are higher priced in all of the western states than in the East or Middle West. Table 1 may be used as a general guide to the price of drain tile at the factory, and the weights given may be used as a basis for figuring freight charges. Both price and weight, however, may vary from the figures given. Frequently prices are quoted on pipe delivered at the rail point nearest the consumer or along the trench by truck. Excavation of hand dug trenches will cost, at the present price of common labor, from 40 to 60 cents an hour, from 10 to 20 cents a lineal foot for depths of from three to five feet and width sufficient 28 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION for 8-inch tile. The cost varies somewhat with the season, the con- dition of the soil and the amount of labor available. Machine-dug trenches under favorable conditions will cost about one-half as much as hand-dug trenches. Laying and backfilling will vary somewhat, but for the smaller sizes of tile will probably cost from 3 to 5 cents a lineal foot. This will bring the cost of a completed 6-inch drain to about 30 cents a foot. It may be roughly estimated that the cost of tile is from 30 to 40 per cent of the cost of the completed system. DRAINAGE OF PEAT SOILS Peat soils, such as are frequently found in small areas throughout the coast region and in the foothills of the Sierras, often require a different system of drainage than do other soils. Peat is formed by the decaying vegetation that grows in the presence of an abundant water supply. It is often found surrounding or just below a spring or permanent seepage area. For the drainage of these soils, it is essential that the source of the water be found and the water inter- cepted. Peat shrinks and settles markedly when drained, and tile are likely to become misplaced unless some precautions are taken to prevent it. If the peat is not too deep, the drains may be laid directly on the subsoil. If, however, the peat is too deep for this, it may be necessary to support the tile on a cradle made of lumber. Where the depth of the peat is irregular, a cradle is sometimes used to support that part of the drain which does not rest on solid subsoil. The cradle consists of two boards, usually of 1 in. by 3 in. material, laid parallel and about 3 inches apart. These are held together by cleats on the under side ; sometimes the whole cradle is nailed to posts driven in the bottom of the trench. Peat soils can not usually be drained as deeply as others, because the capillary rise of water through them is very low, and, unless irrigation is available or the water table is relatively close to the surface, crops may suffer from drought. Peat land crops are of necessity, therefore, shallow-rooted. ClRC. 304] DRAINAGE ON THE FARM 29 DRAINAGE OF TIDAL MARSHES In the drainage of tidal marshes, it is usually necessary to protect the land from tidal inundation by means of levees, and the drainage water is discharged through tide gates or pumping plants. The designing of these are, however, not within the scope of this circular. Most drainage for reclaimed tidal marshes in California has been of the open ditch type, but the use of tile may prove to be more efficient. The soils are usually very heavy textured and contain large quantities of salt. Drains from 3% to 4 feet in depth and spaced from 50 to 100 feet apart are proving satisfactory. It is necessary to keep the outlet drains, which are usually open ditches leading to the gates or pumps, as nearly empty as possible, so that the lateral drains will operate freely. Except for seepage through the levees, which is collected in an open drain just inside the levee, the run-off for tidal marshes is about the same as from similar-sized areas of adjacent uplands. Tidal marshes usually have no natural fall, and the grades for tile must be made by placing them shallower at the upper end than at the lower. Care should be taken to have the upper ends deep enough to provide adequate drainage, even though it may mean that the lower ends are deeper than would otherwise be necessary. VERTICAL DRAINAGE By vertical drainage is meant the passing of drainage water vertically through the soil into a porous bed of sand or gravel beneath ; it is effected by means of wells or pipes extending into the porous substratum. Vertical drainage is feasible only when the surface soil is underlaid by an impervious layer of clay or hardpan, beneath which is a porous layer of sand or gravel, which contains no water, or affords a channel through which the water may escape. Such a set of conditions is rarely found. The hardpan is usually underlaid by a non-porous subsoil filled with water which does not flow away. It would be useless to attempt vertical drainage if the subsoil were not porous, even though it were dry, because its water holding capacity would soon be reached, and the drain would then become inoperative. Vertical drainage, where practicable, may be accomplished by boring an 8 or 10 inch hole well into the porous stratum and lining this hole with ordinary drain tiles set one on top of another. The 30 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION top must be securer/ covered and screened so as to prevent the entrance of silt or trash into the drain. Another method of accom- plishing vertical drainage where the impervious layer is hardpan is to break up the impervious stratum with dynamite. If this method were used on a layer of clay the clay would have a tendency to puddle back into an impervious layer, and instead of breaking and shattering, would pack and burn at the point of the explosion. Every instance of contemplated vertical drainage should be thor- oughly examined, as subsoil conditions will almost always be found unsuited to this type of drainage. CO-OPERATION IN DRAINAGE It is seldom that a farmer can install an extended and compre- hensive drainage system without cooperating to some extent with other landowners. Cooperation is often necessary to obtain an outlet. The right to drain land should not be abridged by the prejudices of an adjacent landowner. The rights of those owning lower land which must be crossed by the drains of another must not be ignored, how- ever, and if any injury whatever is sustained it should be paid for. As a matter of fact, a drain usually benefits the lower land by crossing it, and some arrangement should therefore be made whereby the cost of such a drain will be borne by both parties. These matters should be amicably settled before work is begun. Where there are a number of persons interested in any particular drain or system of drains better cooperation can be secured through the organization of a drainage district, This provides a means of securing a comprehensive and well planned system, of financing, and of making and collecting assessments. California is now adequately supplied with statutes covering this subject. The organization of a drainage district should not be attempted without the assistance and advice of an attorney to make certain that the proper procedure is followed. STATION PUBLICATIONS AVAILABLE FOR FREE DISTRIBUTION BULLETINS No. 253. Irrigation and Soil Conditions in the Sierra Nevada Foothills, California. 261. Melaxuma of the Walnut, "Juglans regia." 262. Citrus Diseases of Florida and Cuba Compared with Those of California. 263. Size Grades for Ripe Olives. 268. Growing and Grafting Olive Seedlings. 273. Preliminary Report on Kearney Vine- yard Experimental Drain. 275. The Cultivation of Belladonna in California. 276. The Pomegranate. 277. Sudan Grass. 278. Grain Sorghums. 279. Irrigation of Rice in California. 280. Irrigation of Alfalfa in the Sacra- mento Valley. 283. The Olive Insects of California. 285. The Milk Goat in California. 294. Bean Culture in California. 304. A Study of the Effects of Freezes on Citrus in California. 310. Plum Pollination. 312. Mariout Barley. 313. Pruning Young Deciduous Fruit Trees. 319. Caprifigs and Caprification. 324. Storage of Perishable Fruit at Freez- ing Temperatures. 325. Rice Irrigation Measurements and Experiments in Sacramento Valley, 1914-1919. 328. Prune Growing in California. 331. Phylloxera-Resistant Stocks. 334. Preliminary Volume Tables for Sec- ond-Growth Redwood. 335. Cocoanut Meal as a Feed for Dairy Cows and Other Livestock. 339. The Relative Cost of Making Logs from Small and Large Timber. 340. Control of the Pocket Gopher in California. 343. Cheese Pests and Their Control. 344. Cold Storage as an Aid to the Mar- keting of Plums. 346. Almond Pollination. 347. The Control of Red Spiders in Decid- uous Orchards. 348. Pruning Young Olive Trees. 349. A Study of Sidedraft and Tractor Hitches. 350. Agriculture in Cut-over Redwood Lands. 352. Further Experiments in Plum Pollina- tion. 353. Bovine Infectious Abortion. 354. Results of Rice Experiments in 1922. 357. A Self-mixing Dusting Machine for Applying Dry Insecticides and Fungicides. 358. Black Measles, Water Berries, and Related Vine Troubles. 359. Fruit Beverage Investigations. 361. Preliminary Yield Tables for Second Growth Redwood. 362. Dust and the Tractor Engine. No. 363. 364. 365. 366. 367. 368. 369. 370. 371. 372. 373. 374. 375. 376. 377. 379. 380. 381. 382. 383. 384. 385. 386. 387. 388. 389. 390. 391. 392. 394. 395. 396. 397. 398. 399. 400. The Pruning of Citrus Trees in Cali- fornia. Fungicidal Dusts for the Control of Bunt. Avocado Culture in California. Turkish Tobacco Culture, Curing and Marketing. Methods of Harvesting and Irrigation in Relation of Mouldy Walnuts. Bacterial Decomposition of Olives dur- ing Pickling. Comparison of Woods for Butter Boxes. Browning of Yellow Newtown Apples. The Relative Cost of Yarding Small and Large Timber. The Cost of Producing Market Milk and Butterfat on 246 California Dairies. Pear Pollination. A Survey of Orchard Practices in the Citrus Industry of Southern Cali- fornia. Results of Rice Experiments at Cor- tena, 1923. Sun-Drying and Dehydration of Wal- nuts. The Cold Storage of Pears. Walnut Culture in California. Growth of Eucalyptus in California Plantations. .Growing and Handling Asparagus Crowns. Pumping for Drainage in the San Joaquin Valley, California. Monilia Blossom Blight (Brown Rot) of Apricot. A Study of the Relative Values of Cer- tain Succulent Feeds and Alfalfa Meal as Sources of Vitamin A for Poultry. Pollination of the Sweet Cherry. Pruning Bearing Deciduous Fruit Trees. Fig Smut. The Principles and Practice of Sun- drying Fruit. Berseem or Egyptian Clover. Harvesting and Packing Grapes in California. Machines for Coating Seed Wheat with Copper Carbonate Dust. Fruit Juice Concentrates. Cereal Hay Production in California. Feeding Trials with Cereal Hay. Bark Diseases of Citrus Trees. The Mat Bean (Phaseolus aconilifo- lius). Manufacture of Roquefort Type Cheese from Goat's Milk. Orchard Heating in California. The Blackberry Mite, the Cause of Redberry Disease of the Himalaya Blackberry, and its Control. The Utilization of Surplus Plums. No. 87. 113. 117. 127. 129. 136. CIRCULARS No. Alfalfa. Correspondence Courses in Agriculture. The Selection and Cost of a Small Pumping Plant. House Fumigation. The Control of Citrus Insects. Melilotus indica as a Green-Manure Crop for California. 144. Oidium or Powdery Mildew of the Vine. 151. Feeding and Management of Hogs. 152. Some Observations on the Bulk Hand- ling of Grain in California. 154. Irrigation Practice in Growing Small Fruit in California. 155. Bovine Tuberculosis. CIRCULARS— (Continued) No. 157. 160. 164. 166. 167. 170. 173. 178. 179. 184. 190. 199. 202. 203. 209. 210. 212. 214. 215. 217. 220. 228. 230. 231. 232. 233. 234. 235. 236. 238. 239. 240. 241. 242. 243. 244. 245. 247. 248. 249. 250. 251. 252. 253. 254. 255. Control of the Pear Scab. Lettuce Growing in California. Small Fruit Culture in California. The County Farm Bureau. Feeding Stuffs of Minor Importance. Fertilizing California Soils for the 1918 Crop. The Construction of the Wood-Hoop Silo. The Packing of Apples in California. Factors of Importance in Producing Milk of Low Bacterial Count. A Flock of Sheep on the Farm. Agriculture Clubs in California. Onion Growing in California. County Organizations for Rural Fire Control. Peat as a Manure Substitute. The Function of the Farm Bureaii. Suggestions to the Settler in California. Salvaging Rain-Damaged Prunes. Seed Treatment for the Prevention of Cereal Smuts. Feeding Dairy Cows in California. Methods for Marketing Vegetables in California. Unfermented Fruit Juices. Vineyard Irrigation in Arid Climates. Testing Milk, Cream, and Skim Milk for Butterfat. The Home Vineyard. Harvesting and Handling California Cherries for Eastern Shipment. Artificial Incubation. Winter Injury to Young Walnut Trees during 1921-22. Soil Analysis and Soil and Plant. Inter-relations. The Common Hawks and Owls of California from the Standpoint of the Rancher. Directions for the Tanning and Dress- ing of Furs. The Apricot in California. Harvesting and Handling Apricots and Plums for Eastern Shipment. Harvesting and Handling Pears for Eastern Shipment. Harvesting and Handling Peaches for Eastern Shipment. Poultry Feeding. Marmalade Juice and Jelly Juice from Citrus Fruits. Central Wire Bracing for Fruit Trees. Vine Pruning Systems. Colonization and Rural Development. Some Common Errors in Vine Prun- ing and Their Remedies. Replacing Missing Vines. Measurement of Irrigation Water on the Farm. Recommendations Concerning the Com- mon Diseases and Parasites of Poultry in California. Supports for Vines. Vineyard Plans. The Use of Artificial Light to Increase Winter Egg Production. Leguminous Plants as Organic Fertil- izer in California Agriculture. No. 256. The Control of Wild Morning Glory. 257. The Small-Seeded Horse Bean. 258. Thinning Deciduous Fruits. 259. Pear By-products. 260. A Selected List of References Relating to Irrigation in California. 261. Sewing Grain Sacks. 262. Cabbage Growing in California. 263. Tomato Production in California. 264. Preliminary Essentials to Bovine Tuberculosis Control. 265. Plant Disease and Pest Control. 266. Analyzing the Citrus Orchard by Means of Simple Tree Records. 267. The Tendency of Tractors to Rise in Front ; Causes and Remedies. 268. Inexpensive Labor-saving Poultry Ap- pliances. 269. An Orchard Brush Burner. 270. A Farm Septic Tank. 271. Brooding Chicks Artificially. 272. California Farm Tenancy and Methods of Leasing. 273. Saving the Gophered Citrus Tree. 2 74. Fusarium Wilt of Tomato and its Con- trol by Means of Resistant Varieties. 275. Marketable California Decorative Greens. 276. Home Canning. 277. Head, Cane, and Cordon Pruning of Vines. 278. Olive Pickling in Mediterranean Coun- tries. 279. The Preparation and Refining of Olive Oil in Southern Europe. 281. The Results of a Survey to Determine the Cost of Producing Beef in Cali- fornia. 282. Prevention of Insect Attack on Stored Grain. 283. Fertilizing Citrus Trees in California. 284. The Almond in California. 285. Sweet Potato Production in California. 2S6. Milk Houses for California Dairies. 287. Potato Production in California. 1288. Phylloxera Resistant Vineyards. 289. Oak Fungus in Orchard Trees. 290. The Tangier Pea. 291. Blackhead and Other Causes of Loss of Turkeys in California. 292. Alkali Soils. 293. The Basis of Grape Standardization. 294. Propagation of Deciduous Fruits. 295. The Growing and Handling of Head Lettuce in California. 296. Control of the California Ground Squirrel. 297. A Survey of Beekeeping in California; The Honeybee as a Pollinizer. 298. The Possibilities and Limitations of Cooperative Marketing. 299. Poultry Breeding: Records. 300. Coccidiosis of Chickens. 301. Buckeye Poisoning of the Honey Bee. 302. The Sugar Beet in California. 303. A Promising Remedy for Black Measles of the Vine. The publications listed above may be had by addressing College of Agriculture, University of California, Berkeley, California.