UNIVERSITY OF CALIFORNIA AGRICULTURAL EXPERIMENT STATION COLLEGE OF AGRICULTURE " NJ - ,DE WHEELER ' '"••«" THOMAS FORSYTH HUNT, Dean and Director BERKELEY H. E. VAN NORMAN, vice-Director and Dean » University Farm School CIRCULAR No. 174 September, 1917 FARM DRAINAGE METHODS' By WALTER W. WEIR, Senior Drainage Engineer, U. S. Department of Agriculture This circular is intended for use only in sections of the state which are free from alkali; it is not applicable to irrigated land. CONTENTS PAGE Introduction 2 The Need for Drainage 2 Effects of Drainage 2 Open Drains 4 When Open Drains are necessary 4 Objections to Open Drains 5 Importance of Engineering Assistance 5 Outlets 6 Design of Open Drains 7 Methods of Construction 9 Maintenance 9 Underdrains 10 Design of Underdrains 10 Use of Soil Auger 10 Grade 11 Depth 11 Spacing 12 Size of Tile 13 Kinds of Tile 15 Construction of Underdrains 16 Laying out the Drain 16 Ditching Tools and Machinery 17 Digging to Grade 19 Laying Tile 21 Backfilling 23 Box Drains 23 Surface Inlets, Silt Boxes, and Outlets 24 Maintenance of Tile Drains 25 Cost of Tile Drainage 28 Vertical Drainage 29 Co-operation in Drainage 30 1 This circular was prepared under a co-operative agreement between the Office of Public Roads and Rural Engineering, U. S. Department of Agriculture, and the University of California, Agricultural Experiment Station. INTRODUCTION The purposes of this circular are to call attention to the need for drainage on many of the California farms which are located in regions where -the annual rainfall is sufficient for agricultural purposes ; to outline the advantages to be derived from drainage; to recommend the use of tile and the systematic construction of open drains; to offer suggestions regarding the spacing, depth, and size of drains, as well as methods and cost of installing them; and to urge better co- operation between the owners of adjoining farms in the disposal of storm water and surface run-off. THE NEED FOR DRAINAGE The average annual rainfall in the state varies from more than fifty inches in portions of Del Norte, Humboldt, and Mendocino counties and the northern high Sierras to less than ten inches over most of Imperial, San Bernardino, Eiverside, and Inyo counties and the San Joaquin Valley. Most of the Sacramento Valley and the coast region south of San Francisco receive an annual rainfall of from ten to twenty inches. Figure 1 shows the distribution of the rain over the state. A very large proportion of the total annual rainfall occurs during December, January, February, and March. The sections which receive twenty inches or more of rainfall have a tendency to become too wet for proper cultivation during certain periods. Generally the heavier soils which do not absorb water rapidly and which are most in need of drainage are found on the flatter valley floors or in depressions. Almost every farm has some place where the water stands too long after a rain, causing a partial or total failure of crop. Other places remain too wet for plowing and can not be seeded when the rest of the field is ready. These spots must be plowed and seeded later or be left uncropped. In either case, there will be an added expense or a material loss in crops. The saving of this expense may not seem important during any one year, but when the damage is continually recurring it assumes considerable significance. EFFECTS OF DRAINAGE In addition to the obvious benefits obtained by removing excess water and reclaiming swampy areas so that they may be profitably cultivated, drainage has other marked effects upon the soil. Some of the most important benefits thus derived are as follows : Drainage improves the granulation or tilth of the soil. This is accomplished through the removal of the excess water quickly after rains, thus preventing the puddling or running together of the soil mass. Even a stiff clay soil is rendered more porous and granular by the alternate drying and wetting which accompanies a properly drained soil condition. SCALE 0-/O /nches fO-20 /nches 20-30 inches 30-40 inches 40-50 inches over50 inches \ CALIFORNIA Average Annual Rainfall Based on Records for 30 years Y^W^-'A '; goo.— Fig. 1. — Distribution of average annual rainfall in California. Drainage improves the aeration of the soil. As the excess water passes out of the soil, air is drawn in. This aeration or ventilation promotes the growth of desirable micro-organisms, improves the con- ditions for root growth and development, and accelerates oxidation and the, other chemical reactions that liberate and make available the plant food elements. Drainage improves the soil temperature. In poorly-drained soils the heat which should be applied to warming the soil and bringing it to the proper temperature for the germination of seeds is used in evaporating the water ; the soil thus remains cold. If the excess water be removed the soil is warmed much sooner, thus both cultivation of the soil and crops can be started earlier in the spring. This is a very important consideration where it is desirable to have crops as far advanced as possible before the dry summer season arrives. Thorough drainage lessens the effect of drought. Only the excess water or free water is removed by the drains. For most plants the only water that is of use remains in the soil as a film wetting the surface of the grains. The removal of the free water enables the roots to grow deeply into the moist soil and this more extensive root- ing system, touching a large soil area, has a much greater supply of film water to draw upon and to carry the plant through a period of drought. This is an important consideration in California, as the plant should be as far advanced as possible before the long dry season approaches. OPEN DRAINS Open' drains, or ditches, may vary in size from shallow furrows only a few feet in length, to deep, wide dredged ditches many miles in length. The only type of drains here discussed, however, is that suited to the individual farm or to a project comprising but a few small farms. WHEN OPEN DRAINS ARE NECESSARY Open drains are generally used as outlets, both for tile and for other open drains. When the quantity of water to be carried becomes such that it is not feasible to carry it underground in covered drains, the use of open ditches becomes essential. The point at which this necessity occurs will, of course, depend almost entirely upon local conditions. It is often not feasible to design covered drains of the size required to care for the large quantity of surface water which follows a storm. In such cases open drains are essential. Again, where there is con- siderable danger of tile drains becoming filled with sediment or becom- ing obstructed in other ways, open drains are the more satisfactory. It is true that under these conditions open drains may also become obstructed, but they can be cleaned and repaired much more easily than can covered drains. Probably the most desirable feature of the open drain is the lower initial cost of its construction as compared with that of the covered drain. OBJECTIONS TO OPEN DKAINS Open drains are objectionable in that when they are deep enough to thoroughly drain the land they are of such width as to become an inconvenience in the field. Ditches are much more expensive to main- tain than are covered drains. The unavoidable roughness of the sides and bottom of a ditch causes sediment to be deposited and drain- age is thereby impaired. Weeds and brush collect in ditches and must be removed frequently if drainage is to be maintained. If the fall of an open drain is too great the water causes the banks to erode and cave. Open drains waste not only the land which they occupy, but the land along their banks which they prevent from being cultivated. Even a comparatively small ditch, with its waste banks, may easily render uncultivable a strip of land fifty feet wide. Such a drain requires over six acres for each mile in length, whereas this land is saved to cultivation where covered drains are used. Weeds which grow upon the ditch banks are unsightly and difficult to eradicate; they harbor undesirable insects and animals, as well as plant diseases. Open drains necessitate bridges for crossing, and they cut fields into irregular shapes, making cultivation mor difficult. The presence of ditches in small fields make it impractical to use certain heavy farm machinery. Except in that they more readily take care of surface water, open ditches are not as efficient as underdrains ; the sides are more likely to become puddled and the lateral movement of the ground water retarded. IMPOETANCE OF ENGINEEKING ASSISTANCE A drain should not be constructed without first obtaining levels over the line and establishing a definite grade, bottom width, and side slopes. If this is not done there will be difficulty in maintaining uniformity in grade and the drain may become congested at points where irregularities occur. The importance of reliable engineering assistance in designing and constructing large ditches is seldom ques- tioned, but many small farm drains are dug without any engineering assistance whatever. This practice should be discouraged, especially if the farmer himself is not familiar with the fundamental principles of stream flow and the use of the engineer's level. A careful engineer will make a survey, not only of the surface to determine the fall, alignment, etc., but he will make frequent borings into the soil to determine the subsoil conditions. California soils and subsoils are often quite variable within short distances. A knowledge of subsoil r conditions frequently is a great aid in determining such important matters as depth, spacing, and shape of drains. Figure 2 illustrates the various types of drainage systems. One would hardly expect to find complete drainage by open ditches follow- ing the "gridiron" or "herringbone" systems in which the drains follow a regular system of parallel lines with definite spacing between. Such a system would so interfere with cultivation as to make it im- practicable. Probably the greater part of our land to be drained by open ditches, except as the latter are used for outlets, would require the natural or irregular system which follows the natural depressions in the surface and seeks only to remove water from the low places or to divert or collect storm waters. Natural System Intercepting System 1 Y ! r- i Y' I) Gridiron System If Herring Bone System Fig. -Illustrating arrangements of drains. OUTLETS The outlet is the first consideration in drainage. When the outlet is to be in a stream, creek, or natural watercourse, one must determine whether the outlet is adequate ; that is, whether at times when drain- age is most essential it is capable of carrying the added water from the drain, and whether the outlet is deep enough to insure proper drainage to the fields which it is proposed to drain. Outlets are sometimes used when it is known that for short periods after a storm they will be overtaxed. Such a condition is not desirable but often it can not well be overcome. If the outlet is to be a ditch on another man's property, one should obtain the right to use it either by pur- chase or otherwise. When it is not possible to obtain a gravity outlet, pumping is sometimes resorted to and the water disposed of through channels whose elevation is higher than the drainage depth. In rolling land, an outlet is usually easy to obtain, but on the natter lands one should not attempt to determine the sufficiency of an outlet "by eye," and the use of an engineer's instrument is necessary. An outlet to be satisfactory must have the drain discharge freely into it. DESIGN OF OPEN DRAINS For areas up to 160 acres, drains in the humid sections of Cali- fornia should be designed to remove about one surface inch 2 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 areas the run-off may be decreased to three-fourths inch in twenty-four hours. Con- ditions of tilth, topography, and soil are determining factors in the rapidity and amount of run-off. In a field in good tilth and of gentle slopes the soil will retain much more water than in barren 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 determined with reference to the kind of soil through which the ditch passes. An open drain should be both deep 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 feet hori- zontal 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 dis- tance from the edge of the ditch to the toe of the waste bank, is equal to one-half the top width of the ditch. The ditch shown in figure 3 has sloping banks, and a wide berm is left between the ditch and the waste bank. All of the excavated material is in this case placed on one side of the ditch. Rather shallow surface ditches can be dug satisfactorily with teams where the ground is firm enough to permit teams going upon it. Team and scraper ditches are sometimes used where surface water accumu- 2 "Inch" as used in this paper means 1/12 of a foot and must not be confused with the term "miner's inch," frequently used in California by mining and irrigation interests. 8 lates 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 are of much less inconvenience when located along fence or property lines than when located through a field. Fig. 3. — Construction of an open drain by machinery, Marin County, Cal. Drains to which stock have access should have slopes so flat that they can be entered without damage to the drain or injury to the stock. Figure 4 shows a type of hand-dug open drain suitable for a 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 to the ditch bank against washing. METHODS OF CONSTEUCTION Open drains for the farm are constructed in three ways: by machinery, with teams and scrapers, and by hand. There are several types of excavating machinery for digging open drains; these vary in size from the large floating 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 by the larger farms or by several farms adjoining in a general plan of drain- age. Figure 3 shows an open drain being constructed with power machinery, in Marin County, California. When drains are con- structed during the dry season, teams may be used. Ditches excavated in this way are necessarily limited to rather shallow, broad drains "■■ ,-. (mMm^* Bern, ,._. M0M Fig. 4. — Type of hand-dug ditch suitable for heavy soils. in soils stable enough to permit the driving of teams over them. Under certain conditions and for certain types of drain, this method is both cheap and efficient. Digging drains by hand is feasible only when they are small enough to allow the excavated material to be disposed of without rehandling. MAINTENANCE 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 wet season begins. After a year or two it may be necessary to deepen the drain in order to 10 maintain the desired depth. If these things are not done it will not be long before conditions will 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 considerable proportion of the first cost. UNDERDRAINS Underdrains represent the ideal method of reclaiming wet or swamp areas. They may consist of tile or of wooden box-drains, and are covered with soil so that they do not interfere with cultivation. There is little danger of properly constructed tile drains becoming obstructed, and consequently they require little or no maintenance. Tile drains are permanent, and although the initial expense may be in excess of that for open drains they are, in the end, cheaper and better. The two general systems of drainage heretofore described — the regular and the natural — apply to underdrains and each system is capable of greater variation when tile are used. Figure 2 shows some of the variations possible. Unless the slopes are quite uniform, combinations of the various systems are often used. DESIGN OF UNDEEDKAINS Use of Soil Auger: The soil auger is one of the tools most frequently used by the careful drainage engineer. Figure 5 shows a soil auger of the type commonly employed. This auger consists of a li/^-mch carpenter's auger welded to a i/^-inch rod which by the insertion of additional sections can be extended to six feet or more. The point of the auger should be filed away so as to make a straight cutting edge and the points of the worm should be bent downward to facilitate cutting into very hard soil. Subsoil conditions, as for instance the presence or absence of hardpan, gravel, or clay strata, have a marked bearing on the location, depth, and spacing of drains. Borings with a soil auger will quickly determine the true subsoil conditions. The drainage of land which is wet from springs often requires a great deal of care in. the selection of the proper locations for the drains. It is essential that the exact locations of the springs be determined so that the drains shall intercept the water before it has spread through the surrounding soil. When a considerable area has become saturated by springs it may be difficult to determine their exact locations, but the matter is of sufficient importance to justify considerable effort to locate them accurately. The depth, spacing 11 (if more than one is required), and size of drain required for springy land must be determined for each individual case and the information is often most easily obtained by a diligent use of the soil auger. Grade : Other things being equal, the more fall that can be obtained for a tile line, the better and more rapid will be the drainage. A fall of one foot per thousand feet is about as little as it is advisable to use, although many successful tile drains have less. The greater the fall, the greater will be the carrying capacity of the drain or the smaller the drain required to carry a given quantity of water. Too much em- phasis can not be laid on the necessity for accurately determining by means of engi- neering instruments, the available fall, the grade upon which the drain is to be laid, and the sufficiency of the outlet, Figure 6 shows tile on grade lines which have been correctly and incorrectly determined. Wherever it is possible to do so, the grade should be made steeper as the outlet is ap- proached. Such a condition is a reasonable assurance that the drains will not become clogged by particles of soil settling in the tile lines. Depth: The depth to which tile should be laid is variable. In sandy soils tile may be placed deeper than in clay soils, because in the former the water more freely pene- trates the soil and consequently reaches the tile lines more readily. In heavy clay soils percolation is slow, and if drains are placed too deep the water may not reach the tile rapidly enough to make the drain efficient. Generally speaking, the greater the depth to which the soil can be completely drained, the more efficient the system will be. Sandy a a Fig. 5. — Soil auger. 12 or sandy-loam soils usually require drains placed about four to six feet deep, while in clay loams and clay, drains placed three to three and a half feet deep may prove more efficient. Experiments indicate that about three feet should be the minimum depth for tile, even in clay soils. Spacing : The proper spacing of drains depends to a considerable extent upon the depth. The lateral movement of water in the soil is retarded by the fineness of the soil particles, in the same way that the down- ward movement is retarded. Consequently, drains may be spaced farther apart in sandy soils than in clay. The deeper the drains, the farther apart the lines may be placed. Figure 7 illustrates the rela- tion of spacing to depth. In soils ranging from sand to 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. It is not possible to give specific rules for - -.■/ Fig. 6. — Correct and incorrect grading for tile. either the depth of tile or the spacing between lines, even for similar types of soil. Conditions may be such that one line of tile will be sufficient to drain a heavy soil while several lines will be required to drain a sandy loam. The intercepting system illustrated in figure 2 is an example of a single line of tile reclaiming a considerable area. Every drainage problem calls for the exercise of good judgment rather than the use of set rules. A knowledge of both surface and subsoil conditions is even of more importance in designing tile drains than in designing open drains. For example, a soil which is apparently a clay on the surface may be quite sandy at three or four feet below, or the reverse may be the case. A knowledge of these conditions is essential to the proper design of a drainage system. Table I shows the number of feet of tile required per acre when spaced the given distances apart. To these figures would have to be added whatever mains are necessary to afford an outlet. 13 TABLE I Tile Required to Drain AN Acre of Land Spacing, feet Tile required per acre, feet Spacing, feet Tile required per acre, feet 30 1452 150 291 40 1089 200 218 50 872 300 146 75 581 400 109 100 436 Size of Tile: The proper size of tile to use is one of those details for which it is difficult to give definite directions because of the many influencing factors. Farmers' Bulletin No. 187, U. S. Department of Agricul- ture, gives the following summary of the conditions which determine the size of drains, particularly the mains. The relation of spacing to depth. (1) What depth of water per acre will it be necessary to remove from the land in a given time, say twenty-four hours, in order to secure the desired con- dition of the soil? (2) How rapidly will the water be brought to the main drains? (3) What surface drainage does the tract have that will be available for carrying unusual rains? (4) What is the nature of the soil as regards its drainage properties, that is, is it open or retentive? (5) What are the grades upon which the tile must be laid? The amount of rainfall over the state varies, as previously stated, from more than fifty inches to less than ten inches. Drainage, how- ever, has to deal with the extremes of rainfall rather than with the yearly totals. Rather heavy rains during certain parts of the year will cause very little run-off as the water is nearly all absorbed by the soil. On the other hand, a rather moderate rainfall following a period of wet weather, during which the soil has become saturated, 14 . may almost entirely run off. Under extreme conditions, in which the collecting or lateral system of drains is adequate and the soil open, mains may well be designed to carry a run-off of one inch in depth from the tract in twenty-four hours. Under ordinary conditions, mains capable of carrying in twenty-four hours a run-off of one-half inch in depth of water from the entire tract will be found adequate. DISCHARGE CURVES for Drain Tile Based Dn Kutter's Formula('n\015) • i S l ! | i ■ i ! >^ 1-600 -50C -49 -40' -35C - 30C -250 -200 -J 50 - 300 -350 -200 -180 - 160 - 140 -120 -100 - 90 ■ BO - 70 - 60 - 50 - 45 - 40 - 3< ■ 3C 25 - 2C - 15 10 - 5 \^ ^ A ^^ -50C -45C -400 -350 -300 -250 " .^ a i : i j^fj i ! ^ ^y^ , >- _AA^ • f\ Af L* <\ I ^ 1 1 ^r ' a 1 ^ -180 -200- 160 - |80 rl40 -I60| (- 120 -140] - 120^ l0 ° ^ ^ !>*/ s> L."'' &* ^T ■ IOC - 90 - 80 - 70 - 60 - SO - 45 - 40 - 35 - 30 - 25 - 20 - 15 - 10 - 5 - 90 - P0 - 70 - 6U - 50 - 45 ■ 40 - 35 - 30 - 25 - 20 - IS - 10 - 5 ^ i Jr *S\ s' ^ \k^ ^ j i ':• 1 ^ s ^ s fc v ^ ^ U . ■ j (S ^ k s*~ 1 I ^^ \y- 0. X ^-"""J S 5> ' ^ \ ^^ $* 3 5 y §> C -c <3 At ' \ % % £ RJ R'f Rl « ACRES DRAINED ■Slope m Feet per /OO Feet Fig. 8.— Curves showing capacities of drain tile at various slopes, and acres drained at different rates of run-off. 15 When computing run-off, the area contributing water to the badly- drained tract should be considered rather than the area actually to be drained. 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 1500 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. From the diagram in figure 8 the carrying capacities of tile on different grades can be determined. The diagram also shows the number of acres drained at different rates of run-off. Where a complete system is installed 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. 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 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. KINDS OF TILE Two kinds of drain tile are available in the market, clay and cement. Clay drain tile are made in sizes varying from four inches to twenty-four or thirty inches in diameter. The usual practice is to increase the diameter for each succeeding size by two inches up to 16 a diameter of sixteen inches, and by four inches thereafter. Some factories, however, make tile five, seven, and fifteen inches in diameter. Clay tile up to and including twelve inches in diameter are usually made in one-foot lengths, and in two-foot lengths for the larger sizes. The tile should be straight, well-burned, and free from cracks or other defects. The use of so-called "soft" or "porous" tile should be discouraged. From a practical standpoint tile are not porous, and a "soft" clay tile is merely the result of under-burning and should be looked upon as defective. It is sufficient to say, in this connection, that water enters a tile line through the spaces between the individual tile and not by passing through the walls of the tile themselves. It is not essential that tile be vitrified or "salt-glazed," although a vitrified condition is by no means undesirable. Salt- glazed, fully-vitrified sewer pipe is frequently used instead of the regular drain tile; in this case, however, the joints are left un- cemented. The use of sewer pipe is objectionable only in that it usually requires a little more time in laying, and the extra weight caused by the unnecessary "bell" adds somewhat to the freight costs. The cost of first-grade sewer pipe is usually prohibitive so far as drainage. work is concerned, but "seconds" can often be purchased at prices comparable to those of drain tile. Sewer seconds should be rather closely inspected before being used, and inferior tile discarded. Cement tile may still be considered to be in the experimental stage. Satisfactory cement tile under twelve inches in diameter can not be made as cheaply as can clay tile, but over that size the cost of the former is somewhat less. One part of Portland cement and two or three parts of clean sand, properly mixed and cured, make a satis- factory product. Cement tile made of the same constituents will vary considerably if made by different persons. The average tile user is better able to judge the quality of clay tile than he is of cement tile as they are found in the yard or at the local dealers. Home-made cement tile are usually of inferior quality unless experienced work- men are employed. CONSTRUCTION OF TILE DRAINS Laying out the Drain: When laying out a drain, stakes one foot or more in length should be placed by the engineer at intervals of fifty or one hundred feet along the line and plainly marked with a station number indicating the distance from the outlet or beginning of that particular drain. Thus, stakes marked 1 + 00, 1 + 25, or 2 -f- 50, indicate that there are respectively 100, 125, or 250 feet of drain up to these points. 17 Close to each of these stakes the engineer should drive another, the top of which is flush with the ground surface, on which he takes his levels. It is from this latter stake, generally called the ' ' grade stake, ' ' that he measures the ' ' cut ' ' or depth at that point. The grade stakes are so placed as to be reasonably safe and must not be disturbed by the digger. The depth of the trench at this point is either marked Fig. 9. — Trench kept straight by means of cord. on the guard stake or furnished the workmen, the latter method being preferable as the guard stakes are liable to be broken down and lost. Before commencing the excavation, the workmen should stretch a line about six inches to one side of the line of stakes as shown in figure 9; digging to this line will insure a clean, straight cut. Ditching Tools and Machinery: Although there are several hand implements for constructing tile drains, such as the short-handled tile spade and tile fork, grading 18 scoops of various sizes, and tile hooks, the only tools in common use in California are the pick and long-handled shovel. Figure 10 shows several tools which will probably become more common in California as drainage work develops. The grading scoop especially should be more generally used. There are several types of machinery for use in excavating trenches for tile drains. These vary from the plow which costs less than $20 and is suitable for loosening the surface foot of the trench, to the power-driven trenching machine, costing from $1500 to $6000, that will excavate a trench into which the tile can be placed without further Fig. 10. — Tools used in constructing tile drains. work. Figure 11 shows an excavator at work digging a trench for tile drains. The purchase of an expensive, power-driven machine is not advisable unless there are ten or fifteen miles of tile to be laid, or unless the machine can be rented to others who contemplate tile drain- age. A good trenching machine must be able to operate in any soil that is free from rock; it must be capable of cutting true to grade, and it must be strongly and simply constructed. It is often possible to borrow trenching machinery that is temporarily idle, from a town where it has been used in sewer construction. One of the principal advantages of excavating with machinery is in having the work done quickly. Under favorable conditions it is not unusual for a trencher to dig one-quarter to one-half mile of four-foot trench per day. In 19 determining the cost of trenching by machinery, the items of oper- ation, repairs, and depreciation should all be included. Digging to Grade: Digging to true grade is the important operation in excavating for a drain. Several methods are in use by which the bottom can be graded from the grade stakes set by the engineer. If the workmen are not familiar with one of these, the engineer should instruct them. A very simple method, and one which gives the true grade at all points along the line, is to stretch a light, stout cord on cross-bars directly over the trench, and say 5% feet above the proposed bottom. By measuring from this cord with a 5!/2-foot pole, the grade of the Fig. 11. — Drainage excavator digging trench for tile drain. bottom at any point is easily determined. The line is placed just high enough to make the "cut" below the grade stake, plus the dis- tance of the line above the grade stake, equal to 5% feet. Thus, if the cut at station 5 -f- 00 is given as 4.0 feet, and that at station 6 4- 00 is given as 3.5 feet, the cross-bar must be 1.5 feet above the grade stake at station 5 + 00, and 2.0 feet above the grade stake at station 6 + 00. In placing the cross-bar which supports the cord, one stake supporting the cross-bar is driven down alongside the grade stake until the cross-bar is the required distance above the stake ; then another stake is driven on the opposite side of the trench until a car- penter's level shows the cross-bar to be level. If the grade stakes are 100 feet apart it is well to support the cord at one or more points between so that there shall be no sag. This can be done quite accu- 20 rately by sighting along the cord. A measuring pole of other length than 5% feet may be used, but the height of the cord above the grade stakes must then be changed accordingly. Figure 12 shows the method of securing the correct grade by means of an overhead cord. The cord should be retightened frequently as changes in temperature and moisture conditions cause it to sag, and it should always be re- tightened after having remained on the cross-bars over night. Fig. 12. — Grading the trench by means of overhead cord. Engineers usually furnish figures showing cuts and other meas- urements in feet and decimals of a foot, and not in inches. Workmen unfamiliar with this method of measuring should be furnished with measuring rods properly graduated; or, if this for any reason is not feasible, the engineer should change his figures to the form better understood by the layman. Table II gives the decimals of a foot converted to inches. 21 TABLE II Decimals of a Foot to Inches Ft. In. Ft. In. Ft. In. Ft. In. Ft. In. .20 = 23/ 8 .40 = 4% .60 = 7% .80= 9% .01= % .21 = 2% .41 = 4% .61 = 7% .81= 9% .02= % .22 = 2% .42 = 5 .62=7% .82= 9% .03= % .23 = 2% .43 = 5% .63 = 7% .83 = 10 .04= % .24 = 2% .44 = 5% .64 = 7% .84 = 10% .05= % .25 = 3 .45 = 5% .65 = 7% .85 = 10% .06= % .26 = 3% .46 = 51/2 .66 = 7% .86 = 10% .07= % .27 = 3% .47 = 5% .67 = 8 .87 = 10% .08 = 1 .28 = 3% .48 = 5% .68 = 8% .88 = 10% .09 = 1% .29 = 3% .49 = 5% .69 = 8% .89 = 10% .10 = 1% .30 = 3% .50 = 6 .70 = 8% .90 = 10% .11 = 1% .31 = 3% .51 = 6% .71 = 8% .91 = 10% .12 = 1% .32 = 3% .52 = 6% .72 = 8% .92 = 11 .13 = 1% .33 = 4 .53 = 6% .73 = 8% .93 = 11% .14 = 1% .34 = 4% .54 = 6% .74 = 8% .94 = 11% .15 = 1% .35 = 4% .55 = 6% .75 = 9 .95 = 11% .16 = 1% .36 = 4% .56 = 6% .76 = 9% .96 = 11% .17 = 2 .37 = 4% .57 = 6% .77 = 9% .97 = 11% .18 = 2% .38 = 4% .58 = 7 .78 = 9% .98 = 11% .19 = 2% .39 = 4% .59 = 7% .79 = 9% .99 = 11% Laying Tile: The digging of the trench and the laying of the tile should always begin at the outlet and proceed toward the upper end. Figure 13 shows the tile so distributed in the field that it can be laid with the least handling. It is generally best to lay the tile as soon as the trench is ready in order to avoid possible damage to the trench by rains, caving banks, etc. If the bottom of the trench is known to be true to grade at every point, the smaller sizes of tile can be laid from the bank with a tile hook (see fig. 10) ; otherwise they are laid by a man who stands in the trench and places each tile after having made the bottom true to grade with a grading scoop or shovel. The tiles are laid end to end as closely as they will lie in the trench. Tiles will often be found whose ends are not square, but by turning them slightly they can be made to fit quite closely. Figure 14 shows how tiles with such ends can sometimes be matched so as to make a good joint. A tile with a small chip broken from the end but which is otherwise sound can be used by placing the broken side down or by carefully covering the break with a piece of broken tile or a flat stone. A tile that is cracked more than one-quarter of its length, or is broken on the end so that the break can not be properly covered, should be discarded. It should be remembered that a tile which fails after 22 being placed in the ground will completely destroy the usefulness of the entire line above it; it is obviously poor economy to endanger the efficiency of an entire line in order to save a joint of tile. Just as soon as a tile is in its proper place, a little earth should be cut from the side of the trench and placed about the tile so as to pre- vent it from rolling out of line. After 50 or 100 feet of tile are laid, and at the end of each clay's work, the tile laid should be covered SE^S^ailfr r~ \ - ■.•■.;':3il^OT Fig. 13. — Trench ready and tile properly distributed. with earth to a depth of three or four inches so as to prevent possible dislocation or injury to the tile from stones or chunks of earth which might fall upon them. There need be no fear ordinarily that the tile will be laid so close together that the water can not enter. The former practice of covering the joints with straw or gravel to prevent the entrance of soil is now largely abandoned as being unnecessary and expensive. Well-laid tiles will be close enough together to prevent the entrance of any foreign matter and will yet admit water freely. The 23 use of rock or gravel in covering a tile line is not objectionable, but the use of brush or sticks should be discouraged. Backfilling : If the tile are to be inspected by the engineer such inspection should be done just before it is 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 backfilling 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 scrapers or four-horse "fresnos" are sometimes used, in which case the team works on the opposite side of the trench from the scraper. All of the earth excavated from the trench should be replaced; otherwise there will be a depression along the line when the soil settles. Fig. 14. — Tiles whose ends are not square may be rotated to make a good joint. 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. Redwood lumber is relatively durable for underground work and in California should be used in preference to pine or fir. It is reasonable to expect boxes to last for ten or twelve years ; if kept wet during the entire year they will last much longer. A simple form of box is shown in figure 15a. The lumber for the smaller boxes should run lengthwise, and where conditions will permit the sections may be from twelve to sixteen feet long. 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 where the interior dimensions are greater than eight inches square, two-inch lumber should be used and the top and bottom put on cross- 24 wise as shown in figure 15&. In large boxes for main drain, the lum- ber for the top, bottom, and sides should all run crosswise (figure 15c). The bottom pieces should be separated so that when the lumber becomes wet it will not swell and 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. Further- more, the roughness of the ground reduces the capacity of the drain. b c X s s s Fig. 15. — Types of lumber box drains. SUKFACE INLETS, SILT BOXES, AND OUTLETS 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. Figures 16 and 17 show two methods of screening surface water before it enters a tile line. If there is a considerable quantity of water the stone filter, illustrated in figure 16, should extend over a greater length of tile than shown. The types of screen Fig. 16. — Buried stone filter for admitting surface water to a tile line. shown in figure 17 admit water more readily to the tile line, but when located in open fields are somewhat of 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 may be made of lumber, concrete, or brick. A very satisfactory lumber silt-box which combines also manhole and observation well is shown in figure 18. It is inadvisable to construct silt boxes so small that tliey can not be readily entered and cleaned. They should be 25 placed at points where the grade changes to a flatter one, or where there are abrupt changes in direction of the line. The junction of two lines is easily effected through such a box although in a "regular*' 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 concrete, the design depending upon the conditions which exist at the outlet. In any case care Fig:. 17. — Surface inlets with screens. should be taken to secure a good foundation and anchorage so that the structure will not be undermined. Figure 19 shows an outlet protec- tion for small tile, and figure 20 illustrates one suitable for larger tile. Whatever construction material is used in making silt wells may also be used for outlet protections. MAINTENANCE OF TILE DKAINS Tile drains which are properly laid will require very little main- tenance. 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 at all times ; if necessary they should be locked so that they can not be opened by inquisitive persons. Tumble weeds, rabbits, and squirrels may enter the silt boxes and obstruct the tile lines unless this precaution is observed. 26 Soil will not seal the joints and prevent the entrance of water into the tile lines unless very unusual conditions prevail. There need be no 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 would exist when the drain taps a spring which flows long after the surrounding area has become dry. Cottonwood and willow trees Bo/f^ ■2'*6*3"-3'- .^ 2"' 6" Fig. 18. — Combination manhole and silt box with cover, should not be allowed to grow within fifty feet of a tile line as there is more danger from these water-loving trees than from fruit trees. 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 when necessary. These may also be found 27 useful during construction, especially if the tile is laid in a wet, muddy trench. 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 Fig. 20. — Stone or brick outlet protection. 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. Figure 21 shows a cleaning device of this type. Care must be exercised not to use anything that may become detached or which will catch on the tile. Two hundred and fifty feet or more of rod can be operated in a straight tile line. 28 COST OF TILE DRAINAGE The ultimate question with regard to drainage work is, will it pay? In order to determine this one must know what it will cost. From what has been said regarding the varying sizes of tile, spacing and depth of drains, and the various structures required, it is evident that definite statements on the question of cost can be made only when the complete details for a particular project are at hand. Tile are sold by the foot, with discounts from the list price on orders of 1000 feet or more, and further discounts for carload lots. Prices for tile are much higher in California and the other western states than in the east or middle west. There are probably less than a half-dozen factories on the Pacific Coast which manufacture clay drain-tile exclusively, most factories making drain-tile to order or as Fig. 21. — Sewer rods and tile cleaning devices. a side line in the manufacture of other clay products. Table III con- tains quotations and weights per foot as furnished by one of the California factories which makes drain tile exclusively. TABLE III Costs and Weights of Clay Drain Tile ize in. Cost per 1000 ft.* Weight lbs. per ft. Size in. Cost per 1000 ft.* Weight per ft lbs. 4 $40 8 10 $110 27 5 50 10 12 160 40 6 60 14 14 200 44 8 80 21 16 250 55 * F.o.b. factory in carload lots, minimum car 26,000 lbs.; 10 per cent discount for cash. Factories which make drain tile to order or as a side-line quote higher prices, while at least one factory making drain tile exclusively quotes lower prices than those given. To the final cost of tile must 29 be added the freight charges and the cost of hauling from the railroad to the field. The excavation by hand of trenches for drain tile will cost from 5 to 10 cents per linear foot for depths of three to five feet. The cost varies somewhat with the season, the soil, and the amount of labor available. Labor can usually be secured for this kind of work for 25 cents per hour. Laying and blinding will cost from one-quarter to one-half cents per lineal foot, and backfilling from one to two cents per linear foot. The total cost of installing four-inch tile drains at a depth of 3y 2 feet, when all the work is done by hand, may vary from 11 to 18 cents per linear foot. The use of six- and eight-inch tile does not materially increase the cost of excavation, laying, and backfilling. Machine-dug trenches should lower the cost of excavation to from one and one-half to four cents per linear foot, while experienced labor and the use of improved tiling tools may eventually make excavation by hand cheaper than the prices given above. These statements regarding the cost of tile drainage should be used only as a general guide in making estimates. Short drains which follow the natural system may often be installed by the farmer without a great deal of expense beyond the cost of the tile and that of the labor which he usually hires. Extensive systems are generally installed by contractors who are equipped for and familiar with handling this kind of work. Contractors can usually continue work without interruption, whereas the farmer may find it necessary to temporarily discontinue the work at a critical point because of his other farm duties. 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. Whether or not drainage can be accomplished in this way depends entirely upon local conditions and this method is by no means generally applicable. Ideal conditions for vertical drainage would be presented by a surface soil which is kept wet by the accumulation of water above an impervious layer of clay or hardpan, beneath which is a layer of sand or gravel, the latter containing no water or permitting the water to escape readily. Conditions as these are very infrequent; on the contrary, the subsoil is more often filled with water which does not flow away. It would be useless to attempt vertical drainage where 30 there is no porous layer below, even though the subsoil were dry, as the capacity of the latter for water would be very limited and the drain would soon become inoperative. It would also be useless to attempt vertical drainage where the ground water is within a few feet of the surface during the time when surface drainage is most necessary. Vertical drainage, where practicable, may be accomplished by boring an eight- or ten-inch hole well into the porous stratum and lining this hole with ordinary drain tiles set one on top of another. The top must be securely covered and screened so as to prevent the entrance of silt or trash into the drain. Another method of accom- plishing vertical drainage is to break up the impervious stratum with dynamite. This method is more applicable where the impervious layer is hardpan than where it is clay. The clay would have a tendency to soon puddle back into an impervious layer, and instead of breaking and shattering would pack and burn at the point of the explosion. 3 Every instance of contemplated vertical drainage should be thor- oughly examined, as more often than otherwise subsoil conditions will 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 co-operating to some extent with other landowners. Most frequently when co-operation is necessary it is in securing an outlet. The right to drain one's land should not be abridged by the prejudices of his neighbor, especially when there would be no injury to the neighbor; but the rights of those owning lower land which must be crossed by the drains of another must not be ignored, and if any injury whatever is sustained it should be paid for. As a matter of fact, it more frequently occurs that a drain benefits the lower land by crossing it, and some arrangement should therefore be made whereby the cost of such a drain is borne by both parties. So many questions are involved in such circumstances that it is impossible to arrive at any conclusions without a knowledge of all of the facts pertaining to the individual case. These matters, however, should be amicably settled before work is begun. It is frequently desirable for three or four farms to join in one system of drains having a single outlet. Such a system may be in- stalled as if the entire tract belonged to one man, and can be con- 3 Bulletin 209, Kansas State Agricultural College. 31 structed without reference to line fences. Agreements for co-operation may be either oral or written; in either case thorough co-operation is desirable. The cost of the completed system should be apportioned with respect to the relative acreage drained on the individual farms, rather than with regard to the costs of the drains on the different farms. C, whose farm lies higher than those of his neighbors, should help pay for the increased size of the outlet drain through A and B made necessary by C 's drainage, while A and B are both benefited by the drainage of the tracts above them. The adjustment of the cost of cooperative drainage is a delicate matter and the difficulties increase with the number of co-operative parties. Nevertheless, co-operative drainage should be encouraged as it usually results in more thorough and cheaper drainage for all con- cerned than would otherwise be possible. STATION PUBLICATIONS AVAILABLE FOR FREE DISTRIBUTION REPORTS 1897. Resistant Vines, their Selection, Adaptation, and Grafting. Appendix to Viticultural Report for 1896. 1902. Report of the Agricultural Experiment Station for 1898-1901. 1903. Report of the Agricultural Experiment Station for 1901-03. 1904. Twenty-second Report of the Agricultural Experiment Station for 1903-04. 1914. Report of the College of Agriculture and the Agricultural Experiment Station, July, 1913-June, 1914. 1915. Report of the College of Agriculture and the Agricultural Experiment Station, July, 1914-June, 1915. 1916. Report of the College of Agriculture and the Agricultural Experiment Station, July, 1915-June, 1916. BULLETINS No. 230. 241. 242. 244. 246. 248. 249. 250. 251. 252. 253. 255. 257. 261. 262. 263. 264. 265. 266. No. 108. 113. 114. 115. 117. 118. 121. 124. 126. 127. 128. 129. 130. 131. 132. 133. 134. 135. 136. 137. 138. 139. 140. 141 142 143 144 145 Enological Investigations. Vine Pruning in California, Part I. Humus in California Soils. Utilization of Waste Oranges. Vine Pruning in California, Part II. The Economic Value of Pacific Coast Kelps. Stock-Poisoning Plants of California. The Loquat. Utilization of the Nitrogen and Organic Matter in Septic and Imhoff Tank Sludges. Deterioration of Lumber. Irrigation and Soil Conditions in the Sierra Nevada Foothills, California. The Citricola Scale. New Dosage Tables. Melaxuma of the Walnut, "Juglans regia." Citrus Diseases of Florida and Cuba Compared with Those of California. Size Grade for Ripe Olives. The Calibration of the Leakage Meter. Cottonv Rot of Lemons in California. A Spotting of Citrus Fruits Due to the Action of Oil Liberated from the Rind. No. 267. Experiments with Stocks for Citrus. 268. Growing and Grafting Olive Seedlings. 270. A Comparison of Annual Cropping, Bi- ennial Cropping, and Green Manures on the Yield of Wheat. 271. Feeding Dairy Calves in California. 272. Commercial Fertilizers. 273. Preliminary Report on Kearney Vine- yard Experimental Drain. 274. The Common Honey Bee as an Agent in Prune Pollination. 275. The Cultivation of Belladonna in Cali- fornia. 276. The Pomegranate. 277. Sudan Grass. 278. Grain Sorghums. 279. Irrigation of Rice in California. 280. Irrigation of Alfalfa in the Sacramento Valley. 281. Control of the Pocket Gophers in Cali- fornia. 282. Trials with California Silage Crops for Dairy Cows. 283. The Olive Insects of California. 284. Irrigation of Alfalfa in Imperial Valley. 285. The Milch Goat in California. Grape Juice. Correspondence Courses in Agriculture. Increasing the Dutv of Water. Grafting Vinifera Vineyards. The Selection and Cost of a Small Pumping Plant. The County Farm Bureau. Some Things the Prospective Settler Should Know. Alfalfa Silage for Fattening Steers. Spraying for the Grape Leaf Hopper. House Fumigation. Insecticide Formulas. The Control of Citrus Insects. Cabbage Growing in California. Spraying for Control of Walnut Aphis. When to Vaccinate against Hog Cholera. County Farm Adviser. Control of Raisin Insects. Official Tests of Dairy Cows. Melilotns Indica. Wood Decay in Orchard Trees. The Silo in California Agriculture. The Generation of Hvdrocvanic Acid Gas in Fumigation by Portable Ma- chines. The Practical Application of Improved Methods of Fermentation in Califor- nia Wineries during 1913 and 1914. Standard Insecticides and Fungicides vorsns Secrpf Preparations. Practical and Inexpensive Poultry Ap- pliances. Control of Grasshoppers in Imperial Valley: Oidium or Powderv Mildew of the Vine. SucerestionH to Poultrvmen concerning Chicken Pox. CIRCULARS No. 146. Jellies and Marmalades from Citrus Fruits. 147. Tomato Growing in California. 148. "Lungworms." 150. Round Worms in Poultry. 151. Feeding and Management of Hogs. 152. Some Observations on the Bulk Hand- ling of Grain in California. 153. Announcement of the California State Dairy Cow Competition, 1916—18. 154. Irrigation Practice in Growing Small Fruits in California. 155. Bovine Tuberculosis. 156. How to Operate an Incubator. 157. Control of the Pear Scab. 158. Home and Farm Canning. 159. Agriculture in the Imperial Valley. 160. Lettuce Growing in California. 161. Potatoes in California. 162. White Diarrhoea and Coccidiosis of Chicks. 163. Fundamentals Affecting the Food Sup- ply of the United States. 164. Small Fruit Culture in California. 165. Fundamentals of Sugar Beet under California Conditions. 166. The County Farm Bureau. 167. Feeding Stuffs of Minor Importance. 168. Spraying for the Control of Wild Morn- ine-Glorv within the Fog Belt. 169. 1918 Grain Crop. 170. Fertilizing California Soils for the 1918 Crop. 171. The Fertilization of Citrus. 172. Wheat Culture. 173. The Construction of the Wood-Hoop Silo. 174. Farm Drainage Methods.