Drainage channel

“ In a wet swamp a brush drain endures much longer than in sandy land, which is dry a part of the year, because the brush decays in dry land, but will prove nearly imperishable in land constantly wet. In a peat or muck swamp, we should expect that such drains, if carefully constructed, might last twenty years, but that in a sandy loam they would be quite unreliable for a single year.
Our failure on upland with brush drains, has resulted, not from the decay of the wood, but from the entrance of sand, which obstructed the channel. ”

“ Every effort should be directed to make the drainage of the same degree throughout the area; it is therefore necessary to know whether the water can be discharged into a channel or adjacent river, or if the bottom of the drains will be above the general water-discharge level of the district so as to prevent the ground being in the condition of a sponge always full of water and becoming a floating mass. ”

“ It is composed of three concentric arches, forming a channel of fourteen feet in diameter, and proportional height. This was the main trunk, into which was discharged the drainage flowing through a multitude of subterranean channels, together with the vast surplus quantity of water from the aqueducts used to cleanse the net-work of drains. A cart loaded with hay could be driven down the main passages, and Agrippa is said to have performed a sanitary voyage in a boat through the main sewers, when superintending their repair. ”

“ A consideration, too, of the varying inclinations of surface, of which instances will frequently occur in the same field, necessitates a departure from uniformity, not in direction only, but in intervals between drains. Take, for instance, the ordinary case of a field, in which a comparatively flat space will intervene between quickly rising ground and the outfall ditch. It is clear that the soak of the hill will pervade the soil of the lower ground, let the system of drainage adopted be what it may ”

“ Whether, in a particular case, a header alone will be sufficient to cut off the flow of water from the higher land, or whether, in addition to the header, an open catch-water may be required, must depend upon the quantity of water likely to flow through or upon the land. An under-drain might be expected to absorb any moderate quantity of what may be termed drainage-water, but it cannot stop a river or mill-stream; and if the earth above the tiles be compact, even water flowing through the soil with rapidity, might pass across it. ”

“ The whole area of land which naturally discharges toward the drain is not always taken into account. It is generally thought that land lying at some distance from the drain, though sloping toward it, does not affect the capacity required for the drain, whereas in times of heavy rains, when drains are taxed to their utmost, water flows from those more distant parts over the surface to the ground acted upon by the tile drain. We must then provide for the drainage not only of land contiguous to the drains but for an additional amount of water coming from adjoining slopes. ”

“ This has thus far, been our own poor and unsatisfactory mode of protecting our drains. It is only better than none, but it is not permanent, and we hope to see some successful invention that may supply this want. So far as we have observed, no such precaution is used in this country; and in England, farmers and others who take charge of their own drainage works, often run their pipes into the mud in an open ditch, and trust the water to force its own passage. ”

“ Remembering that on the map, the line of steepest descent is exactly perpendicular to the contour lines of the land, it will be profitable to study carefully the system of drains first laid out, erasing and making alterations wherever it is found possible to simplify the arrangement.
Strictly speaking, all angles are, to a certain extent, wasteful, because, if two parallel drains will suffice to drain the land between them, no better drainage will be effected by a third drain running across that land. ”

“ The outlet is the place, of all others, where obstruction is most likely to occur. Everywhere else the work is protected by the earth above it, but here it is exposed to the action of frost, to cattle, to mischievous boys, to reptiles, as well as to the obstructing deposits which are discharged from the drains themselves. In regular work, under the direction [177] of engineers, iron pipes, with swing gratings set in masonry, are used, to protect permanently this important part of the system of drainage. ”

“ We cannot, however, against the overwhelming weight of authority, and against the reasons for deeper drainage, which, to us, seem so satisfactory, conclude, that even three feet is, in general, deep enough for under-drains. Three-foot drains will produce striking results on almost any wet lands, but four-foot drains will be more secure and durable, will give wider feeding-grounds to the roots, better filter the percolating water, warm and dry the land earlier in Spring, furnish a larger reservoir for heavy rains, and, indeed, more effectually perform every office of drains. ”

“ If we have only to take care of the water that falls on our own field, from the clouds, that is quite a different matter from draining the whole adjoining region, and requires a different mode of operation. If your field is in the middle, or at the foot, of an undrained slope, from which the water runs on the surface over your land, or soaks through it toward some stream or swamp below, provision must be made not only for drainage of your own field, but also for partial drainage of your neighbor's above, or at least for defence against his surplus of water. ”

“ By some it was urged that drainage is necessary to lessen the chance of the earthwork slipping. Others contended that any drain which penetrates the dam must facilitate the percolation of water from the reservoir. It is clear that some of the speakers regarded the dam downstream of the core-wall as being partly staunch, and some as being wholly support. If for any reason there seems a chance of water leaking through the core-wall, it is desirable to regard the earth-filling next to it as staunch. ”

“ The foregoing relates only to the main outlets for town sewage. The arterial drainage, (the lateral drains of the system,) which receives the waste of the houses and the wash of the streets, is entirely dependent on the outlet sewers, and can be effective only when these are so constructed as to afford a free outfall for the matters that it delivers to them. In many towns, owing to high situation, or to a rapid inclination of surface, the outfall is naturally so good as to require but little attention. ”

“ The better the fall the quicker the drain will act and the more permanent it will be, as it will tend to clean itself and not fill up with silt. It is important that the outlet be entirely free, and it should be protected with stones or mason work. The roots of some trees, particularly of willows and elms, are attracted by tile drains, and often fill up the pipes. When the drain goes near such trees, therefore, it is well to cement the joints. In general practice, however, the joints should not be cemented, because a large part of the drainage water enters at those places. ”

“ Wherever one stream flows into another, there must be more or less interruption of the course of each. If the water from the minors enters the main with a quick fall, the danger of obstruction in the minor, at least, is much lessened. A frequent cause of partial failure of drains, is their not having been laid with a regular inclination. If, instead of a gradual and uniform fall, there should be a slight rising in the bed of a drain, the descending water will be interrupted there till it accumulate so high as to be above the level of the rising. ”

“ If steam enters a soil-pipe, it heats the water in the traps, injures joints on account of the extreme changes of temperature induced, and hastens corrosion of the pipes.
Fig. 25 shows a system of house-drainage for a city house planned in accordance with the above rules.
Fig. 26.—Field’s flush-tank.
In country houses, where there are no sewers, the best method of disposing of the house-slops is subsoil drainage. The house system may be the same as that already explained for city houses. The fluids are conducted by a pipe with tight joints to a flush-tank (Fig. 26) near the house. ”

“ Men unaccustomed to minute investigation, are slow to appreciate the great effects produced by apparently small causes; and it may seem to many, that the operations of drainage for agriculture, are too insignificant in their details, perceptibly to affect the flow of mill-streams and rivers. A moment's thought will convince the most skeptical, that the thorough-drainage of the wet lands, even of a New England township, must produce sensible effects upon the streams which convey its surplus water toward the sea. ”

“ It may be pointed out here that these expressions are defined by the act, the effect of the definitions being shortly that a drain is a conduit for the drainage of one building or of several within the same curtilage, while a sewer comprises every kind of drain except that which is covered by the definition of a drain as above stated. The result has been that district councils frequently find themselves in the position of being responsible for the repair and condition of drains which, by reason of having been laid for more than one house, are sewers vested in and repairable by them. ”

“ Both here and in England, much of the land requires no under-draining, as it has already a subsoil porous enough to allow free passage for all the surplus water; and it is no small part of the utility of understanding the principles of drainage, that it will enable farmers to discriminate—at a time when draining is somewhat of a fashionable operation with amateurs—between land that does and land that does not require so expensive an operation. ”

“ He states, that there are large tracts of land having clay soil, with sand or gravel beneath the clay, which yet need drainage, and suggests that this may be effected by merely boring frequent holes, and filling them with pebbles, without ditches. In all such soils, if the mode suggested prove insufficient, large wells of proper depth, stoned up, or otherwise protected, might obviously serve as cheap and convenient outlets for a regular system of pipe or stone drains. ”

“ While we would not lay down an arbitrary arrangement for any farm, except upon a particular examination, and while we would by no means advocate what has been called the gridiron system—of drains everywhere at equal depths and distances—yet some system is absolutely essential, in any operation that approaches to thorough drainage. ”

“ Very long main drains are to be avoided. Numerous outlets are also objectionable, from their liability to obstruction. An outlet to an area of from 10 to 15 acres is a good arrangement. These outlets should be faced with mason work, and guarded with iron gratings.
The distance and depth apart of the parallel drains is determined chiefly by reference to the texture of the soil. In an impervious clay the flow of the water is much impeded and the water-table can be controlled only by frequent lines of pipes. On such land it is customary to lay them about 3 ft. ”

“ Water goes down, then, by its own weight, unless there is something through which it cannot readily pass, to bring it out at the surface. It will go into the drains, only because they are lower than the land drained. It will never go upward to find a drain, and it will go toward a drain the more readily, in proportion as the descent is more steep toward it. ”

“ Shedd and Edson, of Boston, whose experience as draining engineers entitles them to a high rank among American authorities, have been in constant communication with us, throughout our labors. The chapter upon Evaporation, Rain fall, &c., which we deem of great value as a contribution to science in general, will be seen to be in part credited to them, as are also the tables showing the discharge of water through pipes of various capacity.
Drainage is a new subject in America, not well understood, [22] and we have no man, it is believed, peculiarly fitted to teach its theory and practice ”

“ Very often, drains are filled up and ruined by these deposits; and, unless the fall be considerable, and the drain be laid with even descent, if earth of any kind find entrance, it must endanger the permanency of the work. To guard against the admission of everything but water, lay drains deep enough to be beyond the danger of water bursting in, in streamlets. Water should enter the drain at the bottom, by rising to the level of the tiles, and not by sinking from the surface directly to them. If the land is sandy, great care must be used. ”

“ It has been found by actual trial that it is not necessary to increase the size of the pipe sewer in exact proportion to the amount of drainage that it has to convey, as each addition to the flow, where drainage is admitted from street openings or from houses, accelerates the velocity of the current, pipes discharging even eight times as much when received at intervals along the line as they would take from a full head at the upper end of the sewer. ”

“ In the same season, the same men opened, laid, and filled 70 rods of four-foot drain, of the same mean width of 12 inches, in the worst kind of clay soil, where the pick was constantly used. It cost 35 days' labor to complete the job, being 50 cents per rod for the labor alone. The least cost of the labor of draining 4 feet deep, on our [218] own land, is thus shown to be 21 cents per rod, and the greatest cost 50 cents per rod, all the labor being by hand. One-half these amounts would have completed the drains at 3 feet depth, as has been already shown. ”