Draining for Profit, and Draining for Health Part 10

Fig. 30 - POSITION OF WORKMAN AND USE OF FINISHING SCOOP.

Three persons are required to finish the bottom of the ditch; one to sight across the tops of the boning-rods, one to hold the plumb-rod at different points as the finishing progresses, and one in the ditch, (see Fig. 30,) provided with the finishing spade and scoop,-and, in hard ground, with a pick,-to cut down or fill up as the first man calls "too high," or, "too low." An inch or two of filling maybe beaten sufficiently hard with the back of the scoop, but if several inches should be required, it should be well rammed with the top of a pick, or other suitable instrument, as any subsequent settling would disarrange the fall.

[Ill.u.s.tration: Fig. 31 - SIGHTING BY THE BONING-RODS.]

Fig. 31 - SIGHTING BY THE BONING-RODS.

As the lateral drains are to be laid first, they should be the first graded, and as they are arranged to discharge into the tops of the mains, their water will still flow off, although the main ditches are not yet reduced to their final depth. After the laterals are laid and filled in, the main should be graded, commencing at the upper end; the tiles being laid and covered as fast as the bottom is made ready, so that it may not be disturbed by the water of which the main carries so much more than the laterals.

*Tile-Laying.*-Gisborne says: "It would be scarcely more absurd to set a common blacksmith to eye needles than to employ a common laborer to lay pipes and collars." The work comes under the head of _skilled labor,_ and, while no very great exercise of judgment is required in its performance, the little that is required is imperatively necessary, and the details of the work should be deftly done. The whole previous outlay,-the survey and staking of the field, the purchase of the tiles, the digging and grading of the ditches-has been undertaken that we may make the conduit of earthenware pipes which is now to be laid, and the whole may be rendered useless by a want of care and completeness in the performance of this chief operation. This subject, (in connection with that of finishing the bottoms of the ditches,) is very clearly treated in Mr. Hoskyns' charming essay,(19) as follows:

"It was urged by Mr. Brunel, as a justification for more attention and expense in the laying of the rails of the Great Western, than had been ever thought of upon previously constructed lines, that all the embankments and cuttings, and earthworks and stations, and law and parliamentary expenses-in fact, the whole of the outlay encountered in the formation of a railway, had for its main and ultimate object _a perfectly smooth and level line of rail_; that to turn stingy at this point, just when you had arrived at the great ultimatum of the whole proceedings, viz: the iron wheel-track, was a sort of saving which evinced a want of true preception of the great object of all the labor that had preceded it. It may seem curious to our experiences, in these days, that such a doctrine could ever have needed to be enforced by argument; yet no one will deem it wonderful who has personally witnessed the unaccountable and ever new difficulty of getting proper attention paid to the leveling of the bottom of a drain, and the laying of the tiles in that continuous line, where one single depression or irregularity, by collecting the water at that spot, year after year, tends toward the eventual stoppage of the whole drain, through two distinct causes, the softening of the foundation underneath the sole, or tile f.l.a.n.g.e, and the deposit of soil inside the tile from the water collected at the spot, and standing there after the rest had run off. Every depression, however slight, is constantly doing this mischief in every drain where the fall is but trifling; and if to the two consequences above mentioned, we may add the decomposition of the tile itself by the action of water long stagnant within it, we may deduce that every tile-drain laid with these imperfections in the finishing of the bottom, has a tendency toward obliteration, out of all reasonable proportion with that of a well-burnt tile laid on a perfectly even inclination, which, humanly speaking, may be called a permanent thing. An open ditch cut by the most skillful workman, in the summer, affords the best ill.u.s.tration of this underground mischief. Nothing can look smoother and more even than the bottom, until that uncompromising test of accurate levels, the water, makes its appearance: all on a sudden the whole scene is changed, the eye-accredited level vanishes as if some earthquake had taken place: here, there is a gravelly _scour_, along which the stream rushes in a thousand little angry-looking ripples; there, it hangs and looks as dull and heavy as if it had given up running at all, as a useless waste of energy; in another place, a few dead leaves or sticks, or a morsel of soil broken from the side, dams back the water for a considerable distance, occasioning a deposit of soil along the whole reach, greater in proportion to the quant.i.ty and the muddiness of the water detained. All this shows the paramount importance of perfect evenness in the bed on which the tiles are laid. _The worst laid tile is the measure of the goodness and permanence of the whole drain_, just as the weakest link of a chain is the measure of its strength."

The simple laying of the smaller sizes of pipes and collars in the lateral drains, is an easy matter. It requires care and precision in placing the collar equally under the end of each pipe, (having the joint at the middle of the collar,) in having the ends of the pipes actually touch each other within the collars, and in brushing away any loose dirt which may have fallen on the spot on which the collar is to rest. The connection of the laterals with the mains, the laying of the larger sizes of tiles so as to form a close joint, the wedging of these larger tiles firmly into their places, and the tr.i.m.m.i.n.g which is necessary in going around sharp curves, and in putting in the shorter pieces which are needed to fill out the exact length of the drain, demand more skill and judgment than are often found in the common ditcher. Still, any clever workman, who has a careful habit, may easily be taught all that is necessary; and until he is thoroughly taught,-and not only knows how to do the work well, but, also, understands the importance of doing it well,-the proprietor should carefully watch the laying of every piece.

_Never have tiles laid by the rod, but always by the day._ "The more haste, the less speed," is a maxim which applies especially to tile-laying.

If the proprietor or the engineer does not overlook the laying of each tile as it is done, and probably he will not, he should carefully inspect every piece before it is covered. It is well to walk along the ditches and touch each tile with the end of a light rod, in such a way as to see whether it is firm enough in its position not to be displaced by the earth which will fall upon it in filling the ditches.

Preparatory to laying, the tiles should be placed along one side of the ditch, near enough to be easily reached by a man standing in it. When collars are to be used, one of these should be slipped over one end of each tile. The workman stands in the ditch, with his face toward its upper end. The first tile is laid with a collar on its lower end, and the collar is drawn one-half of its length forward, so as to receive the end of the next tile. The upper end of the first tile is closed with a stone, or a bit of broken tile placed firmly against it. The next tile has its nose placed into the projecting half of the collar of the first one, and its own collar is drawn forward to receive the end of the third, and thus to the end of the drain, the workman walking backward as the work progresses.

By and by, when he comes to connect the lateral with the main, he may find that a short piece of tile is needed to complete the length; this should not be placed next to the tile of the main, where it is raised above the bottom of the ditch, but two or three lengths back, leaving the connection with the main to be made with a tile of full length. If the piece to be inserted is only two or three inches long, it may be omitted, and the s.p.a.ce covered by using a whole 2-inch tile in place of the collar. In turning corners or sharp curves, the end of the tile may be chipped off, so as to be a little thinner on one side, which will allow it to be turned at a greater angle in the collar.

If the drain turns a right angle, it will be better to dig out the bottom of the ditch to a depth of about eight inches, and to set a 6-inch tile on end in the hole, perforating its sides, so as to admit the ends of the pipes at the proper level. This 6-inch tile, (which acts as a small silt-basin,) should stand on a board or on a flat stone, and its top should be covered with a stone or with a couple of bricks. Wood will last almost forever below the level of the drain, where it will always be saturated with water, but in the drier earth above the tile, it is much more liable to decay.

[Ill.u.s.tration: Fig. 32 - PICK FOR DRESSING AND PREFORATING TILE.]

Fig. 32 - PICK FOR DRESSING AND PREFORATING TILE.

The tr.i.m.m.i.n.g and perforating of the tile is done with a "tile-pick," (Fig.

32,) the hatchet end, tolerably sharp, being used for the tr.i.m.m.i.n.g, and the point, for making the holes. This is done by striking lightly around the circ.u.mference of the hole until the center piece falls in, or can be easily knocked in. If the hole is irregular, and does not fit the tile nicely, the open s.p.a.ce should be covered with bits of broken tile, to keep the earth out.

As fast as the laterals are laid and inspected, they should be filled in to the depth of at least a foot, to protect the tiles from being broken by the falling of stones or lumps of earth from the top, and from being displaced by water flowing in the ditch. Two or three feet of the lower end may be left uncovered until the connection with the main is finished.

In the main drains, when the tiles are of the size with which collars are used, the laying is done in the same manner. If it is necessary to use 3-1/2-inch tiles, or any larger size, much more care must be given to the closing of the joints. All tiles, in manufacture, dry more rapidly at the top, which is more exposed to the air, than at the bottom, and they are, therefore, contracted and made shorter at the top. This difference is most apparent in the larger sizes. The large _round_ tiles, which can be laid on any side, can easily be made to form a close joint, and they should be secured in their proper position by stones or lumps of earth, wedged in between them and the sides of the ditch. The sole tiles must lie with the shortest sides up, and, usually, the s.p.a.ce between two tiles, at the top, will be from one-quarter to one-half of an inch. To remedy this defect, and form a joint which may he protected against the entrance of earth, the bottom should he trimmed off, so as to allow the tops to come closer together. Any opening, of less than a quarter of an inch, can he satisfactorily covered,-more than that should not be allowed. In turning corners, or in pa.s.sing around curves, with large tiles, their ends must he beveled off with the pick, so as to fit nicely in this position.

The best covering for the joints of tiles which are laid without collars, is a sc.r.a.p of tin, bent so as to fit their shape,-sc.r.a.ps of leather, or bits of strong wood shavings, answer a very good purpose, though both of these latter require to be held in place by putting a little earth over their ends as soon as laid on the tile. _Very small_ gra.s.s ropes drawn over the joints, (the ends being held down with stones or earth,) form a satisfactory covering, but care should be taken that they be not too thick. A small handful of wood shavings, thrown over the joints, also answers a good purpose. Care, however, should always be taken, in using any material which will decay readily, to have no more than is necessary to keep the earth out, lest, in its decay, it furnish material to be carried into the tile and obstruct the flow. This precaution becomes less necessary in the case of drains which always carry considerable streams of water, but if they are at times sluggish in their flow, too much care cannot be given to keep them free of all possible causes of obstruction.

As nothing is gained by increasing the quant.i.ty of loose covering beyond what is needed to close the joints, and as such covering is only procured with some trouble, there is no reason for its extravagant use.

There seems to remain in the minds of many writers on drainage a glimmering of the old fallacy that underdrains, like open drains, receive their water from above, and it is too commonly recommended that porous substances be placed above the tile. If, as is universally conceded, the water rises into the tile from below, this is unnecessary. The practice of covering the joints, and even covering the whole tile, (often to the depth of a foot,) with tan-bark, turf, coa.r.s.e gravel, etc., is in no wise to be commended; and, while the objections to it are not necessarily very grave in all cases, it always introduces an element of insecurity, and it is a waste of money, if nothing worse.

The tile layer need not concern himself with the question, of affording entrance room for the water. Let him, so far as the rude materials at hand will allow, make the joints perfectly tight, and when the water comes, it will find ample flaws in his work, and he will have been a good workman if it do not find room to flow in a current, carrying particles of dirt with it.

In ditches in which water is running at the time of laying the tiles, the process should follow closely after the grading, and the stream may even be dammed back, section after section, (a plugged tile being placed under the dam, to be afterwards replaced by a free one,) and graded, laid and covered before the water breaks in. There is one satisfaction in this kind of work,-that, while it is difficult to lay the drain so thoroughly well as in a dry ditch, the amount of water is sufficient to overcome any slight tendency to obstruction.

*Connections.*-As has been before stated, lateral drains should always enter at the top of the main. Even in the most shallow work, the slightly decreased depth of the lateral, which this arrangement requires, is well compensated for by the free outlet which it secures.

After the tile of the main, which is to receive a side drain, has been fitted to its place, and the point of junction marked, it should be taken up and perforated; then the end of the tile of the lateral should be so trimmed as to fit the hole as accurately as may be, the large tile replaced in its position, and the small one laid on it,-reaching over to the floor of the lateral ditch. Then connect it with the lateral as previously laid, fill up solidly the s.p.a.ce under the tile which reaches over to the top of the main, (so that it cannot become disturbed in filling,) and lay bits of tile, or other suitable covering, around the connecting joint.(20)

[Ill.u.s.tration: Fig. 33 - LATERAL DRAIN ENTERING AT TOP.]

Fig. 33 - LATERAL DRAIN ENTERING AT TOP.

When the main drain is laid with collars, it should be so arranged that, by subst.i.tuting a full tile in the place of the collar,-leaving, within it, a s.p.a.ce between the smaller pipes,-a connection can be made with this larger tile, as is represented in Figures 33 and 34.

[Ill.u.s.tration: Fig. 34 - SECTIONAL VIEW OF JOINT.]

Fig. 34 - SECTIONAL VIEW OF JOINT.

*Silt-Basins* should be used at all points where a drain, after running for any considerable distance at a certain rate of fall, changes to a less rapid fall,-unless, indeed, the diminished fall be still sufficiently great for the removal of silty matters, (say two feet or more in a hundred). They may be made in any manner which will secure a stoppage of the direct current, and afford room below the floor of the tile for the deposit of the silt which the water has carried in suspension; and they may be of any suitable material;-even a sound flour barrel will serve a pretty good purpose for many years. The most complete form of basin is that represented in Figure 24.

[Ill.u.s.tration: Fig. 35 - SQUARE BRICK SILT-BASIN.]

Fig. 35 - SQUARE BRICK SILT-BASIN.

When the object is only to afford room for the collection of the silt of a considerable length of drain, and it is not thought worth while to keep open a communication with the surface, for purposes of inspection, a square box of brick work, (Fig. 35,) having a depth of one and a half or two feet below the floor of the drain,-tiles for the drains being built in the walls, and the top covered with a broad stone,-will answer very well.

[Ill.u.s.tration: Fig. 36 - SILT-BASIN OF VITRIFIED PIPE.]

Fig. 36 - SILT-BASIN OF VITRIFIED PIPE.

A good sort of basin, to reach to the surface of the ground, may be made of large, vitrified drain pipes,-such as are used for town sewerage,-having a diameter of from six to twelve inches, according to the requirements of the work. This basin is shown in Figure 36.

Figure 37 represents a basin made of a 6-inch tile,-similar to that described on page 130, for turning a short corner. A larger basin of the same size, cheaper than if built of brick, may be made by using a large vitrified drain pipe in the place of the one shown in the cut. These vitrified pipes may be perforated in the manner described for the common tile.

[Ill.u.s.tration: Fig. 37 - TILE SILT-BASIN.]

Fig. 37 - TILE SILT-BASIN.

In laying the main line _C_, (Fig. 21,) an underground basin of brick work, (Fig. 35,) or its equivalent, should be placed at stake 7, because at that point the water, which has been flowing on an inclination of 1.09, 2.00 and 2.83 per 100, continues its course over the much less fall of only 0.56 per 100.

If, among the tiles which have pa.s.sed the inspection, there are some which, from over burning, are smaller than the average, they should be laid at the upper ends of the laterals. The cardinal rule of the tile layer should be _never to have a single tile in the finished drain of smaller size, of more irregular shape, or less perfectly laid, than any tile above it_. If there is to be any difference in the quality of the drain, at different points, let it grow better as it approaches the outlet and has a greater length above depending upon its action.

*Covering the Tiles, and Filling-in the Ditches.*-The best material for covering the tiles is that which will the most completely surround them, so as to hold them in their places; will be the least likely to have pa.s.sages for the flow of _streams_ of water into the joints, and will afford the least silt to obstruct the drain. Clay is the best of all available materials, because it is of the most uniform character throughout its ma.s.s, and may be most perfectly compacted around the tiles.

As has been before stated, all matters which are subject to decay are objectionable, because they will furnish fine matters to enter the joints, and by their decrease of bulk, may leave openings in the earth through which streams of muddy water may find their way into the tiles. Gravel is bad, and will remain bad until its s.p.a.ces are filled with fine dirt deposited by water, which, leaving only a part of its impurities here, carries the rest into the drain. A gravelly loam, free from roots or other organic matter, if it is strong enough to be worked into a ball when wet, will answer a very good purpose.

Ordinarily, the earth which was thrown out from the bottom of the ditch, and which now lies at the top of the dirt heap, is the best to be returned about the tiles, being first freed from any stones it may contain which are large enough to break or disturb the tiles in falling on to them.

If the bottom of the ditch consists of quicksand or other silty matters, clay or some other suitable earth should be sought in that which was excavated from a less depth, or should be brought from another place. A thin layer of this having been placed in the bottom of the ditch when grading, a slight covering of the same about the tiles will so encase them as to prevent the entrance of the more "slippy" soil.

The first covering of fine earth, free from stones and clods, should be sprinkled gently over the tiles, no full shovelfuls being thrown on to them until they are covered at least six inches deep. When the filling has reached a height of from fifteen to twenty inches, the men may jump into the ditch and tramp it down evenly and regularly, not treading too hard in any one place at first. When thus lightly compacted about the tile, so that any further pressure cannot displace them, the filling should be repeatedly rammed, (the more the better,) by two men standing astride the ditch, facing each other, and working a maul, such as is shown in Figure 38, and which may weigh from 80 to 100 pounds.