PRACTICAL DIRECTIONS FOR OPENING DRAINS AND LAYING TILES.
Begin at the Outlet.--Use of Plows.--Levelling the Bottom.--Where
to begin to lay Pipes.--Mode of Procedure.--Covering
Pipes.--Securing Joints.--Filling.--Securing Outlets.--Plans.
In former chapters, we have spoken minutely of the arrangement, depth,
distance, and width of drains; and in treating of tools for drainage, we
have sufficiently described the use of levelling instruments and of the
various digging tools.
We assume here, that the engineering has been already done, and that the
whole system has been carefully staked out, so that every main,
sub-main, and minor is distinctly located, and the fall accurately
ascertained. Until so much has been accomplished, we are unprepared to
put the first spade into the ground.
We propose to give our own experience as to the convenient method of
procedure, with such suggestions as occur to us, for those who are
differently situated from ourselves.
The work of excavation must begin at the outlet, so that whatever water
is met with, may pass readily away; and the outlet must be kept always
low enough for this purpose. If there is considerable fall, it may not
be best to deepen the lower end of the main to its full extent, at
first, because the main, though first opened, must be the last in which
the pipes are laid, and may cave in, if unnecessarily deep at first. In
many cases there is fall enough, so that the upper minors may be laid
and find sufficient fall, before the lower end of the main is half
opened.
With a garden line drawn straight, mark out the drain, with a sharp
spade, on both sides, and remove the turf. If it is desired to use the
turf for covering the pipes, or to replace it over the drains, when
finished, it should at first be placed in heaps outside the line of the
earth to be thrown out.
A plow is used sometimes to turn out the sod and soil; but we have few
plowmen who can go straight enough; and in plowing, the soil is left too
near to the ditch for convenience, and the turf is torn in pieces and
buried, so as not to be fit for use. Usually, it will be found
convenient to remove the turf, if there be any, with a spade, by a line.
Then, a plow may be used for turning out the next spit, and the drain
may be kept straight, which is indispensable to good work. A good
ditching-machine is, of course, the thing needful; but we are
endeavoring in these directions to do our best without it. We have
opened our own trenches entirely by hand labor, finding laborers more
convenient than oxen or horses, and no more expensive.
Many have used the plow in the first foot or two of the cutting, but it
is not here "the first step which costs," but the later steps. After the
first foot is removed, if the ground be hard, a pick or subsoil plow
must be used. A subsoil plow, properly constructed, may be made very
useful in breaking up the subsoil, though there is a difficulty in
working cattle astride of a deep ditch, encumbered with banks of earth.
A friend of ours used, in opening drains, a large bull in single
harness, trained to walk in the ditch; but the width of a big bull is a
somewhat larger pattern for a drain, than will be found economical.
The ingenuity of farmers in the use of a pair of heavy wheels, with a
chain attached to the axle, so that the cattle may both walk on one side
of the ditch, or by the use of long double-trees, so that horses may go
outside the banks of earth, will generally be found sufficient to make
the most of their means.
It will be found convenient to place the soil at one side, and the
subsoil at the other, for convenience in returning both right side up to
their places.
Having worked down to the depth of two feet or more, the ditch should be
too narrow for the use of common spades, and the narrow tools already
described will be found useful. The Irish spade, on our own fields, is
in use from the first to the last of the excavation; and at three feet
depth, we have our trench but about six inches in width, and at the
bottom, at four feet depth, it is but four inches--just wide enough for
the laborer to stand in it, with one foot before the other.
Having excavated to nearly our depth, we use the lines, as described in
another place, for levelling, and the men working under them, grade the
bottom as accurately as possible. If flat-bottomed tiles are used, the
ditch is ready for them. If round pipes are used, a round bottoming tool
must be used to form a semi-circular groove in which the pipes are to
lie.
We have not forgotten that English drainers tell us of tools and their
use, whereby drains may be open twenty inches lower than the feet of the
workman; but we have never chanced to see that operation, and are
skeptical as to the fact that work can thus be performed economically,
except in very peculiar soils. That such a _crack_ may be thus opened,
is not doubted; but we conceive of no means by which earth, that
requires the pick, can be moved to advantage, without the workman
standing as low as his work.
Having opened the main, and finished, as we have described, the minor
which enters the main at its highest point, we are ready to lay the
tiles.
By first laying the upper drain, it will be seen that we may finish and
secure our work to the junction of the first minor with its main.
Convey the pipes by wagon or otherwise, as is convenient, to the side of
the ditch where the soil lies, and where there is least earth, and lay
them close to the edge of the ditch, end to end the whole way,
discarding all imperfect pieces. If it is designed to use gravel, turf,
or other covering for the pipes, lay it also in heaps along the trench.
Then place the first pipe at the upper end of the ditch, with a brick or
stone against its upper end, to exclude earth. We have heretofore used
sole-tiles, with flat bottoms, and have found that a thin chip of wood,
not an eighth of an inch thick, and four by two inches in size, such as
may be found at shoe shops in New England, assists very much in securing
an even bearing for the tiles. It is placed so that the ends of two
tiles rest on it, and serves to keep them in line till secured by the
earth. A man walking backward in the ditch, takes the tiles from the
bank, carefully adjusting them in line and so as to make good joints,
and he can lay half a mile or more in a day, if the bottom is well
graded. Another should follow on the bank, throwing in a shovel full of
gravel or tan, if either is used, upon the joint.
If turf is to be used to secure the joint, pieces should be cut thin and
narrow, and laid along the bank, and the man in the ditch must secure
each joint as he proceeds. It will be found to cost twice the labor, at
least, to use turf, as it is to use gravel or tan, if they are at hand.
If the soil be clay, we do not believe it is best to return it directly
upon the tiles, because it is liable to puddle and stop the joint, and
then to crack and admit silt at the joint, while gravel is not thus
affected. We prefer to place the top soil of clay land, next the pipes,
rather than the clay in the condition in which it is usually found.
As to small stones above the pipes, we should decidedly object to them.
They are unnecessary to the operation of the drain, and they allow the
water to come in, in currents, on to the top of the pipes, in heavy
storms or showers, and so endanger their security. The practice of
placing stones above the tiles is abandoned by all scientific drainers.
We have, in England, seen straw placed over the joints of pipes, but it
seems an inconvenient and insecure practice. Long straw cannot be well
placed in such narrow openings, and it is likely to sustain the earth
enough, so that when thrown in, it will not settle equally around the
pipes; whereas a shovelfull of gravel or other earth sifted in
carefully, will at once fasten them in place.
Having laid and partially covered the first or upper drain, proceed with
the next in the same way, laying and securing the main or sub-main, at
the same time, to each intersection, thus carrying the work from the
highest point down towards the outlet. After sufficient earth has been
thrown in to make the work safe against accidents by rain, or caving in
of earth, the filling may be completed at leisure. Mr. Johnston, of
Geneva, uses for this purpose a plow, having a double-tree nine and a
half feet long, to enable a horse to go on each side of the ditch.
We suggest that a side-hill plow might well enough be used with horses
_tandem_, or with oxen and cart wheels and draughts.
The filling, however, will be found a small matter, compared with the
digging. In laying pipes in narrow trenches, a tool called a pipe-layer
is sometimes used, a cut of which, showing its mode of use, may be
found in another place.
In filling drains where the soil is partly clay, and partly sand or
gravel, we recommend that the clay be placed in the upper part of the
drain, so as to prevent water from passing directly down upon the pipes,
by which they are frequently displaced as soon as laid.
If the work is completed in Autumn, it is well to turn two or three
furrows from each side on to the drains, so as to raise the surface
there, and prevent water from cutting out the ditch, or standing above
it. If the land is plowed in Autumn, it is best to back-furrow on to the
drains, leaving dead furrows half way between them, the first season.
As to the importance of securing the outlets, and the manner of doing
it, we have spoken particularly elsewhere.
And here, again, we will remind the beginner, of the necessity of making
and preserving accurate plans of the work, so that every drain may be at
any time found by measurement. After a single rotation, it is frequently
utterly impossible to perceive upon the surface any indication of the
line of the drains.
In this connection, it may be well perhaps to remind the reader, that
whatever arrangements are made as to silt-basins, or peep-holes, must be
included in the general plan, and executed as the work proceeds.