Page 248 - Moving the Earth_ The Workbook of Excavation

DITCHING AND DEWATERING

5.50 THE WORK

It may also be placed over a gravel topping to prevent soil from working down into it. The under sur-
face of the dirt often becomes so well stabilized that it will not cause trouble after hay has rotted out.
When the tile is laid on a curve, the wide spaces at the outside of the joints should be covered
with pieces of broken tile.
Connections of branch lines may be made with sewer tile “Y”s or “T”s, or by junction pits
which may be made large enough to serve as line cleanouts. A Y provides a smoother flow and
larger water capacity than a T of the same size.
Cradling. If the ground is muck, or otherwise unstable, the tile should be supported by boards,
as in (D). Cleated boards supporting the haunches are preferable to flat boards because of better
support and more permanent alignment.
Corrugated metal pipe with perforations may be used instead of tile and cradles.

Laying Land Tile. A large part of the land or drain tile used is in farmland. The work is usually on a
fairly large scale, on regular grades and with adequate space. Costs must generally be kept to a minimum.
Ditching machines are particularly adapted to a rapid sequence of operations.
Small machines, with buckets as narrow as 6 or 8 inches, may be used for depths up to 4 feet.
These involve minimum excavation and ensure lining up of tile. As the maximum depth is
approached, it becomes more difficult to place tile accurately, and very difficult to remove stones
or earth that may fall from the sides. It is usually not possible to use a tile-laying shoe. It may be
inconvenient or impossible to place gravel or tar paper with the tile.
Wider buckets will eliminate these difficulties, but will increase the amount of excavation and
backfill.
The tile supply is laid on the field, parallel with the ditch line, just far enough to clear the ditcher,
on the side away from the intended spoil pile. Pieces are placed end to end to give the correct number,
with a few extra placed at frequent intervals to make up for broken or imperfect tiles.
The tile should be placed on the ditch bottom immediately behind the ditcher to minimize the
danger of “losing” the ditch through caving of the sides. The first tile should be plugged with a
stone or half brick to protect the line against entrance of dirt or animals. Pieces are usually picked
up and placed with an L-shaped rod of light iron. A curved bottom ditch will tend to center them,
but they must be checked for alignment anyway.
Tar paper, if used, should be in a narrow continuous strip in a roll, laid over the tile.
If the ditch is wide enough to work in, the tile may be laid in the same manner or by hand. In
the latter case, a picker may be used to supply tiles to the ditch worker.
Gravel is sometimes laid under or over the tile by a dump truck with a small opening in the rear
gate, similar to that used for supplying automatic sand spreaders. It straddles the ditch. The gravel
may pour by gravity, or may be raked or shoveled down the body floor by the person controlling
the gate opening.
It is important to smooth off a bottom layer of gravel before placing tile.

Tile Shoes. If the ground is not firm enough to stand until the pipe and accessories have been
laid down, a tile-laying box or shoe towed by the ditcher must be used. A number of varieties are
available, many of them of only local distribution.
A tile box should be slightly narrower than the bucket side cutters. It includes the bulldozer or
crumber attachment that smooths the ditch bottom behind the buckets, a pair of parallel walls that
will slide between the ditch walls, and a chute on which tile may be placed to be fed by gravity or
manual control into the ditch bottom.
Figure 5.40 shows a simple type of box that is operated from above. A more elaborate box in which
someone can work, and which permits placing of tile, bottom and top gravel, and tar paper, is shown
diagrammatically in Fig. 5.41. This is suitable for the greater depths required in irrigated fields.
Two gravel hoppers are mounted on the box, front and rear. A roll of tar paper is mounted on
an axle across the inside of the box. The tile layer sits near the bottom, with his or her back to the
“bulldozer,” a cleaning blade which follows the wheel. The tiles rest on a shelf in front of the layer
and are replaced as they are used by someone standing on the box, who picks them up with a rod.