Page 301 - Moving the Earth_ The Workbook of Excavation

PONDS AND EARTH DAMS

PONDS AND EARTH DAMS 6.37

When a dozer is used for swamp digging, means should be provided for prompt rescue in case
the bottom proves too soft, or careless operation gets it stuck. If the dozer does not have a winch,
a hand or machine winch, or equipment capable of exerting a heavy pull, should be on the bank
with sufficient cable or chain to reach any part of the area. Cut green saplings and hand shovels
should also be available.
Drain holes in the flywheel and steering clutch housings should be plugged to prevent the
entrance of water and mud. Plugs should be taken out periodically to drain any oil that might leak
into them.
Fully sealed rollers which are greased on a twice-a-year schedule require no special attention.
Other types may require greasing every 2 to 4 hours to prevent mud from working past the seals. Sand
in the mud may make it very abrasive so that track wear may be several times as rapid as normal.
Under average conditions, dozer work in a pond bottom offers considerable danger of getting
bogged down, and conditions are often found to be so sloppy that little effective work is done. But
when it works, it’s fine.
Ramps. The ramp should be at the easiest possible gradient to facilitate pushing large loads and
to minimize churning under the tracks.
When the ramp is roughed out, the dozer is backed into the pond mud until a good load is ahead
of the blade or bucket. This is then pushed through the ramp to the disposal point, or parked in the
ramp to be moved along with an additional load or loads.
The floor of the ramp will usually soften from absorbing water out of the mud being moved over
it, and it will be worn down continuously by the push of the tracks and cuts by the blade. These
effects are liable to be most severe in the pond at the foot where the dozer turns upward for its climb.
A deep hole may be gouged here which will usually fill with a very thin mud. This ordinarily does
not bother the machine any more than the same quantity of water, but will eventually reach the fan
or other nonsubmersible parts, and the ramp will have to be abandoned or its foot relocated.
Such a hole may be convenient in freezing weather as the tractor may be placed in it overnight,
so that the tracks will be underwater and the mud on them will not freeze. This will save a long
and messy job of putting it up on blocks and of cleaning and hosing it at the end of the day. It is
of course not practical unless the bottom is entirely safe.
The cleared space may be widened by other cuts fanning out from the ramp. This uniform
expansion of area is not particularly efficient from the pushing standpoint, as mud tends to spread
on each push over ground cleaned by previous passes, and both mud and subsoil become increas-
ingly sloppy from reworking. However, it keeps the dozer close to dry land while bottom conditions
are observed. This pattern is shown in Fig. 6.25.

Dozer and Dragline or Backhoe. Ramp difficulties, or lack of nearby disposal areas, may make
dozer cleaning impractical even when the bottom conditions are favorable. In such cases, the dozer
may push the mud so that it can be reached by a dragline or backhoe standing on the shore or the
dry pond bottom, which can pile it on the bank or load it into trucks, as in Fig. 6.26.
This method can be rather widely applied and is usually more economical than doing the whole
job with the dragline.

Pump. Cleaning by machinery usually mixes some of the mud with so much water that it
becomes too thin to be picked up or pushed, but can often be pumped. A diaphragm pump will
handle heavier mud than a centrifugal, but the volume moved is much smaller.
If a water source is nearby, clean water can be pumped into a hose line and the mud stirred up,
thinned, and driven to the mud pump or gravity outlet by a stream directed from a nozzle. If
patience and workforce are sufficient, whole ponds can be cleaned in this manner.
After removal from the pond, the mud may be allowed to flow away from the work area, or to
accumulate in natural depressions; it may be held in a settling basin from which it can be dug after
it has dried; or it may be placed directly in tight-bodied trucks. The very thin muds which pump
most easily are usually the hardest to dispose of. The contractor is liable for mud damage down-
stream or on adjoining property.