Page 10 - Moving the Earth_ The Workbook of Excavation

LAND CLEARING AND CONTROLS

1.10 THE WORK

Unless he or she is completely protected by a cab with windows, an operator should have hand
clippers to cut a path out if necessary.
Brush and small trees may be removed by a bulldozer moving with its blade in light contact
with the ground. It will uproot or break off a number of the stems and will bend the rest over so
that by a return trip in the opposite direction, it can take out more. If the distance is short, it is best
to doze the whole patch in one direction, then across or backward.
Individual small trees are first knocked over, then pushed out with another pass in the same
direction.
Results will vary with the type of vegetation and the condition of the soil. Hard-baked soils
will cause a high percentage of broken stems, while wet or sandy conditions favor uprooting,
which is more satisfactory for most purposes. The work can be speeded up by having a laborer cut
out or pick up individual bushes that would otherwise require another pass by the dozer.
If the job requires removal of light stumps and roots, they may be overturned in one pass and
pushed out in the next. It may be necessary to dig several inches into the soil to get a grip on them,
then backblade the soil into the holes.
Brush heaps may be largely freed of dry, loose dirt by rolling them over with the blade and shak-
ing the blade up and down. If this is ineffective, rolling them over backward or pushing them from
the side may be tried. A dozer with a blade which can be easily tilted down on either end is very
good at this work, as one corner can be used for taking out roots and pushing piles without taking a
bladeful of dirt along with it, and the blade can be returned to flat position to skim off surface brush.

Rake Blade. Rake blades, which are made for the larger bulldozers and loaders, add to clearing effi-
ciency under most conditions. See Fig. 1.2. They allow working below ground level, to take out roots
as well as surface material, usually without bringing the soil along with them, if it is dry or sandy.
However, they may be somewhat specialized. A blade with teeth close-set enough to handle
brush may bend a tine if it collides with something solid, while one strong enough for impact is
apt to have too wide spacing for brush. This type of equipment is described in Chap. 21.
With or without rakes, any mechanical loosening and removal of brush that is to be burned
should be done when the soil is dry for best results. If it is wet, it lumps and sticks.
If the loosened material is allowed to dry, much of the dirt can be shaken out while piling, by
rolling and shaking.
Burning. Generally in the United States it is necessary to get a permit from the local authorities
to burn for clearing. In general, it is best to burn machine-cleared vegetation at the same time that
it is piled. A hot fire, including heavy wood, is prepared, and brush piles are pushed up on it. A
new fire is made when the push gets too long.
Best results are obtained if the vegetation is uprooted and allowed to dry at least a few days before
burning. This may be done by backing the dozer into the woods from the cleared edge, and uproot-
ing small patches, or individual trees, pushing them clear of the ground, and then leaving them.
The trash dries more rapidly scattered on the ground than in piles. Dirt will tend to dry and
break away from stumps, and to sift out of roots and stems. When burning, the brush nearest the
fire is put on it first.
Fires fed by a dozer tend to get choked up with dirt. In general, matted light brush is more dif-
ficult to clear and to burn than heavy brush or small trees, as it tends to slip under the blade or to
bring too much dirt with it.

Fire Box or Trench. The local authority which issues a permit probably would be more inclined
to do so if the burning was to be done in a fire or burner box or trench prepared for the burning.
The system for doing this controlled burning is described and illustrated later in this chapter.

Dozer Protection. When a dozer is clearing dense undergrowth, there is the danger that it will
fall into some hole, natural or artificial, whose presence is concealed by the brush. This may be
guarded against by scouting the area on foot, and by moving forward in a succession of short
pushes overlapping each other on the side, as in Fig. 1.3. This enables the operator to watch from