Page 36 - Moving the Earth_ The Workbook of Excavation

LAND CLEARING AND CONTROLS

1.36 THE WORK

FIGURE 1.28 Use of guide pulley.
straight in line with the winch, or to any on the opposite side from the anchor, as the pulley will lead the
line almost straight in, at the price of a small friction loss. The pulley is best placed at a moderate dis-
tance from the winch so that the cable can feed evenly onto the drum, instead of tending to pile up in the
center. The line from pulley to anchor should be short, to keep shifting of the pulley to a minimum.

STUMP BLASTING

Blasting may be used to break up and remove stumps when machinery heavy enough for the work is
not available. Explosives may do the complete job, or just weaken them for removal by equipment.
The standard explosive is 40 percent dynamite, but only because it is most convenient. Slower
dynamites and even black powder may be more effective. Charges are generally too small to jus-
tify using ammonium nitrate.
Precautions. Stump blasting is dangerous work at best, because of unpredictable conditions
underground. Particularly, a rock may be held just over the charge by roots in a position that will
cause it to take off like a mortar shell. Split pieces of wood will also fly long distances. Mud or
earth packs over charges should be free of stones or pebbles, and personnel should move a long
way back from the blast, unless good shelter is available.
All stumps should be accounted for after a blast, as they are sometimes blown up in trees, where
they stay until dislodged by wind or another blast, with serious results to persons underneath.
If the blasting is to be done near buildings, logs or saplings chained together should be piled on
the ground on the side of the stump toward the building, to stop stones and fragments from flying.
Regular blasting mats are safer, but if machinery capable of handling them is on the job, it gen-
erally can pull the stumps without the necessity of using explosives in close quarters.

WOOD DISPOSAL

Methods. Some of the methods for disposing of the ground materials in clearing the land have
been discussed earlier in this chapter. For many years in the past, brush, tree slash, and stumps to