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BLASTING AND TUNNELING
BLASTING AND TUNNELING 9.31
Deep Holes. It is a good plan to check a deep large borehole before loading it, by inspecting it
with a flashlight or sunlight reflected from a mirror, or sounding it with a tamping block, to make
sure it is not obstructed. The block can be used to knock obstructing pieces or scale to the bottom.
Cartridges may be dropped into shallow holes or deep smooth ones. (See Fig. 9.25.) If the hole
is deep and rough, and there is a possibility that they may stick partway down, they should be low-
ered. All explosives manufacturers will provide cartridges equipped with means to attach a lower
rope. A band of special Scotch tape and a readily disengaged hook are used.
The impact of the cartridges on the bottom and the weight of the column above frequently
compress charges well enough so that tamping is not necessary.
FIGURE 9.25 Loading deep holes.
