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 Sounding. Sounding is a common method of inspecting poles for inter-
nal voids. The pole is firmly hit with a hammer from ground level to as
high as one can reach. A crisp sound usually indicates the pole is solid.
A dull sound thus indicates wet and possibly rotten wood and a "drum"
sound indicates a void.
WARNING
Sounding Usually Detects Only The
Worst Poles.
To develop experience, poles that are sounded should then be bored to
confirm which defects are actually present.
Boring. Where decay or insect attack is suspected, the pole is generally
bored for confirmation. Increment borers [Figure (4)] are most com-
monly used. The core can be closely examined at the site and also saved
for later culturing or microscopic examination. An effective, but simple
way to save increment cores is to insert them into soda "straws", seal the
ends and label for identification. Protected in this manner, increment
cores can be shipped to a laboratory for biological studies.
Poles that sound suspicious should be bored near deep checks and at the
pole base or at ground line. If rot is detected, the poles should be bored
at three or four points around the circumference. The shell thickness,
depth of preservative treatment, and pole circumference are determined.
Requirements for replacement, reinforcement, field treatments or
schedules for reinspection can then be determined.
When boring holes above ground, the tool should be oriented slightly up-
ward. This prevents water from accumulating in the hole. All openings
made during inspection should be treated with a registered preservative
and plugged with preservative-treated dowels. Protective goggles and
other safety equipment, as appropriate, should be worn.
Shell Thickness Indicator. A shell thickness indicator [Figure (5)] can be
used to determine the thickness of the non-decayed wood when poles
are drilled rather than using an increment borer. The rod is inserted
into the hole and then pulled back with pressure against the side of the
hole. The hook at the end will catch on the remaining sound wood.
When pushing a tight fitting shell-thickness indicator into a hole, you can
feel the tip of the hook pass from one growth ring to another in solid
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